Article by Wayne L. Westcott, Ph.D., Jose Vaighese, M.D., Nancy Moynihan, M.S., Rita La Rosa Loud, B.S., Scott Whitehead, B.S.
Older Adult Fitness – The Statistics
According to recent reports on older adult fitness by the National Institutes of Health and Centers for Disease Control and Prevention 55, fewer than 2.5 percent of older adults (age 60 and above) attain 30 or more minutes of moderate intensity physical activity (3 METs -3 times resting level of energy expenditure) on a regular basis (5 days a week).
Lack of physical activity, which leads to poor levels of older adult fitness, in general is associated with increased fat weight and resting blood pressure readings.3 Lack of resistance training/strength training exercise in specific is associated with reduced muscle mass (sarcopenia) and bone density (osteopenia) 27. Armed with this knowledge, a good senior fitness specialist can make a huge difference in the life of an older adult.
Older Adult Fitness and Osteoporosis
Without an older adult fitness regimen that includes strength training exercise, osteopenia typically progresses to osteoporosis. This is a condition characterized by low bone mass and bone matrix deterioration 23. According to the U.S. Department of Health and Human services 56, more than 30 percent of women and 15 percent of men will experience bone fractures resulting from osteoporosis.
Hurley 27 has reported that bone mineral density is associated with muscle mass and strength and research clearly confirms these associations 1,5,14,45,49. Although it is tempting to assume a cause and effect relationship between strength training and increased bone mineral density, some older adult fitness studies have supported this premise while others have not. Several longitudinal studies have shown significant increases in bone mineral density following 4 to 24 months of resistance exercise 8,15,17,24,30,32,33,34,35,37,39,40,42,43,48,51,53,58,60,66.
Strength training/resistance training exercise interventions – can they prevent or reverse osteoporosis?
According to a meta-analysis by Wolfe and associates 65, strength training exercise interventions prevented or reversed approximately 1 percent per year of the bone loss (lumbar spine and femur neck) in pre and post- menopausal women. A 2009 review by Going and Laudermilk 23 concluded that resistance training increased bone mineral density by about 1 to 3 percent in pre and postmenopausal at the lumbar spine and femoral neck sites.
A number of other longitudinal senior fitness studies, however, have not demonstrated significant increases in bone mineral density after 4 to 36 months of strength training 11,22,36,41,47,52,57,61,62,63. There are many possible reasons for these inconsistent research results for older adult fitness studies.
Possible causes for these inconsistent research results for older adult fitness studies
According to Cussler and colleagues 15, much of the research on bone mineral density changes resulting from resistance training exercise has been limited by small sample sizes. In addition, short intervention periods, low completion rates, lack of randomization to exercises, and low resistance training/strength training intensity impedes results for older adult fitness and senior fitness training studies. Other variables include hormone replacement therapy in women 24,30,39 and growth hormone administration in men 66. And finally, the overall knowledge of the senior fitness specialist involved may have been inadequate.
It is also possible that nutritional factors, such as intake of protein, calcium, and vitamin D may influence skeletal responses to strength training exercise. Interestingly, a meta-analysis of exercise effects on bone mineral density by Kelley and colleagues 31 showed no significant interactions for calcium and vitamin D intakes.
On the other hand, some older adult fitness studies have demonstrated a positive association between dietary protein intake and increased bone mineral content 12,25,54. In fact, research in older adult fitness has revealed a positive association between protein intake and change in bone mass density in those with the highest consumption of protein along with calcium and vitamin D supplementation 16.
A closer look at protein along with calcium and vitamin D supplementation
Assuming a close relationship between muscle loss (sarcopenia) and bone loss (osteopenia), research showing a positive association between resistance training with supplemental protein and muscle development should also have application for bone development in senior fitness training. Numerous older adult fitness studies have demonstrated that a post-exercise protein – carbohydrate supplement enhances muscle development in men and women of all ages 4,13,18,19,26,28,29,44,46.
