Bashing aerobics seems to be in vogue these days. Many bodybuilders believe that doing aerobics in addition to their normal weight-training routine will lead to a loss of muscle. That fear does come with some justification. Several studies have indicated that excessive endurance, or aerobic, training may interfere with strength and muscle gains.
Strength training promotes increased muscle protein synthesis, while aerobics promotes increased capillary formation in muscle and increased oxidative enzymes. Most important, it may interfere with muscle protein synthesis by blocking the production of muscle contractile proteins. In effect, strength training takes you in one direction; aerobics takes you in another.
Why would bodybuilders engage in aerobics? For one thing, aerobic training, because of greater oxygen intake, leads to the most efficient way to burn bodyfat. Fat can only be burned in the presence of oxygen. High-intensity bodybuilding routines use primarily muscle glycogen and glucose as fuel because they are more readily available than stored fat.
Bodybuilders interested in the health aspects of training are aware that nothing beats aerobics for cardiovascular conditioning, since you must elevate your heart rate for a sustained time to obtain cardiovascular benefits. That’s difficult to do with typical weight-training routines, although it can be accomplished through circuit-style training, which features a number of exercises done in nonstop fashion.
But studies also show that circuit training sacrifices maximum bodybuilding gains because you can’t train with sufficient weight to promote reasonable strength gains. The oxygen intake of circuit training is also inferior to straight aerobic training.
Perhaps the most overlooked aspect of combining strength and aerobic training, however, is that aerobic training may foster improved recovery and more efficient training. For example, creatine phosphate is a major fuel source during high-intensity exercise, and the replenishment of CP during exercise in part depends on oxygen availability. Developing a better oxygen delivery system in muscle through aerobics promotes more efficient CP repletion.
The burn in a muscle that signals the end of a set is caused by increased lactate and particularly hydrogen ions in muscle, which increase the acidity level. The acidity interferes with the function of energy-producing enzymes within muscle, throwing a metabolic monkey wrench into the situation.
Aerobic exercise makes the body more efficient at buffering the increased acidity, which results in better energy production and less fatigue.
Among the many processes improved by aerobic training are an upgrade in muscle buffering substances, which soak up excess hydrogen ions and thus lower muscle acidity levels. They include creatine, phosphate, histidine residues and carnosine, an amino acid by-product. Excess acid is buffered in the blood by sodium bicarbonate, better known as baking soda, and the lactate is recycled to the liver, where it’s converted back to glucose, a usable fuel source. Lactate may also be converted into pyruvate, which can be used as an energy source during exercise. That process also uses up extra hydrogen ions, thus lowering muscle acidity levels.
Some exercise scientists even suggest that aerobically fit people may be able to tap into stored fat more easily, thus sparing limited anaerobic fuel sources, such as glycogen and glucose. That would have the effect of increasing both muscle endurance and power. The increased blood flow into muscle that results from aerobic fitness promotes more efficient removal of metabolic waste products, such as hydrogen ions and even heat.
Enhanced oxygen delivery to muscles following exercise also leads to greater creatine phosphate synthesis in muscle, thus aiding recovery.
The key to efficient aerobic training lies in moderation. You don’t want to spend hours in the gym doing aerobics, as that will lead to overtraining and a rise in cortisol levels, which result in muscle breakdown. The most efficient aerobics may be interval style, which features alternating periods of high and low intensity, as determined by exercise heart rate. That produces the benefits of aerobics without making inroads into bodybuilding progress. IM