The three main components of physical fitness are strength, endurance and flexibility. Most bodybuilders' training routines effectively cover the first two components with weight training and aerobic exercise; however, it's rare that you see competitive bodybuilders engaged in stretching exercises.
One school of thought says that if bodybuilders warm up properly and train with a full range of exercise motion, it may not be necessary to do separate stretching exercises. Other studies show that adding stretching to a typical weight-training routine may not only help prevent injuries, but it may even add to the strengthening effect of the weights.
Flexibility is usually defined as a joint's ability to move freely through its range of motion. While most athletes recognize the importance of flexibility to success and longevity in sports, what they know appears to differ from what they actually practice. For example, a study of 238 athletes reported that only 39 percent stretched daily.
Flexibility can be further divided into two basic types. The first type, static flexibility, is what most people think of when they consider flexibility. It's characterized by the ability to flex and extend a joint through a wide range of motion. The other type of flexibility, dynamic, involves speed factors, or the ability to flex and extend a joint rapidly with little resistance. It's crucial to many sports activities.
Dynamic flexibility, while appearing to be more important to competitive athletes, also plays a role in injury prevention. Common sense seems to indicate that the tighter you are, the more prone you are to various injuries, such as muscle strains or joint injuries. Despite that, however, few studies show that flexibility helps prevent injuries.
A recent analysis of previous studies that examined whether stretching before exercise helps to prevent muscle injuries concluded that it doesn't. Among other findings, the researchers determined that stretching before training doesn't affect muscle flexibility during eccentric muscle contractions, where most muscle strain occur. Eccentric muscle contractions involve a lengthening of muscle and usually take place during the lowering of a weight. That places more strain on individual muscle fibers and causes more muscle damage.
In addition, some evidence shows that stretching before a weight workout may inhibit strength performance. In fact, several studies show that having a relatively stiff musculotendinous system promotes increased muscle force production. They also show that acute stretching before weight training leads to a loss of strength, as measured by one-rep-maximum lifts on the bench press, leg extension and leg curl.
Why would that be so? It has to do with structures found in muscles and joints called proprioreceptors, specifically Golgi tendon organs and muscle spindles. For effective stretching, most experts prescribe static rather than ballistic stretching. Static stretching involves taking a stretch position and holding it for 20 to 30 seconds. Ballistic stretching involves shorter, bouncier movements that activate muscle spindles. That shortens the muscle, making it tighter, precisely what you're trying to avoid when you stretch. Static stretching, on the other hand, shifts the emphasis to the Golgi tendon organs, which promote relaxation of the stretched muscle.
So you can see why stretching before weight training may not be such a good idea. Activating the Golgi tendon organs through stretching reduces muscle tension, which is great for flexibility but a definite liability when you want to induce maximum force production in the muscle. For that you want the muscle-and-tendon unit to be tight.
Stretching after training or between sets is another story, however. For example, one study looked at the effects of stretching in 53 subjects during a 10-week strength-training program. Some of the subjects stretched after each weight exercise, while another group stretched after the weight session, and a third didn't stretch at all. The results showed that those who stretched after the weight workout experienced a 54 percent strength increase. Those who stretched between exercises showed a 37 percent strength gain, and the group that didn't stretch showed a 29 percent gain.
Regardless of when you stretch, the scientific consensus is that you should never stretch a cold muscle. The usual suggestion is to warm up first with about five minutes of light aerobics, just enough to increase body temperature and induce a light sweat. The consistency of a cold muscle has been compared to Turkish taffy. Warming the muscle first decreases muscle tissue viscosity, leading to safer and more effective stretching.
Easy stretching between sets may help to increase blood flow, thus increasing muscle pump. Raising a weight, or the concentric contraction, leads to a shortening of muscle fibers, and stretching between sets may help to realign muscle fibers, which increases the efficiency of the contractile muscle proteins. As a result you get a more intense set. Some people also suggest that stretching between sets may decrease muscle soreness, though other studies dispute that contention.
Are Bodybuilders Muscle-bound?
If you ever attend a bodybuilding contest, you'll quickly notice that the posing routines that impress the audience most usually include a flexibility component. Back in the 1940s John C. Grimek routinely performed movements like back flips and splits in his routine. More recent examples of bodybuilding flexibility include Flex Wheeler's splits, which are often accompanied by a huge grin, or Tom Piatz's ability to go far past his toes while bending over with stiff legs, in spite of his humongous thighs.
An interesting study published 36 years ago compared the current Mr. America, a world-champion weightlifter and a group of 16-year-old boys in various measures of flexibility The bodybuilder showed greater flexibility in 16 tests, the same flexibility in eight and less flexibility in six. The weightlifter showed greater flexibility in 14 tests, the same in six and less in 10. The researchers thought the decreased values in flexibility in the bodybuilder and weightlifter were due to increased muscle mass in their shoulder and chest areas. Nevertheless, their overall good scores on the flexibility tests led to the conclusion that weight training for increased muscle size and strength also increases flexibility.