We recently completed a 6-month study in which 46 older adult men and women (mean age, 59 years; range 24 – 90 years) performed a standard senior fitness training program of resistance training and aerobic activity (ACSM recommended training protocol 2) with or without post-exercise protein/carbohydrate supplementation 64. The 22 participants who did not receive nutritional supplementation increased their lean (muscle) weight by 3.9 pounds, whereas the 24 participants who did receive nutritional supplementation increased their lean (muscle) weight by 5.5 pounds.
New Study for Older Adult Fitness Measuring Effects of Exercise + Nutrition for Bone, Muscle and Blood Pressure
Based on the research literature and our previous findings, we designed a new senior fitness study to examine the effects of a specifically designed older adult fitness program that included both exercise and nutrition on bone, muscle, and blood pressure in those older adults. Specifically, 52 men and women (mean age, 59 years; range 39 – 82 years) completed the 9-month older adult fitness research program in 1 of 3 study groups:
- (1) a Control Group that did not exercise or take nutritional supplements;
- (2) an Exercise Group that performed resistance training and aerobic activities, but did not take nutritional supplements; and
- (3) an Exercise Plus Nutrition Group that performed resistance training and aerobic training, plus did take nutritional supplements.
Both the Exercise Group and the Exercise Plus Nutrition Group performed the following training program, 2 or 3 days each week for a period of 36 weeks.
Resistance Training/Strength Training Workout Specifics of the Older Adult Fitness Research Study
Participants performed 1 set of 8 to 12 repetitions on 12 Nautilus:
- (1) leg extension;
- (2) leg curl;
- (3) hip abduction/adduction;
- (4) leg press;
- (5) chest press;
- (6) seated row;
- (7) shoulder press;
- (8) lat pulldown;
- (9) low back;
- (10) abdominal;
- (11) rotary torso;
- (12) neck flexion/extension.
Resistance/weight was increased by approximately 5 percent whenever 12 repetitions were completed with proper form (controlled movement speed and full movement range).
Aerobic Training Workout Specifics of the Older Adult Fitness Research Study:
Participants completed 24 minutes of recumbent cycling performed in an interval training manner, with 5 higher-effort intervals (2 minutes each) alternated with 5 lower-effort intervals (2 minutes each), in addition to a 2-minute warm-up and 2-minute cool-down. Heart rate responses were at the lower end of the age-adjusted target heart rate range during the lower-effort intervals.
In contrast, they were at the higher end of the age-adjusted target heart rate range during the higher-effort intervals. Resistance was increased when the peak heart rates dropped to the middle of the age-adjusted heart rate range. Resistance was also increased when rating of perceived exertion fell to the “moderate effort” level 6.
Nutrition Specifics of the Older Adult Fitness Research Study:
In addition to performing the resistance training/strength training and aerobic workouts, the Exercise Plus Nutrition Group of older adults drank a protein/carbohydrate shake immediately after each training session. The shake provided approximately 24 grams of protein and 36 grams of carbohydrate. Participants in this group also took a daily vitamin complex that contained 500 mg of calcium and 1200 IU of vitamin D throughout the course of the older adult fitness study.
Older Adult Fitness Research Study Results
The 9-month changes for our older adult study participants in body composition (percent fat, fat weight, lean weight), resting blood pressure (systolic, diastolic), and bone mineral density (lumbar spine) are presented in Table 1. Analysis of variance revealed statistically significant findings in 5 of the 6 assessment categories, as follows.
- Percent Body Fat: Over the course of the 9 month older adult fitness study, both the Exercise Group and the Exercise Plus Nutrition Group experienced statistically significant reductions in percent body fat.
- Fat Weight: Similar to percent body fat, the 9-month older adult training program significantly decreased fat weight in both the Exercise Group and the Exercise Plus Nutrition Group our older adult fitness study participants.
- Lean Weight: Although both the Exercise Group and the Exercise Plus Nutrition Group gained lean weight during the study period, only the Exercise Plus Nutrition Group attained a statistically significant increase in lean weight in our older adult study participants.
- Resting Blood Pressure: The Exercise Group experienced a non-significant decrease in systolic blood pressure. The Exercise Plus Nutrition Group achieved statistically significant reductions in both systolic and diastolic blood pressure over the 9-month older adult fitness study period.
