Kettlebell training in clinical practice: a scoping review · 2019. 9. 3. · RESEARCH ARTICLE Open...

RESEARCH ARTICLE Open Access

Kettlebell training in clinical practice: ascoping reviewNeil J. Meigh1* , Justin W. L. Keogh1,2,3, Ben Schram1 and Wayne A. Hing1

Abstract

Background: A scoping review of scientific literature on the effects of kettlebell training. There are no authoritativeguidelines or recommendations for using kettlebells within a primary care setting. Our review objectives were toidentify the extent, range and nature of the available evidence, to report on the types of evidence currentlyavailable to inform clinical practice, to synthesise key concepts, and identify gaps in the research knowledge base.

Methods: Following the PRISMA-ScR Checklist, we conducted a search of 10 electronic databases from inception to1 February 2019. There were no exclusions in searching for publications. A single reviewer screened the literatureand abstracted data from relevant publications. Articles were grouped and charted by concepts and themesrelevant to primary care, and narratively synthesised. Effect sizes from longitudinal studies were identified orcalculated, and randomised controlled trials assessed for methodological quality.

Results: Eight hundred and twenty-nine records were identified to 1 February 2019. Four hundred and ninety-sixwere screened and 170 assessed for eligibility. Ninety-nine publications met the inclusion criteria. Effect sizes weretypically trivial to small. One trial used a pragmatic hardstyle training program among healthy college-ageparticipants. Two trials reported the effects of kettlebell training in clinical conditions. Thirty-three studies explicitlyused ‘hardstyle’ techniques and 4 investigated kettlebell sport. Also included were 6 reviews, 22 clinical/expertopinions and 3 case reports of injury. Two reviewers independently evaluated studies using a modified Downs &Black checklist.

Conclusions: A small number of longitudinal studies, which are largely underpowered and of low methodologicalquality, provide the evidence-informed therapist with little guidance to inform the therapeutic prescription ofkettlebells within primary care. Confidence in reported effects is low to very low. The strength of recommendationfor kettlebell training improving measures of physical function is weak, based on the current body of literature.Further research on reported effects is warranted, with inclusion of clinical populations and investigations ofmusculoskeletal conditions common to primary care. There is a need for an externally valid, standardised approachto the training and testing of kettlebell interventions, which better informs the therapeutic use of kettlebells inprimary care.

Keywords: Scoping review, Kettlebell, Physiotherapy, Exercise

BackgroundHistoryThe kettlebell is a round-shaped steel or cast ironweight, commonly described as resembling a cannonballwith a handle [1]. In Russia, kettlebells are a matter ofpride and a symbol of strength, with a colourful historythroughout the twentieth Century from circus strong

men to the Red Army. Use of kettlebells as measures ofweight dates back to Russia in the 1700s [2] and theword girya (kettlebell) first appears in a Russian diction-ary in 1704 [3], with excavations in Poland pre-datingearly kettlebells to the seventeenth century [4].Kettlebell sport, also referred to as Girevoy Sport origi-

nated in Eastern Europe in 1948 [5]. The InternationalUnion of Kettlebell Lifting World Championship held inOctober 2018 attracted more than 500 competitors from32 countries, testament to its popularity and growth.

© The Author(s). 2019 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, andreproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link tothe Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver(http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.

* Correspondence: [email protected] of Health Sciences and Medicine, Bond University, Institute of Health& Sport, Gold Coast, Queensland 4226, AustraliaFull list of author information is available at the end of the article

Meigh et al. BMC Sports Science, Medicine and Rehabilitation (2019) 11:19 https://doi.org/10.1186/s13102-019-0130-z

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Kettlebell sport uses competition kettlebells of standar-dised dimensions made of steel, most commonly avail-able from 8 kg to 32 kg in 2-4 kg increments. Kettlebellsport techniques are the jerk and snatch in differenttimed events.Kettlebells described as ‘traditional’ in shape are typic-

ally made from cast iron, with dimensions increasingwith weight. Kettlebells are now widely available in anarray of construction materials, from 2 kg to 92 kg. Withincreasing popularity has come diversity in use andadaptation of common exercises, however only a limitednumber of styles are widely recognised: Sport, hardstyle,juggling, and a small number of techniques associatedwith CrossFit.The popularity of kettlebells outside of Eastern Europe

and kettlebell sport can be largely attributed to Russianémigrés former World Champion Valery Fedorenko, andformer Soviet Special Forces physical training instructorand Master of Sport, Pavel Tsatsouline. Fedorenkofounded the American Kettlebell Club and Tsatsoulinethe hardstyle Russian Kettlebell Certification (RKC),which commenced training in 2001. Pavel has beenwidely credited with introducing kettlebells to the West[6] following a publication in the December 1998, Vol. 6,No. 3 Issue of MILO A Journal For Serious StrengthTraining Athletes. That was followed by Power to thePeople [7] which outlines many of the training principlesused in Enter the Kettlebell [3], and remains the founda-tion of hardstyle kettlebell training courses worldwide.Enter the Kettlebell has been the most widely cited textin academic publications where a hardstyle techniquehas been used. The six fundamental hardstyle techniquesare the Swing, Clean, Press, Squat, Snatch and Turkishget-up (TGU). Academic investigation of hardstyle train-ing represents around 50% of publications (refer toResults: report characteristics), with the two-handedkettlebell swing investigated most frequently. Neitherkettlebell sport nor hardstyle are limited to only thetechniques listed.A third person of note is former Master RKC, Kenneth

Jay. A small unpublished Bachelor of Science study com-pleted at the University of Copenhagen [8] investigatedthe VO2 and lactate effects from two weeks of dedicatedhardstyle kettlebell snatch training in a group of well-conditioned, kettlebell-trained college-age males. Jay’straining protocols later described in Viking WarriorConditioning [9] and those from Enter the Kettlebellrepresent the majority of study formats used to date.

Conceptual and contextual backgroundExercise prescription is an integral part of Physio-therapy practice [10]. Prescription of exercise asmedicine for a broad range of chronic diseases andfor relieving pain and improving musculoskeletal

function have been described [11, 12] with many atleast as effective as drug therapy [13]. The mecha-nisms of mechanotherapy in clinical practice havebeen reported [14, 15], with an understanding ofmechanobiology of musculoskeletal tissues critical toprimary care [16]. Therapists commonly seek to in-crease tissue capacity and build physical and psycho-logical resilience in their patients, from the younginjured athlete to the elderly and frail.Evidence-based Physiotherapy is an area of study, re-

search, and practice in which clinical decisions are basedon the best available evidence, integrating professionalpractice and expertise with ethical principles [17].Where high quality clinical research does not exist, goodpractice must be informed by knowledge derived fromother sources of information. When relevant and reliabledata is not available, clinicians still need to make deci-sions based upon the best available information [18].In elite sport, there is a constant need to increase

strength, power and endurance, and the kettlebell hasbecome a part of that effort [19]. Kettlebells have beenused in strength and conditioning research and injuryprevention programs for mixed martial arts [20], hand-ball [21], shot put [22], sprinting [23] and soccer [24]. Inclinical practice, kettlebells have been included in pro-grams for lower limb amputees [25], metabolic syn-drome in women [26], early treatment of breast cancer[27], for osteoporosis and fall and fracture prevention[28], home-based Physiotherapy with older adults show-ing signs of frailty and following hip fracture [29], forhealthcare workers [30] and in programs for improvinghealth-related physical fitness [31].Military and law enforcement agencies train with ket-

tlebells, reporting improvements in field performance[32]. Kettlebells have been recommended as part of theRoyal Air Force aircrew conditioning programme [33]and for simulated military task performance [34]. Thekettlebell deadlift has been recommended by the NorthAtlantic Treaty Organization to be used alongside theRanger test, which is a loaded step test, deemed to haveexcellent content validity and high inter-rater reliabilityin relation to five common physically demanding mili-tary work tasks for soldiers [35].Kettlebells have also been used to modify other com-

mon training protocols [36–38], and as a novel methodof providing valgus stress with good reliability, duringultrasound examination of the ulnar collateral ligamentof the elbow [39]. University studies have investigatedkettlebell training, including analysis of the TGU [40],for improving dynamic knee stability and performancein female netball players [41], in anterior cruciate liga-ment (ACL) injury prevention among female athletes[42], and for reducing work related musculoskeletal dis-orders of the low back [43].

Meigh et al. BMC Sports Science, Medicine and Rehabilitation (2019) 11:19 Page 2 of 30

Whilst kettlebells have been adopted by popular fitnessprograms such as CrossFit, the use of kettlebells remainsa relatively niche sport and knowing how to use a kettle-bell is perhaps not as intuitive as the more popular bar-bells, dumbbells and machine weights. In spite of this,kettlebells have been recommended for their ease ofteaching, cost effectiveness and being less intimidatingto use [44]. Kettlebells have already been integrated intoclinical practice but does the current body of evidencesupport their use for therapeutic purposes, and howdoes the evidence help inform clinical decision making?The aim of this review is to identify what is known

about the effect of kettlebell training from publishedacademic research, with the objective to systematicallyevaluate and critically appraise the literature and high-light areas for further investigation.

Kettlebell swing descriptorsThe ‘hip hinge’ is associated with a deadlift movementpattern and a hardstyle kettlebell swing. This has alsobeen described as a “Russian swing”, or a swing to chestheight. It can be performed with one or two hands hold-ing the bell. The two-handed overhead swing is associ-ated with a ‘squatting’ motion of the lower limbs, alsodescribed as an “American swing” and most commonlylinked with CrossFit. The ‘double-knee-bend’ pattern isassociated with kettlebell sport.

