EFFECTS OF CLIMATIC CONDITIONS ON MOUNTAIN ULTRA-MARATHON RUNNERS’ HEART RATE VARIABILITY AND PARASYMPATHETIC ACTIVITY
S. S. Sahota, P. K. Singh, I. J. Foster, A. L. Wookey, M. J. Rogers, C. Q. Malcolm, M.D. White
Simon Fraser University, Burnaby, BC, Canada
PURPOSE: Heart rate variability (HRV) can be employed to give an indication of parasympathetic activity as an index of fatigue. Following two 50 km mountain ultra-marathons, run on the same course but in different years and in differing climatic conditions, HRV was employed to assess fatigue of the runners. The root mean square of successive electrocardiogram R-R intervals (RMSSD), which reflects parasympathetic activity, was employed to give an index of fatigue, where a lower RMSSD value indicates greater fatigue. It was hypothesized that there would be a lower post-race RMSSD in 2014 when there was a greater heat stress relative to post-race RMSSD for the same race in 2015. METHODS: Five males volunteered for the study after an orientation session and completed a medical history, PAR-Q and informed consent forms for the study that was approved by the SFU Office of Research Ethics; one runner competed in both years. In both years, pre-race, and immediate post-race heart rate RMSSD was collected using chest heart rate straps and fitness computers. In 2014 the temperature was 22.3 ± 3.4°C (mean ±SD) and the ambient vapor pressure was 10.7 ± 0.3 mm Hg. For the 2015 race the temperature was 12.9 ± 4.5°C and ambient vapor pressure was 10.4 mm Hg. From each volunteer a 5 min section of the R-R data was analyzed using online software for HRV. The statistical analysis included a 2 factor non-repeated ANOVA with factors of Year (2014 and 2015) and Race Day Time (Pre-Race and Post-Race). The p-value set a 0.05. RESULTS: For RMSSD the main effect of Year (F=0.1, p=0.740) was not significant whereas there was a trend for an effect of Race Day Time (F=2.9, p=0.1). Pre-race RMSSD in 2014 was 34.7 ± 9.7 ms and the post-race RMSSD in 2014 was 19.3 ± 17.1 ms. In 2015, pre-race was 35.5 ± 18.1 ms, whereas the post-race value 23.9 ± 6.1 ms. CONCLUSION: The hypothesis that there would be a lower post-race RMSSD in 2014 when there was a greater heat stress compared to the same race in 2015 was not supported by the data.
Supported by NSERC and CFI.
Sahota, SS; Singh, PK; Foster, IJ; Wookey, AL; Rogers, MJ; Malcolm, CQ; and White, MD
"EFFECTS OF CLIMATIC CONDITIONS ON MOUNTAIN ULTRA-MARATHON RUNNERS’ HEART RATE VARIABILITY AND PARASYMPATHETIC ACTIVITY,"
International Journal of Exercise Science: Conference Proceedings:
4, Article 34.
Available at: http://digitalcommons.wku.edu/ijesab/vol8/iss4/34
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