Cardiorespiratory development should be the focal point of a physical fitness program. However, it should not be the only component. Evidence has steadily mounted during the last decade regarding the growing importance of muscular development for fitness, health, and aesthetic purposes.The body contains more than 600 muscles, and 65% of these are located above the waist. All muscles, regardless of location, respond to the physiological law of use and disuse. “Use it or lose it” is an axiom that applies to all human beings during every phase of the life cycle. Americans tend to become more sedentary as they age. The declining stimulation results in a progressive shrinking and weakening of the muscles.
With few exceptions, notably cross-country skiing, rowing, and swimming, aerobic activities provide limited stimulation of upper body musculature. Sedentary living neglects the muscular system entirely and accelerates the loss of muscle tissue and body strength. The need for resistance training was illustrated in a study of runners during a 10 year period. Runners who did no resistance training suffered muscle atrophy in their upper bodies while maintaining muscle size in their legs. Their arms, which received little stimulation from jogging, decreased in circumference.
The loss of muscle tissue leads to a predictable loss in muscle strength. By the age of 74, 28% of american men and 65% of american women cannot lift objects that weigh more than 10 pounds. Because of this limitation, everyday functions taken for granted by the young become physical challenges, including opening bottle caps and jar lids, carrying groceries, and climbing stairs. If muscle atrophy progresses unabated, walking without assistance or an aid becomes very difficult if not impossible and the likelihood of falling increases.
Strength remains essentially unaffected to approximately 45 years of age and then declines by 5% to 10% per decade thereafter. On the average, people lose 40% of their muscle mass and 30% of their strength by the time they reach the age of 70. The aging process itself is responsible for only minor changes in the ability of muscles to generate tension. Inactivity, which results in muscle atrophy (loss of muscle mass), is the major contributor to the loss of strength as people age.
Resistance training ideally begins during middle or late adolescence and continues throughout life, but starting at any age provides significant benefit if training is done properly. For example, 12 weeks of weight training increased the strength and size of the exercised muscles in men aged 60 to 72. Strength training also improved the ability of the trained muscles of these older people to use oxygen. Even frail men and women with an average age of 90 years responded positively to 8 weeks of resistance training. These very old subjects averaged a 174% increase in strength and a 9% increase in muscle size. After training, they walked a specified course 48% faster than they could previously. Two subjects discarded their walking canes and walked unassisted. Of three subjects who could not rise from a chair without using their arms before training, two of them were able to accomplish this feat after training.
The same research team expanded on this study by including more subjects (100, average age 87 years), by increasing the number of resistance exercises performed, and by increasing the length of the training program to 10 weeks. Muscle strength increased dramatically, muscle mass by 3%, walking speed by 12%, and stair climbing by 28%.
These studies indicate that the muscular systems of older people are indeed trainable. Improving or maintaining muscle strength enhances mobility and independence during the later years. Cessation of training leads to physical decline at all age levels. Four weeks of detraining led to substantial decreases in maximum strength.
Tags:aerobic activities, Exercise, muscle strength, muscular development, physical fitness program resistance training