摘要:

The effects of an exercise training program on R-wave amplitude (Ramp) changes during graded exercise were investigated in 14 adolescent females. The experimental group (EG) (N = 6) underwent a 20-wk aerobic exercise program. Eight subjects served as controls (CG). Oxygen uptake (&OV0312;O2), heart rate (HR), and &U1E58;ampwere determined during incremental exercise to exhaustion, pre- and post-program. The Rampwas calculated by using the average of 10 electrocardiographic complexes to provide a stable criterion. Pre-training, EG and CG were not significantly different for &OV0312;O2maxand HRmax; Rampdecreased significantly between rest and 5 min prior to exhaustion for both groups (P< 0.05). Ramp changes were significant between the first min of exercise and 2 min prior to exhaustion for EG (P< 0.05) and between the first min of exercise and 1 min prior to exhaustion for CG (P< 0.05). These changes occurred at 87% of &OV0312;O2maxand 95% of HRmaxfor EG and at 93% of &OV0312;O2maxand 97% of HRmaxfor CG. CG showed no change in these variables post-program except for Rampexhibiting a significant change between rest and the first min of exercise (P< 0.05). EG showed a significant increase in &OV0312;O2max(P< 0.05), and Rampchanges during exercise were delayed. The first significant change occurred between rest and 3 min prior to exhaustion (P< 0.05), and the second change occurred between the first min of exercise and exhaustion (P< 0.05). Thus the latter Rampchange was delayed to 100% of &OV0312;O2maxand HRmaxpost-training. These data showed that Rampexhibits a continual decrease from rest to exhaustion during incremental exercise. Aerobic training appeared to significantly alter the time course of the Rampresponse during exercise.

ISSN:0195-9131    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

This study compares the left ventricular performance of chronically conditioned pentathletes(N = 10) with less-conditioned subjects (N= 10) during dynamic upright exercise. The pentathletes were found to have a superior treadmill performance [24 ± 4 vs 17 ± 2 min (SD),P< 0.01], reduced resting heart rate (41 ± 13 vs 62 ± 6 bpm,P< 0.01), and increased left ventricular mass (254 ± 85 vs 179 ± 35 g,P< 0.05) compared to the control group. Radionuclide ventriculography and heart rate controlled-bicycle ergometry were employed to examine changes in left ventricular ejection fraction, end-diastolic volume, end-systolic volume, arid stroke volume. Heart rate was controlled by adjusting the resistance of the ergometer until stable heart rates of 90, 110, 130, and 150 bpm were achieved. Following heart rate stabilization,99mTc images were acquired during 3-min stages at each target heart rate level. In the pentathletes, left ventricular ejection fraction, end-diastolic volume, and stroke volume increased (P< 0.01) during exercise, and end-systolic volume tended to decrease. No difference was noted in left ventricular ejection fraction between groups when heart rates were matched. However, the exercise-induced changes in end-diastolic volume and stroke volume were greater (P< 0.01) in the pentathletes. In conclusion, the athletes studied relied on the same mechanism as the less-conditioned subjects for improving pump performance during exercise stress, but the athletes' ability to mobilize a greater end-diastolic volume accounts for their larger stroke output during each stage of heart rate-matched exercise.

ISSN:0195-9131    

出版商:OVID    

年代:1986

数据来源: OVID

ISSN:0195-9131    

出版商:OVID    

年代:1986

数据来源: OVID

ISSN:0195-9131    

出版商:OVID    

年代:1986

数据来源: OVID

ISSN:0195-9131    

出版商:OVID    

年代:1986

数据来源: OVID