Stretching can have numerous definitions, from the type of semi-distracted hurdler’s stretch one might see from a pregame NFL lineman to the intense stretching that is part of a ballerina’s daily routine; as can performance, from turning in a flawless “Swan Lake” to sacking a quarterback. But while these terms can display a subjective definition and wide variance, the effects of one (stretching) impacting the other (perfomance) have been studied in numerous permutations.
Four recently published studies give us insight into how stretching effects various performances, using different modalities(note: clicking any of these links will give you the full text PDF of the study), from Stretching and Isometric Contractions, to Stretching and Explosive Performance, to Stretching and Running (1 mile), or even The Impact of Stretching on Sprinting.
In the first study, which examined subjects’ ability to exert maximal isometric torque after static stretching, 19 women participated in 2 randomly ordered experimental trials: 5-minutes of stretching or 5-minutes without stretching. Then they performed isometric maximal voluntary contractions (MVCs) of the right plantar flexor muscles. The result was a decrease in their ability to maximally contract the muscles being tested.
This is bad news if your sport includes maximally contracting your muscles with no external resistance or movement…like…uhh…no sport ever. The second study was a bit more useful, as it examined static stretching and explosive strength. Sixteen soccer players performed either no stretching, a dynamic warmup, or static stretching consisting of 2 sets of 7 minutes and 30 seconds (2 repetitions of 30 seconds with a 15-second passive recovery) for 5 muscle groups (quadriceps, hamstring, calves, adductors, and hip flexors). Twenty-four hours later, after warming up but not stretching, they were tested in 30m sprints (10m and 20m lap times), a jump test, and a repeated sprint test. later (without any kind of stretching in warm-up), the playerswere tested for the 30-m sprint test (with 10- and 20-m lap times),5 jump test (5JT), and RSA test. Significant differences were observed. A significantly better performance in the jump test and sprint test, though not the repeated sprint test, was observed after Dynamic Stretching as compared with that after the control group and the static stretching group.
Static stretching can impair explosive performance up to 24 hours later – which is obviously not good. But what about something a bit longer – like running a mile? In another study, scientists had ten male subjects perform a 5-minute treadmill warm-up then a series of 6 lower-body stretches for three 30-second reps, or sit still for 10 minutes. Time to complete a 1-mile run under stretching and nonstretching conditions took place in randomized order on different visits. Stretching made the runners slower:
The final study we’re looking at, examined active adolescent boys and girls, who were tested after static stretching versus dynamic stretching (40 seconds on quadriceps, hamstrings, hip extensors, and plantar flexors) with no stretching was performed at the control group. Pretreatment and posttreatment tests measured 20-m sprint, countermovement jump height, and sit and reach flexibility test. In terms of performance, static stretching hindered 20 m and jumping in boys and girls by 2.5 and 6.3%, while dynamic stretching had no effect on 20 m in boys and girls but impaired the jump by 2.2%. Both modalities improved flexibility, with static stretching being far more beneficial (12.1%) compared with dynamic (6.5%).
Based on these studies and our own experience, for increasing flexibility static stretching is a necessary evil. But it shouldn’t be performed prior to training, where a dynamic warmup would be far more effective, and it probably shouldn’t be performed within 24 hours of a heavy training session, where explosive strength is the goal. Find a few days per week that fit this description, maybe two or three at most (for the majority of athletes), and focus on static stretching to get more flexible – but leave it out of your programming for the rest of the week.