- Bone Mineral Density: Neither the Exercise Group nor the Exercise Plus Nutrition Group made statistically significant improvements in lumbar spine bone mineral density. However, some interesting changes did occur within the 3 older adult fitness study groups. The Control Group experienced a 1 percent decrease in lumbar spine bone mineral density, the Exercise Group maintained lumbar spine bone mineral density, and the Exercise Plus Nutrition Group achieved a 1 percent increase in lumbar spine bone mineral density.
Changes in body composition, blood pressure and lumbar spine, bone mineral density for Control Group, Exercise Group, and Exercise Plus Nutrition Group over 9-month older adult fitness study period (N=52).
|Exercise & Nutrition Group (N=25)|
|Percent Body Fat||+0.6%
(24.2 – 24.8)
(27.3 – 24.0)
|Fat Weight||+0.2 lbs
(32.0 – 33.1)
(47.4 – 41.1)
|-5.3 lbs *
(41.8 – 36.5)
|Lean Weight||-2.1 lbs
(99.4 – 97.3)
(113.4 – 117.3)
|+5.2 lbs *
(110.7 – 115.9)
|Systolic Blood Pressure||+2.9 mmHg
(117.1 – 120.0)
(124.3 – 121.8)
|-10.0 mmHg *
(118.0 – 108.0
|Diastolic Blood Pressure||+6.0 mmHg
(68.0 – 74.0)
(68.6 – 70.3)
(70.5 – 65.7)
|Bone Mineral Density Lumbar Spine||-1.0% g/cm²
(1.178 – 1.164)
(1.163 – 1.159)
|+1.0 % g/cm²
(1.071 – 1.083)
*Statistically significant improvement (p<0.05)
Discussion and Application for Our Older Adult Fitness Research Study
With respect to bone mineral density, our results were consistent with previous research studies for older adult fitness. For example, the meta-analysis by Wolfe and associates 65 indicated that resistance training/strength training interventions prevented a 1 percent per year bone loss in the lumbar spine of their older adult fitness study participants. And that is essentially what we found between our Control Group and Exercise Group in our older adult fitness study.
After 9 months, the sedentary subjects in our older adult fitness study experienced a 1 percent lumbar spine bone loss, whereas the Exercise Group maintained their lumbar spine bone mineral density. The recent literature review by Going and Laudermilk 23 revealed that resistance training produced a 1 to 3 percent increase in lumbar spine bone mineral density for older adults. This is inclusive of the 1 percent increase attained by our Exercise Plus Nutrition Group.
Although our group differences in the older adult fitness study did not reach statistical significance, it would appear advisable to provide a combined senior fitness program of resistance training and nutritional supplementation for better bone-building benefits.
To maximize improvements for older adult fitness, consider a post-exercise protein/carbohydrate snack
With respect to muscle development, the findings of this older adult fitness study were in agreement with previous research 13,18,19,26,28,29,44,46,64. Although both groups of our older exercisers gained lean (muscle) weight, only the Exercise Plus Nutrition Group experienced a statistically significant increase. Consequently, we suggest that older adult fitness trainees who wish to maximize muscle development consume a post-exercise protein/carbohydrate snack.
With respect to resting blood pressure, only the Exercise Plus Nutrition Group in our older adult fitness study experienced significant decreases in systolic and diastolic readings. While the reasons for these results are unclear, the fact that the Exercise Plus Nutrition Group of older adult participants made significant improvements in all body composition components (percent body fat, fat weight, lean weight) may have played a role in the blood pressure reductions.
According to the 2004 report by the Surgeon General 56, an estimated 10 million Americans had osteoporosis, and this number was predicted to increase almost 40 percent by the year 2020 23. It is therefore essential to identify successful strategies for preventing the insidious series of degenerative processes starting with sarcopenia, leading to osteopenia, and progressing to osteoporosis.
