Assessing overreaching with HRR: what is the minimal exercise intensity required?

Le Meur Y, Buchhei M, Aubry A, Coutts AJ and Hausswirth Ch. Assessing overreaching with HRR: what is the minimal exercise intensity required? IJSPP 2016, In press.

Full text here

Figure 1 – Changes in heart rate recovery (HRR) at all running intensities during the maximal incremental running test during the overload period. f-OR: functional overreaching.

ABSTRACT

 Purpose: Faster heart rate recovery (HRR) following high-to-maximal exercise (i.e. ≥90% HRmax) has been reported in athletes suspected of functional overreaching (f-OR). This study investigated whether this response would also occur at lower exercise intensity. Methods and Results: Heart rate recovery and rate of perceived exertion (RPE) responses were compared during an incremental intermittent running protocol to exhaustion in twenty experienced male triathletes (8 control and 13 overload subjects led to f-OR) before (Pre), immediately after an overload training period (Mid) and following a 1-week taper (Post). Both groups demonstrated an increase in HRR values at Mid, but this change was very likely to almost certainly larger in the f-OR group at all running intensities (large to very large differences, e.g. +16 ±7 bpm vs. +3 ±5 bpm, in the f-OR and control groups at 11 km×h^-1, respectively). The highest between-group differences in changes in HRR were reported at 11 km×h^-1 (13 ±4 bpm) and 12 km×h^-1 (10 ±6 bpm). A concomitant increase in RPE values at all intensities was reported only in the f-OR group (large-to-extremely large differences, +2.1 ±1.5 to +0.7 ±1.5 AU). Conclusion: These findings confirm that faster HRR does not systematically predict better physical performance. However, when interpreted in the context of the athletes’ fatigue state and training phase, HRR following submaximal exercise may be more discriminant than HRR measures taken following maximal exercise for monitoring f-OR. These findings may be applied in practice by regularly assessing HRR following submaximal exercise (i.e., during warm-up) for monitoring endurance athletes responses to training.

 Keywords: fatigue, overtraining, heart rate, cardiac response, endurance training