Browsing by Subject "Respiratory Exchange Ratio"
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Item The Effect Endurance Training has on Resting Metabolic Rate, Heart Rate, and Respiratory Exchange Ratio Variability(2016-03) Rhodes, GregoryTechnology advances provide exercise and sport physiologist real-time data allowing for precision in assessing the interaction between external stimuli and physiological responses. The results of these advances provide valuable data points specific to clinical disease as well as performance measures. This increase in data points as well as the scientific and medical interpretation has provided improved insight specific to the interactions of training interventions and their influence on an individual’s physiology. The aim of this study was to utilize the method of variability analysis to assess the effect of a 16-week endurance running training program has on resting metabolic rate, substrate utilization, and heart rate variability in college-aged runners preparing for their first marathon. A sample population of 17 of the total 106 recreational marathoners who were enrolled in a Marathon Training course at the University of Minnesota volunteered to participate in this specific research. All participants completed two lab testing sessions that consisted of three visits over the course of 5 months. These visits consisted of a 2-mile time trial on an indoor track, assessment of body composition and aerobic capacity, and a resting metabolic test. The first period of testing was completed in early December prior to the start of the training program. The second period of testing was during the final two weeks of training before all participants ran the same marathon. Data collected from all visits was examined for changes pre- to post-training. Time series data (heart rate and respiratory exchange ratio) was analyzed using the non-linear variability analysis method of sample entropy. Participants in this study showed increases in fat oxidation during submaximal steady-state running (p<0.001) as well as increased running economy (p<0.001) . However, metabolic and heart rate changes were not observed at rest (p=0.915). Analysis of metabolic and heart rate data using both linear and non-linear methods provided insight into the effect that training for a running marathon has on human physiology. Additionally, more in-depth methods of analysis have increased the level in which individual variations in adaptations can be identified.Item Respiratory Exchange Ratio is Not Associated with Slowing in the Marathon(2016-08) McGuirk, ErinBackground: Previous research has shown that males slow more throughout the course of a marathon than females. Proposed reasons for differences in slowing include the fact that females oxidize proportionately more lipids and fewer carbohydrates during exercise when compared to males, and possible differences in thermoregulation. Respiratory exchange ratio (RER) can be used to estimate the ratio of fat to carbohydrates being metabolized. Purpose: To compare the degree of slowing (time in the first vs. second half of a marathon) between men and women, and determine if steady-state RER or ambient temperature differences predict the rate of slowing in male and female novice marathon runners. Methods: Chip times for 123 female and 44 male recreational marathon runners (21.0 ± 1.7yrs) were used to determine change in pace observed in the second half of the marathon compared to the first half. A two-mile time trial (2MI) was used to assess baseline fitness and pace for steady-state measurements. A submaximal 6-minute treadmill run at 75% of 2MI velocity was completed 1-3 weeks before the marathon. RER was collected using a metabolic cart (Medical Graphics Diagnostics, St. Paul, MN). Baseline measures and outcomes (RER and percent slowing) were analyzed using independent samples t-tests to detect differences between the groups (men vs. women and by year 2014, cool weather vs. 2015, warm weather). Univariate ANOVA tests were run to analyze the differences in percent slowing (%slowing) and RER by year and sex. Pearson’s Product Moment Correlation Coefficient (r) was used to determine the strength of the relationship between RER and %slowing as well as the relationship between %slowing and percent body fat (%BF), weight, height, body surface area (BSA), and BSA to mass ratio (BSA/M). Results: The mean %slowing for the total sample for 2014 and the total sample in 2015 was 14.1± 12.0% and 22.0 ± 16.5%, respectively (p<0.05). The mean %slowing for the combined group from 2014 and 2015 males and females was 20.6± 14.8% and 17.02 ± 14.8%, respectively (p <0.05). Females had a significantly lower RER during steady-state exercise in comparison with males (Female = 0.87 ± 0.05, Male = 0.89 ± 0.05, p<0.05). Sex and year were predictors of %slowing. There was no significant relationship between RER, temperature of marathon, weight, %BF, BSA, or BSA/M and %slowing in the total group, but RER and height were significantly related (p<0.05). Conclusion: Consistent with previous research, males slow more than females from the first to second half of the marathon. However, RER was not associated with slowing during the marathon. Temperatures of the race did affect the rate of slowing, but men and women were not affected differently. This suggests that pace maintenance is not due to substrate metabolism.