Numerous older adult fitness studies have shown that the most productive means for increasing muscle mass for older adults is resistance training coupled with a post-exercise protein/carbohydrate snack. Consuming additional protein, especially after exercise, may be particularly important, as our older adult fitness research indicates that people over age 50 need more protein than younger adults 10,19,20,21,50. In fact, according to leading nutrition researcher Wayne Campbell, exercisers over age 50 need 50 percent more protein than the recommended daily allowance (RDA) in order to add muscle tissue 50.
To maximize improvements for older adult fitness, consider supplemental calcium and vitamin D for enhanced musculoskeletal health
Because there is a positive relationship between muscle mass/strength and bone mineral density 9,15,23,42, resistance training/strength training coupled with a post-exercise protein/carbohydrate snack would seem to be an effective means for increasing bone mineral density in older adults. Based on recent research and the trend observed in our study, it would also appear appropriate for older adults to take supplemental calcium and vitamin D for enhanced musculoskeletal health 7,16,38,54,57,59.
Summary of Recommendations from Our Older Adult Fitness Research Study
Based on the research literature and the results of our older adult fitness study, we suggest that the combination of regular exercise (resistance training and aerobic activity) and supplemental nutrition (post-exercise protein/carbohydrate snack, daily calcium, daily vitamin D) represents a relatively comprehensive and productive approach for enhancing musculoskeletal fitness (increasing muscle mass and bone mineral density) and for reducing cardiovascular risk factors (decreasing resting systolic and diastolic blood pressures) in older adults.
Assuming physician approval, our recommended exercise and nutrition older adult fitness program for men and women over age 50 is as follows:
- Perform 1 set of 12 basic resistance training exercises that cumulatively address all of the major muscle groups, 2 or 3 non-consecutive days per week.
- Perform about 25 minutes of aerobic activity using an interval training protocol, 2 or 3 days per week.
- Consume a protein/carbohydrate shake/snack (approximately 24 grams protein and 36 grams carbohydrate) immediately after each exercise session.
- Take daily calcium supplementation (e.g., 500 mg) and daily vitamin D supplementation (e.g., 1200 IU).
Create a niche for yourself in older adult fitness
You can make a difference in the lives of older adults by implementing a good older adult fitness training program for your mature clients. This article taught you some of the reasons that a good training program is important and what should be included. But, you need to have an adequate knowledge base to create a niche for yourself in older adult fitness.
The American Academy of Health and Fitness is here to help you with this all-important training you will need to be a safe and effective trainer of older adults. We offer a varied selection of in-depth, advanced continuing education courses.
You will find training in areas such as senior health and fitness, fitness assessment, senior strength training, back stability, nutrition for special dietary needs, lifestyle wellness coaching and cancer exercise. The home study continuing education course SrFit Mature Fitness is definitely one not to miss! Certainly, everything you need to create your niche in older adult fitness!
- Aloia, J., D. Mc Gowan, A. Vaswani, et al. Relationship of menopause to skeletal and muscle mass. American Journal of Clinical Nutrition, 53: 1378-1383, 1991.
- American College of Sports Medicine. ACSM’s Guidelines for Exercise Testing and Prescription (7th Edition). Philadelphia: Lippincott, Williams and Wilkins, 2006.
- American College of Sports Medicine. ACSM’s Guidelines for Exercise Testing and Prescription (8th Edition). Philadelphia: Lippincott, Williams and Wilkins, 2010.
- Anderson, L., G. Tufekovic, and M. Zebis. The effects of resistance training combined with timed ingestion of protein on muscle fiber size and muscle strength. Metabolism, 54: 151-156, 2005.
- Bevier, W., R. Wiswell, G. Pyka, et al. Relationship of body composition, muscle strength, and aerobic capacity to bone mineral density in older men and women. Journal of Bone and Mineral Research, 4: 421-432, 1989.
- Borg, G. Borgs perceived exertion and pain scales. Champaign, IL: Human Kinetics, 1998.
- Bowen, J., M. Noakes, and P. Clifton. A high dairy protein, high-calcium diet minimizes bone turnover in overweight adults during weight loss. Journal of Nutrition, 134: 568-573, 2004.
- Braith, R., R. Mills, M. Welsch, et al. Resistance exercise training restores BMD in heart transplant recipients. Journal of the American College of Cardiology, 28: 1471-1477, 1996.
