Static Stretching for Runners
When you first start out as a runner, you will probably think about stretching. It seems like the standard advice to new runners is to stretch your muscles before and after every run, and sometimes during too. Runners often see stretching as a way to recover from muscle soreness and tightness, lack of flexibility and improve your running efficiency.
For anyone unfamiliar with stretching, there are two basic types: dynamic and static stretching. Static stretching involves gradually lengthening your muscles for a short while, typically 30 seconds, while your body is at rest. Dynamic stretching involves elongating your muscles as you are moving your body. This article will focus on static stretching.
Stretching a muscle will decrease the tension in the muscle, which in turn will reduce muscle stiffness. Initially, you might think that this is a good thing, and it is for many sports. However, running relies on the elastic storage of energy and return. As your foot hits the ground, your tendons absorb some of the energy and release it when you push off again.
If you think of your legs acting like a shock absorber, or spring, then you might see why loose muscles are not a good thing for a runner. Stiffer springs can store and release more energy than looser springs, and the same applies to tendons. This is the reason that distance runners become more inflexible as they increase the distance they run. It is the body adapting to the distance by making itself as efficient as possible.
As you stretch, the effects on the elastic parts of the body are initially transient, but can also be long term too. If you stretch before a run, you will decrease your efficiency for that run. Stretching regularly will increase your flexibility over the long term and make you a less efficient runner.
Stretching can also decrease the rate of recruitment of muscle fibres and inhibits stretch receptors. More muscle fibres will allow the body to do more work for longer, while stretch receptors improve the speed that the muscles spring back on each stride. Those who run regularly will need both of these to improve performance and running efficiency.
That in itself does not mean that stretching in itself is completely bad for runners and is something to avoid. However, runners should probably not stretch statically before running, and limit stretching after running to avoid increasing your flexibility.
Anyone that has run a hard training session will know the pain of lactic acid build-up in the muscles, or the discomfort of Delayed Onset Muscle Soreness (DOMS) the next day. Stretching is reputed to decrease this muscle soreness or remove lactic acid faster. If you look at the evidence, stretching will clear lactate quicker than sitting still, but even a slow stroll around the house or a gentle cool down will remove lactate faster than stretching will. Many scientists have studied the effects of stretching on DOMS, but almost all of them found that stretching had no discernable benefit.
Many runners, in particular older runners, will tell you that there is a link between running efficiency and flexibility. However, as discussed above the mechanisms within the body that impact running efficiency are actually only improved by running, with stretching having either a minimal or a negative effect.
Another perceived wisdom of runners is that stretching can help to prevent injury. If you look at the scientific evidence, it suggests that this is not only doubtful, but stretching could actually increase the possibility of injury by inhibiting the feedback mechanisms within the body that prevent help to injury. It is difficult to undertake a scientific study of the effects of stretching on runners, as comparative studies between two groups of runners have too many variables to certain, but no correlation has been found between stretching and injury prevention.
Most organized sports activities start with a stretching warm-up, so it follows that stretching must enhance performance. However, yet again scientific studies show no correlation between stretching and improved performance. In fact, several studies found a significant decrease in performance after static stretching during the warm-up.
Not only has stretching been found to be detrimental to running performance, but the length of the stretch was not found to be a factor either. Just one stretch for 15 seconds will have a measureable effect on running ability.
Should I Stop Stretching?
From the evidence, runners should probably ditch their pre-run stretch in favour of a more active warm-up featuring running, strides and dynamic stretching. However, there is some evidence that post run stretching might increase the production of several growth factor hormones, which could help to increase muscle growth and boost performance.
Rather than stop stretching completely, the evidence seems to suggest limiting static stretching to after the workout and as part of a structured cool-down routine.