The Acute Effect of Mental Fatigue on Badminton Performance in Elite Players.

PURPOSE: Several studies have examined the effect of MF on sport performance, but no studies have been conducted on badminton performance. The purpose of the present study was to examine the acute effect of mental fatigue (MF) on badminton performance in elite players. METHODS: In total, 19 elite Danish badminton players completed 2 test days in randomized order, separated by 48 h. On day 1, to elicit MF, a 60-min incongruent Stroop task was performed. On day 2, 60 min of an emotionally neutral documentary was used for the control condition. After either condition, subjects performed a badminton-specific test (BST) where performance time was measured, as well as countermovement-jump height, heart rate, rating of perceived exertion, and lactate. Psychological questionnaires were answered under both conditions. RESULTS: Subjects were significantly more mentally fatigued (P = .002) after the Stroop intervention than in the control. No differences between conditions were detected in the BST (control 32.43 [1.96] vs MF 32.43 [2.36] s; P = .99, Student t test). In addition, no effect of condition (P = .64), time (P = .14), or condition × time (P = .87) was found (2-way analysis of variance). Furthermore, no differences in heart rate, countermovement jump, or rating of perceived exertion were observed between conditions. Lactate showed no effect of condition (P = .46). CONCLUSION: Despite being more mentally fatigued after the Stroop test than in the control condition, performance was not negatively affected during a BST. In addition, no differences in physiological measures were observed.

Exercise-induced molecular mechanisms promoting glycogen supercompensation in human skeletal muscle.

OBJECTIVE: A single bout of exercise followed by intake of carbohydrates leads to glycogen supercompensation in prior exercised muscle. Our objective was to illuminate molecular mechanisms underlying this phenomenon in skeletal muscle of man. METHODS: We studied the temporal regulation of glycogen supercompensation in human skeletal muscle during a 5 day recovery period following a single bout of exercise. Nine healthy men depleted (day 1), normalized (day 2) and supercompensated (day 5) muscle glycogen in one leg while the contralateral leg served as a resting control. Euglycemic hyperinsulinemic clamps in combination with leg balance technique allowed for investigating insulin-stimulated leg glucose uptake under these 3 experimental conditions. Cellular signaling in muscle biopsies was investigated by global proteomic analyses and immunoblotting. We strengthened the validity of proposed molecular effectors by follow-up studies in muscle of transgenic mice. RESULTS: Sustained activation of glycogen synthase (GS) and AMPK in combination with elevated expression of proteins determining glucose uptake capacity were evident in the prior exercised muscle. We hypothesize that these alterations offset the otherwise tight feedback inhibition of glycogen synthesis and glucose uptake by glycogen. In line with key roles of AMPK and GS seen in the human experiments we observed abrogated ability for glycogen supercompensation in muscle with inducible AMPK deletion and in muscle carrying a G6P-insensitive form of GS in muscle. CONCLUSION: Our study demonstrates that both AMPK and GS are key regulators of glycogen supercompensation following a single bout of glycogen-depleting exercise in skeletal muscle of both man and mouse.