Recreational Injury Interventions

Physical Conditioning & Stretching

Background Stretching

Many athletes stretch their muscles before exercise because of the common belief that this reduces the risk of injury. However, the data on the effectiveness of stretching in preventing injury are very limited. Basic science data would argue against stretching as a mechanism to prevent injury (Shrier 1999). Increases in resting muscle compliance are associated with a decrease in resistance to injury in resting animal muscle.

We found two RCTs and one before-after study evaluating the effectiveness of stretching in preventing musculo-skeletal injuries.


Review of stretching studies:

Author

Pope et al, 2000

Study design and target population

Australian Army recruits RCT of platoons: 19 platoons (735 subjects) to intervention and 20 platoons (803 subjects) to control.

Intervention

Stretch protocol of 20 sec static stretch for each muscle group.

Outcomes

Any lower extremity injury that prevented returning to full activity within 3 days.

Results

Overall risk of injury was 5.5 injuries per 1000 training hours.

HR for the intervention group= 1.04 (95% CI 0.82, 1.33).

No significant effect of stretching on either soft tissue or bony injuries.

Study quality and conclusions

Well done study.


Author

Cross et al, 1999

Study design and target population

Before/after study.

195college football players.

 

Intervention

Static stretch program for LE.

Outcomes

Strain acute injury as certified by an athletic trainer, resulting in 1 day or more absence from practice.

Results

Pre: 155 injurie, 28% LE

Post: 153 injuries, 13.7% LE.

Study quality and conclusions

Weak study design.

 



Author

Van Mechelen, 1993

Study design and target population

RCT 421 male recreational runners.

 

Intervention

16 week intervention of warm up and stretching.

 

Outcomes

 

Results

RR= 1.12

Study quality and conclusions

Lot of non-compliance in both groups.

 

Summary of stretching interventions

There is evidence that stretching does not prevent musculo-skeletal injury. The best evidence comes form the RCT by Pope. This had sufficient power to detect any clinically important protective effect. This RCT is also supported by a prior systematic review by Shrier (1999) who found no protective effect of stretching.

Shrier (2000) also points out that there are no biological reasons to suspect that stretching would be protective.

1. An increase in tissue compliance is associated with a decreased ability to absorb energy.

2. Injuries usually occur within the normal range of motion.

3. Even mild stretching can cause damage at the cytoskeletal level.

4. Stretching increases tolerance to pain, which might result in further damage to injured tissues.

 

Recommendations on stretching programs

There is no evidence to recommend stretching programs to prevent athletic injuries.

 

Background Conditioning

Conventional wisdom and common sense indicate that athletes in good physical condition are less susceptible to injury. Cardiovascular fitness, muscle strength and flexibility are important for general health and well being as well as athletic performance. Studies which have evaluated various types of conditioning programs are summarized below.

Review of physical conditioning studies:

Author

Bixler and Jones, 1992

Study design and target population

Most closely resembles cohort study design with elements of case-cross-over design.

Population: Football players from 5 high schools in the Mid-Penn Football Conference.

Intervention

3 minute warm up and stretching routine prior to start of second half of game. 3 teams assigned to intervention group, two to control group.

Outcomes

Sprain and strain injuries occurring in the third quarter of game. Also recorded the number and severity of injuries. Injury defined as an event that was recognized by a trainer and that altered athletic performance. Severity defined as: Class 1 (any recognized injury) or Class 2 (injuries which caused player to miss one or more days of practice)

Results

108 injuries occurred in 55 games. 38% of injuries were ligament sprains and muscle strains. Number of third quarter sprains and strains per game significantly lower in intervention group (p<0.05).

Study quality and conclusions

Authors conclude short half time routine may reduce sprains.

Program implemented at the school level; for analysis intervention group teams were treated as controls when stretching routine not done at a specific game. No information available about players, equipment, fields, or football program.



Author

Cahill and Griffith, 1978

Cahill and Griffith, 1984

Study design and target population

Before/after study design.

Population: high school varsity football players in the Midstate Eight conference, Peoria . 12 years; 3,789 players

Intervention

Preseason conditioning program (PSC), duration 6 weeks. Program emphasizes total body conditioning, cardiovascular stressing, acclimatization to heat, flexibility drills, and agility exercises.

NC 1969-72

(no conditioning)

C1 1973-76, PSC with close supervision

C2 1977-1980, PSC not as closely supervised by sports medicine staff; coaches could modify program.

Outcomes

Knee injuries, defined as an injury severe enough to cause an athlete to miss 2 consecutive practices or one practice and a game.

Results

Injury rate:

NC 68 per 1000

C1 40 per 1000

C2 40 per 1000

Surgical operations:

NC 15.2 per 1000

C1 5.7 per 1000

C2 2.3 per 1000

Non-surgical hospitalization decreased C1, C2 from NC levels, p<0.05.

Study quality and conclusions

District wide program appears to reduce knee injuries (NC vs C1). Program success maintained under less supervised conditions (C2).

No information given on other facets of the football program, types of shoes worn, playing surfaces or physical condition of individual players.



Author

Heiser et al., 1984

Study design and target population

Before/after study design.

Population: Intercollegiate football players at University of Nebraska, 1973-1982

Intervention

Cybex II testing to detect muscle imbalances monitor hamstring strain rehabilitation. Isokinetic rehabilitation program to correct muscle imbalance initiated prior to season.

Outcomes

Hamstring muscle strains (both primary and recurrent)

Results

Group I (pre-Cybex) 41 primary hamstring strains in 534 player-years (7.7%); 13 players had recurrences (31.7%).

Group II (post Cybex) 6 injuries in 564 player-years (1.1%), no recurrences.

Study quality and conclusions

Isokinetic testing and rehabilitation of muscle imbalances can prevent hamstring strains, aid in rehabilitation and prevent recurrences.

Data not presented in article. No information on injury by player position. Group II: Conditioning program changed with the addition of closely supervised strength training for all players and increased emphasis on stretching.

Summary of physical conditioning interventions

The Heiser and Cahill sudies25-27  indicate that specific conditioning programs may reduce hamstring muscle strain and knee injuries in football. While one would expect that a well conditioned athlete would be less likely to be injured, there is no research evidence to support this statement.

Recommendations on physical conditioning programs

No recommendations can be made based on the available evidence.

Recommendations for future research

Randomized controlled trials are possibly the only way to control for all the individual and situational variations and study the contribution of conditioning to injury prevention in various sports.