Another study that looked at the flexibility characteristics of various people engaged in weight training included male bodybuilders, college football players, students from a college conditioning class, Olympic weightlifters and a control group of students. The results showed that the Olympic lifters and the student control group exhibited the greatest degree of muscle flexibility; however, none of the bodybuilders engaged in a regular stretching routine. A study of 13 novice weight trainees engaged in an 11-week training program found that not only didn't weight training impair muscle flexibility but might actually help increase it.
Thus, it appears that there's nothing inherently limiting in the association between weight training and flexibility; however, increased flexibility that may be due to weight training can only occur with full-range movements. Consequently, training systems that focus on short-range, or partial, reps wont help increase flexibility and may actually hinder it. The true definition of muscle-bound involves a chronic shortening of muscle, which would be induced by partial-rep training.
Another thing to consider is performing a prestretch before you execute a rep of any exercise. That means you stretch the target muscle at the start of each rep. Studies show that prestretching helps to line up contractile muscle proteins, which in turn induces far more muscle power. While you can't perform a prestretch on all exercises, you should do it when you can. In short, if you can begin any repetition with a stretch, do it.
What Happens If You Don't Stretch?
If you don't do any type of flexibility exercise, you'll get stiffer and less flexible with age. Studies show that flexibility declines 20 to 30 percent between the ages of 30 and 70. As you age, a structural protein of connective tissue called collagen changes. With the passing years, collagen proteins become more cross-linked, making connective tissue less flexible. The range of motion of various joints throughout the body decreases, which decreases mobility. The good news is that exercise helps to decrease that fibrosis of tissue and may prevent it to a great degree.
Studies done with older people show that those who are engaged in regular exercise, including weight training and stretching, show flexibility measures comparable to much younger people. The adage Use it or lose it is abundantly relevant here.
Types of Stretches
The scientific literature describes three types of stretches: 1) ballistic, 2) static and 3) proprioceptive neuromuscular facilitation (PNF). As noted above, ballistic stretching is the least desirable for most people interested in increasing their range of movement. By virtue of its bouncy, quick movements, ballistic stretching increases muscle tension by activating the myotatic, or stretch, reflex, which is initiated by the muscle spindles.
Static stretching involves assuming a stretch position, then holding it for six to 60 seconds. Most stretching experts usually suggest holding a stretch for 20 to 30 seconds, then repeating it four to five times. Static, or slow, stretching promotes the inverse stretch reflex induced by Golgi tendon organs, which leads to muscle relaxation and more effective stretching. You should only stretch to the point of mild tension in the muscle. Exceeding that level, or trying to overstretch, leads to activation of the muscle spindles, which, in turn, leads to muscle shortening and tightening. It's possible to get an overload effect by holding each stretch for gradually longer times.
The third type of stretch, PNF, is considered to be the most effective of all stretching movements; however, it also has the notable disadvantage of requiring a partner's assistance. PNF involves assuming a static stretched position, then contracting the muscle isometrically, meaning without movement. The muscle is then relaxed, followed by a second stretch, which leads to a greater range of movement thanks to the isometric muscle contraction. It works because the isometric contraction activates the Golgi tendon organs and the effects discussed above.
While studies show that PNF stretches bring about the greatest improvement in joint range of motion, it may not be practical for many people to have a partner around when they stretch. Your partner provides the resistance for the isometric-contraction phase of the stretch, and if he or she over-stretches the muscle after the contraction, it may activate muscle spindles, leading to a shortening of the muscle and even possible injury.
While most stretching involves freehand movements, some stretching machines, such as Precor's StretchTrainer, are also available. The primary advantage of such machines is that they place you in a biomechanically correct position while preventing bouncy stretch motions that are antithetical to increased range of motion. That's an important concept. Doing stretches with a rounded back, for example, can make an existing lower-back injury worse or produce a new one. Assuming stretch positions in which you tuck your lower leg under your body can overstretch knee joint structures and is definitely contraindicated for people who have knee injuries or are undergoing knee rehab.
Another possible advantage of stretch machines is that they can partially simulate the effects of having a partner for extended stretches, such as what you get with PNF stretching. One type of machine, the MedX, offers the ability to calibrate stretch positions, thus providing a way to quantify flexibility gains as well as a motivation to stretch, since measurable progress is always an encouragement to keep doing something. The primary drawback of at least one type of stretching machine is the expense, which makes it a realistic choice only for commercial gyms. There are, however, home models that are considerably less expensive and within the financial means of the highly motivated.
Compared to lifting weights or even doing aerobics, stretching is relaxing, reduces tension and may effectively extend both your mobility and your years of effective training. So there's no excuse not to include some type of flexibility exercise in your training. One more point: Men shouldn't try to compete with the women in their lives in this area. Women are naturally more flexible than men, at least when it comes to stretching.