Gait Analysis and the Mechanics of Running and...

Running Technique – Dr Neil Miller 15/04/2015

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Gait Analysis and the

Mechanics of Running and Injuries

Dr Neil Miller Director, Core Analyst Ltd.

Westbury Harriers, 13th April 2015

‘Survey’

• Are you interesteda) As a coach (including sports teacher and PTI)b) As a physio (or other therapist)c) As an athlete?

• Do you (or your client base) covera) Sprints (and jumps)b) Middle distance and club road and cross-countryc) Fitness and recreational running?d) Young athletese) Triathlon

© 2015

Handouts

Slides available as pdf

• Westbury Harriers site ‘members only’ area

• Others please sign up

• Also sign up for ‘Core Analyst’ newsletter

© 2015

Between 1992 and 2003, Paula Radcliffe’s maximum oxygen uptake stayed roughly the same, but her running economy improved by 15%

� 2:15:25 world record

Overview

© 2015

Max. O2 Uptake Running Economy


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Overview

• What do we ‘need’ to do to run? (Physicist)

+ How can your body perform this (Anatomy)

� Train for more efficient running,

with fewer injuries (Coach)

© 2015

Overview

• The Running Cycle (Outline)

• The same physics for runners of all types

• The big forces: gravity and momentum (inertia)

• If only we had wheels instead of legs!

• Wind resistance is actually quite small

• Rocking and twisting(the penalty of having two arms and two legs)

© 2015

Overview

• Slow Motion Video

• 240 fps = 1/8th speed

• Two cameras - side and end cameras (different runs stitched together with software)

• Comparative studies may be clocked at different rates

© 2015

Overview

• The Big Forces• Gravity and Momentum

• Elastic Bands and Energy Return

• Posture and Core Control

• Two Arms, Two Legs• Doing the Twist

• Rocking and Rolling

• Hitting the Ground: Crossing Over & Pronation

© 2015


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Follow-On

• Practical drills and exercises• 7pm Thursday 14th May, Coombe Dingle

• Structured as per this talk (slight re-ordering)

© 2015

Overview







© 2015

Forces and Phases

• The big forces: Gravity and ‘momentum’ (overcoming inertia)

• Leg movement – the phases

• Stance (or Contact)

• Flight (or Aerial)• Recovery (or Swing) = Flight + Stance + Flight

• Stance:First Contact � Braking (or Cushion) � Mid Stance

� Drive (or Propulsion) � Toe Off

Gravity and Momentum © 2015

Minutes/Mile Relative Speed Energy ↑(Pugh, 1971)

2:40 min 22.5 mph 13%

4:00 min 15 mph 6%

5:20 min 11.25 mph 3.3%

6:40 min 9 mph 2.1%

8:00 min 7.5 mph 1.5%

(Air Resistance)

How much energy used in overcoming wind resistance (relative speed)?



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(Air Resistance)


� Ignore air resistance in basic model, (treat it as an

adjustment, later)

+ Newton’s First Law

� Drive is mainly needed to compensate

for braking

(waste of energy)

Weights and Measures

Typical rates and

timesSprints

Club

1500mFitness

RR *

LeaderRR Tail

Steps / minute 270 200 170 195 160

Contact time 0.10 s 0.15 s 0.23 s 0.20 s 0.31 s

Flight time 0.12 s 0.14 s 0.12 s 0.10 s 0.06 s

Recovery time 0.34 s 0.44 s 0.47 s 0.41 0.43 s

Average force 2.2 bw 1.9 bw 1.5 bw 1.5 bw 1.2 bw

Peak force (est.) 3.5 bw 2.9 bw 2.1 bw 2.1 bw 1.6 bw


* RR = Riverbank Rollick (muddy 10 miles), filmed 4 miles in.

Weights and Measures

% of

Total

55 kg Youth

or Woman72 kg Man

Leg (each) 10% 5.5 kg 7.2 kg

Arm (each) 6% 3.3 kg 4.3 kg

Head 8-9% 4.7 kg 6.1 kg

Torso 60% 33 kg 43 kg


Gravity

• Peak force on the ground

• 2 to 3½ x bodyweight (peak) off one leg

• The lifting muscles

• Gluteus maximus and quadriceps

(also hamstrings and adductors)

• Running (stance phase) = rapid lifting

• Peak force ~0.05 – 0.12s after landing

�� Need Pre-engagement of muscles ≡ correct landing



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Momentum

• Halt backwards rotation, move the leg forwards, and halt again, ready for landing

• ~5.5 – 7.2kg leg recovers in ~ ⅓ – ½ sec• Hip and knee flexors: Rectus Femoris & Iliopsoas

• Halting the leg: The hamstrings

• Overcoming Gravity v Overcoming Momentum• Handling one well ↔ handling the other well


The Big Force Breakdown

Importance seen when things go wrong!(Ignore hips for now)

