1. ABSTRACT INTRODUCTION Mental Fatigue and the Effects on Anaerobic Power Output J. Zepernick 1, N. VanDomelen 1, K. De Jong 1, C. Nilson 1, K. Long 1, E. Ameluxen-Coleman 2, B. Pearson 1, and C.P. Katica 1 1 Pacific Lutheran University, Tacoma, WA & 2 University of Michigan-Flint, Flint, MI METHODSRESULTS Participants: - N = 10 (7 males, 3 females) healthy, active college-aged students (Mean ± SD Age = 22 ± 4 y; Weight = 76.4 ± 12.2 kg; Body fat = 18.8 ± 6.7). Procedures (3 Lab Visits, Lasting ~ 60 – 80 min. each ) - 1 st Visit – Collect descriptive data and familiarization (2 WAT) - 2 nd & 3 rd Visit: - Intervention – HR and BP taken after 5 min of rest followed by 60 min of watching a sitcom (CON) or taking a GRE Verbal Reasoning test (MF). During the 60 min, HR and BP were taken to monitor any physiological strain. RPE and the SOFI-20 questionnaire were given to assess any mental fatigue that may have occurred following the 60 min experimental trial. - WAT – Following the 60 min intervention, 5 min warm-up was allowed followed by 2 WAT with 5 min of active recovery following the first WAT. - Post WAT – Immediately after each WAT, HR, BP, RPE, peak power output, fatigue index and average power were recorded. - Statistical Analysis – Paired sample t-tests were ran to assess the differences between CON and MF. The fact that mental fatigue has an effect on cognitive and skilled performance is well known, but limited research has been conducted looking at the effects of mental fatigue on athletic performance. PURPOSE: To investigate if there are any effects on anaerobic power following a mental fatiguing test. METHODS: In this repeated measures counterbalanced designed study, 10 active, healthy, college-aged participants (7 males and 3 females) completed 2 Wingate Anaerobic Tests (WAT). Each participant reported to the lab on 3 separate occasions. The first lab visit consisted of obtaining descriptive data and conducting 2 WAT for familiarization. Each experimental trial started with 60 min of either a mentally fatiguing test (MF) or 60 min of watching a non-mentally fatiguing sitcom (CON). After each 60 min session the BORG RPE scale and the 20 question Swedish Occupational Fatigue Inventory (SOFI-20) were used to assess mental fatigue. Furthermore, we assessed Heart Rate (HR) and Blood Pressure (BP) every 10 min throughout the beginning 60 min of the MF trial and CON trial to quantify any physiological strain that may have occurred. Following the 60 min sessions, 2 WAT were performed with 5 min of low intensity cycling between each WAT. Immediately after each WAT, HR, BP, RPE, peak power output, fatigue index and average power were recorded. RESULTS: No differences were found between HR and BP during the 60 min MF trials and CON trials. However, RPE and SOFI-20 revealed a state of mental fatigue (p 0.05) between the different variables assessed following the MF trials and CON trials. CONCLUSION: Our findings show that mental fatigue did not have an impact on anaerobic power output; however, further research should be conducted looking at the affects of mental fatigue on athletic performance. - Muscle fatigue is thought to not only originate from the peripheral component of the human body caused by metabolic changes in the muscles, but also from the central effects (i.e. brain). - Studies have reported that mental fatiguing tasks have actually equated to the development of muscular fatigue and a decrease in athletic performance (1, 2). - Majority of the studies conducted have assessed the effects of mental fatigue on aerobic events, but have not assessed the effects of mental fatigue on anaerobic power. (1, 3 & 4). - Does mental fatigue have an effect on Anaerobic power output? - Our findings showed through subjective findings that mental fatigue was achieved. - Mental fatigue, however, did not have an impact on anaerobic performance. - Further research should be conducted looking at the long term affects of mental fatigue on athletic performance. - Following the 60 min intervention, mental fatigue was achieved -RPE (MF = 11 ± 3; CON = 8 ± 3; p = 0.017) -SOFI-20 (MF = 36 ± 19; CON 25 ± 14; p = 0.007) - There were no differences for MF and CON for any of the main outcome variables tested (WAT, HR, BP, RPE, peak power output, fatigue index and average power, p > 0.05). VariablesCON WAT 1MF WAT 1CON WAT 2MF WAT 2 Heart Rate (bpm) 169.4 ± 13.69 167.20 ± 14.81173.8 ± 11.98172.50 ± 10.84 Blood Pressure (mmHg) 148/58 140/58 150/52145/57 RPE 16 ± 2 17 ± 1 Peak Power Output (W) 705.81 ± 156.50693.13 ± 151.97684.73 ± 171.58690.36 ± 176.34 Fatigue Index (%) 48.12 ± 6.0049.46 ± 8.9051.493 ± 6.9052.76 ± 10.30 Average Power (W) 547.81 ± 123.95536.52 ± 113.07502.44 ± 118.36508.64 ± 118.10 Figure 1. Participant undergoing MF intervention. Figure 2. Participant performing WAT Figure 3. Values assessed between WAT 1 and WAT 2 for both MF and CON (mean ± SD). REFERENCES CONCLUSION 1.S.M. Marcora, W. Staiano, V. Manning. Mental fatigue impairs physical performance in humans. J Appl Physiol 106: 857–864, 2009. 2.M. Hargreaves. Fatigue mechanisms determining exercise performance: integrative physiology is systems biology. J Appl Physiol 104: 1541-1542, 2008. 3.D.R. Bassett & E.T. Howley. Limiting factors for maximum oxygen uptake and determinants of endurance performance. Med Sci Sports Exerc 32:70-84, 2000. 4.R. Wright, T. Junious, C. Neal, A. Avello, C. Graham, N. Walton. Mental fatigue influence on effort-related cardiovascular response: difficulty effects and extension across cognitive performance domains. Motiv Emot 31: 219- 231, 2007