The chronotype can influence the perceived exertion during self-paced exercise performed at different times of day

Aim: Individual differences can influence circadian rhythms, resulting in a person’s preference for morning or evening activities. The aim of this study was to analyze the psychophysiological responses during morning (M) (0830 hours) and afternoon (A) (1530 hours) self-paced walking session in different chronotypes. Method: Forty-six college students (24.81 ± 7.18 years) filled in the Morningness–Eveningness Questionnaire (MEQ) to determine their chronotype. In order to evaluate the psychophysiological responses during the walking sessions (1530 m long, uphill altitude gap 127.5 m and downhill altitude gap 85 m) at different times of day, the heart rate (HR) and the walking times were recorded; moreover, the subjects reported their rate of perceived exertion (RPE) using Borg’s scale at completion of the every walking session. Results: The results showed that both M-types and E-types tended to walk slower during the M session, while presenting opposite trend in HR and RPE; M-types, as expected, had higher HR and lower RPE, while, E-types had lower HR and higher RPE during the morning session. Based on the multivariate analysis of covariance (MANCOVA) we found an effect for the individual chronotype (as an ordinal covariate) on HR mean, RPE and walking speed parameters (p = .05). A post hoc analysis showed a significant difference (p = .02; Cohen’s d = -1.21) between M-types vs. E-types for RPE in the morning, while no differences were found in the afternoon. Conclusion: This study draws attention to the possibility that psychophysiological responses to physical activity can be influenced by individual chronotype. The subjects had lower perceived exertion in accordance with their chronotype. Knowledge of chronotypes could be important when prescribing physical exercise with the aim to increase the health and well-being in the population. References Adan A (1994) Chronotype and personality factors in the daily consumption of alcohol and psychostimulants. Addiction 89:455–462 Borg GA (1982) Psychophysical bases of perceived exertion. Med Sci Sports Exerc 14:377–38 Horne H, Ostberg O (1976) A self-assessment questionnaire to determine morningness–eveningness in human circadian rhythms. Int J Chronobiol 4:97–110