Effects of Exercise and Nutrition on Bone, Muscle, and Blood Pressure

By Wayne L. Westcott, Ph.D., Jose Vaighese, M.D., Nancy Moynihan, M.S., Rita La Rosa Loud, B.S., Scott Whitehead, B.S.

According to recent research reported 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 in general is associated with increased fat weight and resting blood pressure readings 3, and lack of resistance exercise in specific is associated with reduced muscle mass (sarcopenia) and bone density (osteopenia) 27.

Osteopenia typically progresses to osteoporosis, which is 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 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.  According to a meta-analysis by Wolfe and associates 65, 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 studies, however, have not demonstrated significant increases in bone mineral density after 4 to 36 months of resistance exercise 11,22,36,41,47,52,57,61,62,63.  There are many possible reasons for these inconsistent research results.  According to Cussler and colleagues 15, much of the research on bone mineral density changes resulting from resistance exercise has been limited by small sample sizes, short intervention periods, low completion rates, lack of randomization to exercises, and low training intensity.  Other variables include hormone replacement therapy in women 24,30,39  and growth hormone administration in men 66.  It is also possible that nutritional factors, such as intake of protein, calcium, and vitamin D may influence skeletal responses to resistance 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, studies have demonstrated a positive association between dietary protein intake and increased bone mineral content 12,25,54.  In fact, research with older adults 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.

Assuming a close relationship between muscle loss (sarcopenia) and bone loss (osteopenia), research showing a positive association between resistance exercise with supplemental protein and muscle development should also have application for bone development.  Numerous 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 men and women (mean age, 59 years; range 24 – 90 years) performed a standard program of resistance exercise 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

Based on the research literature and our previous findings, we designed a new study to examine the effects of exercise and nutrition on bone, muscle, and blood pressure in older adults.  Specifically, 52 men and women (mean age, 59 years; range 39 – 82 years) completed the 9-month 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 strength and aerobic training, but did not take nutritional supplements; and (3) an Exercise Plus Nutrition Group that performed strength and aerobic training, and 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.

Strength Workout:

Participants performed 1 set of 8 to 12 repetitions on 12 Nautilus resistance machines: (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; and (12) neck flexion/extension.  Resistance was increased by approximately 5 percent whenever 12 repetitions were completed with proper form (controlled movement speed and full movement range).

Aerobic Workout:

Participants performed 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 and 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, and when rating of perceived exertion fell to the “moderate effort” level 6.

In addition to performing the strength and aerobic workouts, the Exercise Plus Nutrition Group 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 study.

Research Results

The 9-month changes 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 9 months, 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 training program significantly decreased fat weight in both the Exercise Group and the Exercise Plus Nutrition Group.

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.

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 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 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.

Discussion and Application

With respect to bone mineral density, our results were consistent with previous research.  For example, the meta-analysis by Wolfe and associates 65 indicated that exercise interventions prevented a 1 percent per year bone loss in the lumbar spine, and that is essentially what we found between our Control Group and Exercise Group.  After 9 months, the sedentary subjects 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 exercise produced a 1 to 3 percent increase in lumbar spine bone mineral density, which is inclusive of the 1 percent increase attained by our Exercise Plus Nutrition Group.  Although our group differences did not reach statistical significance, it would appear advisable to provide a combined program of exercise and nutritional supplementation for better bone-building benefits.

With respect to muscle development, the findings of this study were in agreement with previous research 13,18,19,26,28,29,44,46,64.  Although both of our exercise groups gained lean (muscle) weight, only the Exercise Plus Nutrition Group experienced a statistically significant increase.  Consequently, we suggest that 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 experienced significant decreases in systolic and diastolic readings.  While the reasons for these results are unclear, the fact that the Exercise Plus Nutrition Group 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 have osteoporosis, and this number is 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 studies have shown that the most productive means for increasing muscle mass is resistance training coupled with a post-exercise protein/carbohydrate snack.  Consuming additional protein, especially after exercise, may be particularly important for older adults, as 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.

Because there is a positive relationship between muscle mass/strength and bone mineral density 9,15,23,42, resistance training coupled with a post-exercise protein/carbohydrate snack would seem to be an effective means for increasing bone mineral density.  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.

Recommendation

Based on the research literature and the results of this study, we suggest that the combination of regular exercise (strength 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 program for men and women over age 50 is as follows:

  1. Perform 1 set of 12 basic resistance exercises that cumulatively address all of the major muscle groups, 2 or 3 non-consecutive days per week.
  2. Perform about 25 minutes of aerobic activity using an interval training protocol, 2 or 3 days per week.
  3. Consume a protein/carbohydrate shake/snack (approximately 24 grams protein and 36 grams carbohydrate) immediately after each exercise session.
  4. Take daily calcium supplementation (e.g., 500 mg) and daily vitamin D supplementation (e.g., 1200 IU).

Table 1.  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 study period (N=52).

 

Assessment Control Group

(N=9)

Exercise Group

(N=18)

Exercise & Nutrition Group  (N=25)
Percent Body Fat +0.6%

(24.2 – 24.8)

-3.6%*

(29.1-25.5)

-3.3%*

(27.3 – 24.0)

Fat Weight +0.2 lbs

(32.0 – 33.1)

-6.3 lbs*

(47.4 – 41.1)

-5.3 lbs *

(41.8 – 36.5)

Lean Weight -2.1 lbs

(99.4 – 97.3)

+3.9 lbs

(113.4 – 117.3)

+5.2 lbs *

(110.7 – 115.9)

Systolic Blood Pressure +2.9 mmHg

(117.1 – 120.0)

-2.5 mmHg

(124.3 – 121.8)

-10.0 mmHg *

(118.0 – 108.0

Diastolic Blood Pressure +6.0 mmHg

(68.0 – 74.0)

+1.7 mmHg

(68.6 – 70.3)

-4.8 mmHg*

(70.5 – 65.7)

Bone Mineral Density Lumbar Spine -1.0% g/cm²

(1.178 – 1.164)

0% g/cm²

(1.163 – 1.159)

+1.0 % g/cm²

(1.071 – 1.083)

*Statistically significant improvement (p<0.05)

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