Biology subjects

Lepers, R.

Publications and source records attributed to Lepers, R..

4 recordsLinked to original sources

bioRxiv2026

Motor learning under mental fatigue: the compensatory role of rest periods

Mental fatigue is known to impair cognitive and motor performance, but its impact on motor learning remains unclear. This study examined how mental fatigue affects skill acquisition in a sequential finger-tapping task. Twenty-eight participants were assigned to either a mental fatigue group, which completed a thirty-minute Stroop task, or a control group, which watched a documentary of equivalent duration. Both groups then trained on the finger-tapping task across multiple practice blocks with brief rest periods. Overall motor skill improved similarly in both groups. However, mental fatigue altered the pattern of acquisition: participants in the fatigue group showed decreased performance during practice blocks, which was compensated by larger gains during inter-block rest periods. A strong negative correlation was observed between online decrements and offline improvements, indicating that greater declines during practice were associated with larger gains during rest. This study highlights the critical role of rest periods in maintaining learning under cognitively demanding conditions and provides insight into how internal states, such as mental fatigue, can selectively influence the expression of performance without compromising overall learning.

neuroscience↗

bioRxiv2026

The central motor command, but not the muscle afferent feedback, is necessary to perceive effort

Two theoretical models are proposed on the signal processed by the brain to generate the perception of effort (PE): the corollary discharge model and the afferent feedback model. To test the validity of these models, we used electromyostimulation to manipulate the magnitude of the central motor command during voluntary (high motor command), evoked (no motor command) and combined (low motor command) contractions at similar torque outputs. As electromyostimulation evokes sensory volleys to the central nervous system, it was used to evoke muscle contractions and to stimulate afferent feedback. We hypothesized that PE would reflect the magnitude of the central motor command and that evoked muscle contractions in the absence of central motor command would not elicit any PE. Twenty participants (n=10 experienced and n=10 novice with electromyostimulation) volunteered in this study. Participants reported their PE after isometric (10% and 20% MVC) and dynamic (5% and 20% MVC) voluntary, evoked, and combined contractions. For the same torque, participants reported no PE during evoked contractions, but all reported PE during voluntary contractions. Experienced but not novice participants reported lower PE during the combined than during voluntary contractions. This study questions the validity of the afferent feedback model and highlights the key role of motor command-related signals in PE generation. However, results from the novice participants during the combined contractions suggest that other factors such as inhibitory control may affect PE. Future studies should investigate the relationship between the central motor command and PE during physical tasks at various levels of complexity.

neuroscience↗

bioRxiv2023

Quantifying paddling kinematic through muscle activation and whole body coordination during maximal sprint of different duration on a kayak ergometer: a pilot study

Paddling technique and stroke kinematics are important performance factors in flatwater sprint kayaking that require important energetic demand and high strength from the muscles of the trunk and upper limb. The various distance competed (from 200-m to 1000-m) requires the athletes to optimize their pacing strategy to maximize power output distribution throughout the race. This study aims to characterize paddling technique and stroke kinematics during two maximal sprints of different duration. Nine national-trained participants performed a 40-seconds and a 4-min sprint at maximal intensity on a kayak ergometer. The main findings demonstrated a significantly greater mean stroke power (237 {+/-} 80 W vs 170 {+/-} 48 W) and rate (131 {+/-} 8 spm vs 109 {+/-} 7 spm) during the 40-s sprint compared to the 4-min sprint. Athletes used an all-out strategy for the 40-sec exercise and a parabolic-shape strategy during the 4-min. Despite different strategies implemented and higher muscular activation during the 40-s sprint, no change in paddling technique and body coordination occurred during the sprints. The findings of the present study suggest that athletes constructed a well-defined profile that is not affected by fatigue despite a decrease in power output during the all-out strategy. Also, they regulate paddling kinematics during longer exercise with no change in paddling technique and body coordination.

bioengineering↗

bioRxiv2022

Eccentric cycling involves greater mental demand and cortical activation of the frontoparietal network

Eccentric, compared to concentric exercise, is proposed to involve different neuro-motor processing strategies and a higher level of mental demand. This study compared eccentric and concentric cycling at matched perceived effort and torque for the mental demand and related-cortical activation patterns. Nineteen men (30 {+/-} 6 yrs) performed four different 5-min cycling conditions at 30 RPM on a semi-recumbent isokinetic cycle ergometer: 1) concentric at a moderate perceived effort (23 on the CR100(R) scale) without torque feedback; 2) concentric and 3) eccentric at the same average torque produced in the first condition; and 4) eccentric at the same moderate perceived effort than the first concentric condition. The conditions 2-4 were randomised. After each condition, mental demand was monitored using the NASA Task Load Index scale. Changes in oxy-(O2Hb) and deoxy-(HHb) haemoglobin during exercise were meas-ured over both prefrontal cortices and the right parietal lobe from a 15-probe layout using a continuous-wave NIRS system. Mental demand was significantly higher during eccentric compared to concentric cycling (+52%, p = .012) and when the exercise intensity was fixed by the torque rather than the perceived effort (+70%, p .001). For both torque- or perceived effort-matched exercises, O2Hb increased significantly (p < .001) in the left and right prefrontal cortices, and right parietal lobe, and HHb decreased in the left, and right, prefrontal cortices during eccentric compared to concentric cycling. This study supports that acute eccentric cycling, compared to concentric cycling, involves a higher mental demand and frontoparietal network activation.

physiology↗