MethodsA scoping review was conducted to synthesise currentevidence of kettlebell training as it applies to therapistsworking in primary care, where movement and loadingare used clinically for therapeutic purposes. As an evolv-ing field of research, the scoping review was chosen toprovide an overview of kettlebell training, to identify keyconcepts, knowledge gaps, and types of evidence cur-rently available.

Research questionWhat evidence is available to guide therapists using ket-tlebells within a clinical therapeutic framework?

ProtocolThis scoping review was conducted by a single re-searcher (NM) using the PRISMA Extension for ScopingReviews (PRISMA-ScR): Checklist and Explanation [45].A priori protocol was not developed.

Study designThe scoping methodology proposed by Arksey andO’Malley [46] was used to map the concepts and typesof science-based evidence that exists on kettlebell train-ing. The methodology was informed by later recommen-dations [47] and guided by the Joanna Briggs Institute

framework [48, 49]. This framework includes the follow-ing steps: 1) Identify the research question by clarifyingand linking the purpose and research question, 2) iden-tify relevant studies by balancing feasibility with breadthand comprehensiveness, 3) select studies using an itera-tive team approach to study selection and data extrac-tion, 4) chart the data incorporating numerical summaryand qualitative thematic analysis, 5) collate, summarizeand report the results, including the implications for pol-icy, practice or research [50].

Information sources and literature searchA search was conducted, assisted by a health sciences li-brarian, on 10 electronic databases (CINAHL, CochraneLibrary, Embase, Medline, PEDro, ProQuest, PubMed,SportDISCUS, Web of Science, Google Scholar) frominception to 1 February 2019, using search terms “kettle-bell”, “kettle bell”, “kettlebells”, “kettle bells” in the Titleor Abstract. The search strategy was not limited bystudy design, publication type, or language. Duplicate re-cords were removed in EndNote. Backward referencesearching was performed, and additional studies wereidentified by consultation with subject matter experts.

Eligibility criteriaThe eligibility criteria were defined by the Population(therapists in primary care), Concept (prescription ofkettlebells for therapeutic purposes) and Context (evi-dence-based practice: research evidence and clinical ex-pertise). All types of study design and reviews wereincluded where kettlebells were the primary modality ofinvestigation. Any population, intervention, comparator,outcome, and setting were included, together with thesesand unpublished material from academic settings. Arti-cles/publications were excluded if, a) they were unre-lated to kettlebell training (e.g. gave historical contextonly), b) were not specific to kettlebell training (e.g. in-terventions involving kettlebells and other equipmentwhere the outcome(s) could not be attributed to thekettlebell), c) were unavailable in full text, or d) werestudies conducted on Eastern European Military popula-tions. The absence of standardised reporting guidelines(as recommended by the Enhancing the QUAlity andTransparency Of health Research network), and style ofreporting from countries of the former Soviet Union,were deemed incompatible for synthesis. The followingwere also excluded from our review: books, patents, fit-ness articles, web pages, blogs and opinion pieces fromnon-clinical or non-academic/clinical authors. Resourcelimitations precluded the translation of articles not pub-lished in English. One exception was a clinical trial ofhardstyle kettlebell training for people with Parkinson’sdisease, published in Portuguese with an English ab-stract; this was deemed to be specifically relevant to the


population, concept and context of the review and in-cluded but not translated. All levels of evidence [51]were considered.

Data abstraction and data itemsA standardised data abstraction form was not utilised. Asingle reviewer (NM) independently screened titles andabstracts for relevance and obtained full text articles ofpublications potentially relevant. As the scope and na-ture of the available evidence was not known in advance,the development of categories and grouping for mappingpurposes was developed iteratively as the data was ex-tracted and tabulated. Effect sizes were extracted wheregiven, or calculated if enough data had been provided.Cohen’s δ or standardised mean difference (SMD) wereused and magnitude of effect compared based on partici-pant’s resistance training status: untrained, recreationallytrained or highly trained [52].

Methodological quality appraisalWith the primary intent to inform clinical practice,the authors chose to critically appraise the rando-mised controlled trials using a modified Downs andBlack quality checklist [53]. This scoring system isbased on a checklist of 27 questions and has beenfound to be valid and reliable for critically evaluatingexperimental and nonexperimental studies. Thechecklist included 4 categories for evaluation: report-ing, external validity, internal validity/bias, andinternal validity/confounding [54]. Studies wereappraised by a second independent reviewer. Dis-crepancies were resolved by discussion and agree-ment reached. Quality of evidence and strength ofrecommendation was based upon the GRADEapproach [55, 56].

SynthesisData were narratively synthesised by author-defined cat-egory: (1) acute profiling, (2) athletic performance, (3)health-related physical fitness, (4) injury & rehabilitation,(5) expert/clinical option and (6) Review, with key char-acteristics and findings discussed. Publications weregrouped by nature of the study (acute vs longitudinal)and measures/outcomes. Acute profiling studies werefurther categorised by outcome: ‘sEMG’, ‘motion ana-lysis’, ‘hormonal response’, ‘cardiometabolic’, ‘mechanicaldemand’ or ‘performance’. Experiments and trials weremapped based on the population profile (age, gender,training history, kettlebell experience), types of exer-cise(s) used, style (hardstyle, sport or ‘other’), trainingformat (work-to-rest ratio, frequency, duration, inten-sity/load), measurements (sEMG, motion analysis,ground reaction force, HR, RPE, VO2), outcomes, andstudy design.

ResultsThe literature search yielded a total of 829 citations(Fig. 1). Three hundred and thirty-two records wereremoved as duplicates or not meeting the inclusioncriteria. Upon completion of the title and abstractscreening, 170 were potentially relevant and screened.Subsequently, 99 publications fulfilled the eligibilitycriteria and were included. Study flow diagram Fig. 1.Publications by category Fig. 2.

Report characteristics (extent, range, nature)The number of academic publications relating to the useof kettlebells has increased steadily since 2009 (Fig. 3)Sixty-eight (69%) of the publications were research stud-ies, including 47 (70%) measures of acute trainingresponse and 21 (31%) longitudinal investigations. Twolongitudinal trials involved clinical populations. Publica-tions were categorised as ‘acute profiling’ [47], ‘Athleticperformance’ [11], ‘Health related physical fitness’ [9],‘Injury & rehabilitation’ [4], ‘Opinion’ [22] or ‘Review [6](Fig. 4). Included in these were a Systematic Review, oneClinical Review, four Brief/Narrative Reviews, and 3 casereports from medical practitioners of injury attributed tokettlebell training. Acute profiling studies, which repre-sent almost half of the publications, were further cate-gorised based on outcomes: ‘sEMG’ [11], ‘motionanalysis’ [6], ‘hormonal response’ [3], ‘cardiometabolic’[16], ‘mechanical demand’ [6], ‘performance’ [2] or notcategorised [3] (Fig. 5).Fifty-four experiments and trials (79%) used healthy

college-age participants, with participants in 62 studies(91%) recreationally active. In fifty-five studies (> 80%),participants were novices unfamiliar with kettlebelltraining, and almost half (n = 33) explicitly used hard-style techniques and/or training principles described byTsatsouline. Only 4 investigations (2 acute, 2 longitu-dinal) involved kettlebell sport. Of the 68 experimentsand trials, 43 were published in peer-reviewed journals.The remainder were un-published conference presenta-tions [5], Theses [9], Pilot studies [3], papers acceptedfor publication [4], and University publications [4]. Re-sults described herein as significant where reported withp-values ≤0.05.

Acute profilingForty-seven studies of acute response to kettlebell train-ing were identified. Thirty-nine (83%) involved healthycollege-age participants, 7 (15%) involved adults whowere not of college-age, and 1 study did not report par-ticipant age. Twenty-one (47%) involved only males, 5(11%) involved only females, and 19 (40%) had malesand females. One study did not report gender. Only 1study had participants who were not recreationallyactive. In 34 studies (72%), participants were not


Fig. 1 Study flow diagram (PRISMA-ScR flow chart)

Fig. 2 Kettlebell publications by category


Fig. 3 Number of academic publications by year involving kettlebells to February 1, 2019

Fig. 4 Kettlebell publications by category Fig. 5 Acute profiling studies by category


Table

1Stud

ycharacteristicsinvestigatingacutesEMGwith

kettlebe

llexercise

Autho

rParticipants

Observing

(muscles

/region

)

Exercise

Hardstyle

Sport

‘other’

Load

(kg)

Com

parator

nAge

(yrs)

Weigh

t(kg)

Gen

der

Active

Kettlebe

llproficient

/no

vice

And

ersonet

al.(2016)

1625

±6

80±8

MY

novice

trun

k2H

swing

othe

r16

1Hsw

ing

Caravan

etal.(2018)

3322.2±3.5

91.8±8.0

MY

novice

serratus

anterio

rbo

ttom

s-up

carry

othe

r12

deg.

ofabdn

DelMon

teet

al.(2017)[63]

1430.1±3.9

89.89±19.72

MY

proficient

hamstrin

g2H

swing

hardstyle

16–48

squatsw

ing+db

l.knee

bend

Dicus

etal.(2018)[64]

2121.4±0.5(F)

20.9±0.7(M

)69.7±20.4(F)

79.2±12.1(M

)M

/F

Yno

vice

delto

id+pe

c.Major

press

othe

r25%

1RM

dumbb

ell

Lim

etal.(2018)

2422.5±3.3

70.82±7.2

M/F

Yno

vice

trun

k+lower

limb

2Hsw

ing

hardstyle

3multip

le

Lyon

set

al.(2017)[65]

