More on stretching

A few months ago I posted a Stretching Q&A which debunked a few myths about stretching based on the advice from a sports physio. In essence, stretching is useful but not to the extent that is commonly believed, and the timing and type of stretching is critical to performance.

The latest edition of “Modern Athlete & Coach” (published by the Australian Track & Field Coaches Assoc) reports on some recent studies on the topic that have been published. Here’s a summary of the key points:

• There is increasing evidence that stretching before exercise does not improve performance or reduce injury risk.
• Do not complete static stretching during your warm-up – it has been shown to decrease subsequent performance**. Only dynamic stretches pre-activate the muscles and prime them for performance.
• The warm-up is not the time to develop flexibility.
• Do not ignore static stretching. It is essential for flexibility but NOT in a warm-up context.
• Static stretching MAY increase the range of movement after fatiguing exercise, and some people gain a sense of well-being doing so. However there is no evidence that it reduces muscle soreness after heavy training sessions.
• Examples of dynamic stretching that are beneficial during a warm-up include ankle flicks, buttock kicks, knee lifts, skipping, walking lunge and stride-throughs.

** - There are 2 mechanisms that may explain why pre-exercise stretching is detrimental to performance. It damages the contractile proteins in skeletal muscle. Skeletal muscle contains thick filaments and this is connected to cross-bridges. When a nerve signal reaches the muscles, the thin filaments slide over the thick. Movement cannot occur if the cross-bridges are broken. In animal studies, the bridges are broken if the muscle is stretched 20% beyond its resting length. The nerve signals are electrical. Electrodes have been used to monitor muscle activity and force production are reduced after stretching. These findings suggest that stretching produces some kind of neural inhibition that is detrimental to performance.

The "take home" messages from all of this are:

• Pre-exercise you should only perform dynamic stretching as part of your warm-up routine.
• No static stretching should be done pre-exercise.
• Post-exercise there is no evidence that static stretching helps recovery or prevent soreness.
• However many athletes will feel an improved well-being from post-exercise stretching in which case there no reason to stop doing so.