- Burr, D. Muscle strength, bone mass, and age-related bone loss. Journal of Bone and Mineral Research, 12: 1547-1551, 1997.
- Campbell, W., T. Trappe, R. Wolfe, and W. Evans. The recommended dietary allowance for protein may not be adequate for older people to maintain skeletal muscle. Journal of Gerontology Series A: Biological Sciences and Medical Sciences 56: M373-M380, 2001.
- Chilibeck, P., A. Calder, D. Sale, and C. Webber. Twenty weeks of weight training increase lean tissue mass but not bone mineral mass or density in healthy, active women. Canadian Journal of Physiology and Pharmocology 74(10): 1180-1185, 1996.
- Cooper, C., E. Atkinson, D. Hensuid, et al. Dietary protein intake and bone mass in women. Calcified Tissue International, 58: 320-325, 1996.
- Cribb, P. and A. Hayes. Effect of supplement timing on skeletal muscle hypertrophy. Medicine and Science in Sports and Exercise, 38(11): 1918-9125, 2006.
- Cummings, S. Factors associated with appendicular bone mass in older women. Annals of Internal Medicine, 118: 657-665, 1993.
- Cussler, E., T. Lohman, S. Going, et al. Weight lifted in strength training predicts bone change in postmenopausal women. Medicine and Science in Sports and Exercise, 35: 10-17, 2003.
- Dawson-Hughes, B., and S. Harris. Calcium intake influences the association of protein intake with rates of bone loss in elderly men and women. American Journal of Clinical Nutrition, 75: 773-779, 2002.
- Dornemann, T., R. McMurry, J. Renner, and J. Anderson. Effects of high-intensity resistance exercise on bone mineral density and muscle strength of 40-50 year-old women. Journal of Sports Medicine and Physical Fitness, 37(4): 246-251, 1997.
- Elliot, T., M. Cree, A. Sanford, et al. Milk ingestion stimulates net muscle protein synthesis following resistance exercise. Medicine and Science in Sports and Exercise, 38(4): 667-674, 2006.
- Esmarck, B., J. Anderson, S. Olsen, et al. Timing of post-exercise protein intake is important for muscle hypertrophy with resistance training in elderly humans. Journal of Physiology, 535: 301-311, 2001.
- Fukagawa, N. and V. Young. Protein and amino acid metabolism and requirements in older persons. Clinical Geriatric Medicine, 3(2): 329-341, 1987.
- Gersovitz, M., K. Motil, H. Munro, et al. Human protein requirements: Assessing the adequacy of the current recommended dietary allowance for dietary protein in elderly men and women. American Journal of Clinical Nutrition, 35: 6-14, 1982.
- Gleeson, P., E. Protas, A. LeBlanc, et al. Effects of weight lifting in premenopausal women. Journal of Bone and Mineral Research, 5:153-158, 1990.
- Going, S. and M. Laudermilk. Osteoporosis and strength training. American Journal of Lifestyle Medicine, 3: 310-319, 2009.
- Going, S., t. Lohman, L. Houtkooper, et al. Effects of exercise on BMD in calcium replete postmenopausal women with and without hormone replacement therapy. Osteoporosis International, 14, 637-643, 2003.
- Hannon, M., K. Tucker, B. Dawson-Hughes, et al. Effect of dietary protein on bone loss in elderly men and women: The Framingham Osteoporosis Study. Journal of Bone and Mineral Research, 15: 2504-2512, 2000.
- Hoffman, J. Protein intake: Effect of timing. Strength and Conditioning Journal, 29(6): 26-34, 2007.
- Hurley, B. Strength training in the elderly to enhance health status. Medicine, Exercise, Nutrition and Health, 4: 217-229, 1995.
- Ivy, J. and L. Ferguson. Optimizing resistance exercise adaptations through the timing of post-exercise carbohydrate – protein supplementation. Strength and Conditioning Journal, 32(1): 30-36, 2010.
- Josse, A., J. Tang, M. Tarnopolsky, and S. Phillips. Body composition and strength changes in women with milk and resistance exercise. Medicine and Science in Sports and Exercise, 42(6): 1122-1130, 2010.
