Chapter 6: Training for Strength 128 example, if the individual performed bench press on Monday, he/she could perform squats on Tuesday but would have to wait until at least Thursday before performing bench press again. The principle of individuality states that each individual has unique strengths and weaknesses and will respond to training differently. There are several factors that influence strength training potential such as age, gender, training experience, injury status, muscle fiber type, tendon insertion points and hormonal balance. The principle of reversibility states that the physiological adaptations associated with training are lost when training is stopped; however, detraining effects can be reversed when training is resumed. Impact of Strength Training on Body Composition and Bone Density Research has shown that strength training has a larger impact on body composition than endurance training (Boutcher, 2011). Additionally, regular strength training has been proven to decrease fat mass, increase fat-free mass and lessen the effects of sarcopenia (age-related loss of muscle mass and strength). Between the ages of 30 and 65, the average American loses a half-pound of muscle and gains one pound of fat each year (Walters & Byl, 2013). Figure 6.1 depicts a magnetic resonance imaging (MRI) scan of the upper leg. The scan shows some of the body composition changes associated with aging. Although the circumference of the thigh remained relatively unchanged, there is a significant increase in the amount of subcutaneous fat as well as a notable decrease in muscle mass. Additionally, there is a significant amount of bone loss, thereby increasing the risk of fractures and/or osteoporosis. Figure 6.1. Impact of Aging on Body Composition
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