The validation of HRV for the quantification of fatigue in athletes : a review

Abstract

Overview of the topic: Load and fatigue monitoring has become an important part of ensuring efficacy and in the monitoring of training regimes. These techniques don’t only ensure the appropriate results are achieved but are also of great use in the prevention of overtraining and injury. HRV is one said method which although not yet appropriately validated, has gained significant traction. Research question: Through the PICO framework the following research question was formulated: ‘Can HRV (I) be considered a valid (O) and reliable method to quantify fatigue in athletes (P), through its correlation with other validated ITL monitoring methods (C) TRIMP and sRPE?’. Eligibility Criteria: Articles published in English, comparing HRV to other validated internal training load monitoring, TRIMP and SRPE in athletes were considered eligible. Outcome of the search: A search of Pubmed, Cochrane Library, and HyDi resulted in the retrieval of 297. However, only 3 studies were finally eligible to be included in this review. Methods of appraisal used: The 3 included articles, were scrutinised using the National Heart, Lung, and Blood Institute’s Quality Assessment Tool for Observational Cohort and Cross-sectional Studies, ensuring a high degree of consistency between their analyses. Main results and conclusions: All 3 included articles concur that when the athletes are exposed to higher training loads, a dip in value for HRV measurement was noted. As a result, the researcher postulates that an inverse correlation between HRV and both TRIMP and sRPE exists. In conclusion, the evidence found suggests that although promising, HRV must be used cautiously and in conjunction with other metrics allowing for a broader assessment of the athlete. Recommendations: Since evidence regards HRV as a method to quantify fatigue in athletes is still scarce, further research is needed, with highly powered, longitudinal studies, also assessing decision making strategies dependant on the interpretation of HRV measurements is suggested. Simple adjustments to the research method, such as the comparison with a greater variety of ITL and fatigue monitoring metrics as well as the impact of daily measurements is also recommended.