Interaction Between Exercise And Supplementation
March 3, 2009 by rainier
The same training approach was adopted in a group of frail institutionalized older men and women (mean age 90 ±3 years, range 87–96) (206). After eight weeks of training, the study’s ten subjects had increased muscle strength by almost 180% and muscle size by 11%. More recently, a similar intervention among frail nursing-home residents demonstrated not only increased muscle strength and size but also improved gait speed, stair-climbing power and balance. In addition,
spontaneous activity levels increased significantly, while the activity of a nonexercising control group was unchanged. The study also examined the effects of combining exercise with a protein/calorie supplement—a 240 ml liquid supplying 360 kcalth in the form of carbohydrate (60%), fat (23%) and soy-based protein (17%)—which was designed to augment caloric intake by about 20% and provide one-third of the RDA for vitamins and minerals. While no interaction was seen with muscle strength, functional capacity or muscle size, i.e. no differences were detected between the supplemented group and a non-supplemented controls, the men and women who consumed the supplement and exercised gained weight compared to the three other groups examined (exercise/control, non-exercise supplemented and non-exercise control).The non-exercising subjects who received the supplement reduced their habitual dietary energy intake so that total energy intake was unchanged. It is important to note that this was a very old, very frail population with diagnosed multiple chronic diseases. The increase in overall levels of physical activity has been a common observation in studies (204, 203, 207). Since muscle weakness is a primary deficit in many older individuals, increased strength may stimulate more aerobic activities such as walking and cycling.
The increased calorie requirements resulting from strength training may be a way for older persons to improve their overall nutritional intake when the calories are chosen as nutrient-dense foods. It is particularly important to increase intake of calcium, which was found to be one of the only limiting nutrients in the diet of free-living older men and women in the Boston Nutritional Status Survey for assessing free-living and institutionalized older men and women (208). Careful nutritional planning is needed to reach the recommended calcium levels of 1500 mg/day for post-menopausal women with osteoporosis or who are using hormone replacement therapy, and 1000 mg/day for post-menopausal women taking estrogen. Increased calorie intake from calcium-containing foods is one way to help achieve this goal.
In one of the few studies to examine the interaction of dietary calcium and exercise, 41 post-menopausal women consuming either high-calcium (1462 mg/ day) or moderate-calcium (761 mg/day) diets were investigated. Half of these women participated in a yearlong walking program (45 minutes/day, 4 days/week, 75% of heart-rate reserve). Independent effects of the exercise and dietary calcium were seen. Compared with the moderate calcium group and irrespective of whether they exercised, the women consuming a high-calcium diet displayed reduced bone loss from the femoral neck. The walking prevented a loss of trabecular bone mineral density seen in the non-exercising women after one year. It thus appears that calcium intake and aerobic exercise are both independently beneficial to bone mineral density at different sites.
