The more stiffness the better? The stiffer one becomes the better they perform. Apparently with increased rigidity comes improved responsiveness, better handling and more traction. Unsurprisingly men are stiffer than women, even if men engage in regular stretching (Allison et al., 2015). The fact is that stiffer joints may actually make runners faster by improving their running economy. Running economy basically means efficiency – a runner with better economy uses less energy to go the same speed and distance as a runner with poor economy, it can vary between runners as much as 30%. Not surprisingly running economy is an excellent predictor of running performance. Inflexibility of the musculoskeletal system may enhance running efficiency in runners by increasing storage and return of elastic energy from the foot contact on the ground. Basically stiffer joints around the ankle, knee and hip will return more energy and bounce then more flexible joints, making the least flexible runners the most economical (Craib et al., 1996; Jones, 2002; Jones, 2006).
img_0463The main arguments in favour of adopting a regular stretching routine are that it reduces the risk of injury, prevents excessive muscle soreness and improves athletic performance. Traditionally, many runners believe they can increase their running economy by becoming more flexible, it was always assumed it was always better to be more flexible. Run training results in reduced flexibility in the joints of the lower legs, so the more you run the harder it may be to touch your toes. This loss of flexibility that results from running has generally been thought of as a bad thing, but there is little or no evidence to support this theory (Witvrouw et al., 2004). Far from being hurtful or unwanted, the natural tightening of the lower leg joints and connective tissues that occurs in response to training allows the legs to function as stiffer springs. This means that well trained runners can better capitalise on energy from ground impact and reuse it to propel them forward. This improves running economy by allowing the runner to use less energy to sustain any given pace. So stretching and improving flexibility has no impact on improving performance but surely it helps to prevent injuries? ……. Actually it doesn’t. USA Track & Field (USATF) conducted a massive study on pre-run stretching involving almost 3,000 teenaged and older runners, and sought to determine the effect of pre-run stretching on running injuries. The purpose was to examine specifically if pre-run stretching is beneficial for overall injury prevention or reduction. The participants were randomly assigned to groups, one performing a specified pre-run stretching routine and the other performing no pre-run stretching for a period of three months. It was found that there was no difference in the risk of injury for those who stretched before running and those who did not, stretching did not provide protection against injury.

If flexibility is bad for running economy, and doesn’t protect against injury then why would any runner want to stretch? Unfortunately it’s more complex than that.
Industrial, technological and social progress have considerably reduced physical activity levels and greatly increased the amount of time we spend sitting (Matthews et al., 2012). When compared to our parents and grandparents, this generation work and live in surroundings that discourage movement and physical activity – we are required to sit for prolonged periods in work, school and home (Owen et al., 2010). While running itself won’t reduce your range of motion to a degree that hampers your running, sitting for extended periods of time on a consistent basis at work or home could be the root cause of many running injuries. Sitting can cause muscle imbalances resulting in some muscles become extremely tight and others extremely weak. These imbalances can cause injuries in runners and result in poor performance. Stretching, and to an even greater extent, doing functional strength exercises that take these muscles and joints through their natural movements can counteract this process and help you run better. But a bit of stiffness in the right places helps too!

References
Allison KF, Keenan KA, Sell TC, Abt JP, Nagai T, Deluzio J, McGrail M & Lephart SM. (2015). Musculoskeletal, biomechanical, and physiological gender differences in the US military. US Army Med Dep J, 22-32.

Craib MW, Mitchell VA, Fields KB, Cooper TR, Hopewell R & Morgan DW. (1996). The association between flexibility and running economy in sub-elite male distance runners. Med Sci Sports Exerc 28, 737-743.

Jones AM. (2002). Running economy is negatively related to sit-and-reach test performance in international-standard distance runners. Int J Sports Med 23, 40-43.

Jones AM. (2006). The Physiology of the World Record Holder for the Women’s Marathon. International journal of Sports Science & Coaching 1, 101-116.

Matthews CE, George SM, Moore SC, Bowles HR, Blair A, Park Y, Troiano RP, Hollenbeck A & Schatzkin A. (2012). Amount of time spent in sedentary behaviors and cause-specific mortality in US adults. Am J Clin Nutr 95, 437-445.

Owen N, Healy GN, Matthews CE & Dunstan DW. (2010). Too much sitting: the population health science of sedentary behavior. Exerc Sport Sci Rev 38, 105-113.

Witvrouw E, Mahieu N, Danneels L & McNair P. (2004). Stretching and injury prevention: an obscure relationship. Sports Med 34, 443-449.

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