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  • Author: Holden MacRae x
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David Alexander Leaf and Holden MacRae

The purpose of this study was to examine the criterion-related validity of two indirect measures of energy expenditure (EE): American College of Sports Medicine (ACSM) predictive equations, and estimated EE based on the Caltrac accelerometer. These measures were compared in 20 community-dwelling older men and women (mean age 71 years). The strength of the relationships among major determinants of EE during self-selected speeds of treadmill and outdoor walking was also examined. EE measured by respiratory gas analysis during an exercise stress test was highly correlated with ACSM predictive equations and poorly correlated with Caltrac. Multivariate regression equations were established to evaluate the ability of independent variables—body weight and height, age, and preferred treadmill walking speed—to predict EE (dependent variable). It was concluded that the ACSM predictive equations are suitable for use in elderly individuals, and that the apparent differences in the relationships between treadmill and outdoor walking speeds on EE deserve further investigation.

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Holden S-H. MacRae and Kari M. Mefferd

We investigated whether 6 wk of antioxidant supplementation (AS) would enhance 30 km time trial (TT) cycling performance. Eleven elite male cyclists completed a randomized, double-blind, cross-over study to test the effects of twice daily AS containing essential vitamins plus quercetin (FRS), and AS minus quercetin (FRS-Q) versus a baseline TT (B). MANOVA analysis showed that time to complete the 30 km TT was improved by 3.1% on FRS compared to B (P ≤ 0.01), and by 2% over the last 5 km (P ≤ 0.05). Absolute and relative (%HRmax) heart rates and percent VO2max were not different between trials, but average and relative power (% peak power) was higher on FRS (P ≤ 0.01). Rates of carbohydrate and fat oxidation were not different between trials. Thus, FRS supplementation significantly improved high-intensity cycling TT performance through enhancement of power output. Further study is needed to determine the potential mechanism(s) of the antioxidant efficacy.

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Amy C. Brown, Holden SH. MacRae and Nathan S. Turner

The purpose of this study was to determine whether ingestion of a multinutrient supplement containing 3 tricarboxylic-acid-cycle intermediates (TCAIs; pyridoxine-alpha-ketoglutarate, malate, and succinate) and other substances potentially supporting the TCA cycle (such as aspartate and glutamate) would improve cyclists’ time to exhaustion during a submaximal endurance-exercise test (~ 70% to 75% VO2peak) and rate of recovery. Seven well-trained male cyclists (VO2max 67.4 2.1 mL · kg–1 · min–1, 28.6 ± 2.4 y) participated in a randomized, double-blind crossover study for 7 wk. Each took either the treatment or a placebo 30 min before and after their normal training sessions for 3 wk and before submaximal exercise tests. There were no significant differences between the TCAI group (KI) and placebo group (P) in time to exhaustion during cycling (KI = 105 ± 18, P = 113 ± 11 min); respiratory-exchange ratio at 20-min intervals; blood lactate and plasma glucose before, after, and at 30-min intervals during exercise; perceived exertion at 20-min intervals during exercise; or time to fatigue after the 30-min recovery (KI = 16.1 ± 3.2, P = 15 ± 2 min). Taking a dietary sport supplement containing several TCAIs and supporting substances for 3 wk does not improve cycling performance at 75% VO2peak or speed recovery from previously fatiguing exercise.