Monday, 14 March 2016

Stretching

Have you ever wondered why stretching is incorporated into a workout routine?  To gain insight into the benefits and limitations of stretching, it is important to have an understanding of the underlying physiology and to define the different types of stretching.

Physiology
Specialised nerve endings called proprioceptors (found in joints, muscles and tendons) detect any changes in tension or force within the body. These proprioceptors related to stretching are located in both tendons and muscle. When a muscle is stretched, proprioceptors detect the change in length and trigger a stretch reflex that initially attempts to resist the change in muscle length by causing the stretched muscle to contract. When you hold a stretch for a prolonged period of time (greater than 30 seconds) the muscle spindle becomes accustomed to the new length and reduces its signaling of being ‘on stretch’. There are also ‘golgi tendon organs’ which are located in the tendons of the muscle .Again, they detect the change in tension. When this tension exceeds a certain threshold, it triggers a lengthening reaction that inhibits the muscle from contracting and causes it to relax.

Stretching types
There are several different ways to stretch, including: static, dynamic, ballistic and PNF (proprioceptive neuromuscular facilitation).

When you hold a static stretch there is an immediate increase in length of the muscle, this is called visoelastic deformation. However, the lengthening is not permanent and usually goes back to it’s original length shortly after finishing the stretch. Longer-term flexibility from stretching is thought to be due to a muscle’s increased tolerance to an uncomfortable stretch sensation. To gain this flexibility, a stretch stretch should be held for longer than 30 seconds.

Proprioceptive Neuromuscular Facilitation (PNF) involves a stretching and contraction component. Similar to static stretching, when the force is sensed the muscles first resists the stretch and then the golgi tendon organs activate and inhibit force produced which means the muscle relaxes, becomes more accustomed to an increased muscle length. The muscle is stretched so that tension is felt, the individual then contracts the stretched muscle group for 5 – 6 seconds while a partner, or something that they can use to apply tension to, applies sufficient resistance to inhibit movement. The contracted muscle group is then relaxed and a controlled stretch is applied for about 20 to 30 seconds.

During a ballistic stretch, the muscle is taken to a stretched range of movement and then a “ballistic” movement is repeatedly applied followed by an equally short relaxation period in an attempt to force the muscle past its normal range of motion. Research has found that ballistic stretching does increase flexibility, however, it is generally not recommended due to excessive muscle forces that place high levels of stress on the muscle and tendon, making injury more likely than a static stretch.

Timing of stretching

Research indicates that stretching before a workout can cause an acute decrease in both maximal strength and power; a feeling of weakness in the stretched muscle; along with a minimal decrease in risk of injuries. Thus, static and PNF stretching is more effective if completed post training or on a separate day (such as a stretching class).

Rather than static stretches, research indicates that best practice before a workout is to increase blood flow along with some dynamic stretching (moving your body through an active range of motion). Research has found that a dynamic warm up can result in short-term increases in strength, power and other measures of muscle performance. It gradually allows your brain to coordinate the passive elements (ligaments and joint capsules) with the active elements (muscle and tendons), which in turn warms up the whole system (your joints, muscles, nerves, coordination, technique, mind) not just one part of the system (muscles)! It's important to do 2-5 minutes of cardio pre dynamic stretches.

Summary:

Static stretching           
  • Completed after training or on a separate day (such as a stretching class)
  • Hold stretch from 30 seconds up to 2 minutes
  • Click here for example.
Ballistic
PNF
  • Completed after training or on a separate day.
  • Hold resisted stretch for 6-10seconds and static stretch for 30 seconds, repeat 2-4 times
  • Click here for an example
Dynamic
  • Completed before training
  • Dynamic movements for a warm up should be specific to the activity. A dynamic warm up should be done for 5 – 10 minutes after 2-5 minutes of easy cardio
  • Start with a walk and then a light jog then include such movements as
    • Standing leg swings
    • Walking lunges
    • Monster walks
    • Butt kicks
    • Each movement can be done for 10-20 repetitions or over a 10-20m distance and repeated 2-3 times. For examples, click here.
       
Experiment with different dynamic warm ups and static/PNF stretches for cool down - see if you notice a difference in your workout performance and recovery!