Browsing by Subject "Marathon"

Now showing 1 - 6 of 6
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    Examining the Respiratory Compensation Point with Automated Methods in Recreational Runners Training for a Marathon
    (2019-05) Hesse, Anton
    Background: The respiratory compensation point (RC) approximates the lowest intensity of unsustainably difficult exercise, making it an important measure for endurance athletes. Thus, accurate determination of RC is important to athletes. There are many methods to determine RC, but few large studies to date have compared multiple automated methods. Previous studies have shown that rates of detection of RC (i.e. determinate cases) vary. The purpose of this study was to compare four common methods used to detect RC: Jones-Molitoris (JM), Orr, Beaver’s V-slope (Beaver), and the Dmax method. Methods: Recreationally active college students (n = 131, 45 males, 86 females) completed 2-mile time trials and graded exercise tests both before and after training for a marathon. The four methods were used to detect RC (as a % of VO2max) from the VE vs. VCO2 slope. The number of determinate RC cases were recorded for each method at pre and at post. Determinate counts of RC were expressed as a percentage, were compared pre to post with Fisher’s exact tests, and were simulated with bootstrap resampling. Average differences between methods were compare using a linear mixed effects model (LMEM) with data from participants who displayed RC at both pre and post testing for at least one of the four methods. Comparisons between methods and with 2-mile performance were also compared by correlations and with limits of agreement (LOA) plots. Results: The order of determinate rates from highest to lowest was JM, Dmax, Orr, and Beaver. Fisher’s exact tests produced odds ratios significantly higher than 1 for all but Beaver. Histograms of bootstrap resampling showed large overlap for all but the Beaver method. LMEM analysis showed that JM predicted significantly higher RC than Beaver and Dmax, but not Orr. All methods were significantly correlated with one another at both timepoints. LOA were wide. Conclusions: Beaver detects RC more infrequently than other methods. It is unknown if the higher %VO2max at RC predicted by JM is an overestimate. Although all methods highly and significantly correlate to one another, they have wide LOA. A better automated method may combine the results of several methods.
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    Maximal Aerobic Capacity, Running Economy, and Performance in Highly Trained Marathon Runners and Master Long-Distance Runners
    (2018-11) Lee, Emma
    Maximal aerobic capacity (VO2max) and running economy (RE) are key predictors of distance-running performance. Whether VO2max and RE change with marathon-specific training in competitive sub-elite runners is unclear. While VO2max is known to decline with age, RE may be maintained in older runners. PURPOSE: The purpose of this study was to evaluate VO2max and RE at the beginning and end of a marathon training block in highly trained runners. Furthermore, master athletes training for a long-distance running event were evaluated shortly prior to their goal race to investigate relationships between age and running performance variables. Physiological and training factors were assessed to determine predictors of race performance in master runners. Several measures of RE were used. METHODS: In the study of younger competitive runners, participants were studied ~10 and 1-2 weeks before their goal marathons. They logged their workouts throughout a 12-week training period. The study on master athletes was cross-sectional. These runners were surveyed about recent and long-term training patterns. All participants completed a treadmill marathon-intensity effort (MIE) and VO2max test. RESULTS: Among the sub-elite runners, VO2max increased across the training period, while the percent of VO2max used during the MIE decreased. Race performance, quantified using a temperature-converted VDOT score, was negatively correlated with MIE allometrically scaled oxygen consumption (alloVO2). Among master runners, age was negatively associated with VO2max and alloVO2. Age was positively related to the MIE energy cost (EC) of running in females and to MIE oxygen consumption (VO2) in males. The most important predictors of converted VDOT in master runners were VO2max and three-year peak weekly training distance (3YP). Other significant predictors of VDOT were alloVO2 and EC. CONCLUSION: Experienced open-age marathon runners may experience an increase in VO2max with a block of marathon training. Age is negatively associated with VO2max and alloVO2 in fit master runners. Long-distance race performance in master athletes is positively associated with VO2max, 3YP, and alloVO2, and negatively associated with EC. Allometrically scaled MIE VO2 may therefore be a useful and performance-related measure of RE in trained runners of all ages.
