If you participate in any physical activity, odds are you do some sort of warm up that involves a form of stretching. Two common stretching protocols are static stretching and dynamic stretching:
- Static stretching is used to stretch the muscles while the body is at rest. Static stretching involves several techniques that gradually lengthen a muscle to the point where it is uncomfortable, meaning the muscles is elongated. Each stretch is usually held for 30 seconds to 2 minutes. This form of stretching was once believed to prevent injury and delayed onset muscle soreness (DOMS), but that theory has been refuted by several studies.
- Dynamic stretching is comprised of active movements of muscle that induce a stretch, but are not held in the end position. Due to research proving its effectiveness, dynamic stretching is becoming more popular compared to static stretching.1
Recently, there was a study conducted that compared the effects of these two stretching protocols on the reactive strength index in female soccer and rugby players.2
The study involved 15 Division I female soccer and rugby players who were in their offseason at the University of Northern Iowa. The testing consisted of three tests that took place over a 3 week period. Each test session included a 10 minute general warm-up on a cycle ergometer, followed by 1 of 3 randomized treatment methods: warm-up only, static stretching, and dynamic stretching. The warm-up only session was 10 minutes of pedaling on a cycle ergometer at a minimum of 70rpm with no resistance. The static stretching session started with 10 minutes of cycling followed by four static stretches targeting the glutes, hamstrings, quads, and the calves. Each stretch was performed to a point of mild discomfort for a total of three times for 30 seconds, followed by a 10 second rest interval between sets. The dynamic stretching session involved 10 minutes of pedaling on the ergometer accompanies by four dynamic stretches that targeted the same muscle groups. The exercises performed were walking knee hugs, walking single-leg toe touches, walking lunges, and walking single leg calf raises. These stretches were done in 10-rep sets, and included a 10 second rest interval between sets.3
After the subjects performed their assigned treatment, they performed drop jumps from a height of 45cm onto a force plate. Upon landing, the athletes were required to immediately jump into the air to minimize contact time and maximize flight time. This method was used to calculate the reactive strength index by using the ratio of FT: CT (flight time to contact time).4
The results of the study revealed that the reactive strength index and flight time were significantly greater in the dynamic stretching group compared with the static stretching and warm-up only group. This study reiterated the reason why dynamic stretching is usually the preferred stretching protocol before an athletic event that involves jumping. As more and more research continues to prove the of dynamic stretching, we may find that static stretching becomes a thing of the past.5