474 METHODS: Participants (N=57, mAge = 23.1) provided consent and were randomly assigned into the HIIT-A (n=20), HIIT-AR (n=18), or the control group (n=19). Information processing was assessed via a reaction time (RT) task using a serial response box, integrated with a Biopac MP100 system allowing for measurement of sEMG. The sEMG signals of the agonist synced with RT were temporally partitioned to assess central (premotor time (PMT)) and peripheral processing (motor time (MT)). A 3 (HIIT-A, HIIT-AR, & controlled) x 2 (pre-test & post-test) ANCOVA was performed for RT, PMT, and MT. RESULTS: For regular foreperiods (consistent time), the interaction between group and time for RT and MT was not significant ( p > .05). There was a significant interaction between group and time for PMT, F(2, 51) = 4.194, p = .021, partial ƞ2 = .141. This interaction was likely due to a simple main effect of time (pre to post) and not group allocation. For irregular foreperiods (variable time), the interaction between group and time for RT (F(2, 51) = 4.543, p = .015, partial ƞ2 = .151) and PMT (F(2, 51) = 3.219, p = .048, partial ƞ2 = .112) was significant while the interaction for MT was not (p > .05). For RT, there was a significant simple main effect of group, F(2, 53) = 7.271, p = .002, partial ƞ2 = .215. Post hoc analyses revealed that both exercise groups had significantly faster RTs than the control group (p < .01). Additionally, for PMT, there was a significant simple main effect of group (F(2, 53) = 4.275, p = .019, partial ƞ2 = .139). Post hoc analyses revealed that both exercise groups had significantly faster PMTs than the control group (p < .01). CONCLUSION: Improved RT appeared to be a result of reduced central processing rather than a significant change in peripheral processing. This study demonstrated that acute HIIT-A and HIIT-AR can significantly improve information processing speed in young adults. 1787 May 30 4:30 PM - 4:45 PM The Effects of Acute Bout of Aerobic Exercise on Cognitive Function in Older Adults Justin Mason 1 , Salvador Jaime 2 , Nelson Roque 3 , Arun Maharaj 4 , Gershon Tenenbaum 5 , Arturo Figueroa, FACSM 4 . 1 University of Florida, Gainesville, FL. 2 University of Wisconsin - La Crosse, La Crosse, WI. 3 Penn State University, State College, PA. 4 Texas Tech University, Lubbock, TX. 5 Florida State University, Tallahassee, FL. (Sponsor: Arturo Figueroa, FACSM) Email: justinmasonr@gmail.com (No relationships reported) ABSTRACT: Age-related cognitive decline affects several aspects of cognitive performance, including processing speed, inhibition, executive function, and visual scanning. Aerobic exercise is a potential solution to mitigate age-related cognitive decline. Furthermore, older adults are more susceptible to benefits from the effects of both chronic and acute aerobic exercise compared to younger adults. PURPOSE: To determine the associations of life-long aerobic exercise as well as the effects of acute aerobic exercise on cognitive function among healthy older adults (65 - 84 years old). METHODS: Model-based cluster analyses were conducted based on parameters of the participant’s cardiovascular health: (1) age; (2) VO 2 max; (3) Carotid Augmentation Index; (4) Carotid- femoral pulse wave velocity (cfPWV); (5) Aortic systolic blood pressure (SBP); (6) Carotid intima-media thickness (IMT). A cross-sectional design was utilized to compare 27 active (A) with 31 inactive (I) older adults (70±5yrs). Cognitive function was measured at rest and after 15 minutes of moderate intensity exercise (55-65% HRR) via the trail-making test (TMT Form A and Form B). A series of one-way ANOVAs were performed on dependent variables. A repeated measures MANOVA was used to test differences on the TMT-A and TMT-B at rest compared to after an acute bout of exercise. Pearson’s correlation analysis tested the associations among VO 2 max, age, carotid IMT, cfPWV, and cognitive performance. RESULTS: VO 2 max was not related to carotid IMT (r = .15, p = .27) or cfPWV (r = -.12, p = .38). Time to complete TMT-A (26±1 vs 23±1 seconds, F(1,57) = 15.12, p <.001 ) and TMT-B (57±2 vs 53±2, F(1,57) = 7.20, p <.01) increased after an acute bout of exercise compared to at rest. VO 2 max (r = -.16, p = .23), carotid IMT (r = .17, p = .21), and cfPWV (r = .15, p = .26) were not significantly correlated with cognitive performance on the TMT-A and TMT-B. Age was correlated with cognitive performance on the TMT-A and TMT-B (r = .60, p <.01). CONCLUSION: An acute bout of aerobic exercise may diminish cognitive performance among healthy older adults. 