- Judge, J, A. Kleppinger, A. Kenny, et al. Home-based resistance training improves femoral bone mineral density in women on hormone therapy. Osteoporosis International, 16(9): 1096-1108, 2005.
- Kelley, G., K. Kelley, and Z. Tran. Exercise and lumbar spine bone mineral density in postmenopausal women: A meta-analysis of individual patient data. Journals of Gerontology: Series A, Biological Sciences and Medical Sciences, 57: M599-M604, 2002.
- Kerr, D., A. Morton, Dick, and R. Prince. Exercise effects on bone mass in post-menopausal women are site-specific and load-dependent. Journal of Bone and Mineral Research, 11: 218-225, 1996.
- Kerr, D., T Ackland, B. Masten, et al. Resistance training over 2 years increases bone mass in calcium-replete postmenopausal women. Journal of Bone and Mineral Research, 16: 175-181, 2001.
- Kohrt, W., A. Ehsani, and S. Birge, Jr. Effects of exercise involving predominantly either joint-reaction or ground-reaction forces on BMD in older women. Journal of Bone and Mineral Research, 12: 1253-1261, 1997.
- Lohman, t., S. Going, R. Pamenter, et al. Effects of resistance training on regional and total BMD in premenopausal women: A randomized prospective study. Journal of Bone and Mineral Research, 10: 1015-1024, 1995.
- McCartney, N., A. Hicks, J. Martin, and C. Webber. Long-term resistance training in the elderly: Effects on dynamic strength exercise capacity, muscle, and bone. Journal of Gerontology: Series A, Biological Sciences and Medical Sciences, 50: B97-104, 1995.
- Menkes, A., S. Mazel, R. Redmond, et al. Strength training increases regional BMD and bone remodeling in middle-aged and older men. Journal of Applied Physiology, 74: 2478-2484, 1993.
- Metcalfe, L., Women’s Health: The Best strength training program for osteoporosis prevention. ACSM’s Certified News, 20(4): 7-11, 2010.
- Milliken, L., S. Going, L. Houtkooper, et al. Effects of exercise training on bone remodeling, insulin-like growth factors, and BMD in post-menopausal women with and without hormone replacement therapy. Calcified Tissue International, 72: 478-484, 2003.
- Nelson, M., M. Fiatarone, C. Morganti, et al. Effects of high-intensity strength training on multiple risk factors for osteoporotic fractures: A randomized controlled trial. Journal of the American Medical Assosciation, 272: 1909-1914, 1994.
- Nichols, J., K. Nelson, K. Peterson, and D. Sartoris. BMD responses to high intensity strength training in active older women. Journal of Aging in Physical Activity, 3: 26-28, 1995.
- Nickols-Richardson, S., L. Miller, D. Wootten, et al. Concentric and eccentric isokinetic resistance training similarly increases muscular strength, fat-free soft tissue mass, and specific bone mineral measurements in young women. Osteoporosis International, 18(6): 789-796, 2007.
- Notelovitz, M., R. Martin, R. Tesar, et al. Estrogen therapy and variable-resistance weight training increase bone mineral in surgically menopausal women. Journal of Bone and Mineral Research, 6: 583-590, 1991.
- Phillips, S., J. Hartman, and S. Wilkinson. Dietary protein to support anabolism with resistance exercise in young men. Journal of the American College of Nutrition, 24(2): 1345-1395, 2005.
- Pocock, N., J. Eisman, T. Gwinn, et al. Muscle strength, physical fitness, and weight but not age predict femoral neck bone mass. Journal of Bone Mineral Research, 4: 441-447, 1989.
- Poole, C., C. Wilborn, L. Taylor, and C. Kerksick. The role of post-exercise nutrient administration on muscle protein syntheses and glycogen syntheses. Journal of Sports Science and Medicine, 9: 354-363, 2010.
- Rockwell, J., A. Sorensen, S. Baker, et al. Weight training decreases vertebral bone density in premenopausal women: A prospective study. Journal of Clinical Endocrinology and Metabolism, 71: 988-993, 1990.
