OVERUSE INJURIES IN RUNNING

CONTENTS Overview; Basic biomechanics of running; Epidemiology of running injuries; Causative factors; Dose-response relationship; and Prevention strategies Evaluation strategies

OVERVIEW Commonest type of sports in Hong Kong Mass entrants in the Tsing Ma Bridge

Marathon and ‘98 New Airport International Marathon and 10 km. run

BENEFITS OF RUNNING

Improve physical fitness level;

Positive feeling of good health;

Friendship and socialisation;

Enjoyment; and Rewards

1. Establishing the extent of the sports injury problem• Incidence• Severity

Sequence of PreventionSequence of Prevention

2. Establishing 2. Establishing aetiology & aetiology & mechanism of mechanism of injuriesinjuries

4. Assessing their 4. Assessing their effectiveness by effectiveness by repeating step 1repeating step 1

3. Introducing 3. Introducing preventive preventive measuresmeasures

EPIDEMIOLOGY OF RUNNING INJURIES Knutzen and Hart (1996) A comprehensive review on running

injuries Retrospective studies (16) Prospective studies (5) Annual incidence 48-65% (P); 24-60% (R)

EPIDEMIOLOGY OF RUNNING INJURIES

Retrospective studies Marti et al. (1980) Surveillance study of 4,358 runners in

a road race 1,994 injured (46%)

26.5

27

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Knee Leg and ankle Foot

Marti

PROSPECTIVE STUDY Walter et al. (1989) Ontario Cohort study enrolled 1,680 runners at two races prospective survey for 12 months. 1,288 completed the follow-up data 48% were injury.

SITE OF INJURIES

Case series studies

Clement et al. (1981) Review 1,650 patients between 78-80.

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Knee Leg and ankle Foot

ClementMarti

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Knee Leg &ankle

Foot Hip Back Thigh

Walter et al.

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Knee Leg &ankle

Foot Hip Back Thigh

Walter et al.Clement et al.

EPIDEMIOLOGY OF INJURIES Data collection far from comprehensive Subjects selection bias Injuries ill-defined True incidence of injuries yet to be determined

(for details, refer to Caine et al., (1996) epidemiology of sports injuries. Human Kinetics. Chapter 22)

ESTABLISHING AETIOLOGY & ESTABLISHING AETIOLOGY & MECHANISM OF INJURIESMECHANISM OF INJURIES

RUNNING EVENTSRUNNING EVENTSRUNNING EVENTSRUNNING EVENTS CHARACTERISTICS NEURO-MUSCULAR PREDOMINANCE

(SPRINT & HURDLES) CARDIO-RESPIRATORY PREDOMINANCE

(MIDDLE & LONG DISTANCE) CAPACITY BASED ON STRENGTH &

ENDURANCE (AEROBIC & ANAEROBIC) PHYSIOLOGICAL ADAPTATION TAKING

PRECEDENCE OVER TECHNIQUE

RUNNING CYCLE

No double support phase

Stance (40%) Float (30%) Swing (30%) Contact,

midstance,propulsion forward swing & foot

descent

Jogging: Stance > Swing

Distance: Stance = Swing

Sprinting: Stance < Swing

RUNNING BIOMECHANICSRUNNING BIOMECHANICSINITIAL GROUND REACTION FORCESINITIAL GROUND REACTION FORCES

VERTICAL GROUND REACTION FORCES VERTICAL GROUND REACTION FORCES

2-3 TIMES BODY WEIGHT2-3 TIMES BODY WEIGHT ANTERIOR /POSTERIOR FORCES - 50% B.W.ANTERIOR /POSTERIOR FORCES - 50% B.W. MEDIAL /LATERAL SHEAR - 10% B.W.MEDIAL /LATERAL SHEAR - 10% B.W. DURATION - 200 - 600 ms.DURATION - 200 - 600 ms. PEAK IMPACT FORCES AT 20-30 ms.PEAK IMPACT FORCES AT 20-30 ms.

CAUSATIVE FACTORS IN RUNNING INJURIESEXTRINSIC Training error Running Terrain and Surfaces Running shoes

TRAINING ERROR Clement et al. (1981) Sudden increases in mileage or intensity High intensity without rest High level of competition

Marti et al. (1980) Increased association of injuries when

mileage (>50 km./week) Ontario Cohort study > 40 km/week.

