Is heart rate a convenient tool to monitor over-reaching? A systematic review of the literature

Abstract

Objective: A meta-analysis was conducted on the effect of overload training on resting HR, submaximal and maximal exercise HR (HR), and heart rate variability (HRV), to determine whether these measures can be used as valid markers of over-reaching. Methods: Six databases were searched using relevant terms and strategies. Criteria for study inclusion were: participants had to be competitive athletes, an increased training load intervention had to be used, and all necessary data to calculate effect sizes had to be available. An arbitrary limit of 2 weeks was chosen to make the distinction between short-term and long-term interventions. Dependent variables were HR and HRV (during supine rest). Standardised mean differences (SMD) in HR or HRV before and after interventions were calculated, and weighted according to the within-group heterogeneity to develop an overall effect. Results: In these competitive athletes, short-term interventions resulted in a moderate increase in both resting HR (SMD = 0.55; p = 0.01) and low frequency/ high frequency ratio (SMD = 0.52; p = 0.02), and a moderate decrease in maximal HR (SMD = 20.75; p = 0.01). Long-term interventions resulted in a small decrease in HR during submaximal (SMD = 20.38; p = 0.006) and maximal exercise (SMD = 20.33; p = 0.007), without alteration of resting values. Conclusion: The small to moderate amplitude of these alterations limits their clinical usefulness, as expected differences may fall within the day-to-day variability of these markers. Consequently, correct interpretation of HR or HRV fluctuations during the training process requires the comparison with other signs and symptoms of overreaching to be meaningful.Peak performance in sport requires training loads that will occasionally push the adaptation capabilities of the human body to their limits. If significant improvements are expected when sufficient recovery is allowed before competition, 1 2 athletes may also experience unexplained underperformance.3 4 Various terms have been used in the scientific literature over the past decades to describe this disruption in the training adaptation process. In an effort to clarify the terminology, the Task Force of the European College of Sports Science distinguished functional over-reaching (FOR), non-functional over-reaching (NFOR) and overtraining syndrome (OTS) to mark out the continuum that leads to long-term underperformance. Over-reaching refers to an accumulation of training and/or non-training stress resulting in short-term decrease in performance capacity with or without related physiological and psychological signs and symptoms of overtraining, in which restoration of performance capacity may take several days to several weeks.5-7 FOR is occasionally used by athletes during a typical training cycle. An improvement in performance capacity above what would be achievable after a normal training cycle is expected if the athlete is allowed sufficient recovery to permit the occurrence of the supercompensation effect. As suggested by Meeusen et al...

Prediction of Functional Overreaching From Subjective Fatigue and Readiness to Train After Only 3 Days of Cycling

“…6 In our study heart rate also increased during the TFL but without differences between the groups. Many factors influence the resting heart rate, such as body position and autonomic activity.…”

“…1,2 Training load, mood disturbances, resting heart rate, and the combination of heart-rate recovery with perceived fatigue fit these criteria and are often used in monitoring studies. [6][7][8][9] Monitoring of the external training load, quantified by the training volume and intensity, is insufficient because many circumstances can influence the ability of an athlete to handle a given external load. 10 The internal load is the physiological and psychological stress that results from the external load.…”

Prevention, diagnosis and treatment of the overtraining syndrome: Joint consensus statement of the European College of Sport Science (ECSS) and the American College of Sports Medicine (ACSM)

“…A meta-analysis (Bosquet et al 2008) concluded that short term (< 2 weeks) overload training results in an increased resting heart rate (mean value + 4.5 bpm), decreased maximal heart rate (-7.5 bpm) and a higher ratio between low and high frequency HRV. However, this was no longer the case after longer intensified training interventions lasting > 2 weeks, where the only significant difference remained a decreased maximal heart rate (-3.6 bpm).…”

“…For example, the HPA adaptation to normal training is characterised by increased ACTH/cortisol ratio only during exercise recovery (due to decreased pituitary sensitivity to cortisol) (Lehmann et al 1993b;Duclos et al 1997Duclos et al , 1998, and by modulation REVISION : Consensus Statement "Overtraining" (17-07-2012) 10 of tissue sensitivity to glucocorticoids (Duclos et al 1999(Duclos et al , 2003). However, it should be emphasized that during a resting day, in endurance-trained athletes 24 h cortisol secretion under non-exercising conditions is normal Duclos et al 1999Duclos et al , 2003.…”

Cuantificación y análisis de situaciones ofensivas en partidos reducidos en fútbol = Quantification and analysis of offensive situations in sided games in soccer

“…However, these two variables were not correlated with 20 m speed performance, which also seemed to be coherent since changes in sprint performance would have a rather peripheral impact than central fatigue. Several researchers, in addition to other signs or symptoms, validated the use of HRrest, as a predictor of over-trained athletes (25). The use of these two markers is essential in the individual monitoring made by medical and technical staff in soccer clubs.…”