1421.5±2.03

85.53±8.11

MY

novice

trun

k+up

per+lower

limbs

swing,

clean+

snatch

othe

r4.5–32

clean+snatch

Rajala

etal.(2016)

921.4±1.8

67.4±9.6

FY

novice

lower

limb

2Hsw

ing

othe

r4.5

OHsw

ing

St-Ong

eet

al.(2018)[66]

1231.6±8.2

72.4±13.2

M/F

Yproficient

shou

lder

girdle

Turkishge

t-up

hardstyle

8(F)16

(M)

none

VanGelde

ret

al.(2015)[58]

2324

±1.97

61.8±8.79

(F)

80.5±10.0(M

)M

/F

Yno

vice

gluteal+

biceps

femoris

2Hsw

ing

othe

r8–16

1Hsw

ing

Wuet

al.(2019)

1922.2±1.1

76.0±13.3

MY

novice

lower

limb

squat+lung

eothe

r20

-

Zebiset

al.(2013)[67]

1623

±3

66.2±7.4

FY

novice

hamstrin

g2H

swing

hardstyle

12–16

multip

le

1Hon

e-ha

nded

,2Htw

o-ha

nded

,1RM

1repe

titionmaxim

um,O

Hov

erhe

ad,a

bdnab

duction,

dbl.do

uble


Table

2Stud

ycharacteristicsinvestigatingacutemotionanalysiswith

kettlebe

llexercise

Autho

rParticipants

Measuremen

tsExercise

Hardstyle

/Sport/

othe

r

Load

(kg)

Con

trol

/comparator

nAge

(yrs)

Weigh

t(kg)

Gen

der

Active

Kettlebe

llproficient

/no

vice

Back

etal.(2016)[68]

732

±1(exp)

30±1.41

(beg

)70.5±1.8

78.33±3.86

unknow

nY

proficient

jointsegm

entangleandvelocity

atthepe

lvis,hip,kne

e,ankle,

shou

lder,elbow

andwrist

2H swing

hardstyle

16kg

expe

rt

Bullock

etal.(2017)[57]

1526.7±4.3

77.6±13.5

M/F

Yproficient

cycletim

e+jointsegm

ent

angleandvelocity

attheankle,

knee

andhip

2H swing

othe

r12

-20

kgoverhe

ad+Indian

club

swing

Oikarinen

etal.(2016)a[69]

528–50

unknow

nM

Yno

vice

jointsegm

entangles

atthe

shou

lder,elbow

andwrist+

segm

entangleandvelocity

atthelumbar

2H swing

othe

r16

-24

kgoverhe

ad

Ross

etal.(2015)[70]

429–47

68.3–108.1

MY

proficient

horizon

taland

vertical

displacemen

t+velocity

ofthekettlebe

ll

snatch

Sport

32kg

none

Silvaet

al.(2017)b[71]

125

72M

Yno

vice

jointsegm

entankles

ofarm-trunk,thigh

-trunk

and

leg-thigh+tim

e

OH

swing

othe

run

know

nun

stablesurface

VanGelde

ret

al.(2015)[58]

2324

±1.97

61.8±8.79

(F)

80.5±10.0(M

)M

/F

Yno

vice

jointsegm

entangleat

thehip

2H swing

othe

r8-16

kg1H

swing

Zinet

al.(2018)b[72]

324

±0.82

70.2±5.18

MY

novice

jointsegm

entangles

atthehip,

knee

and

ankle

2H swing

hardstyle

4-8kg

load

a the

sis,

bconferen

cepa

per,2H

two-ha

nded

,OHov

erhe

ad,exp.e

xpert,begbe

ginn

er


kettlebell-trained i.e. novices. Twenty-three studies(50%) explicitly used hardstyle techniques, and 3 (6%)investigated kettlebell sport. Training style/techniquewas unclear or not reported in 21 studies (43%). Threestudies were given 2 category allocations [57–59] and3 were uncategorised, deemed incompatible for syn-thesis [60–62].

Acute profiling - surface electromyography (sEMG)Eleven studies investigated sEMG. Muscles and re-gions investigated with exercise(s) and load(s) usedare shown in Table 1. It appears that the TGU pro-vides a roughly equal mechanical challenge to bothshoulder girdles, one acting to stabilise the arm andkettlebell overhead and the other acting to supportthe body, through transitions from lying to kneelingand vice versa [66]. Among 14 common lower limbexercises used for therapeutic purposes, a two-handed swing was found to have the highest peaksEMG (115 ± 55%max), with greatest preferentialexcitation of the medial hamstring (Δ 22.5 ± 9.7%peak nEMG) [67]. A similar observation was notedwith mean medial activity ≈10% greater than lateralactivity across types of swing [63] with mean sEMGgreatest during the hip hinge swing (35.74 ± 16.66),although the mean difference between styles wassmall (≈4–6%). In a dataset with large variation,excitation of the hamstring muscles was also ob-served to occur before the gluteal muscle in a oneand two handed swing regardless of gender or rangeof movement [58].

Acute profiling – motion analysisSeven acute studies investigated motion of joint seg-ments or kettlebell trajectory (Table 2). Novices werefound to perform a two-handed kettlebell swing differ-ently to experts. Significant differences in joint segmentangles and angular velocities at the hip and shoulderjoint were reported during a two-handed hardstyleswing, with the order of movements reversed betweenconditions. During the up-swing (ascent), experts leadwith the hips, then the shoulders followed. In the down-

swing (descent), the arms drop first, then the hips flex.In novices, these joint segment sequences are reversed.Experts ‘hinge’ at the hips rather than squat (≈20o

greater hip flexion at the bottom of the swing and ≈15o

less knee flexion on the descent) stand up straighter(≈10o more hip extension) and ‘swing’ the bell ratherthan ‘lift’ it (≈15o less shoulder flexion at the bottom and≈20o less at the top) [68]. These findings are consistentwith Tsatsouline [3] and with what is observed inpractice.Among a cohort of 23 novices, none of the partici-

pants obtained neutral hip position while performingany of the kettlebell swings, despite the notable availabil-ity of passive hip extension ROM, and cueing during theinstructional sessions. Average terminal hip extensionlacked a mean of 9.7° (± 7.8°) from neutral for both gen-ders during the 2-handed swing. Of note, participantswere only allowed to perform a maximum of 10 repeti-tions of each swing during the instructional session [58].The kinematic similarities and differences between a

swing to chest-height, a swing overhead, and an Indianclub swing have been reported [57] although the clinicalutility of these data is unclear. Cycle time for the over-head swing was 34% longer than the shoulder heightswing and Indian club swing, with no differences in peakjoint angles between the movements reported. No iden-tifiable risk of injury from kinematic observation of thelumbar spine was identified when performing a two-handed swing to chest-height or overhead using a 16and 24 kg bell, although reliability of these data isunclear [69].Bell trajectory during a 32 kg single-arm snatch per-

formed by four elite kettlebell sport lifters was reportedto be similar between lifters and highly consistent withinlifters. Anthropometric differences were suggested tomost likely influence movement and performance effi-ciency [70]. On an unstable surface, reduction in trunkand knee flexion angles and reduced shoulder range ofmotion were reported during an overhead swing [71]; anexpected compensation strategy to increase stability.Limited low-quality data suggested a possible trend to-ward decreasing mean flexion angles at the ankle, knee

Table 3 Study characteristics investigating acute hormonal response to kettlebell exercise

Author Population Measures Exercise Hardstyle/ Sport /other

Format Load(kg)n Age (yrs) Weight

(kg)Gender Active Kettlebell

proficient/ novice

Budnar et al.(2014) [73]

10 19–30 78.7 ± 9.9 male Y novice testosterone, growthhormone, and cortisol

Swing hardstyle 30:30 × 12 16

Greenwald et al.(2016) [74]

6 24.3 ± 4.1 80.7 ± 10.2 male N novice glucose tolerance Circuit other 25 mins 9–11.3

Raymond et al.(2018) [75]

10 19–43 82.2 ± 14.6 male Y novice testosterone andcortisol

Swing hardstyle 12min30:30

8–16


and hip with increasing bell weight among males novicesusing very light weights [72].

Acute profiling – hormonal responseVery limited data is available regarding acute hormonalresponse to kettlebell training (Table 3). Changes inserum testosterone, growth hormone and cortisol havebeen observed following 12 rounds of two-handedswings with 16 kg [73]. Heavier bells had a larger effecton testosterone and cortisol when performing 12min ofswings in which workload was matched, however ca-dence was significantly different (8 kg at 42SPM Vs 16kg at 21SPM) [75]. In practice, cadence typically remainsconsistent irrespective of kettlebell weight. A single 25-min kettlebell training session had similar effects onacute post-exercise glucose tolerance to high intensityinterval running [74]. The clinical utility of these data isunclear.

