Cardiorespiratory fitness and hip bone mineral density in women: a 6-year prospective study.

Cross-sectional studies and short term interventions focusing on fitness and bone mineral density (BMD) are common. However, few investigations have studied the effect of fitness on BMD over an extended period of time. The present study was conducted to determine the extent to which cardiorespiratory fitness influences risk of BMD loss at the hip over 6 yr. A prospective cohort design was used with 245 healthy, middle-aged women. Hip BMD was assessed using dual energy x-ray absorptiometry. Calcium and vitamin D were measured using the Block Food Frequency Questionnaire. Menopause status was measured by a questionnaire. Results showed that fit and unfit women experienced similar changes in hip BMD over time. Specifically, unfit women experienced a non-significant 7% increased risk of losing hip BMD compared to their counterparts (RR = 1.07, 95% CI = 0.66, 1.73). Adjusting statistically for differences in age, initial body weight, and hip BMD, weight change, menopause status, calcium and vitamin D intake, and time between assessments had little effect on the relationship. Fitness level did not influence risk of hip BMD loss over time.

Changes in hip bone mineral density and objectively measured physical activity in middle-aged women: a 6-year prospective study.

PURPOSE: This study was conducted to determine if physical activity volume (PAv) and intensity (PAi) at baseline influence the likelihood of gaining hip bone mineral density (BMD) over 6 years. DESIGN AND SAMPLE: In a prospective study, the sample was limited to 244 female nonsmokers, ages 35 to 45 years, and was approximately 90% white. SETTING AND MEASURES: PAv and PAi were measured in daily living conditions using accelerometers at baseline. BMD, measured by dual energy x-ray absorptiometry, and several confounding factors were measured in the lab. ANALYSIS: On the basis of BMD change scores, participants were divided into three categories: BMD loss, minimal change, and BMD gain. Risk ratios were used to show the likelihood of BMD gains over time across different levels of PAv and PAi at baseline. RESULTS: Women with higher PAv were more likely to show improvements in hip BMD from baseline to follow-up than their counterparts, as indicated by the Mantel-Haenszel chi-square (χ(2)(mh)  =  6.1, p  =  .01). Women with high PAv were 2.50 times (95% CI, 1.19-5.24) more likely to experience hip BMD gains than women with low PAv, and women with moderate PAv were 2.20 times (95% CI, 1.08-4.45) more likely. PAi was not predictive of gains in hip BMD. Adjusting for potential confounders had little influence on the results. CONCLUSIONS: Middle-aged women with moderate or high levels of PAv are more likely to experience BMD gains at the hip over time compared with those who have low levels of PAv. However, PAi does not appear to influence the likelihood of gaining BMD at the hip over 6 years.

Metabolic energy expenditure during spring-loaded crutch ambulation.

CONTEXT: Individuals using traditional axillary crutches to ambulate expend approximately twice as much energy as individuals who perform able-bodied gait. A relatively novel spring-loaded crutch now being marketed may reduce metabolic energy expenditure during crutch ambulation. This idea, however, had not yet been tested. OBJECTIVE: To determine whether the novel spring-loaded crutch reduces oxygen consumption during crutch ambulation, relative to traditional-crutch ambulation. A secondary purpose was to evaluate the design for subject-perceived comfort and ease of use. DESIGN: Within-subject. SETTING: Indoor track. PARTICIPANTS: 10 able-bodied men and 10 able-bodied women. INTERVENTIONS: The independent variable was crutch design. Each subject ambulated using 3 different crutch designs (traditional, spring-loaded, and modified spring-loaded), in a randomized order. MAIN OUTCOME MEASURES: The primary dependent variable was oxygen consumption. Secondary dependent variables were subject-perceived comfort and ease of use, as rated by the subjects using a 100-mm visual analog scale. Dependent variables were compared among the 3 crutch designs using a 1-way repeated-measures ANOVA (α = .05). RESULTS: Oxygen consumption during spring-loaded-crutch ambulation (17.88 ± 2.13 mL · kg⁻¹ · min⁻¹) was 6.2% greater (P = .015; effect size [ES] = .50) than during traditional axillary-crutch ambulation (16.84 ± 2.08 mL · kg⁻¹ · min⁻¹). There was no statistically significant difference (P = .068; ES = -.45) for oxygen consumption between spring-loaded-crutch ambulation and ambulation using the modified crutch (17.03 ± 1.61 mL · kg⁻¹ · min⁻¹). Subjects perceived the spring-loaded crutch to be more comfortable (P < .001; ES = .56) than the traditional crutch. There was no difference (P = .159; ES = -.09) between the spring-loaded and traditional crutches for subject-perceived ease of use. CONCLUSIONS: Compared with traditional axillary crutches, the novel spring-loaded crutch may be more comfortable but does not appear to benefit subjects via reduced metabolic energy expenditure.

Telephone-based diet and exercise coaching and a weight-loss supplement result in weight and fat loss in 120 men and women.

PURPOSE: Determine the effects of telephone-based coaching and a weight-loss supplement on the weight and body fat (BF) of overweight adults. DESIGN: Randomized, placebo-controlled experiment with assessments at baseline, 2 months, and 4 months. SETTING: Community. SUBJECTS: Sixty overweight or obese men and 60 overweight or obese women, 25 to 60 years INTERVENTION: Eleven 30-minute telephone coaching sessions were spaced throughout the study; the initial conversation lasted 60 to 90 minutes. Supplement or placebo capsules were taken daily over the 17 weeks. MEASURES: Weight was measured using an electronic scale, and BF was assessed using dual energy x-ray absorptiometry. RESULTS: Subjects taking the placebo lost 1.8 +/- 3.3 kg of weight and 0.7 +/- 2.2 kg of BF, whereas supplement users lost more: 3.1 +/- 3.7 kg of weight (F = 4.1, P = .045) and 1.7 +/- 2.6 kg of BF (F = 4.4, p = .039). Participants receiving no coaching lost 1.8 +/- 3.3 kg of weight and 0.7 +/- 2.2 kg of BF, whereas adults receiving coaching lost more: 3.2 +/- 3.6 kg of weight (F = 4.8, p = .032) and 1.6 +/- 2.5 kg of BF (F = 4.2, p = .044). Adults receiving both the supplement and coaching had the greatest losses of weight and BF, suggesting an additive effect (F = 3.2, p = .026; F = 2.9, p = .039, respectively). CONCLUSIONS: Both treatments, coaching and the supplement, viewed separately and in combination, worked to help subjects lose weight and BF. Adults can be educated and motivated via telephone to change behaviors leading to weight loss, and a weight-loss supplement can be included to increase success.