• The “Big Force Breakdown”

• Chicken and Egg:Braking heel-strike � Long push �

Leg left behind �Foot arrives late, hamstring braking �

Braking heel-strike…

• Also no pre-engagement � running low

• Hallmarks: Leg left behind; shin swings through late


(The Big Force Breakdown)

Sprinters particularly affected

• Historically, plagued by hamstring problems

• Understanding gait leading to big improvements

• Trickle-down to endurance running

• (Tony Hadley national sprints coach mentor)

Unfortunate Consequence of Pre-Engagement:• Outwards rotation just before landing

(Common amongst sprinters)


What to Watch For

What to look for in real life (BFB):• Impression of the legs


Good Bad

Foot flat, shin vertical Breaking heel-strike

Short sharp drive Long drive

Foot tucked under ‘Leaving the leg behind’

Good knee drive Lack of knee drive

Tall, urgent action Sinking, long loping stride


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Motion of the Foot

Even foot flight Leaving the foot behind

© 2015Gravity and Momentum

Watch the flight of the foot• Foot ‘left behind’, tucked behind, falls steeply, jerks back on landing

Potential Consequences

• Waste of Energy• Heel-strike:

• Front shin pain, stress fractures �

• Aggravate any pronation problems (q.v.)

• Running low, over-striding:• Patella tendon strains, Osgood Schlatters,

patellofemoral pain

• Reach and breaking • Hamstring overuse


Causes

What causes this?

• Unbalanced training (too much distance, running tired)

• Other sports (football, rugby, triathlon)

• ‘Style switch’

• Benefits as well as problems

• Growing (bone length before muscle mass)

• Sitting down (underactive gluteus maximus, tight iliopsoas)

• Poor control of the pelvis (more later…)


Overview







© 2015


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Tendons and Fascia

The ‘Stringy Bits’• Tendons (e.g. Achilles tendon)

connecting muscle to bone

• Not always given separate name (‘hamstrings’ = muscle + long tendons)

• Fascia (e.g. Plantar Fascia) covering and connecting

• ‘Aponeuroses’ (≡ Fascia)

All have similar composition & properties

Elastic Bands and Energy Return © 2015

Muscle v Tendons

Muscle Tendon, Fascia

(Inelastic) Elastic (80% - 93% energy return)

Eats up energy when engaged No energy required

Adapt in weeks (or days) Adapt in months

Loved by coaches, PTIs, sports scientists

Loathed by surgeons

Relatively weak Strong (by cross-section)

Variable force / Variable length (Hooke’s law: δ. length ∝ force)


Running Economy

• Muscle and tendon often paired in a chain

• Muscles used as ‘adjustable spanners’; Tendons used as elastic bands

• Achilles tendon and calf muscles (+ Plantar fascia)

• ‘Hamstrings’ (both stopping the swing and tucking the foot)

• Patellar tendon and quadriceps

• Up to 50% energy can be recycled


Potential Injuries

• Muscle adapts faster than fascia/tendon� Fascia/Tendon strains when building up

(e.g. Plantar fasciaν, Achilles tendon)

• Muscle atrophies faster than tendon� Muscle strains when coming back

(e.g. calf muscle)

� Introduce speed work progressively but consistently+ Come back from injuries slowly



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Overview







© 2015

• Weight pushed down in front

• Spine (only) pushes up

• 24 joints �Mechanically Unstable

Instability of the Back

© 2015Posture and Core Control

Thoracolumbar Fascia (TLF)


• Key central structure• Fascia, connects to spinous

process

• Thick, strong, deep

• Mechanically important

• Multiple muscular attachments• At edges, top and bottom

• Multi-layer, encloses muscles

Simplistic Analogy

• Smooth fly-sheet on a tent• Muscles are ‘guy ropes’; correct length / gentle tension

• Backbone (spinous process) defines the shape



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Posture

• Long (straight) back≡ Smooth even TLF

• Muscles as guy ropes• Adjustable length

• Any over-tight or slack muscle affects the whole

• Slight (natural) lean• Average drive up spine

• Stability mechanics

• Wind resistance


Rectus Abdominis

(RA)

↕(6 or 8 Pack)

(Little Fascia)

Abdominals and Fascia


TransverseAbdominals

(TA)

↔

Note the fascia (in white)

Note attachments:TLF; Pelvis

‘Core’ Connections


Transverse Abs form a continuous girdle with the TLF ″ Internal Obliques

Core Control ↔ Posture

All abdominals have connections

to the pelvis

Controlling the Pelvis


Pelvis: ‘Chassis’ of the body

Control of abdominals ↔

Control of the legs

Poor control of pelvis �big force breakdown

• (more later …)

� Need good use of core abs to run properly


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What to Watch For

Watch for:• Shape of the back (‘posture’)

• Forwards lean• = Hips Behindc

• Core• Tilt of pelvis (tuck T-shirt in)• Hinge at lower back

• Foot left behind mechanics, BFB

In real life


Causes


What causes this?• Posture

• Study; Nintendo

• Attitude (feeling down v sparky)

• Other sports (football, cycling, orienteering)

• Core / Control of Pelvis• Tight hip flexors (sitting down)

• Lack of lifting (homeowner lifestyle), asymmetry ~

• Underweight (growing etc.)More later …

M



What consequences and injuries might result?

