Stretching and exercise. Stretching is generally thought of as a slow, sustained process of relaxing the muscles. Good range of motion for a particular joint indicates no abnormalities or muscular limitations. It can be assumed that the more flexible one is, the less likely one is to be injured. Also the better one will perform. Athletes with “tight muscles” can be thought of as having a handicap in athletic performance. This is due to their decreased range of motion. Flexibility helps to reduce the shock of impact during contact sports. Also when landing on a hard surface.
Stretching And Exercise: Two Types Of Stretching – Ballistic and Static.
- Ballistic stretching – This is an older stretching technique that involves a repetitive bouncing or bobbing motion. You hold this for 5 seconds to produce a stretch. This type of stretch is usually not recommended for individuals that do not exercise regularly. This is because injury may occur. Here’s an argument concerning athletes performing activities that require bouncing/ ballistic movements. It’s said they should use ballistic stretching for better performance. There is no scientific evidence that currently supports this idea.
- Static stretching – This is a slow, continuous stretch (10-30 seconds). It can be performed actively or passively. It involves placing the muscle in a maximum stretch to the point of slight discomfort.
- Hatha Yoga, for example, generally uses static stretching techniques. Most would agree that this is the safer stretch for athletes to do. However, there is no evidence supporting that static stretching is better than ballistic stretching.
Muscle Cell Physiology:
Our muscle cells contain Golgi Tendon Organs (GTO). They are located where muscle fibers insert into the tendons. GTOs sense when our muscles are stretching. During a static stretch, the GTO fires. This relaxes the muscle being stretched (agonist). It does this while sending messages to the brain to contract the opposite (antagonist) muscle. For example, you’re stretching the hamstrings. In this case, the hamstrings are the agonist. The quadriceps are the antagonist. What’s the idea behind stretching with the involvement of the GTO? It is that the efficiency of the stretch will improve over time. This leads to long term flexibility.
Stretching And Muscle Contraction
What happens during a muscle contraction? Collagen fibers in the muscle tendon stretch while muscle fibers are contracting. The GTO senses this. It then sends a message to the nerve cells within the muscle. This relays the message to the brain. Certain centers of the brain then relay messages back to the nerve. Then on to the muscle to tell it what to do/how to react.
For example, you’re standing on a rock but started to slip off. The GTO would fire when the muscle tendons began to stretch. This sends a message to the nerves and then to the brain. Next, this would stimulate the cerebellum (part of the brain responsible for balance). In turn it would signal to the appropriate muscles to contract in an attempt to stop the individual from falling.
Our body’s ability to know where it is in space is called proprioception. Stretching and strengthening forces our body to constantly be testing our proprioception. Thus, having stronger proprioceptive awareness while exercising will lower our incidence of injury.
Stretching Can Be Passive Or Active.
In passive stretching, someone or something besides you is doing the work. For example, in stretching hamstrings with a partner. Or using a strap or band to assist with the stretch. In these cases active stretching is done by the individual. For example, bending at the waist to stretch your hamstring. Evidence suggests that active stretching is best when corelated to sport specific performance.
PNF Stretching
Proprioceptive Neuromuscular Facilitation (PNF) is another method of stretching. This technique involves GTO and multiple other sensory organs. They facilitate a stretch through contracting and relaxing the agonist and antagonist muscles. It is widely used in rehabilitation by physical therapists when building a patient’s proprioceptive awareness. It is easiest to perform these stretches with a partner.
There are 2 main types:
- Contract-Relax: A 10s passive stretch is held by the partner. The athlete then contracts the muscle being stretched for 5 seconds. At the same time, the partner resists the athlete. Next, the athlete relaxes as the partner stretches for another 30 seconds.
- Hold-Relax: A 10s passive stretch is held by the partner. The athlete then isometrically contracts the muscle being stretched for 5 seconds. Next, the athlete relaxes and the partner stretches for another 30s.
Research suggests that PNF stretching produces the greatest improvements in flexibility. However, it may cause muscle soreness. The PNF techniques are more time consuming that static stretches. They should be performed with an experienced partner.
The American College of Sports Medicine (ASCM) recommends that athletes undergo a general stretching routine. It should involve static or PNF techniques for major muscle groups a minimum of 2-3d/wk. Stretching should only be intense enough to produce mild discomfort. Stretches should be held 10-30 seconds each for 3-4 repetitions per stretch.
When Should You Stretch?
There is conflicting evidence on whether or not to stretch prior to exercise versus after. Also versus both before and after. Generally speaking, the more flexible a joint is, the greater the range of motion it can produce. This results in more optimal performance of the individual.
A Study On Static & PNF Stretching
However, here’s a study by Marek and Cramer et al. Static and PNF stretching prior to weight training was found to cause decreases in peak torque, strength and power output. Overall muscle activation at both slow and fast velocities. The study does discuss the increases in range of motion of specific joints as a result of the passive and active stretching.
The best advice is to find a stretching regimen specific to the individual and make it consistent. Over time, a regular stretching program will account for better full body flexibility. This is important later in life as our muscle elasticity begins to decrease. There is nothing incorrect about stretching before any form of activity. However, your body should be properly warmed up.
Pre-Workout Stretching
Pre-workout stretching should be a personal decision. A good warm-up increases blood flow. It increases the body’s metabolic rate and increases connective tissue extensibility. It also improves joint range of motion which leads to better muscular performance.
The warm-up should consist of light activity, such as jogging. It should be intense enough to cause a mild sweat. Stretching after a workout may help to relax the whole body. Yoga is an excellent way to attain full body flexibility and relaxation. You also use meditation at the same time. Post workout stretching may help to speed up the delivery of amino acids to our muscles. It also moves lactic acid out of our muscles to allow for faster repair time. If you stretch after a workout, it is a good idea to allow the muscles some time to relax. This is so that the lactic acid has a chance to leave the area.
Delayed Onset Muscle Soreness (DOMS)
DOMS is generally caused by eccentric contractions (as in downhill running and plyometrics). DOMS may occur one to three days after exercise and may increase in soreness for up to three days. It sometimes taking up to 7 days to resolve. DOMS involves microtears in the muscles. It may also include swelling and inflammation.
It is often a misconception that DOMS is caused by a build-up of lactic acid. Blood lactate levels typically return to pre-workout levels about an hour after working out. Prevention of DOMS includes a good warm-up and gradually increasing exercise intensity. There is conflicting evidence as to: whether or not post exercise stretching, post exercise massage or a post exercise ice pack resolves the problem. There’s no evidence to suggest taking anti-inflammatory drugs prior to a workout will prevent DOMS.
Overall, flexibility is important to athletic performance for a myriad of reasons. Selecting the proper time and type of stretch to perform should be specific to the individual. It should also be specific to the sport or activity.
References:
Marak SM, Cramer JT, et al. Acute Effects of Static and Proprioceptive Neuromuscular Facilitation Stretching on Muscle Strength and Power Output. J Athl Train. 2005 Apr–Jun; 40(2): 94–103.
American College of Sports Medicine. Guidelines for Exercise Testing and Prescription. 6th Edition.Baltimore, MD: Library of Congress;2000.