Stretching is NOT the best way to become flexible!
Stretching in America is a cult. every fitness-junkie guru preaches flexibility. they growl, they drool and they promise hell to the infidels who don't or won't stretch. yet the stretching methods they offer are at best laughable, at worst dangerous.
Americans lose flexibility as they grow older because they are used to relying on the elasticity of their tissues. a lifetimes of activity builds up microtrauma in our muscles, tendons and fascia. when it heals, a scar is formed. it pulls the wound together, making the muscle "shorter." some american doctors believe that relaxed stretching after exercise can prevent the muscle from healing at a shorter length. that point of view giver some credibility to some sick stretching methods.
I heard that sumo wrestlers used to assume their deepest split position, then have their sensei jump in their thighs to rip the tissues and bring the big boy down to a full split. in a few weeks or months the ground meat supposedly heald at a new length and splits were no longer a problem. I do not know if someone was pulling my leg with this story, but i do know an aerobic instructor who purposedly tears her hamstrings by overstretching them, then spends hours in the position to insure that the muscles will heal at a new, greater, length. sick --very sick.
even if you could prevent the muscle from shortening--and that is questionable--a stiffening of the tendons and ligaments is certain. "there isn't an exercise that can prevent the aging of connective tissues. it's a certain as radioactive decay," quipped Academician Nikolay Amosov from the former USSR.
Ligaments and tendons are made of collagen, which gives them strength, and elasting, which, as its name implies, provides elasticity. as you age, the elastin/collagen ratio changes in favor of collagen, or scar tissue. If you relied on tissue elasticity for flexibility, you can kiss your flexibility good-bye. and if you put up a fight and try to literally stretch yourself, change the mechanical properties of your muscles, tendons and ligaments, your desperate attemps will bring more injuries than flexibility.
------------------------------------------------------
Proprioceptive Neuromuscular Facilitation - If you can spell it, splits ought to be a piece of cake!
A more proactive way to relax the muscle into the stretch is Proprioceptive Neuromuscular Facilitation, a spelling test nightmare from the physical therapists' arsenal.
Developed by the American Dr. Henry Kabat, half a century ago, PNF works by fooling your stretch reflex. Here you are, stretched out to what your body thinks is the limit. The muscle does not seem to be able to get any tenser. yet you make it happen by flexing it.
Everything in this world is relative. What felt maximally tense before the contraction, does not feel quite tight in the aftermath. You eke out a little more stretch.
Put it more scientifically: Contracting a muscle inhibits the stretch reflex in this muscle, via an element in your spinal cord called a Renshaw cell. Essentially the Renshaw cell tells the stretch reflex, "Hey, don't panic, man! the muscle is already contracting, no sense in overdoing it."
It has been known since Russian dog abuser Pavlov's times that neural processes are inert--they respond to stuff with some delay. They are like those dull-witted comrades whom we called 'brakes' in the Russian military.
Applied to stretching, this means that after you terminate a contraction, the stretch reflex in the given muscle will be temporarily suppressed--and the muscle will not resist stretching much. At least for a little while. The window of opportunity is narrow: studies show that the muscle's resistance to stretch is minimal within the first second after the contraction; by the fifth it is up to 70% of the initial tension, then it is back to square one.
To sum up the standard PNF technique, contract the stretched muscle for the specified duration, anywhere from a second to a few minutes, then relax it, and immediately--understand the difference between 'immediately' and 'rapidely' for your own good!-- stretch the temporarily sooperating muscle a little further.
-------------------------------------------------------------------
Effect of stretching on risk of injury
Two studies evaluated the effects of stretching before exercising on the risk of injury in new military recruits undergoing 12 weeks of initial training. The first study investigated effects of supervised stretching of calf muscles before exercising (two stretches of soleus and gastrocnemius muscles for 20 seconds on each limb, total stretch time 160 seconds) on risk of six specific leg injuries (lesions of the Achilles tendon, lateral ankle sprains, stress fractures to the foot and tibia, periostitis, or anterior tibial compartment syndrome). The second study investigated effects of supervised stretching of six muscle groups in the lower limbs before exercising (one 20 second stretch to each muscle group on each limb, total stretch time 240 seconds) on risk of soft tissue injury, bone injury, and all injury. Recruits were considered to have sustained an injury if they were unable to return to full duties without signs or symptoms in three days. In both studies, subjects in both stretch and control groups also performed gentle warm up exercises. The two studies yielded similar estimates of risk reduction (hazard ratios 0.92 (0.52 to 1.61) and 0.95 (0.77 to 1.18 )).
Risks of injury in the two studies differ because injury is defined differently. Time to event data (2630 subjects, 65 platoons) were combined; 1284 subjects (32 platoons) were allocated to stretch groups and 1346 (33 platoons) to control groups. The discrepancy in sample size occurred because subjects were quasi randomly allocated to an odd number of platoons by military personnel who did not participate in the studies, and then platoons were randomly allocated to groups by the experimenters. A total of 181 injuries occurred in stretch groups and 200 injuries in control groups. Survival curves for stretch and control groups were similar . For the meta-analysis the data were analysed with a Cox regression model that incorporated a study factor (study 1 or 2) and a stretch factor (stretch or control). An interaction term was also included in the model initially but was subsequently omitted because it did not contribute significantly (P=0.88 ). Additional analyses were undertaken to take account of possible clustering of outcomes by platoon, but the results were essentially identical so are not reported here. The pooled estimate of the hazard ratio for the stretch factor was 0.95 (0.78 to 1.16, P=0.61).
