About 40 percent of the body consists of muscles that are used for movement, work, and play (Fahey, Insel, and Roth 2003). When your muscles are strong, you can confidently lift, reach, move, push, and pull without much thought. Strong muscles reduce the possibility of injuries, improve body composition, provide a sense of confidence, and allow you to recover more quickly from physical activities (ACSM 2001). Here, we discuss a number of important reasons for strength training.
Sarcopenia (a reduction in muscle strength and size) occurs as a result of aging. Muscle loss can result from a variety of factors, including inadequate dietary protein intake, reduced muscular activity, physical inactivity, injury, or illness. Middle-aged and older women need to consume adequate amounts of protein to maintain their muscle mass.
Weight training programs for women are effective in preserving muscle mass and preventing sarcopenia and the decline of metabolic rate (ACSM 2001). Most health and fitness experts believe that people are never too old to start a resistance training program and will benefit both physically and psychologically from it. And, following the advice of one expert, you are “probably too old not to exercise” (Westcott and Baechle 1998, 2).
Most adults will lose between five and seven pounds of muscle every decade (Westcott and Baechle 1998). After women reach the age of 30, decreases in muscle density and increases in intramuscular fat are found in cross-sectional areas of the thighs (ACSM 1998c). This trend continues as lean body mass decreases by approximately 15 percent between the ages of 30 and 80 (Cohn et al. 1980). In general, there is almost a 30 percent decrease in overall strength between the age of 50 and 70 years, with dramatic losses after age 70 (ACSM 1998c). To emphasize this point, research from the Framingham Study shows that 40 percent of women 55 to 64 years old, 45 percent of women in the 65 to 74 age category, and 65 percent of women between the ages of 75 and 84 could not lift 10 pounds (Jette and Branch 1981). Over the years, the result is less functional ability and a higher percentage of body fat, which contribute to a declining metabolic rate.
The good news is that following a well-planned resistance training program increases muscle fiber size in older women (Fleck and Kraemer 1997). Increasing the size of muscle fibers helps combat the age-related sarcopenia that normally occurs in women. Therefore, your resistance training program helps slow this process.
Every decade as you lose muscle tissue, your metabolism also decreases by about 5 percent (Westcott and Baechle 1998). This slower metabolic rate contributes to middle-aged weight gain when you eat the same amount of calories but don’t burn all the calories consumed. Strength training can slow the metabolic decreases, muscle loss, and weight gain that normally occur in middle-aged women. Muscle is metabolically active tissue that requires energy (calories). Each day, your body uses more than 35 calories to maintain each pound of muscle, while only 2 calories are needed to sustain a pound of fat (Westcott and Baechle 1998). Therefore, an ongoing resistance training program makes sense so you can maintain or increase your muscle mass and not feel as if you are constantly dieting to maintain a healthy weight as you age. Additionally, no cosmetic surgery, supplements, or special foods are necessary for this achievement.
There’s more good news about the benefits of resistance training, especially for women before and after menopause. Strength training is linked to high bone mineral density in adults of all ages and both sexes (ACSM 2004). Osteoporosis is a type of skeletal deterioration, characterized by decreasing bone density that weakens the bone structure (Graves and Franklin 2001). Osteoporosis is partially preventable with adequate amounts of calcium in the diet, along with progressive high-intensity resistance training (Graves and Franklin 2001). Dense, healthy bones are created in a constant rebuilding process as osteoclasts, cells that break down bone, are replaced by osteoblasts, cells that form bone (Graves and Franklin 2001). One way to stimulate the osteoblasts is to repeatedly use greater-than-normal loads on the bones. The amount of bone building is relative to the amount of overload on the bone, so within limits, increases in the overload will cause greater amounts of bone to be formed (Ebben and Jensen 1998, ACSM 2004). New formation of bone develops on the bone’s outer surface, creating stronger bones that are less likely to fracture (Graves and Franklin 2001). Incremental bone formation occurs within 8 to 12 weeks of strength training, but four to six months of progressive resistance training is the minimum amount of time needed to increase bone mineral density (Graves and Franklin 2001). The greatest increases in bone density occur in previously inactive postmenopausal women who participate in resistance training (Kerr et al. 2001).
A progressive resistance program can be used for the prevention of osteoporosis or when combined with other osteoporosis treatment programs for postmenopausal women (Kerr et al. 2001). It may help to “achieve the highest possible peak bone mass in premenopausal women, and in maintaining or increasing bone in postmenopausal women” (Singh 2000, 380). According to a variety of research studies, the load (i.e., the amount of resistance placed on the bone and muscles) is more important for improving bone density than the type of exercises (free weights, machines, elastic bands) used in progressive resistance training (Singh 2000). “Improvements in bone density have been seen after training regimens of 1, 2, or 3 days per week, provided the intensity (relative load) is high” (Singh 2000, 381). Because bone loss, muscle loss, and decreases in strength and endurance occur when strength training ends, postmenopausal women are urged to continue regular progressive resistance training as long as their health allows (Singh 2000; ACSM 2004).
Strength training provides still more health benefits (Westcott and Baechle 1998):
- Reduced risk of adult-onset diabetes
- Lower blood pressure
- Decreased arthritis pain
- Maintenance of or improvement in lower back health
Glucose metabolism improves because resistance training contributes to an increased metabolism and the resulting increases in energy needed for larger muscles. After participation in a strength training program, decreases in blood pressure in middle-aged participants have been noted (Westcott and Baechle 1998). Resistance training strengthens the muscles around joints, which aids in joint functioning. These stronger muscles can then absorb and cushion the impact of shock to the joints.
Other clinical outcomes of high-intensity resistance training include the following (Singh 2000):
- Increased functional independence
- Improved gait velocity
- Improved sleep
- Decreased depressive symptoms
- Increased self-efficacy
- Increased overall physical activity level
- Improved static and dynamic balance
In adults there is a strong correlation between desired walking speed and muscular strength (Bassey, Bendall, and Pearson 1988), so resistance training is an effective way to maintain physical activity. Strength conditioning exercises that utilize standing positions while using free weights can increase balance and coordination (ACSM 1998c). Thanks to these types of physiological changes, the postmenopausal woman who was fearful of falls or a broken hip is more likely to believe she can be active without injury (Singh 2000).
In summary, muscle loss reduces your ability to function normally and can become a vicious cycle of decreasing activity and additional muscle loss. To break this cycle, we advise women to use strength conditioning routines that include increasingly heavier weights over time.
This is an excerpt from Action Plan for Menopause.