The Impact of Bimodal Daily Training on Circadian Rhythms of Motor and Cardiac Performance in State-Level Athletes

Abstract

Introduction: The influence of circadian rhythms on athletic performance is well-documented, yet the acute effects of a typical bimodal (two-a-day) training schedule on these rhythms are less understood. Optimizing training requires knowledge of how performance variables fluctuate throughout a training day. Objective: This study investigated the circadian variations of selected motor abilities and cardiac variables in state-level athletes at four distinct time points throughout a standard training day: before morning workout (06:00), after morning workout (10:00), before evening workout (14:00), and after evening workout (18:00). Methods: Sixty state-level male athletes (20 runners, 20 jumpers, 20 throwers), aged 20-26, participated. Eight variables were measured at each time point: motor abilities (speed, agility, balance, coordination) and cardiac variables (cardiorespiratory endurance, mean arterial blood pressure [MABP], forced vital capacity [FVC], and resting pulse rate [RPR]). A repeated measures ANOVA was used to analyze the data, with Scheffe’s post-hoc test for paired comparisons, at a significance level of p < 0.05. Results: Significant circadian variations were found across all motor and cardiac variables (p < 0.05). Post-hoc analysis revealed that motor abilities such as agility and coordination peaked after the morning workout (10:00) and evening workout (18:00), showing significant improvements compared to pre-workout states. Cardiac variables also showed significant fluctuations. Cardiorespiratory endurance was highest after the morning session. MABP and RPR were generally lower before workouts and showed complex variations post-exercise. FVC was highest after the morning session. Conclusion: A bimodal training schedule induces significant and predictable intra-day variations in both motor and cardiac function in state-level athletes. Performance readiness for motor skills appears to peak post-workout, while cardiac parameters demonstrate a dynamic response to the exercise-and-recovery cycle throughout the day. These findings suggest that the timing of training and performance evaluation is a critical factor for coaches and sports scientists to consider.