Effects of Mental Fatigue on Endurance Performance in the Heat

Abstract

Purpose: Mental fatigue is a psychobiological state caused by prolonged periods of demanding cognitive activity and has been observed to decrease time-trial (TT) endurance performance by ~3,5% in normal ambient temperatures. Recently it has been suggested that heat may augment the negative effect of mental fatigue on cognitive performance, raising the question whether it may also amplify the effect of mental fatigue on TT-performance. Methods: In 30 °C and 30% relative humidity, ten endurance-trained male athletes (Age: 22 ± 3 y; W max : 332 ± 41 W) completed two experimental conditions: intervention (I; 45-min Stroop task) and control (C; 45-min documentary). Pre and post intervention/control, cognitive performance was followed up with a 5-min Flanker task. Thereafter subjects cycled for 45 min at a fixed pace equal to 60%-W max , immediately followed by a self-paced TT in which they had to produce a fixed amount of work (equal to cycling 15 min at 80%-W max ) as fast as possible. Results: Self-reported mental fatigue was significantly higher after I compared to C (P<0.05). Moreover electroencephalographic measures also indicated the occurrence of mental fatigue during the Stroop (P<0.05). TT-time did not differ between conditions (I: 906 ± 30 s, C: 916 ± 29 s).Throughout exercise, physiological (heart rate, blood lactate, core and skin temperature) and perceptual measures (perception of effort and thermal sensation) were not affected by mental fatigue. Conclusion: No negative effects of mild mental fatigue were observed on performance and the physiological and perceptual responses to endurance exercise in the heat. Most plausibly mild mental fatigue does not reduce endurance performance when the brain is already stressed by a hot environment.

The Effects of Performing Mental Exertion during Cycling Exercise on Fatigue Indices

“…cortisol and prolactin). Van Cutsem et al (2017) have shown that performing 45-minute of the Stroop task and an endurance task increases the concentration of cortisol (a physiological index of mental fatigue) [16]. Carrasco Páez et al (2007) also reported that prolactin secretion, known as a central fatigue index in the blood [17], is also affected by psychological and physical stress [18].…”

“…Following these instructions, participants started cycling at 80 W for 3 min, and thereafter resistance was increased by 40 W every 3 min, until exhaustion (defined as a cadence of less than 60 revolutions per minute (RPM) for more than 5 s despite strong verbal encouragement). The W max (i.e peak power output (PPO)) was calculated with the formula: W max = W out + (t/180) × 40 [W out : workload of the last completed stage; t: time (seconds) in the final stage] [16].…”

Effect of transcranial direct current stimulation on exercise performance: A systematic review and meta-analysis

“…Many studies have shown that the brain plays a key role in the establishment of fatigue and, therefore, exercise performance [6][7][8][9]. In this regard, several centrally-acting performance modifiers have been shown to influence exercise performance [6,10].…”

Mental fatigue might be not so bad for exercise performance after all: a systematic review and bias-sensitive meta-analysis.

“…Mental fatigue might be not so bad for exercise performance after all: a systematic review and bias-sensitive meta-analysis. last few years, with some studies replicating Marcora et al's (2009) findings (e.g., Head et al, 2016;MacMahon, Schücker, Hagemann, & Strauss, 2014;Pires et al, 2018) and others reporting null effects (Holgado, Troya, Perales, Vadillo, & Sanabria, 2020;Silva-Cavalcante et al, 2018;Van Cutsem, De Pauw, et al, 2017). This discrepancy could be accounted for several factors that deserve closer examination.…”