The usual explanation of why resistance training promotes gains in muscular size and strength is that resistance training imposes stress on contracting muscles, which leads to damage to muscle fibers. After the training, the body works to repair the fiber damage and institutes measures that will help prevent further damage. Repairing damaged muscle fibers from exercise leads to increased protein deposition in the damaged fibers. That, in turn, leads to a thickening of the existing muscle fibers, especially those damaged by exercise. That thickening of muscle fibers is what we recognize as increased muscular growth. All this implies that you first need to damage muscle fibers through exercise and then allow enough time for the body to repair the damage by thickening the muscle fibers. The notion that you need to damage muscle fibers to ensure muscular growth has been an accepted bodybuilding tenet for as long as I can remember. But there are a few noticeable problems with the idea that you must always damage a muscle to make it grow.
According to exercise scientists, three minimal conditions need to occur to promote increased muscular growth. Those three conditions are:
- Mechanical tension- This involves the application of resistance to working muscles, such as lifting weights. The applied mechanical tension induced by exercise leads to mechanotransduction, where physical stress is converted into chemical signals within a muscle that promote anabolic or growth effects. Mechanical tension explains why resistance exercise is more effective for building muscle than calisthenics, which involves less resistance, usually only body weight. You can get in great shape by exercises such as calisthenics or yoga, but neither exercise will build much muscle because of insufficient mechanical tension.
- Metabolic stress- Metabolic stress involves accumulating exercise metabolic waste products that can induce anabolic signaling effects within the muscle that promote increased muscle gains. Examples of metabolic stress products include lactate and phosphate. Lactic acid produced during anaerobic training, such as typical bodybuilding workouts, appears to signal growth hormone release from the brain's pituitary gland. Growth hormone then produces anabolic effects in muscle. Metabolic stress explains the recent finding that you can develop just as much muscle by lifting relatively light weights, such as about 40% of maximum one-rep weights, as long as you do more repetitions to complete muscular failure. The higher number of reps completed to muscular failure induces a greater level of metabolic stress in the muscle, providing anabolic effects similar to lifting far heavier weights. The advantage of lifting lighter weights to failure is less risk of possible training injuries and less strain on connective tissue, such as tendons and ligaments that could easily be injured by lifting heavy weights. Gains resulting from blood-flow-restricted exercise, which involves partially impeding blood flow to working muscles through wearing a . . .
Join today and get access to this article and all past and present Newsletters, since September 2014. Each month you’ll get a new issue sent to your inbox. Subscribe today for only $10/month!