The practical application of heart rate variability - monitoring training adaptation in world class athletes

by Daniel Plews

Institution: AUT University
Year: 2014
Keywords: Heart rate variability; Elite performance
Record ID: 1299198
Full text PDF: http://hdl.handle.net/10292/7122


Few will disagree that it is the preparatory exercise training completed that makes the most substantial impact on individual exercise performance. It is not surprising therefore that we often see elite athletes that chronically live between the borders of positive adaptation and maladaptation (overtraining/non-functional overreaching) to training, as they attempt to reach the greatest fitness level possible. The adaptive response to any number of training stimuli however, are individual, with genetic factors likely being a substantial determinant of how an athlete might respond. The ability to effectively track these individual responses (positive or negative) using quantitative physiological measures would be advantageous for sports practitioners and coaches alike. Heart rate variability (HRV) provides an estimate of a person’s cardiac autonomic activity, and has shown promise as a potential tool to monitor individual adaptation to endurance training. However, effective methods for assessment are yet to be established. Therefore, the overarching aim of this doctoral thesis was to establish methods by which vagally-derived indices of HRV can be practically applied to monitor and assess an elite endurance athlete’s adaptation to training in an every-day setting. In order to answer this question effectively, this thesis is made up of one case comparison, two methodological studies, one current opinion and an observational study. In the first study of the thesis, a case comparison, the daily HRV and training (23 h ± 2 h per week) were monitored over a 77-day period in two elite triathletes (one male: 22 yr, V ̇O2max 72.5 ml.kg.min-1; one female: 20 yr, V ̇O2max 68.2 ml.kg.min-1). During this period, one athlete performed poorly in a key triathlon event and was diagnosed as non-functionally over-reached (NFOR). The 7-day rolling average of the log-transformed square root of the mean sum of the squared differences between R-R intervals (Ln rMSSD) were compared to the individual smallest worthwhile change (SWC). Ln rMSSD values declined towards the day of the triathlon event (slope = -0.17 ms/wk; r2 = -0.88) in the NFOR athlete, and remained stable in the control athlete (slope = 0.01 ms/wk; r2 = 0.12). Furthermore, in the NFOR athlete, the HRV coefficient of variation (CV of Ln rMSSD 7-day rolling average) revealed large linear reductions towards NFOR (i.e., linear regression of HRV variables vs. day number towards NFOR: -0.65 %/wk and r2 = -0.48), while these variables remained stable for the control athlete (slope = 0.04 %/wk). These data suggest that trends in both absolute HRV values and day-to-day variations along with the individual SWC may be useful measurements indicative of the progression towards mal-adaptation or non-functional over-reaching. Considering the findings of the case comparison, showing that weekly-averaged Ln rMSSD values provided superior representation of maladaptation compared with values taken on a single day, the aim of the second study of the thesis was to compare relationships between…