1788 May 30 4:45 PM - 5:00 PM Effects of Duration and Intensity of Aerobic Exercise on Cognitive Performance in Trained Individuals Christopher Irwin, Ben Desbrow, Danielle McCartney. Griffith University, Gold Coast, Australia. (Sponsor: Prof. Louise Burke, FACSM) Email: c.irwin@griffith.edu.au (No relationships reported) PURPOSE: This study explored the effect of acute aerobic exercise on cognitive performance in trained cyclists/triathletes. Specifically, it investigated the impact of different exercise durations (completed at a fixed moderate-intensity) and high/maximal intensity exercise (H/MIE) to volitional exhaustion (following a sustained bout of dehydrating activity) on simple and complex cognitive skills. METHODS: On two separate occasions, 21 trained cyclists/triathletes; 11 male (M) (age: 31±8 y; VO 2max : 57±9 mL·kg -1 ·min -1 ) and 10 female (F) (34±7 y; VO 2max : 51±9 mL·kg -1 ·min -1 ), completed 45 min of fixed-intensity cycling (M: 80±8%; F: 74±5% HR max ) followed immediately by an incremental test to volitional exhaustion. Cognitive function was assessed at Baseline, after 15 and 45 min of exercise (15EX; 45EX), and at Exhaustion using a 4-choice reaction time (CRT) and Stroop Word-Color Association test (Incongruent/Congruent Reaction Time [RT]). A placebo treatment (“to improve cognition”) was administered after 15EX on one trial to determine if positive expectancy influenced cognitive responses. RESULTS: Exercise Duration: CRT, Congruent RT and Incongruent RT decreased (improved) at 15EX and 45EX compared to Baseline (p’s<0.005). While CRT and Congruent RT were faster at 45EX than 15EX (p’s<0.020), Incongruent RT was not (p=1.000). Exercise Intensity: The incremental test lasted ~11.4±2.8 min, with participants achieving a maximum heart rate (HR) equal to ~93±7% HR max . CRT, Congruent RT and Incongruent RT decreased at Exhaustion compared to Baseline, (p’s<0.005), despite large fluid losses (M: -2.3±0.3% BM; F: - 1.7±0.3% BM). The placebo treatment did not affect cognitive responses to H/MIE (p’s>0.05). CONCLUSIONS: Acute aerobic exercise improves cognitive performance in trained athletes. These effects are more pronounced when exercising for longer durations (~1hr), employing higher exercise intensities and/or more complex cognitive tasks. 1789 May 30 5:00 PM - 5:15 PM Accelerometer-Measured Sustained MVPA Is Related To Higher Decision-Making Competence Among Young Adults Dominika M. Pindus 1 , Christopher Zwilling 1 , Jennifer Jarret 1 , Hillary Schwarb 1 , Charles H. Hillman 2 , Neal J. Cohen 1 , Arthur F. Kramer 2 , Aron K. Barbey 1 . 1 University of Illinois at Urbana-Champaign, Urbana, IL. 2 Northeastern University, Boston, MA. (Sponsor: Steve Petruzzello, FACSM) Email: pindus@illinois.edu (No relationships reported) More competent decision makers report greater success in avoiding negative decision outcomes irrespective of general cognitive ability. While physically active young adults show more optimal executive functions, the relationship between daily moderate-to-vigorous physical activity (MVPA) patterns and decision-making competence (DMC) remains under-examined. PURPOSE: In this study, we assessed the relationship between accelerometer-measured sporadic and sustained MVPA to DMC in young adults. METHODS: We analyzed pre-intervention data from 220 participants (115 (52%) females, M age =24.3 ±5.4 yrs, BMI=24.4 ± 4.0 kg/m 2 ) from the INSIGHT randomized controlled trial. MVPA was measured over 7 days with a hip-worn wGT3X-BT accelerometer. Valid wear time was defined as ≥4 days, ≥10 hrs/d. Daily (min/d), bouts of sporadic (<10 consecutive min) and sustained MVPA (≥10 consecutive min; frequency and min/d) were estimated using NHANES cut points. DMC was measured with the Adult-Decision Making Competence (A-DMC) battery and expressed as individual subtest scores and an A-DMC index (z-score). The relationships between MVPA and A-DMC variables were assessed with Spearman’s rho controlling for wear time, age, sex, education, intelligence, fat free VO 2 max, BMI and sedentary time (ST; <100 counts/min). RESULTS:After controlling for daily MVPA, frequency and time spent in sustained MVPA bouts were positively related to the ability to recognize social norms (ρs=[0.15; 0.16], Ps≤0.04) and ignore unrecoverable costs when considering future decision outcomes (ρs=[0.14; 0.15], Ps≤0.04). In contrast, neither sporadic nor daily MVPA were related to A-DMC subtests (Ps≤0.08). Copyright © 2019 by the American College of Sports Medicine. 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