One of the fastest growing and most popular types of exercise in recent years is resistance exercise, whether used for the purpose of general fitness, rehabilitation, or athletic performance. Resistance exercise comes in many different forms, each of which can produce distinctly different responses (e.g. increased size, strength, power, contraction velocity, muscular endurance, etc.).
Each individual training session can be described by the five acute training variables: choice of exercise, order of exercise, exercise volume (sets x repetitions), load or intensity (percent repetition maximum), and rest (between sets). Each of these variables present numerous possible combinations resulting in literally thousands of possible single-session protocols.
Over a longer training period or cycle, the training variables can be altered to provide the individual with the necessary variability for long-term improvement. Such variety in the long-term program is called periodization, and helps to ensure that the body is continually being presented with a stress that permits both progress and adequate recovery.
Often associated with training programs for advanced athletes, such training variety is also critical for the individual who is embarking on a lifetime exercise program for general fitness. This variation of the resistance exercise prescription also avoids the monotony that can occur when the identical exercise protocol is performed each session with little or no variation.
Training Volume and Intensity
One common problem when prescribing resistance exercise is determining the appropriate combination of training volume and intensity. Excessive volume or intensity may produce less than optimal results, and may actually create a situation where performance is impaired. If physical performance is depressed for extended periods of time, and requires long recovery periods, overtraining has occurred. This situation may result in a decreased desire to exercise, and can also increase the risk of illness or injury. Such a situation can be avoided through proper prescription of volume and intensity. It must be noted that increasing training volume or intensity is not necessarily bad.
There may even be phases of training where an individual experiences short-term performance decrements that are easily recovered from with several days of decreased exercise stress. This is called overreaching, and when carefully prescribed can contribute to long-term progress.
The typical overtraining scenario, however, occurs when either training volume or intensity is excessive for too long. It is also important to note that training volume and intensity are inversely related. In other words, when training volume is greatest, intensity must be relatively low, and vice versa. Unfortunately, many individuals prescribing resistance exercise programs fail to realize this, and simply follow the axiom that more is better for both volume and intensity. The net result is that performance is either impaired or at best is less than optimal.
Excessive Training Volume
One type of overtraining can occur when training volume is excessive for prolonged periods. This can occur by increasing training frequency, adding exercises, or performing more exercise sets. It appears that this type of overtraining manifests many signs/symptoms similar to those seen with overtraining with endurance exercise.
Two hormones often impacted by overtraining are testosterone and cortisol, and overtraining due to high training volumes often results in a decrease in the ratio between resting concentrations of these hormones (testosterone/cortisol). While this ratio may not be directly responsible for the performance decrements observed, it has been repeatedly shown that this ratio decreases as training volume increases. It also appears that the use and mobilization of free fatty acid, which expends more fat by using energy in the metabolic cycle, increases during high volume phases of resistance exercise. This may contribute in part to decreases in body fat with this type of training stress. Although it has been theorized that the sympathetic nervous system may become exhausted with this type of training (the parasympathetic overtraining syndrome), this has yet to be demonstrated with resistance exercise.
Reprinted with permission of the American College of Sports Medicine, "Overtraining with Resistance Exercise," www.acsm.org.