Sunday, April 29, 2012

Stretch Your Way to Better Fitness
by Bob Wells, PES
Since grade school, perhaps from our first physical education class, we have all been taught the importance of stretching. From the casual runner to the elite athlete, we have long believed in the holy grail of the efficacy of stretching on the prevention of injury. Now, researchers are saying that we have it all wrong--that stretching does not prevent injury.
In a recent study on runners by Pereless, Roth, and Thompson half of the nearly 2,800 participants who met prerequisites for age, greater than 13, and mileage, self reported mileage of more than 10 miles run weekly, were given a 3-5 minute stretch protocol to follow prior to each running session. The other half were to follow no such protocol. The purpose of that study was to determine whether or not stretching was a significant preventer of injury. The authors of the study subsequently determined that stretching did not prevent injury.
While their study was indeed a thought provoking one about the efficacy of stretching on injury prevention, no responsible scientist, coach, or fitness professional should draw much from their conclusions. Their study is flawed, and I will focus on two of those reasons here:
1. The lack of a comprehensive assessment. No stretching protocol should be implemented prior to a proper assessment. Functional movement screens would alert a professional to any muscular imbalances and the likelihood of subsequent injuries due to said imbalances.

For example, limited range of motion at one joint or one muscle could be secondary to an issue at a neighboring joint. For example, if the quadriceps are tight, there is an anterior pelvic tilt of the hips. This increases the length of hamstring complex, which in turn decreases the range of motion of hip flexion.

Such information would necessarily alter the focus and duration of the stretching protocol, serving to correct those imbalances, altered biomechanics and arthrokinetic dysfunction (altered forces at the joint that result in abnormal muscular activity and impaired neuromuscular communication at the joint), thus decreasing the risk of injury.

In all fairness, the runners were to report injuries in the 4 months prior to their beginning the study. However, this self reporting does not necessarily allow time for biomechanical errors to manifest physically, since there may have been recent significant changes in their exercise regimen (e.g. duration, intensity). Biomechanical errors are a significant predictor of injury risk. Yet, they are not accounted for in this study, since no assessment for such errors took place.
2. Improper warm-up protocol. This study instituted a 3-5 minute stretch protocol for participants who were to stretch prior to running. However, NASM suggests a 10-20 minute stretch session prior to such activities. The NASM guidelines are supported and followed by the majority of Division I-A athletic programs. Coaches, such as the legendary track coach John McDonnell (42-time national champion at Arkansas) found such a 3-5 minute protocol "...,ineffective, irresponsible..". Typically, prerace routines, like those at Duke University and the University of Florida include a warm up run, usually 800-1200 meters, followed by a round of stretching. This cycle is repeated as necessary.

Other coaches, like Alan Stein, CCS,CSCS, the head strength and conditioning for national power Dematha Catholic, use to great success a dynamic warm up, which mimics many of the actions that the athlete will soon perform. Additionally, it prepares the mind for competition. While there may be disagreement on the which type of warm up is preferable, it is undisputed that one is necessary for optimum performance and prevention of injury.
 Without controlling for these two very important variables, it is no wonder that Pereless, Roth, and Thompson determined that stretching is not a significant preventer of injury. However, even if they had better accounted for these variables, they may not have found a direct link between stretching and the prevention of injury.

The primary benefits of flexibility are improved force production, jump height, and speed (Shrier, 2004), increased range of motion (Porter et al. 2002) (Sherry and Best, 2004), and proper arthrokinetic function (Clark, Essentials of Personal Training).
It is these benefits that improve muscular imbalances, altered arthrokinetics, and neuromuscular efficiency, which can in turn dramatically reduce the risk of injury due to biomechanical errors. While the correlation coefficient between stretching and the prevention of injury may not be statistically significant, it is readily apparent that a stretching protocol can be extremely beneficial when properly implemented.
Therefore, you should not simply eliminate the stretching from a pre-workout routine. Rather, consult a qualified professional (click to email) in order to set up a comprehensive evaluation.

They will then be able to design a 10-15 minute stretching/warm-up program based on that evaluation that will address any deficiencies as well as help you reach your fitness goals, quickly and safely.

1 comment:

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