Physical education teachers, coaches, personal trainers and group exercise instructors have continually suggested that people stretch regularly to alleviate tight muscles or to improve flexibility. However, there has been very little evidence to support these claims. In fact, sports scientists and physiotherapists have been providing some strong evidence that static stretching may not always improve athletic performance.
Static stretching refers to the holding of a muscle stretch for a certain length of time, while dynamic stretching refers to moving a joint or multiple joints repetitively over a predetermined range of motion. In a systematic review published in January, 2011, in Medicine and Science in Sports and Exercise, scientists from the University of Northampton, U.K., examined 106 studies that looked at the quality of the stretching effect and the consensus of the findings. Although about a third of the studies were poorly conducted due to their failure to provide “appropriate reliability statistics,” researchers A.D. Kay and A. J. Blazevich stated that the evidence is clear enough to indicate that stretching for less than 30 seconds or between 30 to 45 seconds had no detrimental or significant effect on strength and power production. However, any stretch that is held for 60 seconds or longer can decrease the muscles’ ability to produce force. Thus, they concluded that shorter-duration stretching does not compromise maximal muscle performance as longer-duration stretching appears to.
However, a more recent review of 43 studies on the effects of stretching on the short-stretch cycle may reveal a different perspective on stretching. Researchers Heidi Kallerud and Nigel Gleeson from Queen Margaret University, who conducted the review that was published in the August 2013 issue of Sports Medicine, mentioned that the effects of static and dynamic stretching are somewhat inconsistent. About half of the studies that assessed the immediate effect of static stretching reported a “detrimental effect on performance,” but the rest of the studies found no effect. Dynamic stretching, however, showed improvements in performance and had no negative effects in half of the studies. The researchers noted that the sample populations in these studies are quite small to average, indicating that “the effect on performance might be limited in practice.” Based on the evidence, it is likely that athletes who perform short-stretch cycle exercises and movements, such as sprinting, bouts of jumping and hurdling, and some types of martial arts, may benefit more from dynamic stretching than the static version.
While stretching for 30 seconds or so may not always improve athletic performance, the stretch intensity and chronic stretching may sometimes backfire. Licensed massage therapist Rick Merriam, who teaches kinesiology at the Parker University School of Massage Therapy in Dallas, Texas, told Guardian Liberty Voice in an online interview that stretching does not necessarily improve performance or prevent an injury. “Stretching is not getting to the source of the tightness that you feel in the muscles,” he said. “Your muscles are tight for a very good reason: To protect you from an injury. The bottom line is this: Optimal function always comes down to timing, and stretching farther in order to feel the ‘stretch’ is only throwing off the muscle’s ability to contract at the right time.”
The bottom line is that the type of stretching needed depends on the sport, the environment and the individual’s health and physical abilities. Sometimes stretching a “stiff” muscle can be counter-productive. “Running a marathon doesn’t require the same amount of motion as a running back driving the football down the field,” Merriam explained. “But when it comes to performance, even running in a straight line requires efficient motion throughout the body. An efficient running gait also requires an optimal amount of stiffness to store elastic energy in the muscles and fascia. The amount of motion, and the direction of the movement, are both determined by the joint structure. On every single leg landing, much like a hinge, your ankle is going to move in that one path of motion. The question is how much motion was available to you. Even though it’s less obvious to the naked eye, every time your foot makes contact with the surface below, your knee has to move through three different paths of motion. No matter the joint, the muscles are going to be responsible for the amount of motion. And taking advantage of the motion doesn’t require any thought on your part. Because of that, it’s easy to fall into a place where we take movement for granted — until you experience an injury.”
Ultimately, the nervous system is the kingpin that dictates how much a muscle can stretch and how well muscles move and coordinate. Stretching a single muscle or muscle group may not always improve performance because it does not prepare the mind and the body to move as a whole. For example, soccer players may need to dynamically stretch their hips and legs in various planes of motions and movement patterns that closely match what the actual sprinting and kicking skills demand. Lying on the floor and raising the leg to stretch the hamstrings would not likely prepare the nervous system to move better. “Stretching by itself will not get the under-performing muscles back online, and stretching will dampen the [neural] input to the weak and tight muscles, making them slow to contract at the right time,” Merriam added. “The one consistent metric with all injuries in sport and life, is this: Can the muscle(s) contract at the right time, in the right plane, and at the right joint? That is a question that is worth asking.”
By Nick Ng