Scott B Going

PMID: 7484276;Abstract:

This study was designed to assess the effects of 18 months of resistance exercise on regional and total bone mineral density (BMD) and soft tissue lean mass (STL) in premenopausal women aged 28-39 randomly assigned to an exercise or control group. Twenty-two exercise and 34 control subjects completed the 18-month training study. All subjects were previously inactive and untrained women. Initial, 5-, 12- and 18-month assessments were made of total and regional BMD and total and regional STL using dual energy X-ray absorptiometry. All subjects consumed a 500 mg/day elemental calcium supplement throughout the study. Initial Ca intake without supplement averaged 1,023 mg/day in total sample. Serum levels of bone osteocalcin and dietary assessments using 12 randomly assigned days of diet records were also completed. Muscular strength was assessed from both 1 repetition maximum (RM) testing of 10 weightlifting exercises and by peak torque for hip abduction/adduction and knee extension/flexion. Training increased strength by 58.1% based on 1 RM testing and by 33.8% based on isokinetic testing at 18 months versus baseline. BMD increased significantly above baseline at the lumbar spine for the exercise group at 5 months (2.8%), 12 months (2.3%), and 18 months (1.9%) as compared with controls. Femur trochanter BMD increased significantly (p 0.05) in the exercise group at 12 months (1.8%) and 18 months (2.0%) but not at 5 months (0.7%) as compared with controls. No changes in total BMD, arm BMD, or leg BMD were found. There was a 20% increase in BGP in the exercise group as compared with controls at 5 months and this difference was maintained throughout the study. For STL, significant increases for total, arm, and leg were found at 5, 12, and 18 months for the exercise group versus control ranging from 1-6% over baseline. These results support the use of strength training for increasing STL and muscular strength with smaller but significant regional increases in BMD in the premenopausal population.

PMID: 2355816;Abstract:

The cardiovascular response to maximal, voluntary, sustained 2-min static contraction by three different muscle groups (right hand finger flexors [RHF], right leg extensors [RLE], and both leg extensors [BLE]) was studied in young adult males (N = 13) and females (n = 14). Systolic blood pressure (SBP), diastolic blood pressure (DBP), and heart rate (HR) were recorded at 30 s intervals prior to, during, and after exercise. Mean arterial blood pressure (MABP) and pulse pressure (PP) were computed from SBP and DBP. The force of muscle contraction was monitored continuously throughout the 2-min task. Data were analyzed by MANOVA. The results showed that impulse (force x time) declined significantly throughout exercise, and there were significant differences in impulse among muscle groups. SBP, DBP, PP, and MABP increased significantly throughout the 2-min contraction period, while heart rate increased initially and then leveled off. The magnitudes of the blood pressure and HR responses were related to the muscles involved: BLE > RLE > RHF. Blood pressures during rest and exercise were significantly lower for females than for males, but there was no sex effect for heart rate. These findings suggest that blood pressure increases throughout sustained static muscular contractions despite significant reductions in force production. Heart rate, on the other hand, does not increase throughout exercise under these conditions. It appears that heart rate and blood pressure responses to sustained static contraction are mediated by different mechanisms, but these mechanisms are similar for males and females.

PMID: 12844212;Abstract:

Osteoporosis is a major public health concern. The combination of exercise, hormone replacement therapy, and calcium supplementation may have added benefits for improving bone mineral density compared to a single intervention. To test this notion, 320 healthy, non-smoking postmenopausal women, who did or did not use hormone replacement therapy (HRT), were randomized within groups to exercise or no exercise and followed for 12 months. All women received 800 mg calcium citrate supplements daily. Women who exercised performed supervised aerobic, weight-bearing and weight-lifting exercise, three times per week in community-based exercise facilities. Regional bone mineral density (BMD) was assessed by dual energy X-ray absorptiometry. Women who used HRT, calcium, and exercised increased femoral neck, trochanteric and lumbar spine bone mineral density by approximately 1-2%. Trochanteric BMD was also significantly increased by ∼1.0% in women who exercised and used calcium without HRT compared to a negligible change in women who used HRT and did not exercise. The results demonstrate that regional BMD can be improved with aerobic, weight-bearing activity combined with weight lifting at clinically relevant sites in postmenopausal women. The response was significant at more sites in women who used HRT, suggesting a greater benefit with hormone replacement and exercise compared to HRT alone.