Key result
Bisoprolol significantly influenced the heart rate at the second lactate turn point in relation to the baseline heart rate performance curve pattern (R = 0.78; P < 0.001).
Why the study?
Does bisoprolol alter the heart rate performance curve deflection during incremental exercise in young healthy males?
RCT (n=16)
randomized order
Does bisoprolol alter the heart rate performance curve deflection during incremental exercise in young healthy males?
Effect estimate: R = 0.78
p-value: p=<0.001
The deflection of the heart rate performance curve during incremental exercise is mediated in part by beta1-adrenoceptor sensitivity.
Bisoprolol variably alters heart rate deflection at lactate threshold by baseline pattern; confirms beta1-adrenoceptor mediation in healthy males.
PURPOSE: The deflection of the HR performance curve (HRPC) has been described as an objective marker of submaximal exercise performance. HR response to incremental cycle ergometer exercise is shown to be neither linear nor uniform and a physiological explanation of the deflection phenomenon is lacking. We hypothesized that differences in the beta1-adrenoceptor site are the source of these differences. The aim of the study was to investigate the influence of the highly selective beta1-adrenoceptor (beta1-AR) antagonist bisoprolol (Bi) on the HRPC in young healthy male subjects with different HR response patterns. METHODS: Sixteen subjects were treated in randomized order with Bi or a placebo (Pl) in two separate trials. HR response during incremental cycle ergometer exercise was compared between the two trials. Blood lactate concentration (La) and ventilatory variables were measured throughout both tests. RESULTS: Bi changed the direction of the HRPC more in subjects with a regular, s-shaped response pattern under placebo than those with a nonregular or linear pattern. The influence of Bi on the HR at the second lactate turn point was significantly related (R = 0.78; P < 0.001) to the pattern of the HRPC in Pl conditions. CONCLUSION: We suggest that differences between the subjects with regular s-shaped versus nonregular HRPC may be due to differences at the beta1-AR site. The origin of the HRPC deflection is mediated in part by the beta1-AR sensitivity.
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Hofmann et al. (2005) conducted an RCT in Healthy (n=16). Bisoprolol vs. Placebo was evaluated on Influence of bisoprolol on the heart rate at the second lactate turn point related to the pattern of the HRPC in placebo conditions (R = 0.78, p=<0.001). Bisoprolol significantly influenced the heart rate at the second lactate turn point in relation to the baseline heart rate performance curve pattern (R = 0.78; P < 0.001).
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