METABOLIC AND CARDIAC AUTONOMIC RESPONSE TO A 1-HOUR CYCLING TIME TRIAL WITH CARBOHYDRATE RINSE

C.M. Williamson-Reisdorph1, E.E. Bechke2, C. McLester2, B. Buresh2, FASCM, M. L. Millard-Stafford3, FASCM, R. Rooks2, B. Nickerson4, B.M. Kliszczewicz, FASCM2 1 University of Montana, Missoula, MT; 2Kennesaw State University, Kennesaw, GA; 3Georgia Institute of Technology, Atlanta, GA; 4Texas A&M International University, Laredo, TX Carbohydrate (CHO) rinsing in the mouth (without ingestion) may improve endurance performance purportedly due to alterations in central command following detection of CHO at receptors in the oral cavity. PURPOSE: To examine the effect of CHO rinsing on autonomic and metabolic responses during the post-exercise recovery period to determine if rinsing could enhance post-exercise recovery. METHODS: Ten male recreational cyclists (age = 30 ± 6 years, VO2max= 54.5 ± 8.1 mL·kg-1·min-1) completed experimental trials in a randomized, double-blind, placebo-controlled, crossover design between CHO and placebo (PLA) rinse. The rinse was administered every 12.5% of prescribed work during a 1-hour cycling time trial at 75% Wmax. Heart rate variability (lnRMSSD), respiratory exchange ratio, and blood sampling for epinephrine, norepinephrine, insulin, glucose, free fatty acids, and lactate were completed pre- and post- exercise. RESULTS: CHO rinsing did not result in improvements in time trial performance (p = 0.545). A prolonged elevation of sympathetic nervous system (SNS) activity was observed at 30-minutes post-exercise in the CHO trial, as measured by lnRMSSD and epinephrine (p = 0.046, p = 0.022). Lactate remained elevated at 30-minutes post-exercise in the CHO rinse trial (p \u3c 0.001). A significant interaction was observed with higher free fatty acid concentrations occurring post-exercise in CHO trial (p = 0.024). A reduction in blood glucose concentrations occurred in the PLA trial (p = 0.021), but not in the CHO trial (p = 0.657). CONCLUSION: Periodic CHO mouth rinsing had no impact on 1-hour time trial performance in recreational cyclists. CHO rinsing resulted in prolonged elevation of SNS activity for up to 30-minutes post-exercise and altered metabolic activity as measured by epinephrine, free fatty acids, glucose, and lactate. Therefore, the use of a CHO rinse does not enhance post-exercise recovery. Supported by the Department of Exercise Science & Sport Management at Kennesaw State University

