Static but not dynamic stretching decreases strength

Until recently, most people stretched before they exercised. Stretching was thought to increase joint range of motion, prevent injury, and increase performance. However, many recent studies showed that stretching does just the opposite. It decreases strength and power output and might increase the risk of injury.

Scientists speculate that stretching interferes with nervous control of movement. Is all pre-exercise stretching bad? A study from the University of Oklahoma by Trent Herda and co-workers found that static stretching decreased muscle strength and activation capacity, but dynamic stretching didn’t. Dynamic stretching involves actively going through a range of motion while static stretching involves holding a stretch for 30 seconds at a time.

We need more research on the optimum warm-up procedure and the risks and benefits of stretching. Actively working muscles and joints through their normal ranges of motion before exercise does not impair strength and might actually activate them for better performance during competition or intense exercise (Journal Strength Conditioning Research, in press; published online May 2008).

Fast curl-ups recruit the most muscle fibers

Most bodybuilders believe that slow, controlled contractions during weight training activate the muscle fibers best. Spanish researchers found the opposite—at least for curl-ups. They measured abdominal muscle activation levels during fast and slow curl-ups by electromyography (EMG). They attached electrodes to the rectus abdominis (six-pack muscle), internal and external obliques (side abs),and the erector spinae (spinal) muscles. They measured muscle activity while the subjects did curl-ups at four different speeds ranging from one rep per four seconds to maximum speed curl-ups.

Activation levels increased in each muscle as speed increased. They concluded that doing curl-ups at fast speeds was best for overloading the abdominal muscles and building dynamic spinal stability. Don’t do ab exercises so fast that you can’t maintain good technique (Journal Strength Conditioning Research, in press; published online May 2008).

Bar diameter doesn’t affect performance during an isometric bench press

Many athletes and coaches think that large diameter bars increase muscle stress and fiber activation during exercises such as the bench press. Also, some coaches recommend training with different bar widths to vary the stress of exercise and increase grip strength. Douglas Fioranelli and Matthew Lee from San Francisco State University concluded that bar diameter did not affect performance during an isometric bench press.

They measured isometric force output at two joint angles (chest and halfway to lockout) using a thick bar (51 millimeters) and a standard Olympic bar (“thin;” 28 millimeters). The standard thin Olympic bar caused the greatest muscle activation at halfway lockout. Isometric exercise might not be the best way to measure the effects of bar width on performance. They might have found different results if they had used a dynamic exercise.

This was an interesting study, but we need more research to help assess the effects of bar width on strength, training load, and muscle activation (Journal Strength Conditioning Research, in press; published online May 2008).

Dehydration decreases upper and lower body power

Dehydration decreases performance during endurance exercise in the heat and is the kiss of death in events such as the marathon and triathlon. Athletes in high-power sports such as soccer, volleyball, and tennis often get dehydrated while playing in the heat. Yet, we don’t know much about the effects of hydration levels on performance in these sports.

A study led by Leon Jones from Chicago State University showed that dehydration decreased upper body power by seven percent and lower body power by 19 percent, as measured by upper and lower body Wingate tests (all-out, 30-second test on a stationary bike or arm ergometer). The subjects were dehydrated through treadmill exercise and rested 1.5 hours before taking the power tests. The subjects said their fatigue levels were 70 percent greater than when they took the tests while normally hydrated, even though they said they were equally motivated.

The authors concluded that dehydration impairs performance and might increase the risk of injury in athletes playing high-power sports (Journal Strength Conditioning Research, 22: 455–463, 2008).

Protein after intense training promotes recovery

One measure of a champion bodybuilder or power athlete is the capacity to train hard, recover quickly, and train hard again. Intense eccentric exercise (negatives or lengthening contractions) causes muscle damage, post-exercise soreness, and delayed recovery. Remedies such as massage, heat, cold, and nonsteroidal anti-inflammatory drugs (e.g., Advil) do not speed recovery or restore normal strength and power more than rest alone.

British researchers found that men who took 100 grams of protein (containing 40 grams of essential amino acids) after an exercise designed to cause muscle soreness and damage (30 minutes of downhill running) showed higher strength levels 24 and 48 hours after exercise compared to a control group. Strength decreased by eight percent in the control group (fake protein) 24 hours after exercise and decreased 10 percent at 48 hours. Strength remained at pre-exercise levels in the protein group during the entire recovery period.

This study showed that taking a supplement containing a large amount of protein (100 grams) promoted recovery and would presumably allow more intense training. It is not known whether this technique would continue to work during repeated exercise sessions

(Applied Physiology Nutrition Metabolism, 33: 483-488, 2008).

Strength and endurance training have different effects on the heart

Weight training and aerobic exercise place different stresses on the heart. Weight training causes a pressure load, which means that the heart must pump harder against pressure to overcome the resistance provided by intense muscle contractions. Aerobics cause a volume load on the heart. Rhythmical exercise such as running increases the amount of blood returning to the heart, which stretches heart walls and expands their volume.

A study from the Massachusetts General Hospital in Boston of endurance and power athletes found that the heart responds differently to pressure and volume loads. Systolic blood pressure (higher blood pressure number) can exceed 400 millimeters of mercury (mmHg) during heavy squats (120 mmHg is normal resting systolic blood pressure), which overload and hypertrophy the walls of the left ventricle that pumps blood into the general circulation. Aerobics cause increases in the chamber size of the right and left ventricles of the heart (the right ventricle pumps blood to the lungs).

The study showed that training rather than genetics accounted for most of the heart changes seen in well-trained athletes. Other studies found that heart changes from intense training reverse when the athletes stop training (Journal Applied Physiology, 104: 1121-1128, 2008).

Don’t be a bench press cripple

How much do you bench? Every guy in America with any athletic talent asks this question when trying to compare his strength with other men. The bench press is the most popular exercise in the gym and is a general measure of strength. Most strong guys can tell you when they achieved landmark bench presses of 205, 225, 300, 315, 350, and 400 pounds. He who lives by the bench, dies by the bench.

Almost all old bench pressers have bad shoulders—usually because of the technique they used to push the big iron. Many athletes prefer using a wide grip when they bench, because they don’t have to push the bar as far. This could be a mistake. Using a wide grip that places the hands greater than 1.5 times the acromial width (measured at the bony endpoints of the shoulders) causes excessive abduction (elbows out) of the shoulders during the exercise. This places high levels of torque on the shoulder joint that can cause arthritis, shoulder cartilage injury, rotator cuff tears, and pectoralis major rupture.

Athletes can decrease range of motion during a bench press by using a better “bench press stance.” Get under you when you bench, bring your shoulder blades together, and brace (tighten) your thigh, butt, and core muscles. This will stick your chest out and give you a powerful platform from which to bench press. It will also save your shoulders. Good technique doesn’t hurt. Do this exercise correctly and you can bench big weights without becoming a bench press cripple when you hit 30 years of age (Strength Conditioning Journal, 29: 10-14, 2007).

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