- Ryan, A., M. Treuth, M. Rubin, et al. Effects of strength training on bone mineral density: Hormonal and bone turnover relationships. Journal of Applied Physiology, 77: 1678-1684, 1994.
- Sandler, R. Muscle strength assessments and the prevention of osteoporosis. Journal of the American Geriatric Society, 38(4): 1192-1197, 1990.
- Schardt, D. Saving muscle: How to stay strong and healthy as you age. Nutrition Action Health Letter, 34(3): 3-8, 2007.
- Simkin, A., J. Ayalon, and Leichter. Increased trabecular bone density due to bone-loading exercises in post-menopausal osteoporotic women. Calcified Tissue International, 40: 59-63, 1987.
- Sinaki, M., H. Wahner, Bergstralh, et al. Three-year controlled, randomized trial of the effect of dose-specified loading and strengthening exercises on BMD of spine and femur in non-athletic, physically active women. Bone, 19: 233-244, 1996.
- Snow-Harter, C., M. Bouxsein, B. Lewis, et al. Effects of resistance and endurance exercise on bone mineral status of young women: A randomized exercise intervention trial. Journal of Bone and Mineral Research, 7(7): 761-769, 1992.
- Thorpe, M., E. Jacobson, D. Layman, et al. A diet high in protein, dairy, and calcium attenuates bone loss over 12 months of weight loss and maintenance relative to a conventional high-carbohydrate diet in adults. Journal of Nutrition, 138(6): 1096-1100, 2008.
- Troiano, R., D. Berrigan, K. Dodd, et al. Physical activity in the Untied States measured by accelerometer. Medicine and Science in Sports and Exercise, 40(1): 181-188, 2008.
- S. Department of Health and Human Services. Bone Health and Osteoporosis: A Report of the Surgeon General. Rockville, MD. US Department of Health and Human Services, Public Health Service, Office of the Surgeon General, 2004.
- Vieth, R., H. Bischoff-Ferrari, B. Boucher, et al. The urgent need to recommend an intake of vitamin D that is effective. American Journal of Clinical Nutrition, 85: 649-650, 2007.
- Vincent, K. and R. Braith. Resistance exercise and bone turnover in elderly men and women. Medicine and Science in Sports and Exercise, 34(1): 17-23, 2002.
- Visser, M., D. Deeg, and P. Lips. Low vitamin D and high parathyroid hormone levels as determinants of loss of muscle strength and muscle mass (sarcopenia): The longitudinal aging study Amsterdam. Clinical Endocrinology and Metabolism, 88(12): 5766-5772, 2003.
- Von Stengel, S., W. Kemmler, W. Kalender, et al. Differential effects of strength versus power training on bone mineral density in postmenopausal women: A 2-year longitudinal study. British Journal of Sports Medicine, 41(10): 649-655, 2007.
- Vuori, I., A. Heinonen, H. Sievanen, et. al. Effects of unilateral strength training and detraining on BMD and content in young women: A study of mechanical loading and deloading on human bones. Calcified Tissue International, 55:59-67, 1994.
- Warren, M., A. Petit, P. Hannan, and K. Schmitz. Strength training effects on bone mineral content and density in premenopausal women. Medicine and Science in Sports and Exercise, 40(7): 1282-1288, 2008.
- Weaver, C., D. Teegarden, R. Lyle, et al. Impact of exercise on bone health and contraindication of oral contraceptive use in young women. Medicine and Science in Sports and Exercise, 33: 873-880, 2001.
- Westcott, W., W. Martin, R. LaRosa Loud, and S. Stoddard. Protein supplementation and body composition changes. Fitness Management, 24(5): 50-53, 2008.
- Wolfe, , J. Van Cronenbourg, H. Kemper, et al. The effect of exercise training programs on bone mass: a meta-analysis of published controlled trials in pre and post meno-pausal women. Osteoporosis International, 9: 1-12, 1999.
- Yarasheski, K., J. Campbell, and W. Kohrt. Effect of resistance exercise and growth hormone on bone density in older men. Clinical Endocrinology, 47: 223-229, 1997.