Acute profiling – mechanical demandSix acute studies investigated mechanical demands ofkettlebell exercise (Table 4). Normalised to body mass,mechanical demands of a two-handed swing with 32 kghad the largest impulse (3.0 (0.2) N.s.kg− 1) when com-pared with peak back squat at 60% 1RM (2.1 (0.2) N.s.

kg− 1) and jump squat at 40% 1RM (2.7 (0.4) N.s.kg− 1).A two-handed swing with 16 kg produced similar im-pulse to the jump squat at 0% or 60% of 1RM, and a 24kg swing produced similar impulse to the 20%1RM jumpsquat [76]. The vertical jump has been used as aproxy for measuring power output, with the swingpurported to be effective for improving activitiesassociated with explosive hip extension, such assprinting. A two-handed swing with 20% bodyweightproduced a smaller average, peak and time-to-peakrate of force development, than a vertical jump [78],suggesting a lack of specificity to improve verticaljump performance.Vertical braking force with a 24 kg bell was reported

to be approximately 25% greater during braking (down-swing) than acceleration (up-swing) during a two-handed hardstyle swing. Horizontally, the swing ap-peared to create approximately double the force andfour-times the power of a single-arm hardstyle snatchusing the same load. These data must be interpretedwith caution however, as the start of the propulsionphase was an upright standing position holding the bellin front of the thighs and included the transition fromupright standing to terminal backswing (bell betweenthe legs). Despite the difference in vertical displacement

Table 4 Study characteristics investigating mechanical demand of kettlebell exercise

Author Participants Measures Exercise Hardstyle/ Sport /other

Load(kg)

Control /comparatorn Age

(yrs)Weight(kg)

Gender Active Kettlebellproficient/ novice

Lake et al.(2012a) [76]

16 24 ± 2 90.2 ±14.4

M Y novice impulse, peak andmean force and power tocentre of mass, kettlebelldisplacement, peak andmean velocity

2Hswing

hardstyle 16 -32 kg

16, 24, 32 kg

Lake et al.(2014) [77]

22 28–41 75.2 ±14.6

M Y proficient impulse, mean force,displacement, magnitude,rate of work, phase durationsand impulse ratio

2Hswing

hardstyle 24 kg snatch

Mache et al.(2016)a [78]

25 22 ± 6 (F)23 ± 2 (M)

66.4 ± 9.2 (F)78.3 ± 8.5 (M)

M / F Y novice peak, average and timeto peak rate of forcedevelopment

2Hswing

other ≈20%BW

vertical jump

McGill et al.(2012) [79]

7 25.6 ± 3.4 82.8 ± 12.1 M Y proficient peak and averagemuscle excitation,lumbar compressionand shear force

1Hswing

hardstyle 16 kg swing withkime, snatch,bottom-up +racked carry

Mitchell etal. (2016)a

[80]

2 early 20’s 53 & 75 F Y proficient position and orientation,joints and centres of massof arm segments. Velocityand acceleration, forcesand moments of theupper limb

OHswing

other 8 -16 kg

8, 12, 16 kg

Ross et al.(2017) [5]

12 34.9 ± 6.6 87.7 ± 11.6 M Y proficient ground reaction forces,velocity and temporalmeasures of resultantkettlebell force

snatch Sport 24 kg none

aconference paper, 1H one-handed, 2H two-handed, OH overhead, BW bodyweight


http://n.s.kghttp://n.s.kghttp://n.s.kghttp://n.s.kg

of the bell (chest height vs overhead), force in the verti-cal direction was roughly equal to the swing, howeverthe swing created approximately 40% more brakingforce. Approximately 15% more Work was performed inthe down-swing during a hardstyle snatch than theswing. The swing has a significantly shorter brakingphase (0.30s Vs 0.40s), larger Impulse ratio (time undertension: 21% Vs 14%) and propulsion (26% Vs 14%) thanthe snatch [77] likely attributable to the bilateral vs uni-lateral nature of the exercises.During a single arm swing with 16 kg, a peak com-

pression force of 3195 N at the lumbar spine wasreported at the bottom of a swing, with an activebracing strategy described as the ‘kime’ increasingaverage compression by a further 1054 N [79]. Aunique property of the kettlebell swing was reportedas a posterior shear force (461 N), said to be sounusual that potential risks are unknown. The samestudy reported lumbar movement from 26o of flexionto 6o during a 2-handed swing with 16 kg.During an overhead two-handed swing, a transition

from tensile to compressive force at the shoulder wasshown to occur approximately in the upper 30% of thebells’ arc in two females, with the majority of force andpower reported to have been derived from the posteriorchain musculature [80]. A peak resultant ground reac-tion force (GRF) of 1768 N (242) was reported amongmale amateur lifters, roughly equal to 2x mean body-weight (87.7 kg ± 11.6 kg) [5].

Acute profiling – performanceTwo studies reported acute performance measures asso-ciated with kettlebell exercise (Table 5). One minute oftwo-handed swings with 16 kg was sufficient to inducefatigue (defined as a reduction in torque production) inthe lumbar extensor muscles, but was significantly lessthan an isolated lumbar extension (MedX) exercise [81].No significant interactions or main effects for any vari-able in countermovement jump performance werereported between kettlebell swings and kettlebell jumpsquats using a load equal to 20% bodyweight [82].

Acute profiling - cardiometabolic responseEstablishing whether kettlebell training has the potentialto increase aerobic capacity has been of interest toresearchers. Sixteen studies reported acute cardiometa-bolic responses to kettlebell exercise (Table 6). Theoxygen cost of completing as many two-handed swingsas possible in 12 min (197 to 333 completed) with 16 kgwas reported and compared with a graded treadmill testto exhaustion [85]. Classified as “hard” by ACSMstandards, average HR (165 ± 13 b·min− 1 = 86.8 ± 6.0%HRmax) was significantly higher than average VO2(34.31 ± 5.67 ml·kg− 1·min− 1 = 65.3 ± 9.8% VO2max). Atmatched RPE, 10 min of two-handed swings comparedwith continuous treadmill running resulted in signifi-cantly lower VO2 (34.1 ± 4.7 Vs 46.7 ± 7.3 ml·kg

− 1·min−1), METS (9.7 ± 1.3) and energy expenditure (12.5 ± 2.5Vs 17.1 ± 3.7 Kcal·min− 1). This was reported sufficientto increase aerobic capacity [88].Twelve rounds of two-handed swings produced sig-

nificant mean increases in HR with each successiveround (67 ± 0 at rest to 169 ± 5 bpm) and significantpost-exercise hypotension at 10 (~ 4 mmHg SBP, ~ 3mmHg DBP) and 30 (~ 4 mmHg SBP, ~ 3 mmHg DBP)minutes after exercise [97]. A reported resting meanHR of 67 ± 0 bpm in a group of 17 participants sug-gests challenges of reliability. Performing as manytwo-handed swings as possible in 12 min was alsoreported to be perceptually harder, with increasingfeeling of heat stress, muscle pain and higher sus-tained HR compared to a kettlebell circuit workoutcompleted at 90% 6RM [92].A Tabata-inspired kettlebell circuit using a 2:1

work:rest ratio was compared to 1:8 (30s:4min) sprintinterval cycling in “very active” males, with the kettle-bell protocol proposed to be more attractive and sus-tainable [96]. The authors concluded that the highintensity kettlebell protocol would be effective instimulating cardiorespiratory and metabolic responses,which could improve health and aerobic performance(mean VO2peak 29.1 ± 0.09 ml·kg

− 1 min− 1 = 55.7%VO2max).

Table 5 Study characteristics investigating acute performance characteristics associated with kettlebell exercise

Author Participants Observing Exercise Hardstyle/ Sport /other

Format Load(kg)n Age

(yrs)Weight (kg) Gender Active Kettlebell

proficient/ novice

Edinborough et al.(2016) [81]

10 20–25 79.94 ± 11.4 M Y novice muscular fatigue(acute torque production)

2Hswing

other 1 mincontinuous

16

Ros et al.(2016)a [82]

7 19.14 ±1.86

70.56 ± 7.25 F Y novice post-activation potentiation oncountermovement jumpperformance

2Hswing

other 5 reps, 1min rest,5 reps, 3mins rest

20%BW

athesis, 2H two-handed, BW bodyweight


Table

6Acute

cardiometabolicrespon

seto

kettlebe

llexercise

Autho

rParticipants

Observing

Exercise

Hardstyle

/Sport/

othe

r

Form

atLoad

(kg)

nAge

(yrs)

Weigh

t(kg)

Gen

der

Active

Kettlebe

llproficient

/no

vice

Chanet

al.(2018)[83,84]

1028.4±4.6

95.1±14.9

MY

proficient

VO2,HR,RER,V E,RPE

snatch

Sport

10mins(con

t.)16

Dun

canet

al.(2015)[59]

1623

±2.9

76.3±14.7

M/F

Yno

vice

HR,Bla

swing

hardstyle

2mins,40BPM

&80BPM

4–8

Farrar

etal.(2010)[85]

1020.8±1.1

77.3±7.7

MY

novice

VO2,HR

swing

hardstyle

12mins

16

Ferreira

etal.(2018)[86]

1224.3±7.0

74.1±9.4

M/F

Yno

vice

BPsw

ing

othe

r20

mins,18

s/min

unknow

n

Fortne

ret

al.(2014)[87]

1418–25

66.5±6.9(F)

81.7±3.0(M

)M

/F

Yno

vice

VO2,HR,Bla,RPE

swing

othe

r4mins,20:10

4.5(F)8

(M)

Hulseyet

al.(2012)[88]

1319–27

73.0±9.2

M/F

Yno

vice

VO2,HR,METS,RER,

ventilatio

n,kcal,RPE

swing

othe

r10

mins,35:25

8(F)16

(M)

Martin

etal.(2012)a[89]

828.5±5.5

86±15

MY

novice

HR,BP

swing

hardstyle

12mins

16

Santilloet

al.(2016)a[90]

1518–35

54.3–101.8

M/F

Yno

vice

Bla

swing

hardstyle

volitionalfailure

(RPE

15or

95%

HR m

ax)

14–16(F)

20–24(M

)

Schn

ettleret

al.(2009)a

[91]

1029–46

59.9–116.6

M/F

Yproficient

VO2,HR,kcal,RPE

snatch

hardstyle

5mins,15:15

12–20

Schreibe

ret

al.(2014)a

[92]

1029–46

59.9–116.6

M/F

Yproficient

HR,Temp,

Bla,pain,

thermalsensation,RPE

snatch

hardstyle

5mins,15:15

12–20

Šentija

etal.(2017)[93]

