HEART-RATE DEFLECTION RELATED TO LACTATE PERFORMANCE CURVE AND PLASMA-CATECHOLAMINE RESPONSE DURING INCREMENTAL CYCLE ERGOMETER EXERCISE

The correlation between the behaviour of the heart rate/work performan ce (f(c)/W) curve and blood lactate ([1a](b)) and plasma adrenaline/no radrenaline concentrations ([A]/[NA]) during incremental cycle ergomet er exercise was investigated. A group of 21 male sports students was d ivided into two groups: group I, with a clear deflection of the f(c)/W curve; group II, without or with an inverse deflection of the f(c)/W curve. The aerobic threshold (Th-aer) and the lactate turn point (LTP) were defined. Between Th-aer and maximal work performance (W-max) the behaviour of the f(c)/W curve as well as the behaviour of [1a(-)](b) and [A].[NA] were described mathematically. The f(c), systolic blood p ressure (BPs), W, [1a(-)](b), [A] and [NA] at rest, Th-aer LTP, W-max after 3 and 6 min of recovery (Re-3/Re-6) were calculated. A significa nt difference between the two groups could only be detected for f(c), at LTP, Re-3 and Re-6 (P < 0.05). No significant correlation could be found between individual f(c)/W-behaviour and individual time course o f [1a(-)](b) [A] and [NA]. However, a significant correlation was visi ble between [1a(-)](b)/W-behaviour and individual catecholamine respon se. These results and the fact that the different flattening at the to p of the f(c)/W curve was related to diminished stress-dependent myoca rdial function led us to the conclusion that it is possible that sympa thetic drive is not directly involved in mechanisms of regulation betw een load dependent f(c) and myocardial function. In addition, individu al f(c)/W behaviour was independent of BPs and W-max, or individual co nditions of energy supply.