ECSS Paris 2023: OP-AP19
INTRODUCTION: Sustained cognitive activity (SCA) induces perceived cognitive fatigue and alters affect, arousal, motivation, and boredom. While studies have shown that SCA impairs endurance performance, limited evidence exists on the modifying effect of training status. This study tested the resistance to perceived cognitive fatigue in male competitive endurance trained vs. untrained participants using a 3000-m time trial (TT). To further elucidate the underlying mechanisms, the temporal dynamics of perceptual responses and prefrontal cortex oxygenation during SCA were analysed for both groups. METHODS: In a randomised, counterbalanced cross-over design, 16 males (25.3 ± 5.7 yrs, 8 competitive endurance athletes, 8 untrained males) completed an SCA task (30 min inhibitory control task, AX-CPT) and a control task (30 min, neutral video). Thereafter, a 3000-m TT was performed. Perceived cognitive fatigue and effort were assessed using visual analogue scales pre, during (3x) and at SCA termination. Prefrontal cortex oxygenation was monitored using functional near-infrared spectroscopy (fNIRS). Data were analysed using repeated measures ANOVA. RESULTS: A significant time × condition interaction was observed for perceived cognitive fatigue (p ≤ .001; ηp2 = .755) and cognitive effort (p ≤ .001; ηp2 = .806). No interactions were found for affective valence, arousal, motivation and boredom. No main effect of group (training status) was determined for any of the perceptual responses. Prefrontal oxygenation (TSI%) showed a main effect of time irrespective of condition. In the 3000-m TT, a significant condition × group interaction was observed for running time (p = .039; ηp² = .269). There was a trend towards significance for the percentage change in running time between groups (p = .060). Average and maximum heart rates did not differ between conditions. CONCLUSION: Findings suggest that 30 min of SCA increased perceived cognitive fatigue and cognitive effort compared to control task. Both conditions resulted in a transient elevation of prefrontal oxygenation (TSI%), irrespective of training status. Despite comparable physiological responses, the subsequent 3000-m TT performance significantly decreased after SCA in comparison to control. The decline in 3000-m TT performance was less pronounced among runners with a higher training status than those with a lower status. This finding aligns with previous research demonstrating the protective potential of endurance training against performance declines in the presence of cognitive fatigue. Further multiparametric assessment is necessary to elucidate the psychophysiological effects of SCA on subsequent cognitive or motor performance and the causal mechanisms involved in the different performance declines between trained and untrained subjects.
Read CV Martin SchlegelECSS Paris 2023: OP-AP19
INTRODUCTION: The harmful effects of mental fatigue (MF) on resistance exercise (RE) have become a growing field of interest. The recent increase in randomized clinical trials (RCTs) evaluating the effects of MF on RE warrants a update of the available meta-analytical evidence. This study presents the results of a comprehensive systematic review and meta-analysis, including GRADE qualification, examining the effects of MF on RE across different subgroups. We summarize the effects of MF on RE volume [i.e., number of repetitions, and total training volume load (TTV; number of repetitions x number of sets x load)] in healthy individuals, comparing cognitive task interventions (e.g., STROOP, PVT, AX-CPT, social networks, video games) with controls (e.g., documentary). The results may clarify whether cognitive effort should be avoided before RE sessions since reduced volume could hinder long-term adaptations (e.g., hypertrophy). Thus, the research question for this systematic review was: Does MF induced by previous cognitive effort reduce subsequent RE volume in apparently healthy adults? METHODS: A systematic search was conducted using PubMed, Web of Science (WoS), SPORTDiscus, Scopus, and PsycINFO. Only randomized controlled trials involving healthy human participants, a central executive task requiring cognitive effort, an easier cognitive comparison task, and an RE performance task (e.g., number of repetitions and total training volume load) were included. RESULTS: A total of 10 studies provided 13 comparisons with more than 185 participants, providing data with a moderate level of evidence. The random-effects meta-analysis revealed a significant mean negative effect of prior cognitive effort on RE volume (g = -0.35). Subgroup analysis showed significant differences between MF and control conditions for multi-joint exercises (p < 0.00001), but not for single-joint exercises (p = 0.09). A greater magnitude of negative effect was observed for moderate-intensity RE (g = -0.56) when compared to low (g = -0.31), high (g = -0.25), and body-weight (g = -0.25) exercises. CONCLUSION: The main analysis results showed that exposure to a cognitively demanding task has a significant, small negative effect on subsequent physical performance (g = − 0.35; 95% CI = −0.50, −0.21; p < 0.00001), without significant heterogeneity in the data (p = 0.10 and I2 = 36%). Also, GRADE analysis gathered the available evidence about the effects of MF on RE volume. Overall, the quality of evidence, as assessed by GRADE, was moderate, indicating moderate confidence in the correlation between true and estimated effects. To contextualize these findings for applied practice, the observed effect sizes translate to meaningful reductions in training volume that may compromise both acute workout quality and potentially long-term adaptations. Thus, based on these findings, strength and conditioning professionals should implement evidence-based strategies to mitigate mental fatigue effects on resistance training quality.
