This constant shortening causes the muscles to become very tight. Just take a moment and clench your fist. That is similar to what happens to the contracted muscle – it becomes tight and rigid, feeling cramped and “heavy.” Now open your hand and stretch out the fingers. Doesn’t that feel good? So why do so many of us skip stretching? Oh, maybe we think we’re too busy, or we just don’t consider it important ... after all, you don’t stretch to build muscle, do you? But as we’ll learn,stretching offers bodybuilders numerous benefits.

What to Stretch

First let’s discuss what exactly is being stretched. For bodybuilders trying to add size and prevent injury, two types of tissue should be stretched on a regular basis: the fascia and the tendons and ligaments. While all are connective tissue, the fascia is more elastic in nature and should get the majority of your attention, especially as it relates to muscle growth. Stretching the tendons and ligaments is also important, however, and has a vital role in promoting strength gains.

Fascia is the protective sheath, or covering, that surrounds muscles. As people age, the soft texture of the fascia begins to harden and takes on the feel of an outer shell. Under certain circumstances, this could restrict muscle growth. Stretching helps keep the fascia soft and supple, allowing the growing muscle to expand. Think of a balloon. New balloons are more difficult to blow up because the rubber is tough. Repeatedly blowing up the balloon softens the rubber, making it easier to stretch and blow up. 

Stretching the tendons will allow you to perform additional reps. Attached to the ends of tendons are small receptors called golgi tendon organs (GTOs). You can think of GTOs as circuit breakers that act as safety switches. When a muscle is stretched beyond a certain point,the GTO fires and shuts the muscle down to prevent further contractions. If the GTOs didn't exist you could easily tear a muscle or tendon from its attachment. You may have experienced this phenomenon: you’re repping out on dumbell presses when your pecs just give out, with little or no warning. You may be sure you have the strength to force out a few extra reps, but the muscle just won’t contract.

Stretching

Benefits of Streching

Decreased Risk of Injury

A regular stretching program helps increase the length of muscles and tendons. This not only reduces muscle tension, but also increases their overall contractile range, which in turn makes them less susceptible to injury. By increasing the muscles’ contractile range, in other words, the range of motion around a joint, we increase the distance our limbs can move before muscle or tendon damage occurs. For example, the muscles and tendons in the back of our thighs are put under great stress when we kick a soccer ball. It only makes sense that the more flexible and pliable those muscles are, the further our leg can travel forward, thus decreasing the chance of injury.

Increased Muscle and Athletic Ability

There is a myth that stretching too much will decrease joint stability and muscle power. This is absolutely untrue! By increasing muscle and tendon length, you are increasing the distance over which the muscles are able to contract. This results in a potential increase to the muscles’ strength and power. You’ll have actually increased your athletic ability, balancing ability, and muscle control.

Reduced Muscle Soreness

Before long you’ll start experiencing tightness and soreness in your muscles the day after your workout, if you haven’t already. Walking up a set of stairs the day after leg training maybe very painful indeed! The muscle soreness that follows strenuous physical activity is usually referred to as post-exercise muscle soreness or delayed onset muscle soreness (DOMS). This discomfort is the result of micro tears (minute tears within the muscle fibers),and a buildup of metabolic waste products, particularly lactic acid. Stretching helps alleviate this soreness by lengthening the individual muscle fibers, increasing blood and nutrient delivery to the muscles, and removing waste products.

Reduced Antagonistic Pressure

Muscle fatigue is a major problem experienced by those who exercise regularly. It results in a decrease in both physical and mental performance. But increased flexibility through stretching can help reduce the effects of fatigue by taking pressure off the muscles being exercised. Most muscles in the body have an opposite or opposing muscle. When these opposing muscles (called antagonists) are more flexible, the working muscles (called agonists) do not have to exert as much force against the opposing muscles. Each movement of the working muscles actually takes less effort.

Mentally Relaxing and Rewarding

With all the attention on the physical components of exercise, we often neglect the mental components. People who regularly stretch are more likely to feel good about themselves. This leads to a boost in self-confidence, which in turn helps enhance physical performance and motivate the individual to participate in regular exercise.

When to Stretch?

Before

Stretching before a workout helps prepare the muscles for the work to follow. It loosens the muscles and increases the blood flow to the area, allowing for more efficient nutrient and oxygen delivery. Stretching also helps remove lactic acid – one of the primary causes of post-workout soreness. Just remember that it’s not a good idea to engage in rigorous stretching the moment you walk in the gym. Cold muscles do not stretch well. Do a light warmup first and then proceed to your stretches.

During

The primary benefit of stretching during a weight-training workout is that it saves you time. While you are taking your minute or so rest between sets, add in a stretch for that particular muscle group. Don’t worry about it affecting your training, as stretching takes little energy to perform. It will keep the muscles limber and help remove lactic acid and deliver nutrients. And you’ll save 10 to 15 minutes at the end of your workout.

After

Most people stretch at the end of their workouts because the muscles are fully warmed up and can endure more vigorous stretching. The muscles will also be full of lactic acid and other metabolic wastes that must be removed. Stretching greatly facilitates this removal process. Also, stretching is relaxing and calming, making it an ideal way to finish off a good workout.