1125.9±4.0

73.1±21.1

M/F

Yno

vice

VO2,HR,Bla,ventilatio

nsw

ing

hardstyle

toexhaustio

nUnkno

wn

Thom

aset

al.(2014)a[94,

95]

1023

±4.4

75.45±20.1

M/F

Yno

vice

VO2,HR,BP,RER,M

ETS,

grip

streng

th,RPE

swing+

deadlift

hardstyle

3x10mins,EM

OM

8(F)16

(M)

Thom

aset

al.(2014)[94,

95]

1025.3±4.3

60.98±16.1

(F)

93.5±16.1

(M)

M/F

Yno

vice

VO2,HR,BP,RER,kcal,RPE

swing+

deadlift

hardstyle

3x10mins,EM

OM

8(F)16

(M)

Wesleyet

al.(2017)[1]

1830

±9.6

68.2±9

FY

proficient

HR,Bla,RPE

swing

hardstyle

15:15,×10

8,12,16

Williamset

al.(2015)[96]

821.5±

0.86

2.95

±11.62

MY

novice

VO2,HR,RER,TV,

breathingfre

quen

cy,V

E,kcal

circuit

othe

r20:10,4mins,×3

10–22

Won

get

al.(2017)b[97]

1723

±1

74.1±4.9

M/F

Yno

vice

HR,BP

swing

hardstyle

30:30,×12

8(F)16

(M)

a the

sis,

baccepted

forpu

blication,

EMOM

everyminuteon

theminute,

RPErate

ofpe

rceivedexertio

n,BP

Mbe

atspe

rminute


At a controlled work rate of 20 two-handed swings(40SPM) and 10 sumo deadlifts performed every mi-nute on the minute, versus continuous cycling on anergometer at 80 rpm, no significant differences werereported in any physiological (HR, VO2), subjective(RPE) or metabolic (RER, MET) response [94]. HRand RPE were significantly higher using the same30-min kettlebell protocol when compared withtreadmill walking at matched VO2, with no differ-ence in RER, kcal.min− 1 and BP [95]. Both studieshad male and female participants, with very largevariation in anthropometrics.No post-exercise hypotensive response was observed

in normotensive individuals performing two-handedswings for 20 min [86]. A statistically significant at-tenuation in BP reactivity compared to control wasreported, immediately following a cold pressor test,however the clinical utility of this phenomenon inpractice is unclear. Significant reductions in post-ex-ercise BP 120 min post-exercise were also reportedfollowing 12-min of discontinuous two-handed swings(88 to 486 swings completed), compared with a ket-tlebell circuit of 6 exercises among hypertensive orpre-hypertensive males [89]. Comparisons of effectare limited due to exposure bias, and a decrease ofonly 4 mmHg to reach clinical significance.Jay’s VO2 snatch cadence test (cMVO2) [9] was

modified by Chan [83] to simulate a kettlebell sportevent and measure VO2 over 10 min. Increasingsnatch cadence with 16 kg and multiple arm changes,was compared with a graded rowing ergometer withincreasing power output. HR was comparable (≈175 ±8-10b.min− 1) but mean peak oxygen consumption(37.5 ± 43.5 Vs 45.7 ± 6.6) respiratory exchange ratio(1.10 ± 0.060 Vs 1.18 ± 0.047) and minute ventilation(132.7 ± 19.2 Vs 157.1 ± 20.1) were significantly lower.VO2 response to the cMVO2 test was also reportedto be significantly lower than the Bruce treadmillprotocol (40.3 ± 2.2 Vs 49.7 ± 6.6 ml·kg·min− 1) amonga small mixed gender group with very large variation

in anthropometrics [91]. Mean VO2 was 31.6 ± 3.71ml·kg·min− 1 however the range in HR (128-180 bpm),%VO2max [3, 69–83, 85, 86, 88, 89, 92, 94–97] andRPE [10–18] suggest these data may be poorlyreliable.An incremental kettlebell swing test (IKT) using in-

creasing bell weight showed a strong correlation inpeak oxygen uptake with the incremental treadmilltest (3.27 ± 0.67 Vs 3.99 ± 0.71 LO2·min

− 1, r = 0.92)[93]. Mean peak values for the IKT were significantlylower for VO2, HR, BLa and VE. It was reported thatin most subjects, muscle fatigue rather than cardio-re-spiratory factors caused exhaustion in the IKT test.Clinical utility, validity and reliability of the IKT arecurrently unknown.With respect to the modifiable factors of swing cadence,

bell weight and rest periods, increases in kettlebell weight(8 kg,12 kg,16 kg) or cadence (32,40,48spm) were reportedto significantly increase cardiometabolic demand (HR, RPE& BLa) [1]. It should be noted that kettlebell proficient par-ticipants reported that a cadence of 32spm was “unnaturallyslow”, with the ballistic hip hinge eliminated and dynamicswinging motion becoming a static resistive motion. Re-searchers suggested that the resultant shoulder-dominantexercise likely inflated the physiological variables. Inaddition, swings have been reported to become perceptuallyharder with increasing bell weight [59], and reduced restperiods have significantly increased metabolic responsewhen volume-matched with low load kettlebells [87]. Theeffect of different recovery strategies on lactate clearancefollowing two-handed swings to volitional failure has beenreported [90]. A statistically significant difference in clear-ance time and post-recovery performance occurred at ≈9-mins post-exercise, which is unlikely to be clinicallymeaningful.

Acute profiling – ‘uncategorised’Three publications (Table 7) were not categorised as theoutcomes were unique and incompatible for synthesis.Small effect size reductions in pain pressure threshold

Table 7 Study characteristics investigating change in pain pressure threshold and task-related predictive test of a bilateral carry


Format Load(kg)n Age (yrs) Weight

(kg)Gender Active Kettlebell

proficient/ novice

Keilman et al.(2017) [60]

60 25.12 ±2.86

70.49 ±13.32

M / F unknown novice pain pressurethreshold

2Hswing

hardstyle 8 rounds, 20:10

8 (♀) 12(♂)

Beck et al.(2016) [61]

73 43.4 ± 9.7(F)40.9 ±10.2 (M)

67.2 ± 9.6(F)90.3 ±12.4 (M)

M / F Y n/a carry distance tovolitional failure

farmer’swalk

n/a at 4.5 and 5.0km/hr

2 × 22

Beck et al.(2017) [62]

67 24–59 82.9 ±15.7

M / F Y n/a carry distance tovolitional failure

farmer’swalk

n/a at 4.5 km/hr 2 × 22

2H two-handed


Table

8Stud

ycharacteristicsinvestigatinglong

term

physiologicalrespo

nseto

kettlebe

lltraining

Autho

rParticipants

Observing

Exercise

Hardstyle

/Sport/

othe

r

Duration

Form

atFreq

/wk

Load

(kg)

Con

trol/

comparator

Rand

omised

nAge

(yrs)

Weigh

t(kg)

Gen

der

Active

Kettlebe

llproficient

/no

vice

Che

net

al.(2018)

[98]

3366.7

±5.3

66.3

±12.1

FN

novice

skeletalandappe

ndicular

musclemass,bo

dyfatmass,

sarcop

eniainde

x,pu

lmon

ary

functio

n,grip

streng

th,

isom

etric

back

streng

th,chron

icproinflammatorycytokine

concen

tration

×11:swing,

deadlift,

goblet

squat,squat

lung

e,row,singlearm

row,b

icep

scurl,tricep

sextension,tw

o-arm

military

press,Turkish

getup

hardstyle

860 mins,5

ex’s,3

sets,8–

12reps,

2–3min

rest

260–

70%

1RM

Con

trol

Y

Marcelino

etal.

(2018)

2664.94±9.29

74.85

±13.94

M/F

(13M,

4F)

Nno

vice

timed

upandgo

,sitandlift,

elbo

wflexion

,6-m

inwalk,lower

limbpe

aktorque,BergBalance

Scale,staticpo

sturalstability

(COPdisplacemen

t)

bottom

-up,

firststages

ofTurkishge

t-up

,farm

erwalk,go

blet

squat,de

adliftand

swing

hardstyle

15–

–60–

85%

1RM

body

building

and

stretching

exercises

N


Table

9Stud

ycharacteristicsinvestigatingmeanlong

-term

perfo

rmance

improvem

entfro

mkettlebe

lltraining

Autho

rParticipants

Observing

Exercise

Hardstyle

/Sport/

othe

r

Duration

(weeks)

Form

atFreq

/wk

Load

(kg)

Effect

Effect

size

Con

trol/

comparator

Rand

omised

nAge

(yrs)

Weigh

t(kg)

Gen

der

Active

Kettlebe

llproficient

/no

vice

Ambrozyet

al.

(2017)

[100]

4027–32

unknow

nF

Yno

vice

hand

speed,

flexibility,explosive

streng

th,stren

gth

endu

rance,agility,

VO2,Wingate

test

circuit

(unkno

wn)

othe

r8

60mins

3un

know

nVO

2+6.31

ml.kg−

1 .min−1

Average

Power+8.30

W Maxim

umPo

wer+

20.53W

Bent

arm

hang

+13

s

Trivial(δ=0.27,

p≤0.05)

Trivial(δ=0.10,

p≤0.05)

Trivial(δ=0.15,

p≤0.05)

Mod

erate(δ=

1.36,p

≤0.05)

Minim

ally

active

Y

Beltz

etal.