----------------------------------------------------------
Effects of stretching on risk of injury
The pooled estimate from two studies was that stretching decreased the risk of injury by 5%. This effect was statistically non-significant. Even if this effect was not simply a sampling error it would not be large enough to be of practical significance. In army recruits, whose risk of injury in the control condition is high (approximately 20% over the training period of 12 weeks), a 5% reduction in relative risk implies a reduction in absolute risk of about 1%. Thus, on average, about 100 people stretch for 12 weeks to prevent one injury and (if the hazard reduction was constant) the average subject would need to stretch for 23 years to prevent one injury. Most athletes are exposed to lower risks of injury so the absolute risk reduction for most athletes is likely to be smaller still
---------------------------------------------------------------
What happened in Australia
Randomized controlled trials might help clear up the picture, but unfortunately there are only two such studies in the literature. In one of them, 1093 male army recruits were randomly divided into stretch and control groups. Recruits in the stretching group unkinked their calf muscles during their warm-ups, while control-group subjects did not. At the end of the experimental period, the total frequency of five different types of lower-leg injury in the stretch group was 4.2 per cent, compared with 4.6 per cent for the control group, but the difference was not statistically significant.
In the second study, 1538 male Australian army recruits were randomly allocated to stretch and control groups. In this second study, recruits in the stretch group statically loosened six key lower-limb muscle groups (gastrocnemius, soleus, hamstrings, quads, hip adductors, and hip flexors) every other day - prior to training - for 20 seconds each. The fitness, age (which ranged from 17 to 35 years), height, weight, body-mass index (BMI), and day of enlistment were recorded carefully for all subjects (the first five factors have been associated with injury risk in various pieces of scientific research; day of enlistment was included because - anecdotally - Australian-army-recruits' injury rates seem to rise later in the year). The training lasted for 11 weeks and included 40 training sessions (about four per week) totalling 50 hours of exercise. Training activities included marching while carrying a rifle and backpack (10 hours), running over distances ranging from four to eight kilometres (10.5 hours), negotiating obstacle courses (12.5 hours), carrying out circuit training (7.5 hours), swimming - plus pool-side press-ups and sit-ups (four hours), and battle training (wrestling, log lifting, fireman's-lift training, and shoulder rolls), which added on another 5.5 hours. Stretch-group members interspersed four minutes of light jogging and side-stepping with their stretching routines (this generally meant 40 seconds of jogging and side-stepping in between the 20-second stretches). Control-group recruits did carry out the warm-up jogging and side-stepping but completed no static stretching at all. Over the course of the 11-week study (which incorporated a total of 60,013 hours of training), there were 175 lower-limb injuries in the control group and 158 maladies in the stretched recruits. The overall injury rate was 5.5 injuries per 1000 hours of physical training, or one injury every 181 hours (by the way, this is not dissimilar to the rate of injury commonly observed in regular endurance runners). Although the total number of injuries was slightly higher in the control group, regression analysis revealed that there was no statistically significant difference in injury rates between the groups, either for skeletal or soft-tissue injuries.
In fact, in a study carried out with 1543 runners who participated in the Honolulu Marathon, exercise physiologist David Lally, PhD. was able to link stretching before workouts with a higher risk of sustaining injury
----------------------------------------------------------
references :
Tsatsouline, Pavel, Relax Into Stretch 2001, pp. 13-14, 27
Stretching before or after exercise does not prevent muscle soreness or reduce risk of injury: systematic review BMJ Volume 325 pp 468-70, 451-2
Pope RP, Herbert RD, Kirwan JD, Graham BJ. A randomized trial of pre-exercise stretching for prevention of lower-limb injury. Med Sci Sport Ex 2000; 32: 271-277.
Pope RP, Herbert RD, Kirwan JD. Effects of ankle dorsiflexion range and pre-exercise calf muscle stretching on injury risk in army recruits. Australian J Physiother 1998; 44: 165-177
Donner A, Donald A. Analysis of data arising from a stratified design with the cluster as unit of randomization. Stat Med 1987; 6: 43-52
Black JD, Stevens ED. Passive stretching does not protect against acute contraction-induced injury in mouse EDL muscle. J Muscle Res Cell Motil. 2001;22(4):301-10
Glasziou PP, Irwig LM. An evidence based approach to individualising treatment. BMJ 1995; 311: 1356-1359
Herbert RD. Critical appraisal of clinical trials. II: Estimating the magnitude of treatment effects when outcomes are measured on a dichotomous scale. Australian J Physiother 2000; 46: 309-313
'Effects of Flexibility and Stretching on Injury Risk in Army Recruits,' Australian Journal of Physiotherapy, vol. 44, pp. 165-172, 1998
'A Randomized Trial of Preexercise Stretching for Prevention of Lower-Limb Injury,' Medicine and Science in Sports and Exercise, vol. 32(2), pp. 271-277, 2000
'New Study Links Stretching with Higher Injury Rates,' Running Research News, vol. 10(3), pp. 5-6, 1994
