There is much debate as to the effects of stretching and whether it is important for injury prevention, performance enhancement, rehabilitation post-injury, flexibility and reducing muscle soreness after exercise. To start with it is important to know what type of stretching techniques are used and what is the difference between these stretches.
What are the different types of stretches?
1 - Static stretches
Static stretching is when the position of the stretch is held for 30-60 seconds. The stretch SHOULD NOT BE PAINFUL! As the stretch is held, there is a reflex reaction which occurs and causes the muscle to relax. You can then stretch the muscle a little further with less discomfort.
2 - Ballistic Stretching
Ballistic stretching is not commonly used, except in gymnastics, ballet and dance. Ballistic stretching is when the muscle is stretched almost to it's limit and then a bouncing movement is used to stretch the muscle further. The bouncing component of this stretch causes a strong reflex muscle contraction. It is thought that stretching in these high tension movements may increase chance of injury.
3 - Proprioceptive Neuromuscular Facilitation Stretching (PNF Stretching)
PNF stretching involves a static muscle contraction, followed by a static stretch of the same muscle groups. PNF stretching is performed with a partner who will move the muscle into a range where you feel a stretch, then you will contract the muscle against your partners resistance and repeat again.
Does stretching have an effect on increasing joint range of motion and strength?
What we know from the research is this:
- It can increase joint range of motion for a short period of time. Best results with 15 to 30 seconds and between 2-4 repetitions
- PNF stretching (a static muscle contraction followed by a static stretch) is proven to be MORE effective at increasing joint range of motion than pure static stretching
- Static stretching actually DECREASES muscle strength output temporarily if performed immediately prior to exercise.
- Dynamic stretching (moving smoothly through your joints range) can increase length AND strength output!
The type of stretching that you should perform will vary depending on your reason for stretching. For example, static stretching of the calf following an ankle sprain could increase joint range of motion and stiffness, allowing you to walk normally. However if a high jumper performed a static stretch of the calf before an explosive jump, there could be temporary decrease in calf power which may result in a lower jump. Therefore the TYPE and TIMING of stretching plays a crucial role on the impact stretching has on performance.
does stretching decrease your chance of injury?
The current research has shown:
- Pre-exercise stretching DOES NOT decrease overall injury rates
- A large study conducted on Fire Fighters and Military recruits who included REGULAR stretching into their training regime (not prior to exercise) resulted in 32% decrease in injury.
- A number of studies have shown that muscle stretching before and after exercise does not produce clinically important reductions in delayed onset muscle soreness
The debate as to whether stretching prevents injury is ongoing. The evidence is conflicting. If you are an active person who feels stretching makes your move and feel better, there is no harm in continuing to stretch. If you are an high level athlete, you need to think harder about the pro's and con's of stretching on your performance. This is an area of ongoing study and hopefully in the future the research will give us more answers.