ECSS Paris 2023: OP-PN19
INTRODUCTION: Mental fatigue (MF) is defined as a psychobiological state induced by prolonged demanding cognitive activity [1]. It induces a subjective feeling of fatigue [2] and has implications for both physical and cognitive performance (e.g. impaired endurance and attention) [1, 3]. However, the level of emergence of MF is highly variable between individuals. Almost no factors have reliably been identified that can predict the response to MF [4]. Therefore, this study aimed to elucidate whether baseline cognitive functions could predict the susceptibility to MF and its impact on performance. METHODS: We employed a randomized, single-blinded, counter-balanced, cross-over research design. Ninety-seven healthy participants (53 male, 32.7 ± 8.7 y) initially completed three cognitive tests (sustained attention to response task, psychomotor vigilance task, and N-BACK task) assessing their cognitive functions (attention, working memory, and response inhibition). In the experimental and control trial, participants respectively engaged in either a 45-minute Stroop task or documentary. Pre- and post-trial, participants rated their feeling of MF using a visual analogue scale (M-VAS). Post-trial, they completed a Go-NoGo task and a 15-minute cycling time trial to evaluate cognitive and physical performance. Linear regression was used to evaluate the relationship between cognitive abilities and MF effects. RESULTS: Baseline cognitive functions did not significantly relate with M-VAS scores (F=1.527; p=.204; R2=.029) or the extent to which MF affects physical performance (F=.591, p=.670; R2=-.019). Additionally, baseline cognitive functions could not predict the effect of MF on cognitive performance, including reaction time on the Go stimuli (F=.647; p=.630; R2=-.016) and accuracy on both the Go (F=2.024; p=.098; R2=.044) and NoGo (F=1.594; p=.183; R2=.026) stimuli. CONCLUSION: Baseline cognitive functions do not appear to reliably forecast susceptibility to MF or its effects on performance in healthy individuals. More research is needed to fully elucidate the individual response to MF, identify individuals who are more prone to MF and to develop targeted interventions. 1. Van Cutsem, J., et al., The effects of mental fatigue on physical performance: a systematic review. Sports Medicine, 2017. 47(8): p. 1569-1588. 2. Habay, J., et al., Mental fatigue and sport-specific psychomotor performance: a systematic review. Sports Medicine, 2021. 51: p. 1527-1548. 3. Russell, S., et al., What is mental fatigue in elite sport? Perceptions from athletes and staff. European Journal of Sport Science, 2019. 19(10): p. 1367-1376. 4. Habay, J., et al., Interindividual variability in mental fatigue-related impairments in endurance performance: a systematic review and multiple meta-regression. Sports Medicine-open, 2023. 9(1): p. 1-27.
Read CV Emilie SchampheleerECSS Paris 2023: OP-PN19
INTRODUCTION: Mental fatigue (MF) arises from extended periods of demanding cognitive activity and impairs cognitive and physical performance [1]. Hypoxia is another stressor known for impairing performance. Typically, changes in cognitive and physical functioning at altitude are associated with alterations in brain oxygenation [2]. These changes are preferably measured in the prefrontal cortex (PFC), renowned for its role in higher-level cognitive function [2]. Therefore, we aim to examine whether oxygenation of the PFC plays a role in the development of MF. METHODS: Twelve participants (age 22.9 ± 3.5 y; height 174.2 ± 8.2 cm; mass 69.9 ± 13.9 kg) completed four experimental trials, 1) MF in (normobaric) hypoxia (3.800m; 13.5%O2), 2) MF in normoxia (98m; 21.0%O2), 3) Control task in hypoxia 4) Control task in normoxia. Participants performed a 2-back task, Digit Symbol Substitution test and Psychomotor Vigilance task before and after a 60-min Stroop task or an emotionally neutral documentary. Brain oxygenation was measured through functional Near Infrared Spectroscopy. Subjective feelings of MF and physiological measures (heart rate, oxygen saturation, blood glucose and hemoglobin) were recorded. A 2 x 2 x 5 three-way repeated-measures ANOVA [Mental State (MF, CON) X FIO2 (normoxia, hypoxia) X Time (baseline, block 1, block 2, block 3, block4)] was used for the MVAS, fNIRS and Stroop task ACC and -RT. For data from the 2BACK, DSST, PVT, SaO2 Mood and BVAS, a 2 x 2 x 2 three-way repeated-measures ANOVA [Mental State (MF, CON) * FIO2 (normoxia, hypoxia) * Time (pre, post)] was performed. RESULTS: The Stroop task resulted in increased subjective feelings of MF (F(1.6, 16.2) = 19.3, p < 0.001) compared to watching the documentary (F(1.6, 15.5) = 6.3, p= 0.014). 