When a person is unable to maintain his exercise program, for whatever reason, detraining or deconditioning occurs rapidly. Numerous studies have investigated the effect of detraining on cardiorespiratory fitness, and significant reductions in work capacity has been noted within two weeks. A 25% decrease in maximal oxygen uptake has been reported after three weeks, which is equivalent to a 1% decline in physiologic function for each day of inactivity. In addition, the proportion and size of the Type II fibers have been shown to decrease with detraining. In contrast, maximal muscle strength appears to be more resilient to periods of inactivity. A reduction in maximal capacity only means that it will be harder for you to do a given task than prior to deconditioning. You will still be able to do the work. Remember:
The benefits of training are transient and reversible.
Although maximal aerobic capacity is not maintained without training, other key factors can lead to a decrease in aerobic capacity which will ultimately reduce your work capacity. These include:
♦ Increasing age
♦ High altitude
♦ Loss of lean body weight
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