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  • Author: Mary P. Horn x
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Robert Murray, William P. Bartoli, Dennis E. Eddy and Mary K. Horn

The purpose of this study was to compare the gastric emptying rates (GER) of water, a 6% carbohydrate (CHO) beverage, and a 20% CHO beverage and to contrast those rates against the rate at which deuterium oxide in the drinks accumulated in plasma (DAR) following beverage ingestion. Ten subjects (8 males, 2 females) cycled at 60% VO2max for 70 min; at 13 min, the subjects ingested 400 ml of one of the beverages. The GER and DAR of water and 6% CHO were similar, while GER and DAR were both significantly slowed by ingestion of 20% CHO. Although there was a significant correlation (r = .63, p < .05) between GER and DAR, only 40% of the variation in DAR could be accounted for by variation in GER. These data support the contention that DAR is partially determined by GER, with differences in the rate of fluid absorption across the intestine and other factors accounting for the remaining variation in DAR.

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Anthony D. Mahon, Megan E. Woodruff, Mary P. Horn, Andrea D. Marjerrison and Andrew S. Cole

The effect of stimulant medication use by children with attention deficit/hyper-activity disorder (ADHD) on the rating of perceived exertion (RPE)—heart rate (HR) relationship was examined. Children with ADHD (n = 20; 11.3 ± 1.8 yrs) and children without ADHD (n = 25; 11.2 ± 2.1 yrs) were studied. Children with ADHD were examined while on their usual dose of medication on the day of study. HR and RPE, using the OMNI RPE scale, were assessed during a graded exercise to peak voluntary effort. The RPE-HR relationship was determined individually and the intercept and slope responses were compared between groups. The intercept was 132.4 ± 19.5 bpm for children with ADHD and 120.6 ± 15.7 bpm for children without ADHD. The slope was 7.3 ± 1.9 bpm/RPE for the children with ADHD and 8.1 ± 1.6 bpm/RPE for the children without ADHD. For the group with ADHD the intercept and slope values fell outside of the 95% CI observed in the control group. The altered relationship between RPE and HR with stimulant medication use in children with ADHD has practical implications with respect to the use of HR and RPE to monitor exercise intensity.

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Andrew S. Cole, Megan E. Woodruff, Mary P. Horn and Anthony D. Mahon

Relationships between physiological parameters and 5-km running performance were examined in 15 male runners (17.3 ± 0.9 years). Running economy (RE) and blood lactate concentration ([BLa]) at 241.2 m/min, VO2max, velocity at VO2max (vVO2max), vertical jump height and muscle power, and isokinetic knee extension strength at 60°/sec and 240°/sec were measured. The participants’ best 5-km race time over the last month of the cross-country season (16.98 ± 0.76 min) was used in the analysis. The data were analyzed using Pearson correlation coefficients. Significant relationships to run time were observed for VO2max (r = -.53), RE (r = .55), and vVO2max (r = -.66), but not [BLa], isokinetic muscle torque, or vertical jump. Identifying the unique strength and power characteristics related to running performance in this age group is warranted.