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Biomedical subjects

C A Gaul

Publications and source records attributed to C A Gaul.

5 recordsLinked to original sources
PubMed1999

Skeletal muscle metabolism during short-term, high-intensity exercise in prepubertal and pubertal girls.

To test the hypothesis that glycolytic metabolism in muscle is attenuated in prepubertal children, (31)P-magnetic resonance spectroscopy was used to determine calf muscle intracellular pH (pH(i)) in nine prepubertal (Pre) and nine pubertal female swimmers (Pub). Maximal plantar flexion work capacity (100% MWC) was established by using a graded exercise test. Between 5 and 10 days later, calf muscle images (magnetic resonance imaging) and phosphorus spectra were acquired at rest, during 2 min of light exercise (40% MWC), and during 2 min of supramaximal exercise (140% MWC) in a 3.0-T NMR system. End-exercise pH(i) was 6.66 +/- 0.11 and 6.76 +/- 0.17 for Pub and Pre, respectively. No significant differences in the mean values for pH(i) or the P(i)-to-phosphocreatine ratio were observed between groups during the protocol; however, an interaction effect was found for the P(i)-to-phosphocreatine ratio during the supramaximal exercise challenge. Cross-sectional area of gastrocnemius was 15.12 +/- 0.46 and 9.37 +/- 0.37 cm(2) for Pub and Pre, respectively (P < 0.05). Differences in muscle size must be considered when interpreting the unlocalized magnetic resonance spectroscopy data. These results suggest that glycolytic metabolism in physically active children is not maturity dependent.

Adolescent↗
PubMed1995

Differences in anaerobic performance between boys and men.

The purpose of this study was to compare the anaerobic performance of 11-12 year old prepubescent boys (stage 1; n = 18) using a maximal effort 90 s cycling test to that of adult men (n = 19). Performance was separated into short-term anaerobic power (SAP; work in 10 s), intermediate-term anaerobic capacity (IAC; work in 30 s) and long-term anaerobic capacity (LAC; work in 90 s). Resistance on the Monark cycle ergometer was chosen as the highest tolerable load for the 90 s test and set at 2.6 and 3.8 J. rev-1.kg body mass-1 for boys and men, respectively. Power drop-off (%PD) was determined as the change in 5 s power outputs from 0-90 s. Blood lactates were measured at rest (pretest; BL) and at 2 (BL2) and 5 (BL5) min post test. Absolute and relative (to weight or thigh volume) scores for SAC, IAC and LAC were 33-40% lower in the boys compared to the men (p < 0.001). The men demonstrated significantly greater %PD over the 90 s (32.2%) compared to the 25.3% PD of the boys (p < 0.001), suggesting that the development of fatigue was greater in the men even though power and work outputs were high. Resting BL values were similar for both groups. Mean BL2 and BL5 were higher (p < 0.01) in the men (13.5, SD = 3.4; 12.5, SD = 2.8 mmol.l-1) than in the boys (9.1, SD = 1.7; 8.3, SD = 1.6 mmol.l-1). The anaerobic performance of the boys compared to the men cannot be completely explained by the lower resistance setting used. Although the boys were 50% lighter than the men, their resistance was 70% of that used for the men. The results do not support the contention that children and adults have similar abilities in short term, exhaustive work when corrected for size. Prepubescent boys appear to be limited in their ability to perform short-term as well as intermediate and long term anaerobic exercise compared to adult males.

Adult↗
PubMed1991

Relationship of body size, physique, and composition to physical performance in young boys and girls.

The present study examined the aerobic, anaerobic and strength performance characteristics of 52 young boys and girls (mean age 10.8 and 11.1 yrs, respectively) on selected laboratory measures. Anthropometrically, the boys and girls were similar, with the exception of measures of body fatness. The boys demonstrated greater values in maximal aerobic power, anaerobic performance, (especially related to body weight), and strength relative to lean body mass. Since body size measures, including height, were similar, the functional differences could not be attributed to such factors. The significant but low correlations between the performance variables failed to support the concept of children as "metabolic non-specialists" as proposed by previous authors. In fact, the large amount of variance not accounted for could be interpreted as supporting the unique contribution of genetic endowment of the effect of habitual activity patterns on the performance measures. Canonical correlations indicated a strong relationship between selected anthropometric and performance variables (rc = .94). For boys, height and weight were strongly related to anaerobic performance, whereas weight and thigh volume were strongly related to all performance measures for the girls.

Adipose Tissue↗
PubMed1987

Helicopter pilot suits for offshore application. A survey of thermal comfort and ergonomic design.

The objective of this study was to determine the existing problems associated with helicopter pilot survival suits currently in use. A survey was conducted of helicopter pilots from both Canadian commercial and military disciplines. Pilots commented on eight different types of survival suits. Reduced thermal comfort as well as lack of ventilation were the two most common criticisms of the pilot suits. The 'greenhouse' effect, common to helicopter cockpits, results in hot working ambients both in summer and winter. The air cooling mechanisms employed in summer may cause a 'chilling' effect following an on-ground stand-by where cockpit temperatures may reach 40 degrees C. Thermal stress may also be induced with high cockpit temperatures caused by the sun's radiation in winter and summer. Suit design was another area considered. 72% and 86% of military and commercial pilots respectively felt their freedom of movement was hindered by their survival suits. Certain designs were considered more hazardous than others with regard to clips and hooks catching switches on the control panel. Difficulty in donning suits appeared to be a universal problem irrespective of type of suit used. Lack of comfort and movement in addition to thermal stress may lead to reduced time to fatigue and, thus, occurrence of errors and accidents. The results of this survey reflect the inadequacies of the helicopter pilot survival suits presently in use. It is suggested that evaluation of these suits be made on the basis of their ventilation capabilities, ergonomic design and thermal properties in a variety of ambient environments.

Journal Article↗