How does static stretching affect an athlete's performance?
Dr. L.W. McDaniel and Bobbi Jo Dykstra discuss stretching and ask, "how may static stretching performed prior to competition affect performance"?
Stretching has been defined as applying a tensile force to lengthen muscle and connective tissue. Many athletes have been taught to stretch before each workout or competition with the purpose of increasing range of motion and potentially reducing the incidence of injuries. Since the early 1980's stretching has been promoted by sports medicine professionals. Stretching has been thought to prevent injury and improve athletic performance. Unfortunately, what most people do not know is that isolated static stretching immediately before exercise may impair a person's strength and power and has no effect on injury prevention. (Fields et al. 2007)
Several papers have been published which has produced a substantial body of evidence that stretching may not be the way to improve performance and decrease the risk of injury. There are two studies that have reported that strength was reduced up to one hour after static stretching (Fowles et al. 2000 and Kokkonen et al. 1998). Another study that focused on peak torque during concentric isokinetic leg extension discovered that after one active and three passive stretches, strength decreased at both high and low speeds (Cramer et al. 2004)
Men taken from a university population were pre-and post-tested for isometric force and surface electromyography activity. These tests were performed on lower limb muscles, a range of motion in seated hip flexion, prone hip extension, ankle plantar and dorsiflexion, no-counter movement jump height, and ground contact time. Male participants were tested thirty, sixty, ninety, and one hundred and twenty minutes after static stretching. The group participated in an eighteen-minute static stretch routine for the hamstrings, quads, and plantar flexors. Each muscle group was stretched for forty-five seconds, which was repeated four times with fifteen-second rests. Shirier found differences in the effects of two different types of stretching, acute stretching just before exercise and regular stretching performed over a period of days outside of exercise. He found that there was no benefit of acute stretching on isometric force production, isokinetic torque, or jumping height. In addition, he found that regular stretching after exercise improved strength, jump height, and running speed. These findings suggest that acute stretching before exercise had no positive effects on strength and power while regular stretching after training or competition improved strength and speed.
Unfortunately, stretching has been associated with muscle damage. A study completed on mice illustrated acute stretching of muscle fibres just 5% beyond resting length resulted in a 5% loss of isometric force. Another study found that stretching 20% beyond resting length have been related to muscle damage and decrease force in humans. Therefore, stretching could provoke enough muscle damage to reduce maximum force and explosive strength.
Table 1 details the results of studies dealing with various activities and the effects of acute stretching. A large number of the activities have shown a decrease in performance, mostly for those activities which require maximum strength and explosive strength.
Table 1: The Effects of Acute Stretching (Warm-up) on Performance Variables
Summary: It would appear that explosive performance can be compromised by acute stretching.
After conducting the study above the results demonstrated that there is no simple answer to whether an athlete should stretch before exercise. Unfortunately, the study suggested that there is no concrete evidence that stretching before an athlete exercises has any benefits, at the same time there is little evidence that stretching will do any harm. Athletes are recommended to warm-up properly, that means light aerobic activities and drills specific to their sport. Performing a proper warm-up will prepare the athlete for training or competition with less risk of a muscle pull or a related injury.
The literature demonstrated that for athletes who participate in sports that require strength, power, and explosiveness need to be aware that static stretching before activity (practice or competition) may cause a temporary decrease in strength. Studies, where participants warmed up for five minutes and then performed static stretching using three sets of forty-five seconds found that this mode of stretching negatively influenced the reaction, movement time, and balance. These results contraindicated static stretching for individuals who were interested in highly improving balance, reaction, and movement times.
In most sports athletes may be required to have an above average range of motion and frequently train to maintain or improve flexibility. If an athlete, who needs to work on flexibility, chooses to stretch before exercise a warm-up with some aerobic activity is recommended. Warm muscles will increase pliability and reduce the possibility of straining or tearing muscles. If an athlete has a high range of flexibility the athlete may find that practicing sport-specific skills may be a more economical use of time. So rather than stretching before exercise, this study recommends stretching after exercise or at home. Studies have shown that an athlete is more likely to benefit from stretching after exercise if stretching is performed on a regular basis.
In conclusion, in most cases, static stretching before exercise reduces an athlete's power and strength. If the athlete participates in power or strength exercises acute stretching may not be recommended. For many competitive athletes warming up completely prior to competition and stretching after competition or training may be more important. By stretching afterwards, the athlete gains flexibility without compromising power and strength. An additional consideration related to stretching would be to not overextend your range of motion (overstretch a muscle) this practice may cause muscle damage.
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About the Authors
Dr. Larry McDaniel is an associate professor and advisor for the Exercise Science program at Dakota State University, Madison SD USA. He is a former All - American in football and Hall of Fame athlete & coach. Bobbi Joe Dykstra is a student in Exercise Science at Dakota State University and is a member of the DSU track team competing in the hurdles.
The following Sports Coach pages provide additional information on this topic: