Every weight lifter may find the need to take a break once in awhile. You may be going on vacation, recovering from an injury, or you want to change your routine. Occasional breaks in your lifting regimen are healthy and a great way to avoid overtraining -- but be aware that prolonged inactivity can cause muscle loss.
When you weight train, you experience an increase in muscle size, or hypertrophy. Conversely, following an injury or period of inactivity your muscles respond with atrophy, a decrease in the cross-sectional size of your muscle fibers. Hypertrophy and atrophy are caused by a shift in balance of protein synthesis and protein breakdown. According to "Alterations of Protein Turnover Underlying Disuse Atrophy in Human Skeletal Muscle," published in the Journal of Applied Physiology, disuse atrophy is caused by a decrease in protein synthesis within your muscles.
Atrophy After Detraining
Detraining, the partial or complete loss of exercise-induced muscle-mass increases, occurs within days of training cessation. The rate of muscle loss depends upon many different factors, including your exercise routine type and frequency, your age and level of inactivity. According to Columbia Health, you begin to lose muscle mass within 10 days, and can lose as much as 80 percent of your gains within two weeks. So, breaks from weight lifting should be limited to no more than approximately one week to prevent significant losses. However, trained muscles regain mass quickly after a period of detraining, taking less time to regain mass than it took to gain mass initially.
The rate of muscle atrophy varies with each individual and with different muscles. Age, gender and underlying health conditions can affect how quickly you lose muscle. In "Skeletal Muscle Adaptations with Age, Inactivity, and Therapeutic Exercise," the Journal of Orthopaedic and Sports Physical Therapy" illustrates this point with data from various space missions. For example, the 59-day zero gravity inactivity of Skylab 3 members caused a 20 percent decrease in thigh muscle force, and a 2 percent decrease in bicep force.
Managing Planned or Unplanned Training Breaks
Inevitably you will lose muscle if you take an extended break from lifting weights. If recovering from injury, follow the advice of your physician before resuming exercise. During non-medical breaks from lifting, keep your muscles as active as possible to minimize atrophy. Exercising at least one day a week can prevent muscle atrophy.