Physical performance: which factors can influence it?

Three major chronotypes exist: Morning- (M-types), Neither- (N-types) and Evening-types (E-types). M-types tend to perform better in the morning, while E-types in the evening [1]. It has been shown that bad sleep habits tend to worsen physical performance [2], but it is still unclear the impact that such chronobiological variables could have on neuromuscular performance. The current study aims to assess if chronotype, time session and sleep can influence physical performance. 13 participants (males=8, 26±4.5 yrs, 26.5±1.7 kg/m2; females=5, 28.4±4.5 yrs, 26±3.5 kg/m2) underwent an anthropometric assessment and filled in the reduced Morningness-Eveningness Questionnaire and Pittsburgh Sleep Quality Index. They performed 3 neuromuscular tests (Squat Jump-SJ, Counter Movement Jump-CMJ, Counter Movement Jump with swinging arms-CMJSA) on a Chronojump jump mat. The tests were carried out at 09:00 am, 01:30 pm and 06:00 pm, following a randomized order in 3 different days. From the 3 tests the jump height was automatically calculated as function of the flight time by the software provided by the jump mat manufacturer. Both the elastic and coordination indices [3] of performance were computed. Mixed ANOVA tested the interactions between chronotype, time session, sleep and physical performance, while a paired t-test assessed the intragroup comparisons. The total sample (n=13, 26.9±4.8 yrs, 26.3±2.7 kg/m2) was classified as M-types (n=4), N-types (n=6) and E-types (n=3), and Good Sleepers (n=5) and Bad Sleepers (n=8). ANOVA analysis did not show any statistically significant difference. Paired t-test showed that, in the total sample, there was a difference between the elastic index obtained at 09:00 am compared to those obtained at 06:00 pm (6.2±6.8 vs 12.5±8.4 %, p= 0.005). The same difference was evident in the male (8.4±6.5 vs 15.4±8.9 %, p= 0.011) but not in the female sample. The comparison of SJ, CMJ, and CMJSA height are worldwide methods to assess neuromuscular capability. The elastic index could be associated with a better ability to use the stretch-shortening cycle, generating more powerful movements. From this perspective, our results may suggest that the elastic index was higher at evening sessions, probably due to the habitual late afternoon/evening training that could act as an environmental synchronizer. [1] Ayala V, 2021, Influence of circadian rhythms on sports performance. Chronobiol Int. 38(11):1522–1536. [2] Fullagar HHK, 2015. Sleep and Athletic Performance, The Effects of Sleep Loss on Exercise Performance, and Physiological and Cognitive Responses to Exercise. Sport Med. 45(2):161–186. [3] Brazo-Sayavera J, Nikolaidis PT, Camacho-Cardenosa A, Camacho-Cardenosa M, Timón R, Olivares PR, 2017. Acute Effects of Block Jumps in Female Volleyball Players: The Role of Performance Level. Sports (Basel). 5(2):30.