METABOLIC AND CARDIOVASCULAR ALTERATIONS DURING CRITICAL TRAINING IN WILDLAND FIREFIGHTERS

S.C. Gurney, K.S. Christison, C.M. Williamson-Reisdorph, K.G.S. Tiemessen, J.A. Sol, T.S. Quindry, M.W. Bundle, C.G. Palmer, J.C. Quindry, FACSM, C.L. Dumke, FACSM University of Montana, Missoula, MT Wildland firefighters (WLFF) are confronted with numerous physical and mental stressors. Pre-fire season includes an intense 2- week critical training (CT) period; a preparatory phase that can result in injury, illness, and rhabdomyolysis. PURPOSE: To identify physiologic changes in metabolic biomarkers that occur during 2 weeks of CT in WLFF. METHODS: Eighteen male (29.4±1.1 yr, 182.1±1.6 cm) and three female (26.7±2.6 yr, 169.5±4.2 cm) participants were recruited from a Type I interagency hotshot fire crew and monitored over their 2-week CT. Fitness was assessed via BLM Fitness Challenge (push-ups, pull- ups, sit-ups, 1.5 mi run). Subjects were asked to fast and abstain from caffeine for blood draws on days 1, 4, 8, and 11. Plasma was analyzed for changes in the metabolic profile and oxidative stress markers 3-Nitrotyrosine (3NT), 8-Isoprostane (8ISO), and Lipid Hydroperoxides (LOOH). A one-way repeated measures ANOVA was used to analyze 8ISO, 3NT, and LOOH. Paired samples t-tests were used to compare metabolic biomarkers. Data presented as mean±SEM. RESULTS: CT elicited decrease in total cholesterol (TC) (173.6±12.1 to 153.4±8.6 mg·dL-1, p=0.01), hemoglobin A1c (5.2±0.1 5.1±0.1 %, p=0.003), hemoglobin (15.5±0.4 to 14.3±0.3 g·dL- 1, p=0.003), and estimated plasma volume to (53.8±0.7 to 50.7±1.4 %, p=0.005) from day 1 to 11. No difference was observed in high- density lipoprotein cholesterol. A main effect for time was observed in 8ISO (p- 1). 3NT was significantly elevated from day 4 to day 8 (d4: 2.4±0.6, d8: 2.9±0.6 mg·mL-1). LOOH showed a significant increase across all days (d1: 2.2±0.4, d4: 2.8±0.5, d8: 3.4±0.5, d11: 4.0±0.6 mM). Fitness was significantly correlated with DTC (r=0.58, p=0.046) and D8ISO (r=0.60, p=0.050). CONCLUSION: These data suggest the exertion required of WLFF during CT results in positive alterations to the metabolic profile. The changes in oxidative stress markers may reflect rapid adaptation to the CT stressors. These data suggest that WLFF are able to adapt quickly to the physical stress of CT, where fitness may be a protector of metabolic perturbations. Funded by the US Forest Service 16-CR-11138200-005

SEASONAL CHANGES IN CARDIOVASCULAR FUNCTION, RISK FACTORS, AND OXIDATIVE STRESS OF WILDLAND FIREFIGHTERS

C.M. Williamson-Reisdorph, K.S. Christison, S.C. Gurney, K.G.S. Tiemessen, J.A. Sol, T.S. Quindry, C.G. Palmer, M.W. Bundle, C.L. Dumke, FACSM, J.C. Quindry, FACSM University of Montana, Missoula, MT Wildland firefighters (WLFF) experience extreme physiological strain throughout a typical season due to intense occupational demands and consistent woodsmoke exposure. There is a rationale to indicate that accumulated physiological strain, and oxidative stress, throughout a WLFF season has the potential to negatively alter cardiovascular function and risk factors. PURPOSE: The purpose of the study was to examine the effects of a season on cardiovascular function, risk factors, and markers of oxidative stress in WLFF. METHODS: Fourteen members of a Type I interagency hotshot crew participated in the study (males: n=13, females: n=1, age: 30.1 years ± 4.8). Pre- and post-seasonal resting measurements (May, October) were obtained for heart rate variability (lnRMSSD, lnHF, lnHF, LF:HF), pulse wave velocity (PWV), blood lipid panels (TC, TG, LDL, HDL), metabolic biomarkers (blood glucose, HbA1c), blood pressure (SBP, DBP) and blood oxidative stress (3-nitrotyrosine, 8-isoprostane, lipid hydroperoxides). Paired samples t-tests were used to identify differences among pre- and post- seasonal values. RESULTS: There were no seasonal effects observed on resting heart rate variability, PWV, 3-nitrotyrosine, 8-isoprostane, TC, TG, LDL, blood glucose, SBP, or DBP (p\u3e0.05). A significant reduction occurred in HDL (Pre: 53 mg/dL ± 14, Post: 45 mg/dL ± 18, p=0.043) and both HbA1c (Pre: 5.2% ± 0.2 , Post: 5.3% ± 0.2, p=0.034) and lipid hydroperoxides (Pre: 2.5 ± 0.5, Post: 4.9 ± 0.6, p = 0.003 ) increased from pre- to post-season. CONCLUSION: These data suggest a WLFF season did not impact resting markers of heart rate variability, pulse wave velocity, 3-nitrotyrosine, and 8-isoprostane. Alterations in metabolic biomarkers of cardiovascular risk factors (HDL and HbA1c) and lipid hydroperoxides demonstrate unfavorable seasonal changes, suggesting that the WLFF season may increase cardiovascular risk. Funded by the USFS 16-CR-11138200-005