(2013)

[101]

1722.1±

2.80

(M)

21.5±

3.93

(F)

77.7±

10.86(M

)64.5±

12.56(F)

M/F

Yno

vice

streng

th,aerob

iccapacity,b

ody

compo

sitio

n,flexibility,balance,

andcore

streng

th.

circuit

hardstyle

845–

60min

2un

know

nDynam

icbalance(PL)

+7.2cm

VO2+5.0

ml.kg−

1 .min−

1 Legpress+

41.7kg

Grip

streng

th+1.7kg

Pron

eplank

+45

s

Mod

erate

(SMD=1.14,

p≤0.05)

Trivial(δ=0.33,

p≤0.05)

Mod

erate(δ=

0.82,p

≤0.05)

Small(δ=0.42,

p≤0.05)

Very

large(δ=

1.32,p

≤0.05)

YN

Che

net

al.

(2018)

[98]

3366.7±

5.3

66.3±

12.1

FN

novice

skeletaland

appe

ndicular

muscle

mass,bo

dyfatmass,

sarcop

eniainde

x,pu

lmon

aryfunctio

n,grip

streng

th,

isom

etric

back

streng

th,chron

icproinflammatory

cytokine

concen

tration

×11:swing,

deadlift,go

blet

squat,squat

lung

e,row,

sing

learm

row,

biceps

curl,

tricep

sextension,

two-

arm

military

press,Turkish

getup

hardstyle

860

mins,

5ex’s,3

sets,8–

12reps,

2–3min

rest

260–70%

1RM

Sarcop

enia

inde

x−0.26

Handg

ripstreng

th(L)

+4.26

kgHandg

ripstreng

th(R)

+4.71

kgBack

streng

th+6.37

kgPeak

expiratory

flow

+0.79

L/s

Med

/Lrg

(δ=

0.79,p

≤0.05)

Very

large(δ=

1.2,p≤0.05)

Large(δ=0.88,

p≤0.05)

Large(δ=0.83,

p≤0.05)

Med

/Lrg

(δ=

0.79,p

≤0.05)

YY

Elbadryet

al.

(2018)

[102]

4020.17±

0.4

75±2.9

FY

novice

Standing

LJ,softball

throw,g

rip,LL

streng

th,h

ammer

throw

unknow

nothe

r8

60mins

3un

know

nStanding

long

jump+

11.37

Softball

throw

+6.94

Handg

ripstreng

th(L)

+12.72

Handg

rip

Med

ium

(δ=

0.66,p

≤0.05)

Hug

e(δ=2.74,

p≤0.05)

Hug

e(δ=2.92,

p≤0.05)

Large(δ=0.94,

p≤0.05)

Med

ium,(δ=

Yun

know

n


Table

9Stud


-term

perfo

rmance

improvem

entfro

mkettlebe

lltraining

(Con

tinued)

Autho

rParticipants

Observing

Exercise

Hardstyle

/Sport/

othe

r

Duration

(weeks)

Form

atFreq

/wk

Load

(kg)

Effect

Effect

size

Con

trol/

comparator

Rand

omised

nAge

(yrs)

Weigh

t(kg)

Gen

der

Active

Kettlebe

llproficient

/no

vice

streng

th(R)

+6.82

Static

streng

th(BS)

+6.06

Static

streng

th(LS)

+9.76

Perfo

rmance

(ham

mer)+

22.27

0.64,p

≤0.05)

Very

large,(δ

=1.37,p

≤0.05)

Very

large(δ=

1.20,p

≤0.05)

Falatic

etal.(2015)

1719.7±

1.0

64.2±8.2

FY

novice

aerobiccapacity

(VO2)

Jay’sMVO

2snatch

protocol

hardstyle

420

mins,

15:15

312

VO2m

ax+

2.3ml.kg−

1 .min−1

Med

ium

(SMD=0.72,

p<0.05)

circuit

weigh

ttraining

N

Holmstrupet

al.

(2016)

[103]

1818–25

unknow

nF

Yno

vice

Sprin

tpe

rform

ance

swing

hardstyle

810:10×8

29.1–13.7

Verticaljump

+2.4cm

Sprin

t-1s

Small(SM

D=

0.48,p

>0.05)

Trivial(SM

D=

0.04,p

>0.05)

NN

Jayet

al.(2011)

[104]

4044

±8

68±11

M/F

Nno

vice

self-repo

rted

pain

(neck/shou

lders,

back),streng

th(back,

trun

k,shou

lder),VO

2

swing

hardstyle

810–

15min,

30:60to

30:30×

10

38–16

Neck/

shou

lder

pain

VAS−

1.7

Low

back

pain

VAS−

1.6

Back

extension

MVC

+19.6

Nm

Trun

kflexion

MVC

+12.0

Nm

Shou

lder

elevation

MVC

+7.0

Nm

VO2m

ax+

2.9ml.kg−

1 .min−1

Small(SM

D=−

0.94,p

≤0.05)

Small(SM

D=−

0.89,p

≤0.05)

Trivial=

(SMD=

0.47,p

≤0.05)

Trivial(SM

D=

0.29,p

>0.05)

Trivial(SM

D=

0.39,p

>0.05)

Trivial(SM

D=

0.39,p

>0.05)

YY

Jayet

al.(2013)

[105]

4044

±8

68±11

M/F

Nno

vice

posturalreactio

nto

externalpe

rturbatio

n,verticaljump

perfo

rmance

swing

hardstyle

810–

15min,

30:60to

30:30×

10

38–16

Verticaljump

+1.5cm

Stop

ping

time-109

ms

Med

ium

(SMD=1.5,p>

0.05)

Large(SMD=

−2.87,p

≤0.05)

YY


Table

9Stud


-term

perfo

rmance

improvem

entfro

mkettlebe

lltraining

(Con

tinued)

Autho

rParticipants

Observing

Exercise

Hardstyle

/Sport/

othe

r

Duration

(weeks)

Form

atFreq

/wk

Load

(kg)

Effect

Effect

size

Con

trol/

comparator

Rand

omised

nAge

(yrs)

Weigh

t(kg)

Gen

der

Active

Kettlebe

llproficient

/no

vice

Lake

etal.

(2012)

2118–27

72.58±

12.87

MY

novice

halfsquat1RM

and

verticaljumphe

ight

swing

hardstyle

630:30×

122

12–16

Halfsquat+

18kg

Verticaljump

+3cm

Small(SM

D=

0.82,p?)

Small(SM

D=

0.60,p?)

Manocchiaet

al.(2013)[106]

3740.8±

12.9

76.6±

14.4

M/F

Yno

vice

transfersof

streng

thandpo

wer+

muscularen

durance

>20

othe

r10

60mins

2un

know

nBarbellclean

&jerk

+4.2

kg Barbell

benchpress

+14.2kg

Mod

erate

(SMD=1.17,

p<0.05)

Small(SM

D=

0.63,p

<0.05)

Maulit

etal.

(2017)

[107]

3123.1±

2.3

83.9±

13.8

MY

novice

streng

thandpo

wer

swing

othe

r4

4sets×5

reps

to6×4

210–

12.5%

MTP

Deadlift

1RM

+8.2kg

Verticaljump

+1.1cm

Mod

erate

(SMD=1.17,

p>0.05)

Small(SM

D=

0.63,p

>0.05)

Ooraniyan

etal.

(2018)

[108]

3018–23

unknow

nM

Yno

vice

lower

limbstreng

th,

muscularstreng

thpistol

squat,

biceps

curl,row,

front

raise

othe

r6

unknow

n3

unknow

nLower

limb

streng

thMuscular

streng

tha m

easures

not

describ

eda

Large(SMD=

0.40,p

≤0.05)

Small(δ=1.02,

p≤0.05)

Mod

erate

(SMD=1.02,

p≤0.05)

Large(δ=0.99,

p≤0.05)

Ottoet

al.

(2012)

[44]

3019–26

78.99±

10.68

MY

novice

streng

th,p

ower,and

body

compo

sitio

nsw

ing,

accelerated

swing,

goblet

squat

othe

r6

1–3sets

(3×6,

4×4,4×

6then

4×6,6×

4,4×6)

216

Verticaljump

+0.18

cmBack

squat+

5.58

kgPo

wer

clean

+3.35

kg

Trivial(SM

D=

0.05,p

≤0.05)

Trivial(SM

D=

0.18,p

≤0.05)

Trivial(SM

D=

0.18,p

≤0.05)

Parasuraman

etal.(2018)[109]

4518–25

unknow

nM

Yno

vice

Max

push-ups,p

lank

endu

rance

vario

usothe

r6

45mins

3un

know

nMax

push-

ups+4

trun

ken

durance+

57s

KB>CON,p

≤

0.05

Smith

etal.

(2014)

[110]

2820–29

unknow

nM

/F

Yno

vice

post-activation

potentiatio

nand

verticaljump

swing

othe

r8

×4–6

squat+

×5CMJS

320–36

Verticaljump

+4.62

cmVery

small(δ=

−0.04,p

>0.05)

Kram

eret

al.

(2015)

[111]

2718–26

80.0(M

)63.9(F)

M/F

Yno

vice

anaerobicpo

wer

vario

us(×5)

othe

r4a

15:45×

5×2

39–16

MeanPo

wer

Peak

Power

Rate

ofFatig

ue

Trivial,p>0.05


Table

9Stud


-term

perfo

rmance

improvem

entfro

mkettlebe

lltraining

(Con

tinued)

Autho

rParticipants

Observing

Exercise

Hardstyle

/Sport/

othe

r

Duration

(weeks)

Form

atFreq

/wk

Load

(kg)

Effect

Effect

size

Con

trol/

comparator

Rand

omised

nAge

(yrs)

Weigh

t(kg)

Gen

der

Active

Kettlebe

llproficient

/no

vice

Kruszewskie

tal.(2017)[112]

2421.2±

1.2

89.83±

9.62

MY

novice

40yrdrun,agility,C

Mjump,

standing

long

jump,

benchpress

vario

usSport

32Com

plex

416–72

Training

effectsno

trepo

rted

Wadeet

al.

