Clyde Williams - Academia.edu (original) (raw)

Papers by Clyde Williams

Sports Medicine, Jul 8, 2023

This is a tribute to the late Professor Edward Winter from colleagues across the sport and exerci... more This is a tribute to the late Professor Edward Winter from colleagues across the sport and exercise science community

Journal of Sports Sciences, 1996

Journal of Pharmacy and Pharmacology, 1983

The metabolism of (±)-o-octopamine and (±)-o-synephrine by rats was studied quantitatively by a g... more The metabolism of (±)-o-octopamine and (±)-o-synephrine by rats was studied quantitatively by a gas chromatography-mass spectrometry-selected ion monitoring (g.c.-m.s.-s.i.m.) method using deuterated internal standards. When o-octopamine was injected intraperitoneally into rats four metabolites were excreted in the urine: (i) unconjugated o-hydroxymandelic acid (OHMA) (16%), (ii) unconjugated o-hydroxyphenylglycol (OHPG) (4·5%), (iii) an acid-hydrolysable conjugate of OHPG (28%) and (iv) unconjugated o-octopamine (10%). When o-synephrine benzoate was similarly administered six metabolites were excreted in urine: (i) unconjugated OHMA (13·5%), (ii) unconjugated OHPG (3·3%), (iii) an acid-hydrolysable conjugate of OHPG (15·6%), (iv) unconjugated o-synephrine (10%), (v) an acid-hydrolysable conjugate of o-synephrine (8·5%) and (vi) unconjugated o-octopamine (0·3%). Adult rats normally excreted OHMA (1·0 μg day−1) but OHPG, o-octopamine and o-synephrine could not be detected in urine. A...

British Journal of Sports Medicine, 2005

Journal of Strength and Conditioning Research, 2016

Journal of Applied Physiology, 2005

The aim of this study was to compare the effect of preexercise breakfast containing high- and low... more The aim of this study was to compare the effect of preexercise breakfast containing high- and low-glycemic index (GI) carbohydrate (CHO) (2.5g CHO/kg body mass) on muscle glycogen metabolism. On two occasions, 14 days apart, seven trained men ran at 71% maximal oxygen uptake for 30 min on a treadmill. Three hours before exercise, in a randomized order, subjects consumed either isoenergetic high- (HGI) or low-GI (LGI) CHO breakfasts that provided (per 70 kg body mass) 3.43 MJ energy, 175 g CHO, 21 g protein, and 4 g fat. The incremental areas under the 3-h plasma glucose and serum insulin response curves after the HGI meal were 3.9- ( P < 0.05) and 1.4-fold greater ( P < 0.001), respectively, than those after the LGI meal. During the 3-h postprandial period, muscle glycogen concentration increased by 15% ( P < 0.05) after the HGI meal but remained unchanged after the LGI meal. Muscle glycogen utilization during exercise was greater in the HGI (129.1 ± 16.1 mmol/kg dry mass) ...

Medicine & Science in Sports & Exercise, 1999

Nutrients, 2022

The aim of the present study was to examine the effects of creatine (Cr) supplementation on power... more The aim of the present study was to examine the effects of creatine (Cr) supplementation on power output during repeated sprints on a non-motorized treadmill. Sixteen recreationally active males volunteered for this study (age 25.5 ± 4.8 y, height 179 ± 5 cm, body mass 74.8 ± 6.8 kg). All participants received placebo supplementation (75 mg of glucose·kg−1·day−1) for 5 days and then performed a baseline repeated sprints test (6 × 10 s sprints on a non-motorised treadmill). Thereafter, they were randomly assigned into a Cr (75 mg of Cr monohydrate·kg−1·day−1) or placebo supplementation, as above, and the repeated sprints test was repeated. After Cr supplementation, body mass was increased by 0.99 ± 0.83 kg (p = 0.007), peak power output and peak running speed remained unchanged throughout the test in both groups, while the mean power output and mean running speed during the last 5 s of the sprints increased by 4.5% (p = 0.005) and 4.2% to 7.0%, respectively, during the last three spr...

Movement, Health & Exercise, 2014

British Journal of …, 2003

British Journal of Sports Medicine, 1983

Adapted physical activity quarterly : APAQ, 2002

The purpose was to examine selected physiological responses of endurance-trained male wheelchair ... more The purpose was to examine selected physiological responses of endurance-trained male wheelchair athletes in different Paralympic racing classes (T2, n = 3; T3, n = 8; T4, n = 7) during a 10-km treadmill time trial (TM:10-km). Peak oxygen uptake (V̇O2peak) was determined, and a TM:10-km was completed on a motorized treadmill. From this, % V̇O2peak utilized and the relationship between V̇O2peak and TM:10-km were established. During the TM:10-km, the following dependent variables were examined: propulsion speed, oxygen uptake, respiratory exchange ratio, and heart rate. The results showed athletes utilize a high % V̇O2peak (78.4 -13.6%) during the TM:10-km. There was a moderate correlation (r = -.57, p < .01) between VO2peak and TM:10-km. No physiological differences were found between the paraplegic racing classes (T3, T4), which suggests that there is some justification in amalgamating these racing classes for endurance events.

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