Aerobic circuit exercise training: effect on adolescents with well-controlled insulin-dependent diabetes mellitus.

OBJECTIVES: To test the safety and effects of exercise conditioning on cardiorespiratory fitness, body composition, muscle strength, glucose regulation, and lipid/cholesterol levels. SUBJECTS: Ten male adolescents with insulin-dependent diabetes mellitus (IDDM) and 10 adolescent nondiabetic (ND) subjects. DESIGN: Pretest, posttest intervention trial with control group. SETTING: University-based human performance laboratory. INTERVENTION: Mixed endurance and calisthenic/strength activities performed at a rapid pace three times weekly for 12 weeks. RESULTS: Only one subject with IDDM experienced hypoglycemia after a single exercise session. Both subject groups improved their cardiorespiratory endurance (p < .05). Lean body mass of IDDM subjects increased by 3.5% (p < .05). Subjects with and without IDDM lowered their percent body fat (p < .05 and .001, respectively). Strength improvement of IDDM subjects ranged from 13.7% (p < .001) to 44.4% (p < .01), depending upon the maneuver. Fasting blood plasma glucose for all subjects was unchanged by training, but glycosylated hemoglobin A1c of IDDM subjects was reduced by .96 percentage point (p < .05). Reductions of HbA1c benefitted subjects exhibiting poor preconditioning glycemic control. Low-density lipoprotein cholesterol was decreased in subjects with IDDM (p < .05), but not total cholesterol or triglycerides. CONCLUSION: Adolescents with IDDM undergoing aerobic circuit training improve their cardiorespiratory endurance, muscle strength, lipid profile, and glucose regulation. Aerobic circuit training is safe for properly trained and monitored adolescent diabetics.

Exercise intervention attenuates emotional distress and natural killer cell decrements following notification of positive serologic status for HIV-1.

The impact of aerobic exercise training as a buffer of the affective distress and immune decrements which accompany the notification of HIV-1 antibody status in an AIDS risk group was studied. Fifty asymptomatic gay males with a pretraining fitness level of average or below (determined by predicted VO2 max) were randomly assigned to either an aerobic exercise training program or a no-contact control condition. After five weeks of training, at a point 72 hours before serostatus notification, psychometric, fitness and immunologic data were collected on all subjects. Psychometric and immunologic measures were again collected one-week postnotification. Seropositive controls showed significant increases in anxiety and depression, as well as decrements in natural killer cell number following notification whereas, seropositive exercisers showed no similar changes and in fact, resembled both seronegative groups. These findings suggest that concurrent changes in some affective and immunologic measures in response to an acute stressor might be attenuated by an experimentally manipulated aerobic exercise training intervention.

Microcomputer servo-controlled bicycle ergometer system for psychophysiological research.

Steady state exercise is widely used for psychophysiological studies in which a constant heart rate at a predetermined level is desired. We have developed a microcomputer servo-controlled bicycle ergometer system that can be used for administering steady state exercise. Fourteen healthy male subjects, with a wide range of fitness levels (measured by VO2max) were exercised to either a fixed workload (130 watts) or a predetermined heart rate level (servo-heart rate) of 122 bpm (i.e., 65% of maximum calculated heart rate for the sample). Servo-heart rate was implemented using a feedback loop that automatically adjusted workload to compensate for immediate variations in heart rate, resulting in a more consistent heart rate. Heart rate varied from the predetermined value by 17 bpm during fixed workload but only 3 bpm during servo-heart rate (p less than .05). Therefore, by using the microcomputer servo-controlled bicycle ergometer, heart rate was maintained at a predetermined level regardless of the subject's fitness level. VO2max and workload during servo-heart rate were significantly correlated (r = .85, p less than .05). Therefore, the workload necessary to maintain heart rate at a constant level may provide an approximate index of aerobic fitness level.