Types of Stretching

Passive Stretching

Passive stretching is often referred to as “static stretching,” and is the type we most often think of. A passive stretch is one in which you hold the stretched position for 15 to 30 seconds. Slow, relaxed static stretching can relieve spasms in muscles that are healing after an injury. It also relaxes your body after a workout. I suggest that you save the static stretches until after your workout. Your muscles will be fully warmed up and it will be easier to hold the positions.

Isometric Stretching

Isometric stretching is a type of passive stretching that involves using the resistance of other muscle groups, a partner or a stationary object. The stretching positions are held for a much longer time than with passive stretching because the ultimate aim is to improve overall flexibility and strength. An example of a partner-assisted stretch would be holding your leg up high and having your partner push it toward you while you try to force it back down to the ground. An example of using a stationary object would be the wall stretch for shoulders. You place your hand against a doorway or beam and then push forward leading with your shoulder.

Ballistic Stretching

Ballistic stretching uses the weight and momentum of a moving body to force the muscle beyond its normal range of motion. Essentially, you are bouncing into (or out of) the stretched position, using the stretched muscles as springs that pull you out of the stretched position. This type of stretching is really only useful for high performance athletes, because the risk of injury is too great for most people. It doesn’t allow your muscles to adjust to the stretched position and relax. Instead, it may cause them to tighten up even more. Unless you are in excellent physical shape to begin with or play intense sports (hockey, rugby, basketball, etc.),avoid ballistic stretching.

Dynamic Stretching

Dynamic stretching involves gradually increasing the distance and speed of a muscle’s range of motion. Please don’t confuse dynamic stretching with ballistic stretching. Dynamic stretching consists of controlled movements that take you to the very limits of your range of motion. Ballistic stretches involve trying to force a muscle beyond its natural range of motion. In dynamic stretching there are no bouncing or sudden movements. A good example of dynamic stretching would be slow, controlled leg swings, arm swings or torso twists.

Common Stretches

Hamstring Stretch

Sit on the floor and place the leg you wish to stretch straight out in front of you. Then bend the other leg alongside to make a triangle with your legs. With a straight back and straight knee, bend from your hips, and reach for the toe of your straight leg with both handsand hold for 20 seconds.

Lying Hamstring Stretch

Lie on your back and pull your leg in toward your chest. Clasp both hands behind your knee. Slowly extend the leg up. Try to straighten your knee as much as possible. Gently pull your (straight) leg toward your chest, and wrap your hands around your ankle. Hold for 10seconds and then try to bring the leg further in toward your chest. Hold for another 10seconds. Repeat with your other leg.

Achilles’ Stretch

Stand facing a wall with one leg in front of the other. Your front knee is bent and your hands are on the wall. Your back leg is straight and your heel is held flat on the floor. Lean toward the front knee, keeping the back foot and heel flat. Hold for 15 to 20 seconds. Relax. Repeat with the other leg.

Quadriceps Stretch

Stand leaning against a wall or other upright with one hand. Wrap your other hand around the ankle and pull the heel to the butt, feeling the stretch in the top of the leg. Try to keep your knees together. Concentrate on pulling the heel into the butt. To maximize the stretch, tuck your pelvis in and gently push your hips out.

Groin Stretch

Sit on the floor. Put the soles of your feet together, with your knees as close to the ground as possible and pointed outward. Grasp your ankles, pull in toward your groin and hold that position for a count of 10. Relax and repeat three times.

Spread Groin Stretch

Begin in a seated position with your legs spread apart, feet facing directly forward. Try to reach the inside of your ankles. Bend forward from the hips, keeping your knees straight. Hold until you feel tightness on the inside of your legs. Relax and repeat.

Calf Stretch

Get into a push-up position, but put one knee on the ground. Put your weight on the toes of your other foot and then push the heel down until you feel a slight pull. Hold that position for a count of 10. Relax and repeat three times with each leg.

Back Stretch

Lie on your back, grasp one leg behind the knee and pull toward your chest, lifting your butt off the ground. Keeping your other leg straight and your head on the ground, hold this position for a count of 10. Repeat three times with each leg.

Chest Stretch

Grab a stationary upright with one hand, and with your arm locked out straight, gently turn away. Hold for a count of 10 and then switch arms.

Shoulder Stretch #1

Move one shoulder toward the other, keeping your arm parallel to the floor. Grasp the elbow of that arm with your other hand and gently pull toward your opposite shoulder. Hold for a count of 10. Repeat three times with each arm.

Shoulder Stretch #2

Interlace your fingers above your head, palms facing up. Push your arms up and back gently. Hold for 15 seconds.

Biceps Stretch

Place your hand on a wall. Lean forward with your feet positioned slightly away from the wall. Hold for 10 seconds. Repeat on the other arm. Alternate the stretch on each arm three times.

Triceps Stretch

Take one arm overhead and bend it at the elbow. Standing as straight as possible, gently press down on the elbow with your other hand until you feel a stretch at the back of your upper arm.

Source:
Robert Kennedy: Encyclopedia of Bodybuilding, The Complete A-Z Book On Muscle Building. 2008
Nick Evans:Bodybuilding Anatomy. 2012
Arnold Schwarzenegger: The New Encyclopedia of Modern Bodybuilding, 2013