Contrary to popular belief, stretching before a workout
does not appear to decrease the occurrence of injury. The
risk of injury seems to be about equal for those who stretch
and those who do not stretch before exercise. The warm-up,
not stretching, seems to be the important deterrent for injury,
performed before an exercise bout. Stretching seems to offer
more long term benefit such as maintaining functional flexibility
and correcting particular muscular
imbalances.
Shrier's (1999) review of the literature found three articles
that suggested stretching was beneficial included a co-intervention
of warm-up. One study found stretching was associated with less
groin/buttock problems in cyclists, but only in women. Five studies
suggesting no difference in injury rates between stretchers and
non-stretchers and three suggesting stretching was detrimental.
One reason stretching is thought to be ineffective in reducing
the risk of injury is the fact that most muscle injuries occur
when the muscle is eccentrically contracted within the normal
range of motion (Shrier 1999). It seems more flexible individuals
do not necessarily have less incidence of injury (Gleim 1997).
In some cases those with greater flexibility may actually experience
more injury, particularly if the excessive flexibility compromises
joint integrity (Surberg 1983; Jones 1997). Although excessive
flexibility may contribute to joint laxity, flexibility and joint
integrity are not necessarily mutually exclusive. It may be possible
for a joint to posses a combination of exceptional flexibility
and excellent joint integrity.
Greater flexibility may impair performance in sports that
that do not require a high degree of flexibility such as running.
Runners with less flexibility are actually more efficient at
running (Jones 2002). Intense static stretching may also reduce
maximum force production. The loss of voluntary strength and
muscular power may last up to one hour after the static stretch
(Evetovich 2003, Young 2003). People who participate in activities
that require more than average flexibility (eg: gymnasts, dancers,
figure skaters) may still find stretching beneficial to their
performance.
The ACSM recommends flexibility training a minimum 2 to 3
days per week holding each stretch for 10 to 30 seconds to mild
discomfort; 3 to 4 repetitions per stretch. On a PNF stretches
ACSM suggests a contract 6 seconds followed by a 10 to 30 second
assisted stretch.
McCallister et. al. (2004) found that longer recovery days
between stretching seemed to enhance stand and reach measurements:
|
Rest (hours) |
Stand & Reach (cm) |
|
24 |
4.2 |
|
48 |
4.8 |
|
96 |
6.9 |
This data suggests it may not be necessary to stretch daily
but instead take a few days recovery between sessions.
Although stretching does not seem to offer many short term
benefits when performed before exercise, stretching does seem
to offer other long term benefits. Improved flexibility may help
prevent back and other orthopedic problems. Individuals with
certain muscular imbalances or postural problems can benefits
from stretching. Stretching can help maintain flexibility which
may otherwise decline with age or inactivity due to an injury.
Stretching may be more safely performed after exercise, when
muscles are warm. Unless an activity requires extreme flexibility,
stretching before is probably unnecessary. And even then, stretches
should be performed after a warmup.
American College of Sports Medicine, (2000) ACSM's Guidelines
for Exercise Testing and Prescription, 6; 158.
Bracko, MR (2002). Can stretching prior to exercise and sports
improve performance and prevent injury? ACSM's Health & Fitness
Journal, 6(5), 17-22.
Evetovich TK, Nauman NJ, Conley DS, Todd JB (2003). Effect
of static stretching of the biceps brachii on torque, electromyography,
and mechanomyography during concentric isokinetic muscle actions.
J Strength Cond Res. 17(3):484-8.
Gleim, GW & McHugh, MP (1997). Flexibility and its effects
on sports injury and performance. Sports Medicine, 24(5), 289-99.
Hedrick A (2000). Dynamic flexibilty training. Strenght and
Conditioning Journal 22, 33-38.
Herbert, RD & Gabriel, M (2002). Effects of stretching
before and after exercising on muscle soreness an risk of injury:
Systematic review. British Medical Journal, 325 (7362), 468-470.
Jones AM (2002). Running economy is negatively related to
sit-and-reach test performance in international-standard distance
runners. Int J Sports Med. 23(1):40-3.
Jones BH (1997). The role of medical surveillance and research
in army injury prevention. American College of Sports Medicine
Conference abstract, Denver.
McCallister TL, et. al. (2004) Days of rest between stretching
bouts increased hamstring flexibility. Journal of Athletic Training.
Supplement 39(2), 99-100.
Ninos J (2001). PNF-Self Stretching Techniques, Strength and
Conditioning Journal 23(4); 28-29.
Shellock, FG & Prentice, WE,(1985). Warming-Up and Stretching
for Improved Physical Performance and Prevention of Sports-Related
Injuries, Sports Medicine, 2: 267-278.
Shrier I (1999). Stretching before exercise does not reduce
the risk of local muscle injury: a critical review of the clinical
and basic science literature. Clin J Sport Med. 9(4): 221-7.
Surberg PR (1983) flexibility exercise re-examined. Athl Tr
18:37-40.
Young WB, Behm DG (2003) Effects of running, static stretching
and practice jumps on explosive force production and jumping
performance. J Sports Med Phys Fitness. 43(1):21-7.