Read CV Dalton de Lima JuniorECSS Paris 2023: OP-AP19
INTRODUCTION: While sex-related differences in fatigability are established in temperate conditions [1], the influence on exercise responses under heat stress remains less understood [2]. This study aimed to investigate sex-related differences in fatigability induced by exercise under heat stress. METHODS: Twelve females (F) and fourteen males (M) of similar training status (maximal oxygen uptake: 45.2 and 53.4 mL/kg/min; maximal metabolic steady state: 59 and 62% of peak power output, for F and M, respectively) completed cycling trials to task failure in the heavy domain in temperate (CONT; 21°C, 52% RH) and hot (HEAT; 42°C, 33% RH) environments. During exercise, core temperature and rate of perceived effort were recorded every 2- and 4-min, respectively. Before, after 30-min of exercise, and at task failure, brief (3-s) and long (1-min) maximal voluntary contractions (MVCs) of the knee extensors were performed with peripheral nerve stimulation delivered during along with electromyography activity (EMG) of vastus lateralis being recorded. Where necessary, repeated-measures ANOVA with three (condition, time, sex) or two (condition, sex) factors were used to evaluate the effects of environment, exercise, and sex on the outcomes. Statistical significance was set at p<0.05. RESULTS: There was no difference in time to task failure (TTF) between sexes in either CONT (F= 97±26 min; M= 89±26 min) or HEAT (F= 37±8 min; M= 35±5 min – condition×sex interaction, p=0.54). Throughout exercise in HEAT, F and M showed similar increases (i.e., linear slope) in core temperature (F=+0.03°C/min; M=+0.04°C/min) and perceived effort (F=+0.12 a.u./min; M=+0.14 a.u./min – condition effect, p<0.01; condition×sex interaction, p>0.20). After 30-min of effort, heat stress exacerbated reductions in voluntary activation during brief MVCs (−5%) along with decrements in mean force and in the ratio of the root mean square of EMG to the amplitude of the evoked M-wave (RMS/M-wave) during long MVCs (−13% and −33%, respectively – condition×time interaction, p<0.01). These changes were similar between sexes (condition×time×sex interaction, p>0.42). At task failure, F presented greater reduction in RMS/M-wave during brief MVC than M (−39% and −13%, respectively), whereas M presented greater reduction in M-wave than F (−32% and 3%, respectively – condition×time×sex interaction, p<0.02). Specifically in F, heat-induced changes in TTF correlated (p<0.05) with both heat-induced exacerbation of perceived effort (r=¬−0.66) and the decline in RMS/M-wave during long MVC (r=0.78). CONCLUSION: Heat stress reduced TTF similarly for both sexes but exacerbated central fatigue in F and worsened the impairment in sarcolemma action potential propagation in M. Correlational results suggest that the heat-induced increase in perceived effort and exacerbation of central fatigue may contribute to impaired performance of F when exercising under heat stress. 1. Ansdell et al., 2020 2. Périard et al., 2021
Read CV Yago DutraECSS Paris 2023: OP-AP19