Prediction of exhaustion time from heart rate drift

Abstract

Beaury and Eclache (1978) proposed to extrapolate the drift of the heart rate up to maximal heart rate (Hrmax measured during an incremental maximal test) as a convenient way of estimation of the exhaustion tim (tlim) of an exercise at constant power (75 or 80% of Maximal Aerobic Power (MAP)). The purpose of this study was to evaluate this method of estimation of exhaustion time for a large range of power (60, 73, 86, 100 and 120% MAP). We compared the exercise duration calculated with this method (1limtheo) and the actual exhaustion time (tlim). The results showed that the subjects did not reach their maximal heart rate (Hrmax) at tlim and consequently that tlimtheo, calculated by extrapolation of heart rate drift, overestimated tlim, for all the loads in our study. The difference between tlimtheo and tlim (delta tlim expressed as a percentage of tlim) is significantly lower at 86% MAP than delta tlim at the other loads. It is likely that delta tlim is minimal around 80% MAP, i.e. the loads used in the study by Beaury and Eclache (1978). The values of heart rate (Hrlim), oxygen uptake (VO2lim) and oxygen puls (O2pulslim) measured at exhaustion suggested that the high level of energy cost is one of the main limiting factors at 86% MAP, in contrast with other loads.

Local critical power is an index of local endurance

“…In contrast with the other fatigue thresholds in the present study, the average value of HR FT was slightly lower (6%, not signi®cant) than CP. This result could be expected because slight but signi®cant drifts in heart rate were observed during general exercises (cycling or running) at constant load, even for power outputs and velocities lower than CP and CV (Sid-Ali et al 1991;Vautier et al 1994).…”

“…According to Gaesser and Poole (1996), a slow component in O 2 is observed during cycling exercises beyond the power output corresponding to maximal lactate steady state or CP. Similarly, the drifts in O 2 (Vautier et al 1995) and heart rate (Sid-Ali et al 1991; Vautier et al 1994) that occurred during constant-power exercises were high only beyond CP and CV. Poole et al (1988Poole et al ( , 1990 considered that CP is the threshold intensity beyond which O 2 gradually increases up to O 2max .…”

“…Poole et al (1988Poole et al ( , 1990 considered that CP is the threshold intensity beyond which O 2 gradually increases up to O 2max . However, in the study by Vautier et al (1994), most of the subjects failed to reach maximal heart rate and O 2max at exhaustion, even for power outputs above CP. On the contrary, recent data on cycling (Hill and Smith 1999) and severe treadmill exercises (Hill and Ferguson 1999) support the hypothesis that above CP or CV, the slow drift in O 2 can lead to O 2max .…”

“…For example, the CP calculated from short-lasting exercises (Moritani et al 1981) is approximately 15% higher than that calculated from exercises for which the t lim ranged between 3 and 45 min (Vautier et al 1994;Vandewalle et al 1997). On the other hand, short protocols are more interesting in routine examination.…”

Prediction of time to exhaustion from blood lactate response during submaximal exercise in competitive cyclists

“…Based on the well-known relationship between relative exercise intensity and TE (Aunola et al 1990;Olds 1998), previous authors have attempted to estimate TE using the heart rate (HR) response and rating of perceived exertion (RPE) measured during the initial phases of submaximal constant workload tests. Vautier et al (1994) examined the validity of a TE estimation method based on the extrapolation, up to maximal HR, of the HR drift commonly found during prolonged submaximal exercise. However, they found that maximal HR was not reached at the point of exhaustion during cycling at different submaximal constant workloads.…”