• ‘Foot left behind’ gait and associated injuries

• Lower back pain, stress fractures

• Loss of control of pelvis �

• Hip drop, crossing over … (more later)

Overview







© 2015


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Doing the Twist

• Push/pull legs forwards/backwards

• 2 x 7kg, offset from centre

≡ Twisting about vertical axis

• Arms counter-swing• Lighter but wider offset

� Need to ‘couple’ shoulders + pelvis

� Use of oblique muscles

Twist board demonstration

© 2015Doing the Twist

Diagonally Linked

ObliquesExternal

⁄Internal

Abdominals and Fascia


Internal Oblique

^

Abdominal Coupling


Coupling

Coupling

• Connection between upper trunk (shoulders) and pelvis to control hip rotation

• Coupling via (abdominal) obliques

• Used with forwards swing ��

• Coupling via back (Lats, TLF)

• Used with backwards swing (�)



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What to Watch For (Arms)

• Drive through back

• Over-use of back instead of abdominals

• Hips rotate, leg corkscrews after drive

• Poor coupling between shoulders and pelvis

• Helicopter arms

• Underweight athletes

• Tight shoulders

• Quiet arms, high hands, wide arms, etc.


What to Watch For (Legs)

Uncontrolled torsion in hips (one leg driving forwards vs other leg driving back �

• Difficulty Controlling Knees

• Lack of coupling between shoulders and pelvis

• Aggravated by tight hip flexors

• Other examples (including asymmetric arm and knee action)

• (more with next section)


Causes

What causes this?

• Upper body problems (arms and obliques):

• Weak abdominals, especially obliques, also pectorals etc.

• Over-use of the back (lats, etc.)

• Habitually poor technique

• Tight shoulders (stress, backpacks, lack of stretching)

• Big force breakdown (see Gravity & Momentum)

(Consequences – with Rock and Roll below)


Overview







© 2015


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Hip Drop

Offset between leg joint and body centre � hip drop

© 2015Rocking and Rolling

Side Lean

Side lean is a ‘cheat’, with a similar cause


What to Watch For

Examples• Hip drop

• Line of shorts

• Tuck T-shirt in! Different coloured shirt + shorts

• Wide arm (‘right hook’); Rise of shoulder

• Side lean• Sway of body

• Focus on distant tree

Hard to Spot


Causes

What causes this?

• Weak (or inhibited) ‘hip abductors’

• Weak or unused (abdominal) obliques

• Women usually have broader hips

• Other sports, unequal use of each side

• Footballer’s syndrome



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What consequences and injuries might result?• Lower back problems (scholiosis)• Internal hip problems• Knee problems from Knee rotated or collapsing in

• Rotates in (hip drop or pronation, see below); or

• Planted in (swings with foot out)• Torsion of femur v tibia

• ITB (TFL) overuse – see below


Overview

© 2015







Line of Feet Cross-Over

Line of feet ‘cross-over’

• Knee swings across / hip drop / side lean / outwards drive

Effects:

• Tight ITB (why?)

• Tensor fascia latae over-use

• Pain at outside of knee

• Foot lands on outside and rolls sharply inwards �Over-Pronation…

© 2015Hitting the Ground

Pronation - Causes

(Over-)Pronation

• Causes:• Lack of support in shoe (worn or inappropriate)

• Poor lacing (loose – young athletes; use of power lacing…)

• Line of feet cross-over +Foot planted outwards, also supinated foot plant

• Tight hamstrings, et al

• (Outwards rotation just before landing)(already covered; pre-engagement)

• Aggravated by heel-strike



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Pronation - Effects

Effects:• Medial (inside edge) shin pain

• Plantar fasciitisAlso caused by ↑ mileage (see slides on fascia)Also flat foot, high arch, tight Achilles

• Knee problems ( rotation of the shin) (see also hip drop)

• Achilles tendon problems from whiplashAlso caused by ↑ use, tight calves

+ various other problems


Power Lacing


Summary







© 2015

Thank You!

... Any Further Questions?

... Any Desire for Further Workshops?

Practical drills and exercises7pm Thursday 14th May, Coombe Dingle

Contact: Neil Miller [email protected]

www.coreanalyst.co.uk YouTube.com/CoreAnalystTV

facebook.com/CoreAnalystLtd

© 2015

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