2-back accuracy was lower post task compared to pre task in MF_NOR and CON_NOR (PRE: 87.1 ± 7.72, POST 75.70 ± 12.88), while no differences were found in the other cognitive tasks. The fraction of inspired oxygen did not impact feelings of MF. Although performing the Stroop resulted in higher subjective feelings of MF, hypoxia had no effect on the severity of self-reported MF. Additionally, no evidence could be provided for a role of oxygenation of the PFC in the build-up of MF. CONCLUSION: The role of PFC-oxygenation during the build up to MF and the associated interaction effects with altered oxygen availability were investigated within this study. Although MF was successfully induced, normobaric hypoxia seemed to have no effect on the severity of self-reported MF and subsequent cognitive function. Additionally, no evidence could be provided for the role of PFC oxygenation during a MF task. References 1. Van Cutsem, J et al. (2017). The Effects of Mental Fatigue on Physical Performance: A Systematic Review. Sports medicine (Auckland, N.Z.), 47(8), 1569-1588. 2. McMorris, T et al. (2017). Effect of acute hypoxia on cognition: A systematic review and meta-regression analysis. Neurosci Biobehav Rev, 74(Pt A), 225-232.
Read CV Manon RooseECSS Paris 2023: OP-PN19
INTRODUCTION: The countermovement jump (CMJ) and squat jump (SJ) are two basic movements that are required during physical activities and are used to monitor human performance. CMJ height is almost always greater than SJ height and the difference is thought to reflect the efficiency of utilizing the slow stretch-shortening cycle (SSC). The mechanisms contributing to the performance enhancing effect of the SSC include history-dependent muscle properties, recoil of elastic energy, pre-activation, and stretch reflexes. Although studies have investigated the mechanisms of the jump-dependent differences in performance, hardly any data exists on the effect of repetitive maximal CMJ and SJ performed until exhaustion on motor performance fatigue of the quadriceps muscle (i.e. decline in isometric maximal voluntary torque (IMVT)) as well as its neural (i.e. voluntary activation) and muscular (i.e. contractile function) underpinnings. It was assumed that a lower number of repetitions will be achieved in the CMJ compared to the SJ condition, with unique SSC-dependent neural and muscular adjustments. METHODS: In a randomized, counterbalanced, crossover design, 14 males performed repetitive maximal CMJ and SJ every 4s until exhaustion, defined as a drop in jump height by 50%. Using peripheral electric nerve stimulation and dynamometry, neuromuscular function was assessed before and after exercise during each condition to analyze the impact of jump type (CMJ, SJ) on motor performance fatigue and its neural and muscular determinants. Additionally, mean heart rate (HR), blood lactate concentration (BLC), and effort perception were recorded during exercise. Motor performance fatigue as well as its neural and muscular determinants were quantified as percentage pre-post changes in IMVT (ΔIMVT), voluntary activation (ΔVA), and quadriceps twitch torque evoked by paired electrical stimuli at 100 Hz (ΔPS100), respectively. RESULTS: Participants tended to perform fewer repetitions during CMJ compared to SJ (CMJ: 510±164, SJ: 663±308, p=0.081), while HR (CMJ: 165±15bpm, SJ: 164±17bpm, p=0.410), BLC (CMJ: 4.1±2.3mmol/l, SJ: 3.8±3.0mmol/l, p=0.370), and effort perception (CMJ: 16.5±1.7, SJ: 16.8±1.0, p=0.455) were similar between conditions. Furthermore, no differences between conditions were found for ΔIMVT (CMJ: -29.1±17.5%, SJ: -25.7±8.5%, p=0.429), ΔVA (CMJ: -30.4±21.4%, SJ: -34.9±16.7%, p=0.380), and ΔPS100 (CMJ: -16.4±20.8%, SJ: -22.7±19.9%, p=0.296) CONCLUSION: Participants tended to perform a lower number of CMJ compared to SJ, while indices of internal load (HR, BLC, effort perception), motor performance fatigue, and the decrease in neuromuscular function were comparable between conditions. This might be related to the involvement of the slow SSC, which resulted in a greater jump height and mechanical strain during the CMJ, probably leading to an earlier exercise termination accompanied by the same extent of motor performance fatigue and neuromuscular impairments.
Read CV Martin BehrensECSS Paris 2023: OP-PN19