Effect of Acute Mental Fatigue on Leg Strength Qualities Among National Level Athletes

Tan, Wai Lok (2025) Effect of Acute Mental Fatigue on Leg Strength Qualities Among National Level Athletes. Final Year Project (Bachelor), Tunku Abdul Rahman University of Management and Technology.

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Abstract

The current study investigated the effects of acute mental fatigue (MF) on leg strength qualities [rate of force development (RFD) and reactive strength] among national-level athletes. Twenty-five national athletes (Age = 20.23±3.33 year, Weight = 58.58±9.66kg; Height = 165.44±8.38cm) were recruited and randomly assigned to a high MF (n = 12, male = 5, female = 7) or a low MF group (n = 13, male = 6, female = 7) preceding a familiarization session. In the high MF group, the subjects’ age, weight, and height were 20.25±2.53 years, 59.07±9.99 kg, and 165.42±7.33 cm, respectively. In the low MF group, the subjects’ age, weight, and height were 20.38±4.03 years, 58.12±9.73kg, and 165.46±9.54cm, respectively. Baseline assessments and post-test included drop jump for reactive strength index and isometric mid-thigh pull for RFD, alongside mental fatigue measures using visual analogue scales for MF, lethargy, and drowsiness, the NASA-TLX workload measure, and a digit span forward test. A 30-minute incongruent Stroop task (high MF) or documentary viewing (low MF) was administered as a mental exertion intervention. Results revealed significant within-group differences for the high MF group in MF (p = 0.01), sleepiness (p < 0.001), and lethargy (p < 0.001) scales, indicating effective MF induction. Significant declines were also found in RSI (p = 0.01), RFD200 (p = 0.02), RFD250 (p = 0.02), and peak force (p = 0.02). In contrast, the low MF group showed significant increases only in MF (p = 0.03) and sleepiness (p < 0.001), with no significant changes in physical performance. Additionally, no significant differences were observed in the digit span forward test in either group. Between-group comparisons revealed significant differences only in the NASA-TLX temporal demand subscale (p = 0.01) and sleepiness scale (p = 0.03) in the post-test. These findings suggest that acute mental fatigue has the potential to induce heightened perceived mental fatigue, lethargy, sleepiness, pressure, lower-extremity reactive strength, RFD (200ms, 250ms), and peak force production among national-level athletes. Future research delving into sex and sports-specific differences in mental fatigue susceptibility, along with the objective examination of neurophysiological mechanisms underlying the interaction between mental fatigue and other aspects of maximal anaerobic performance, is warranted. Keywords: Mental fatigue, leg strength qualities, rate of force development, reactive strength, national athletes