Exercise reverses depressed metabolic rate produced by severe caloric restriction.

The effects of caloric restriction and exercise on resting metabolic rate (RMR) were studied in five obese humans. Subjects consumed a 500 kcal.d-1 diet for 4 wk, with the subjects remaining sedentary during the first 2 wk and then exercising 30 min daily at 60% VO2max during the last 2 wk of caloric restriction. After 2 wk of dieting, RMR decreased to approximately 87% of the pre-dieting control value. Over the last 2 wk of dieting with the addition of daily exercise, the fall in RMR was reversed as it returned to the pre-dieting level. In summary, daily exercise reversed the drop in RMR associated with severe caloric restriction.

Volumes and breathing patterns during speech in healthy and asthmatic subjects.

The lung volumes and ventilatory patterns used by 10 healthy subjects and 14 patients with varying degrees of asthma were studied. The protocol included conversation, monologue, and counting at two loudness levels. Lung-volume changes were measured with a Respitrace and recorded with associated speech sounds. Volumes, durations, and flows were analyzed for sequences of respiratory cycles. Asthmatics used a greater percentage of their reduced vital capacity. Their inspiratory flow rates were slower, and expiratory rates faster. Asthmatics spent a greater proportion of the total respiratory cycle time on inspiration, and expired a greater volume of gas without sound. Patterns of ventilation suggested that asthmatics favored respiratory over communication needs to a greater extent than healthy subjects. Activities that forced priority to communication needs (counting to a metronome) were inadequate for gas exchange in asthmatics and could be sustained for only a limited period of time.

Aerobic walking in slowly progressive neuromuscular disease: effect of a 12-week program.

OBJECTIVE: Poor cardiorespiratory endurance is a common finding in neuromuscular disease (NMD), and the capacity of such patients to respond to aerobic training is unclear. This study was conducted to determine if a 12-week walking program results in increased aerobic capacity in slowly progressive NMD subjects, whether such a program is safely tolerated, and whether such patients can adhere to a self-monitored, home-based training program. DESIGN: Before-after trial. SETTING: Subjects' homes. PATIENTS: A cohort of 8 slowly progressive NMD subjects (4 men, 4 women) followed in the neuromuscular disease clinic participated (age, 36.6 +/- 8.0 yrs; ht, 170 +/- 11 cm; wt, 74.3 +/- 19.0 kg) (Mean +/- SD). INTERVENTION: Subjects walked 15 to 30 min 3 to 4 days a week at 50% to 60% of their heart rate reserve. MAIN OUTCOME MEASURES: Resting, submaximal, and peak heart rates, systolic and diastolic blood pressures, oxygen uptake, and peak power output. RESULTS: Graded exercise testing to volitional fatigue using a semirecumbent cycle ergometer before and after the training program found significant decreases in submaximal heart rate by 7 +/- 3 beats/min (Mean +/- SEM) (95% CI = -23 to 9) (p = .046) and submaximal systolic blood pressure by 11 +/- 4 mmHg (95% CI = -31 to 9) (p = .019), and nonsignificant increases in peak power output and VO2. CONCLUSIONS: These results suggest that moderate-intensity aerobic exercise training is well tolerated and may provide modest improvement in aerobic capacity in slowly progressive NMD subjects.