RUNNING TERRAIN AND SURFACES

Clement et al. 1981 Uneven, hardness, road camber Uphill and downhill

RUNNING SHOES

FOOT MUST BE STABLE

SHOCK ABSORBPTION – REDUCE THE INITIAL HEEL SPIKE

RIGID LEVER FOR THE THRUST OF FORWARD MOTION

RUNNING SHOES SHOCK ABSORPTION EFFECTRUNNING SHOES SHOCK ABSORPTION EFFECT

FACTS:

The Shock absorption effect will easily lost 40% after 400-800 Km. of running

(After Cook et al 1985)

FACTS:

The Shock absorption effect will easily lost 40% after 400-800 Km. of running

(After Cook et al 1985)

CAUSATIVE FACTORS IN RUNNING INJURIESCAUSATIVE FACTORS IN RUNNING INJURIES

INTRINSIC

IMPERFECT MUSCULOSKELTAL ALIGNMENT

FLEXIBILITY

INTRINSIC FACTORS Cowan et al., 1996 Investigate effects of anatomic variation on

risk of overuse injuries Prospective study Subjects: 294 army infantry for 12/52

training Risk of injury increase with Valgus knee

(RR=1.9) and Q angle >15 degree (RR=5.4)

INTRODUCING PREVENTIVE MEASURE

PRINCIPLES OF TRAINING

BIOLOGIC ADAPTATIONS TO IMPROVE PERFORMANCE IN SPECIFIC TASKS

TRAINING PROGRAM

Yeung and Yeung 2001 Investigate the characteristics and training

profile of marathon finishers and non-finishers

Subjects: 113 runners from Standard Chartered Hong Kong Marathon 1998

Personal and training profileProfiles Finishers

(55)Non-finishers (58)

P-value

Marathon finished

4.13 0.42 0.01

Weekly training 51.94 8.57 0.00

Longest distance 27.51 5.44 0.00

Warm-up 11.02 7.65 0.06

Cool down 6.42 4.78 0.27

Optimal mileage 71.58 28.80 0.00

TRAINING AND RECOVERY

Warm (Cool) down Whirpools and Spas Massage Rest and Sleep Psychological Nutritional

COOL DOWN

Lactate can be removed from blood and muscle more rapidly by light continuous aerobic exercise

Optimal rate of removal 30 - 45% VO2 max

50-65%

OVER TRAINING Sign of over training Fatigue and poor performance Increase resting heart rate Weight loss Irritability and sleep disturbance Elevated Serum Creatine Phosphokinase

(CPK)

TRAINING TERRAIN

TRACK vs ROAD CROSS TRAINING – UPHILL vs

DOWNHILL TREADMILL

FUNCTIONAL ANATOMY OF FOOT

Normal Foot arch, flat foot and Pes Cavas

Effects of foot arch or weight bearing

SELECTION OF RUNNING SHOE

RUNNING SHOES

Be ComfortableProtect the wearer from injury Not be a source in injuryFacilitate athletic performanceBe durable and economical

SHOE COMPONENTSSHOE COMPONENTS

Last Straight / Curve Last Slip Last Board Last Shoe Upper Toe-box Heel Counter Achilles Tendon Pad Sole Outsole Midsole Insole

PRONATORPRONATOR

Needs stability and arch support Features: Straight last; Supportive heel counter; Extra support on medial side Increased medial wedging on insole Semirigid orthotic

NEUTRALNEUTRAL

Need good fit, adequate arch and shock absorbing

Features:Semicurved last;Extra cushioning & Medium heel counter

SUPINATORSUPINATOR

Needs flexibility, maximum shock absorbing

Features:Semicurved or curved last;Slip lastMaximum cushioning

ASSESSING THE EFFECTIVENESS ASSESSING THE EFFECTIVENESS OF INTERVENTIONOF INTERVENTION

A systematic review of interventions to prevent lower-limb soft-tissue running injuries

Yeung and Yeung, 2001a and 2001b

Randomised Controlled Trials

Twelve studies, with a total of 8,806 subjects met the criteria for inclusion.

three main preventive strategies for running injuries:

modification of training schedule stretching exercises use of orthotics/support or footwear

modification.

Modification of training schedule

Intervention Relative risk

Reduction of frequency of training

3/7 vs 5/7

0.19 (0.06-0.66)*

Reduction in duration of training

15-30’ vs 45’per session

0.41 (0.21-0.79)*

Reduction in running distance

280 km vs 82 km in 12 weeks

0.70 (0.54-0.91)*

STRETCHING

Stretching outside training session

Andrish et al., 1.27 (0.66-2.43)

Hartig and Henderson 0.57 (0.37-0.89)*

Stretching immediately before training session

Pope et al., 0.85 (0.43-1.67)

Pope et al., 0.83 (0.63-1.09)

Van Mechelen et al., 1.19 (0.71-1.99)

EXTERNAL SUPPORT OR FOOTWEAR MODIFICATION

Use of shocking absorbing insoles

0.87 (0.69-1.11)

Footwear modification 0.83 (0.71-0.98)*

Use of Knee brace 0.35 (0.13-0.91)*

Injuries from running can be reduced by modifying training schedules, but now guidelines are available from trials on training load. Wearing a knee brace with a patellar support ring may be effective in preventing anterior knee pain provoked by running