Runners often ask whether or not they should they warm up first before stretching, how long should each stretch be held, and will stretching improve my performance? These are all excellent questions and the answers sometimes seem a bit confusing. The purpose of this article is to not only address each of these questions but to also explain, in part, the scientific side of stretching.

Let’s start with the physiological response to stretching. Just how does a muscle increase its length and become more flexible? The muscle-tendon unit contains an active (contractile) and passive (non-contractile) component. The active component is related to the muscle fibres whereas the passive components consist of the connective tissue within the muscle and the muscle tendons. A single bout of stretching has its main effect on the passive components and increases muscle flexibility through elongation of the connective tissue and muscle tendons. However, by starting a regular stretching routine over the span of several weeks or months, a muscle gains length primarily through the active component by adding muscle fibres to the ends of the muscle itself.


Researchers have determined that most of the increases in muscle flexibility take place within the first 12 to 18 seconds of stretch and there are insignificant gains in muscle length afterwards. They also found that 80 percent of the “stretch” occurs after the first 3 stretches. Thus, the standard recommendation is for runners to perform each stretch 3 times and hold each stretch “about 20 seconds.”


Stretching before and after a run is beneficial with respect to preparing your muscles and tendons for the run ahead and cooling-down afterwards. However, if you want to make significant gains in muscle flexibility you must stretch at a completely different time from when you run. Researchers have shown that runners who only stretch prior to and following a run demonstrate the same amount of muscle flexibility over an 8-week program. However, runners who stretch at least 4 hours before or after their regular runs demonstrated significant gains in muscle flexibility over the same time span. This finding makes sense if you consider that 1) stretching prior to a run will result in elongation of the connective tissue and muscle tendons, 2) during the run the muscle will undergo tissue shortening, and 3) stretching after the run will return the muscle to its pre-run length. Thus, no change in length of the muscle has been achieved and no consistent chronic stimulus has been provided to the muscle. However, stretching at a completely different time will provide sufficient stimulus and result in increases in muscle flexibility.


It has been shown that increasing the muscle temperature prior to stretching relaxes the passive component of the muscle to a greater degree and thus allows for greater elongation. In fact, an increase of only 1o°C in muscle temperature is necessary for greater elongation and flexibility. Therefore, it is a good idea to partake in some type of gentle warm-up prior to stretching. However, this statement really only applies to stretching a muscle that has been doing little activity for the past several hours; such as in the morning after a night’s sleep. Since it is recommend that runners stretch at a completely different time from running, you should stretch at the end of the day and prior to going to sleep since your muscles have been generally active all day and you are not stretching “cold.”


There has been quite a lot of research done on this topic. It has been concluded that a regular stretching routine will improve muscle force production and jump height. However, the effects on running speed are contradictory as some studies show improvements while other show decreases in sprint speed following single bouts of stretching. In addition, there is some controversy in the research related to whether or not regular stretching improves running economy during long runs. However, most of the studies have found slight improvements in running economy after a regular and long-term stretching routine. Therefore, if you’re looking for that personal best in the upcoming race season … keep training and stretch, stretch, stretch!

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