The purpose of this study was to compare daily calcium (Ca) losses in sweat (S) and urine (U) on an exercise day (E) with losses on the preceding day (i.e., a rest day) during which no exercise (NE) was performed. Ten healthy male volunteers (23.9 ± 3.2 years) performed a single bout of moderate exercise (running at 80% HRmax) for 45 min in a warm (32 °C, 58% relative humidity) environment on E. When E and NE were compared, neither Ca intake (1,232 ± 714 and 1,148 ±482 mg, respectively) nor urinary Ca excretion (206 ± 128 and 189 ± 130 mg, respectively) were different (p > .05). Sweat Ca losses during the exercise bout averaged 45 ± 12 mg. The results indicate that, although a small amount of Ca is lost in sweat during 45 min of moderate-intensity exercise, measured (sweat and urine losses combined) Ca losses (251 ±128 and 189 ± 130 mg) were not different (p > .05) between days (E and NE, respectively). These data suggest that moderate exercise for up to 45 min in a warm, humid environment does not markedly increase Ca intake requirements.
Daryll B. Bullen, Mary L. O'Toole and Karen C. Johnson
Leslie A. Pruitt, Abby C. King, Eva Obarzanek, Michael Miller, Mary O’Toole, William L. Haskell, Laura Fast, Sheila Reynolds and for the Activity Counseling Trial Research Group
Physical activity recall (PAR) reliability was estimated in a three-site sample of African American and white adults. The sample was sedentary at baseline and more varied in physical activity 24 months later. Intraclass correlation coefficients (ICCs) were used to estimate the number of PAR assessments necessary to obtain a reliability of 0.70 at both timepoints.
The PAR was administered ≤ 30 d apart at baseline (n = 547) and 24 months (n = 648). Energy expenditure ICC was calculated by race, gender, and age.
Baseline reliability was low for all groups with 4–16 PARs estimated to attain reliable data. ICCs at 24 months were similar (ICC = 0.54–0.55) for race and age group, with 2–3 PARs estimated to reach acceptable reliability. At 24 months, women were more reliable reporters than men.
Low sample variability in activity reduced reliability, highlighting the importance of evaluating diverse groups. Despite evaluating a sample with greater physical activity variability, an estimated 2–3 PARs were necessary to obtain acceptable reliability.
Stephen P. Messier, Walter H. Ettinger Jr, Thomas E. Doyle, Timothy Morgan, Margaret K. James, Mary L. O'Toole and Robert Burns
The purpose of our study was to examine the association between obesity and gait mechanics in older adults with knee osteoarthritis (OA). Subjects were 101 older adults (25 males and 76 females) with knee OA. High-speed video analysis and a force platform were used to record sagittal view lower extremity kinematic data and ground reaction forces. Increased body mass index (BMI) was significantly related to both decreases in walking velocity and knee maximum extension. There were no significant relationships between BMI and any of the hip or ankle kinematic variables. BMI was directly related to vertical force minimum and maximum values, vertical impulse, and loading rate. Increases in braking and propulsive forces were significantly correlated with increased BMI. Maximum medially and laterally directed ground reaction forces were positively correlated with BMI. Our results suggests that, in subjects with knee OA, obesity is associated with an alteration in gait.