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    Plyometric training, running economy, and marathon running
    (2015-03) Lundstrom, Christopher John
    Plyometric training (PLYO) improves running economy (RE) and performance in distance races up to 5-km in competitive runners. Core training (CORE) is widely practiced by distance runners, though there is little evidence for its efficacy in improving performance or preventing injury. The purpose of this study was to compare the effects of a weekly PLYO or CORE training program over a 12-week marathon training period on a population of recreational marathon runners. Sprint, jump, and distance running performance, and training variables were assessed. In addition, different approaches to quantifying RE were examined. Competitive (COMP) and recreational (REC) runners were compared, and RE variables were used to model marathon performance. Sprint performance improved with PLYO training. Jump performance was maintained with PLYO training while it decreased in the CORE group. No differences were found in training variables between PLYO, CORE and a no additional training (CON) group, though limited evidence suggests a potential benefit of PLYO training. Other groups increased from baseline (a run-in period of 8 weeks) to the marathon training period in rate of perceived exertion, soreness, and days missed due to injury, while the PLYO group did not experience these negative changes. In addition, pre-marathon creatine kinase (CK) levels were lower in PLYO than CORE runners, and post-marathon CK levels trended toward lower as well. Assessment of RE factors found that correcting 02 utilization for velocity is important in capturing differences between COMP and REC runners, with COMP runners using less O2 per km. This measure was a significant predictor of marathon performance. Within groups, the use of allometric scaling was important in using RE to model marathon performance. Implementation of PLYO training in a population of recreational marathoners can improve sprint and maintain jump performance, but the benefits do not transfer to distance running performance, including RE. Other benefits to health and training variables may be seen, and may be more important to this population. Running economy is an important predictor of marathon performance. Competitive runners are more economical than REC runners, and more economical runners perform better in the marathon, relative to their shorter distance performances.
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    Respiratory Exchange Ratio is Not Associated with Slowing in the Marathon
    (2016-08) McGuirk, Erin
    Background: 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.
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    Respiratory exchange ratio variability in novice college-age marathon runners
    (2013-05) Brown, Scott Robert
    The aim of this study was to assess the effects of 16 weeks of marathon training on breath-to-breath (btb) respiratory exchange ratio (RER) variability, measured by sample entropy (SampEn), in college-age, healthy novice marathon runners. Average SampEn scores for participants increased with marathon training. SampEn analysis of RER time series may detect trainability, metabolic adaptations, or provide substrate utilization recommendations with endurance training.
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    Thermoregulation and marathon performance: relationships of predictability of marathon performance, ambient weather conditions, BSA:MT, BSA:ML, percent body fat, and aerobic fitness
    (2012-11) Roach, Laura Elizabeth
    The purpose of this study was to observe individual variance in the ability to predict marathon performance from a two-mile time trial performance and determine whether the variance in predictability is influenced by thermoregulatory advantages of body size. Over three distinct marathon conditions, 126 (n =17 in 2010, n =42 in 2011, n =67 in 2012) aerobically-trained college physical activity students participated in pre- and post-anthropometric testing, a two-mile time trial on an indoor track, and concluded with the Eau Claire marathon. Between 72 and 98% of the variance in marathon performance could be explained by two-mile time trial performance. Variation of predicted performance from actual marathon performance was related to body surface area to mass ratio, body surface area to lean mass ratio, and percent body fat but depended on the race temperature, sex, and aerobic fitness. Notably, high body surface area to mass ratio was advantageous for sub-15 minute two-milers racing at an effective temperature of 12 degrees Celcius even though conditions were compensable. (r = 0.399, p< 0.033). The evidence shows that even in cold and mild conditions body surface area to mass ratio can affect marathon performance.