The objective analyses of workload and recovery has become a prominent focus in elite team sports. Soccer and rugby in particular have extensively incorporated the use of GPS to determine a range of variables associated with training and competition loads. Though we agree that this objectified information plays an important part in the complete monitoring of athletes, a more in depth understanding of its impact is required.
We’ll focus here on the use of heart rate variability (HRV) in soccer, but the content is generalisable to other sports. Firstly, we consider the theory underpinning the use of heart rate (HR) monitoring as a marker of workload and recovery. Secondly, we consider the challenges facing extrapolation of useful indices from this information. And finally, we consider some additional parameters that can enhance the breadth and depth of HR measures used for monitoring load and recovery.
HRV is well established as a marker of autonomic nervous system response (ANS). Under normal conditions HR is controlled by the parasympathetic nervous system. During intense exertion, the sympathetic nervous system takes over. As a byproduct of training, adaptation occurs in the body and the amount of HRV increases, indicating a more malleable interplay between the two branches of the ANS. Similarly, HR itself is considered a prime measure of physiological function because it removes the resource and time demands associated with more invasive physiological procedures such as blood testing etc. It can be used to assess HRV in a few ways: resting HR, exercise HR, and HR recovery.
Resting HR is optimally measured over a five minute period first thing in the morning, and resting HRV over time is considered valid as a measure of adaptation to training. It is important to note beat to beat variation is required to get an accurate picture of cardiac variability, but limitations in HR monitors can skew the data as missing a single beat has been shown to lower parameters in HRV measure by 30%. Similarly, it is necessary to consider the training phase and type of each athlete; someone who is highly trained is likely to reach a point in periodisation where HRV decreases as a function of habituation.
Recovery HR (HRR) and exercise HR (HRex) are considered less reliable than resting HRV due to the amount of confounding determinants (other than ANS function) that can influence the outcome of these measures. For example, individually experienced level of exertion, temperature, noise, light and altitude can all play a part in influencing HRex and HRR.
Ideally, including psychological and neuromuscular markers of fatigue can allow sports scientists and coaches determine how much HRV is as a result of responses to these factors. Perceived exertion and mood states influence HRV, and thus assessing players well-being in corroboration with HR monitoring can give a more comprehensive picture of load and recovery status. Another important consideration is the discrepancy between ANS recovery and neuromuscular recovery; the neuromuscular system can be fatigued independently of the cardiac autonomic response. Aerobic and respiratory links are well established with cardiac response, but anaerobic work, such as that experienced during training and competition for high-intensity intermittent sports (i.e. soccer/rugby), measures of neuromuscular fatigue and recovery are required. Including countermovement jump measures to substantiate HRV monitoring procedure is advised.
At the end of the day, HRV data provides yet another dimension to the conclusion that objective and subjective information together provide the best platform for making informed decisions with regards to an athlete’s health.
Buchheit, M., Mendez-Villanueva, A., Quod, M. J., Poulos, N., & Bourdon, P. (2010). Determinants of the variability of heart rate measures during a competitive period in young soccer players. European journal of applied physiology, 109(5), 869-878.
Buchheit, M., Voss, S. C., Nybo, L., Mohr, M., & Racinais, S. (2011). Physiological and performance adaptations to an in?season soccer camp in the heat: Associations with heart rate and heart rate variability. Scandinavian journal of medicine & science in sports, 21(6), e477-e485.
Buchheit, M., Simpson, M. B., Al Haddad, H., Bourdon, P. C., & Mendez-Villanueva, A. (2012). Monitoring changes in physical performance with heart rate measures in young soccer players. European journal of applied physiology, 112(2), 711-723.