(2016)

[113]

1730.4±

6.9

81.4±

12.4

M/F

Yno

vice

USA

Ffitne

ss,spe

ed,

power,and

agility

swing

othe

r10

5×2

mins,30s

rest

36–14

Body

fat

(2.5%)

Max

push-

ups[6]

Max

sit-up

s[3]

1.5-mile

run

(12s)

Max

grip

streng

th(3.1

kg)

Proagility

(0.1s)

Verticaljump

(1.3cm

)40-yarddash

(0.4s)

Small(δ=

−0.37,p

≤0.05)

Very

small(δ=

−0.03,p

>0.05)

Small(δ=−

0.47,p

>0.05)

Med

ium/Large

(d=−0.79,p

>0.05)

Small(δ=0.10,

p>0.05)

Small(δ=−

0.40,p

>0.05)

Small(δ=0.36,

p>0.05)

Small(δ=−

0.40,p

≤0.05)

a discontinuo

us


(PPT) have been reported in lumbar and hip muscula-ture following a Tabata-inspired (2:1) work:rest ratio,using a low-load, load-volume protocol [60]. A bilateralkettlebell carry was shown to be highly predictive ofstretcher carry performance among Australian Army sol-diers [61] with lean leg mass determined to be the mostinfluential physical characteristic [62].

Long-term physiological responseTable 8 shows the outcomes from two randomised con-trolled trials using pragmatic hardstyle kettlebell trainingwith older adults. Large effect sizes were reported in amixed-gender group with Parkinson’s disease following15 weeks of training [99]. Significant improvements werereported for the Timed Up and Go, Sit and Lift, elbowflexion and lower limb strength and torque measurescompared to the Non-Periodic Activities Group whichperformed bodybuilding and stretching exercises. Very en-couraging medium to large effect size increases in hand-grip strength, back strength and sarcopenia index werereported in a good-quality RCT in women with sarcopenia[98]. Improvements in axial skeletal muscle mass and sar-copenia index were maintained at four weeks after cessa-tion of training, with signification reductions in the samemeasures occurring in matched controls.

Long-term performance improvementTable 9 shows the long-term performance improvementsfrom kettlebell training. Changes in postural reactiontime following kettlebell training have been reported ina good-quality RCT [105]. A basic low-volume, low-in-tensity program of kettlebell swings performed twice aweek for 8 weeks, resulted in a large (109ms) reductionin reaction time to perturbation. In a separate publica-tion with the same participant demographics, relative re-ductions in mean musculoskeletal pain intensity of 57and 46% in the low-back and neck/shoulder regions re-spectively were also reported [104].Moderate increases in upper limb endurance (bent

arm hang time) have been reported in a moderate-qual-ity trial [100]. Large improvement in trunk endurance(prone plank time), moderate improvements in dynamicsingle leg balance and leg press strength, and small im-provement in grip strength, were also reported from amoderate-quality hardstyle kettlebell circuit performedtwice a week for 8 weeks with young, heathy, active par-ticipants [101]. When compared to weightlifting training[44], there was no statistically significant difference be-tween groups for the power clean, and only a small ef-fect size difference in back squat strength wasstatistically significant. Changes in half squat strengthand vertical jump height have been reported [114] al-though the effect size was small for a trained population.Small improvements in mean bench press 1RM and

moderate mean improvement in barbell clean and jerkwere reported from a comprehensive (> 20 exercises)pragmatic hardstyle kettlebell program performed twicea week for 10 weeks [106].No conclusions can be drawn from a Pilot study com-

paring complex training protocols, in which kettlebellswings were compared with barbell back squats [110].No statistically significant difference was found betweengroups on vertical jump performance, although reportedto be “practically significant”. No significant differencewas found in vertical jump and sprint performance inrecreationally active females, although the training vol-ume was described as inadequate [103]. Kettlebell swingsusing a ‘kettleclamp’ was reported to increase power andstrength when compared with explosive deadlift training,however these conclusions were not supported by thedata presented [107]. Limitations in study design preventany conclusions being made from kettlebell trainingwhen compared with battle ropes [109, 111], on thephysical performance of American Football players usingkettlebell sport [112], male handball players [108], col-lege females performing a hammer throw [102], or inmilitary fitness training [113].

Injury and rehabilitationBased on a large differential in vastus lateralis (VL) to semi-tendinosus (ST) sEMG pre-activity during standardisedside-cutting manoeuvres, a single case study was describedof a female soccer player, retrospectively identified post-in-jury as a high risk of ACL rupture [115]. Risk was charac-terized by reduced sEMG pre-activity for the ST andelevated sEMG pre-activity for the VL, with a high-riskzone defined as one SD above the mean VL-ST difference[116] (Table 10). Ten months post-ACLR and standardpost-surgical rehabilitation, the player was deemed ready toreturn to play despite persistence of the high-risk neuro-muscular pattern. Based on the author’s previous work[67], a low-volume intervention (< 1000 swings,

‘functional training’, proposed to “mirror the challengesone faces in day to day activities” [121].The TGU was described for patient self-management,

to teach “the motor control needed for daily activities,occupation, and sports” [122] and specifically for inte-grating mobility, stability, symmetry (left, right, front,back), coordination, balance and strength [123], as atherapeutic exercise for injury prevention and perform-ance enhancement [124], as a strength and conditioningtool for a variety of athletes [125], and as a componentof kettlebell training to develop strength and power[126]. Only one article written for instructional purposesillustrates each of the ‘big 6’ techniques as descried byTsatsouline [127]. Five kettlebell exercises have beenindividually described with proposed clinical or perform-ance benefits; a modified swing [128], thruster [129],arm bar [130], reverse lunge with overhead press [131]and a lunge clean [132].In sports, the use of kettlebells within program design

has been described as a safe and effective modality thatenhances the training experience [19] and was discussedin a point/counterpoint for inclusion in strength andconditioning [133]. A sample periodised program for theclean and jerk and snatch exercises within an athlete’sgeneral conditioning for kettlebell sport has also beenoffered [134].Three case reports of injury have been published.

An onset of De Quervain’s tenosynovitis was attrib-uted to repetitive trauma to the extensor pollicisbrevis tendon [135], exercise induced non-traumaticrhabdomyolysis without complication [136], and aradial stress fracture [137]. Each case report appearsto outline a training load error which may haveaccounted for the injury however, the potential influ-ence of training load was not identified in any case.Broad risk management strategies appropriate for fit-ness professionals have also been described [138].

Quality of evidence strength of recommendationsTwo reviewers independently evaluated randomisedcontrolled trials using a modified Downs & Black

quality assessment checklist [53]. Trials were ex-cluded from quality assessment for the following rea-sons: i) single participant [115], ii) effects could notbe attributed to only the kettlebell [113], iii) the trialwas discontinuous [111] and iv) pre-interventiondata was not captured [112]. The quality scores areillustrated in Fig. 6.

DiscussionWe conducted a scoping review which included 99 pub-lications. The current body of evidence is represented bya small number of longitudinal studies, which are largelyunderpowered and generally of low methodological qual-ity [56]. Three publications [104, 105, 108] from twostudies had participants randomised to an interventionor inactive control. With high risk of bias, confidence inreported effects is low. Further research is very likely tohave an important impact on our confidence in the esti-mate of effect. Trial descriptions of exercise interven-tions are suboptimal and no publication has used theConsensus on Exercise Reporting Template (CERT)[139] with only 1 RCT pre-registered. The validity of re-ported outcomes likely to have clinical utility, have yetto be established with repeated trials. Largely based onhealthy college-age participants, the current body ofresearch has limited applicability to clinical or high-per-formance athletic populations.Our findings highlight a growing research interest in

the effects of kettlebell training since 2009. There havebeen no adverse events reported during clinical trials,and no clear or quantifiable risk of harm from kettlebelltraining has been identified. It is unclear if the absenceof reported adverse events is a true representation ofkettlebell training or a limitation in reporting. Only 1publication [127] illustrates how to perform each of thefundamental hardstyle exercises. Clinicians unfamiliarwith kettlebell training wanting to prescribe them fortherapeutic purposes, would be wise to consult withtrained practitioners. Anecdotal reports of delayed onsetmuscle soreness, bruising and discomfort from repetitiveimpact force to the forearm among novices are not

Table 10 Single case study characteristics investigating kettlebell swings 10-months post-ACLR surgery


Duration(weeks)

Format Freq/wk

Load(kg)

Effect

n Age(yrs)

Weight(kg)

Gender Active Kettlebellproficient /novice

Zebis(2017)[115]

1 21 unknown F Y novice differential invastus lateralis tosemitendinosuspre-activity(% of max EMG)Counter movementjump

swings hardstyle 6 3–5 sets,×20 reps,20s rest(×10sessions)

