运动负荷对青年学生和运动员心脏功能的影响

用无创法(阻抗法)测量了40名青年学生和40名运动员在两种运动负荷(50W和150W)运动前、运动后即刻和恢复时程的收缩时间间期(STI)和心率(HR)。在静态时,“运动员组”的心率较缓(P<0.01)、QS_1较长(P<0.05)、PEP/LVET比值较大(P<0.05和P<0.01)、LVETc较短(P<0.001)。运动后即刻,“学生组”和“运动员组”都表现为QS_z、LVET、PEP、IVCT、QS_1缩短、PEP/LVET比值减小、心率增速和LVETc延长。但“运动员组”QS_2、LYET的缩短和心率增速的程度较少,而PEP/LVET比值的减小和LVETc延长的程度较大。除PEP/LVET比值外,其余各项指标的恢复速度均与负荷量有关。“运动员组”的恢复速度较快,尤其在150W时更为明显。本文指出:1)用阻抗法测算动态下的STI更为实用;2)系统训练可提高心脏活动的潜力,改善泵功能,促进心脏活动的调节速度。

EFFECTS OF WORK LOADS ON CARDIAC FUNCTION IN YOUNG STUDENTS AND ATHLETES

Systolic time intervals ( STI ) and heart rates ( HR ) were measured by a non-invasive method ( the electrical impedance method ) before, immediately after 4-minute bicycle exercise at 2 separate ( 50 W and 150 W ) work loads and during the recovery period in 40 young students and 40 athletes. At rest the HR was lower ( P<0.01 ) and QSt was longer (P<0.05)and the ratio PEP/LVET was larger (P<0.05 and P<0.01 ) and LVETc was shorter ( P<0.001 ) in the athletes. Immediately after cessation of exercise the mean values of QS2, LVET, PEP, IVCT, QS,, and PEP/LVET decreased and those of HR and LVETc increased in both the young students and athletes. However, the degree of QSZ and L\ ET shortening and HR rising in the athletes was not as great as in the young students, but the degree of the ratio PEP/LVET falling and LVETc rising was greater in the athletes. The speed of return toward control of all the indices except the ratio PEP/LVET was load-dependent throughout recovery. The recovery in the athletes was faster , particularly after exercise at 150 Watts. This study shows that 1 ) impedance cardiography is a useful method for evaluating changes in STI during exercise and 2 ) regular physical training improves the pump performance and en hances the contractility of the heart and promotes the adjusting speed of the heart to exercise.