2 16–20 ST - 23%↑ 61%BF - 26%↓ 17%-0.3 cm

ST semitendinosus, BF biceps femoris


unusual. As a dynamic skilled activity using a freeweight, it is advisable for a novice to receive appropriateinstruction to mitigate avoidable error in execution orinappropriate loading.Kettlebells are increasingly being used to perform ex-

ercises typically associated with other equipment, suchas the one-arm bent over row and sumo squat. In thesecases, the tool simply becomes a weight with a handleand the exercise (or potentially the outcome) not uniqueto the equipment. There may be instances where this ismore desirable or necessary within a clinical context,however this becomes generalised exercise prescriptionand ‘training using a kettlebell’ rather than kettlebelltraining. Kettlebells are also being used to augment trad-itional exercises, such as hanging kettlebells by elasticbands to the end of an Olympic bar during a squat orbench press [37], which bear no resemblance to kettle-bell training.The differences between kettlebell sport and hardstyle

could be summed up by a statement made by ValeryFedorenko in 2013, “It’s not about 5 or 10 sets of 10, its1 set of 100; that’s the principle” [140]. In contrast, Jaydescribed hardstyle training as “intermittent, high-pow-ered work at maximal or supramaximal intensity in thecorrect ratio of work and rest” [9]. There are similaritiesand differences between kettlebell sport and hardstyle.For the primary care therapist or strength and

conditioning specialist, there is no indication that onetechnique or style is better, more appropriate, or moreeffective than any other. Recommendation would mostlikely be based upon the provider’s experience with orexposure to kettlebells, and the person’s values, expecta-tions and preference about an exercise program theymay wish to engage in. Only 4 studies published inEnglish have investigated kettlebell sport. Two in-volved acute biomechanical analysis of kettlebellexercises [5, 70], 1 involved the development of a ket-tlebell snatch protocol for kettlebell sport that couldbe used in the laboratory [83], and 1 was a Universitystudy showing medium to huge effect size changes instanding long jump, strength and throw performance,although with high risk of bias the results are unreli-able [102].The U.S. Department of Energy “Man Maker” protocol

was described by Tsatsouline as “alternate sets of kettle-bell swings to a comfortable stop, with a few hundredyards of easy jogging for active recovery”. Performed twicea week for an arbitrary time of 12 min, it was recom-mended that people also complete 2 days each week of5 min continuous TGUs. The program would continueuntil they could perform 100 single-arm swings < 5 minsand 10 TGUs < 10 mins at a target weight. In the re-search literature, the Man Maker challenge was firstcited by Farrar [85] as a “popularly recommended

Fig. 6 Modified Downs & Black quality assessment of Randomised Controlled Trials


kettlebell workout”, however the study protocol usedwas 12 min of continuous two-handed swings. The same12-min continuous format was subsequently used tomeasure blood pressure response [89] and later com-pared to a high-resistance circuit workout [92]. Whilsthardstyle techniques were cited, these studies illustratean evolution in the literature away from the principlesand practices described by Tsatsouline, based upon re-searcher’s interpretation of training practices.Due to the variety of ways in which an exercise pre-

scription could possibly include kettlebell exercises forclinical and athletic populations, it is vital that the exer-cise professional has a clear idea of the acute stressesimposed on the body by this form of exercise prior to itsutilisation. An initial understanding of these acutestresses is being provided by studies assessing the acutehormonal, kinetic, kinematic, cardiometabolic and elec-tromyographic responses to kettle bell exercise in arange of populations.Surface electromyography (sEMG) is a popular re-

search tool which records the electrical potential of skel-etal muscle, with a wide variety of clinical andbiomedical uses. Within rehabilitation sciences, EMGsignals are collected as participants perform the activityunder investigation, frequently using different loadingconditions. Common methodology involves the com-parison of EMG amplitudes, with researchers makingconclusions based on the neuro- and electrophysio-logical correlation with muscle force. Hypotheses maybe made regarding potential longitudinal adaptations inthe characteristics and performance of skeletal muscle,such as strength and hypertrophy. However, conclusionscannot be made about muscle activation, force andmechanisms of force production, or inferences madefrom longitudinal outcomes based solely on sEMG amp-litude [141] The use of unconventional exercises [64, 65]adds further complexity to the interpretation. With exe-cution of a swing influenced by so many variables, it islikely that the differences between swing types may notbe clinically meaningful, although considered importantwithin their own discipline.The difference in movement pattern between expert

and novice performing a two-handed hardstyle swing[68] is consistent with 1o of hip extension observed atthe top of a swing in kettlebell-trained subjects [79] andwith what trainers report in practice. The skill acquisi-tion of a hardstyle swing appears clear and consistent,however its utility in clinical practice is unclear. The ob-served difference between expert and novice is likely toapply to other kettlebell exercises, thus the experience ofparticipants in research studies should be consideredwhen assessing validity of findings, and the generalisabil-ity of outcome data to other populations. Other factorslikely to influence outcomes include kettlebell specific

differences such as training style, bell weight and swingcadence, and factors common to other training modal-ities such as work-to-rest ratio, peripheral and central fa-tigue. Each of these should be assessed when prescribingkettlebell exercises and their relative importance estab-lished for clinical populations on a case-by-case basis.There is no indication that one type or style of swing

has greater clinical utility than another. No data suggeststhat someone performing a swing counter to the pre-scriptive hardstyle pattern, is at increased risk of harm.When performing a hardstyle swing in practice, muchemphasis is placed on the production of power (in thehorizontal plane) and of developing “power-endurance”[3] however, no published data currently exists whichquantifies or validates these claims. The potential forusing movement(s) associated with kettlebell training fortherapeutic purposes has not been investigated.Although limited, ground reaction force data is clinic-

ally helpful, particularly where the mechanical demandsof a kettlebell swing are compared to other commonlyused exercises, or where some objective quantifiableloading of tissues is indicated. Large increases in groundreaction force relative to bodyweight [5] may be of inter-est to clinicians where manipulation of lower limb loadis needed, such as with symptomatic knee osteoarthritis.The load influence from kettlebell training on specificjoints, or with musculoskeletal conditions more gener-ally, remains unknown and warrants investigation.Lumbar motion, compression and shear force data

during a kettlebell swing offer meaningful information,albeit limited to a single study [79]. These data are en-couraging, that in the absence of spinal pathology,mechanical loads through the lumbar spine during a 16-kg two-handed hardstyle kettlebell swing are low andnot indicative of increased risk of harm. Indeed, com-pression loads were reported below the National Insti-tute for Occupational Safety and Health action limit, andhalf that of lifting 27 kg on an Olympic bar. Resultantspine loads were described as “quite conservative” and“not be problematic”. How these forces might changewith increasing kettlebell weight is not known and clini-cians should be cautious not to assume they remain low.Biomechanical modelling identified a unique posteriorshear force in the lumbar spine during a kettlebell swing.Whether this is a consistent feature across individualsremains to be seen, and the potential effect on patho-logical presentations such as spondylolisthesis, a parsinterarticularis defect, or osteoporosis is unknown. Morecommon resistance training exercises such as a barbelldeadlift produce an anterior shear force at the level ofL4/5, with forces of much larger magnitude reportedamong competitive power lifters [142]. Until further datais available, clinicians would be wise to use caution ifconsidering a kettlebell swing with someone who has a


significant or unstable lumbar spine pathology. Add-itionally, among kettlebell-trained subjects, the lumbarspine was reported to flex approximately half full range(up to 26o) at the bottom of the swing [79].Greater time-under-tension (impulse) may support the

premise of enhancing power endurance, however theclinical utility of impulse when compared with otherforms of resistance exercise is unclear [76]. The manipu-lation of resistance training variables is widely consid-ered an essential strategy to maximise muscularadaptations, and guidelines exist in relation to volumeload to maximise muscle hypertrophy. No consensushowever currently exists for a metric of volume load inresistance training [143] and kettlebell weight is likely tobe well below an intensity threshold sufficient to stimu-late anabolism. Any difference in impulse per repetitioncompared with back squat and jump squat [76] are un-likely to be clinically meaningful when compared withthe kettlebell weight and number of repetitions per-formed in a training session. Further research is requiredto better understand the mechanical demands of kettle-bell training, which may involve several hundreds of rep-etitions and multiple exercises.The clinical utility of reduced torque in the lumbar ex-

tensor muscles following swings is unclear [81]. Consist-ent with temporal and kinetic data [78], no significantdifference in countermovement jump performance [82]suggests that kettlebell swings are unlikely to provideany meaningful benefit to jump performance. Change inpain pressure threshold may be used in clinical practice,however there is no suggestion that this phenomenonwould be unique to a kettlebell swing, or that change inpain pressure threshold following kettlebell swings [60]has a clinically meaningful effect. Loaded carries are alsonot unique to kettlebells, so the utility of carry data forclinical practice in relation to the specific prescription ofkettlebell exercises remains limited [61, 62]. Kettlebellcarries however (rack, bottoms-up, overhead, suitcase)have been proposed as good exercise to increase trunkstiffness and reduce “energy leakage” when transmittingpower generated by the hips, to sporting and daily livingtasks involving pushing, pulling, lifting, carrying, andtorsional exertions [144]. These principles do have clin-ical utility but have not been investigated.Kettlebell training appears to induce a cardiometa-

bolic response sufficient to improve cardiovascularfitness [1, 59, 84, 85, 87, 88, 91–96] provided thatthe dose (kettlebell weight, volume load and work:rest ratio) is appropriate for the individual and suffi-cient to provide a supraphysiological load. Effectshave often been over-reported, and reliable clinicallymeaningful effects remain to be demonstrated in ahigh quality randomised controlled trial. Many of thesame investigations have also demonstrated kettlebell

training produces a lower peak VO2 when otherphysiological and metabolic variables are matched[83, 88, 93, 95]. These data are consistent with sug-gestion that hardstyle kettlebell training is not themost effective form of exercise for improving cardio-vascular capacity. Physiological mechanisms for thepressor response (disproportionately elevated HRwhen compared to oxygen consumption during re-sistance training) have been proposed, however theseclaims have not been validated in practice [8].A basic kettlebell swing protocol has shown to pro-

duce a similar cardiometabolic demand to other formsof physical activity such as walking [95] and cycling [94].For someone who is home-bound with a ca

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