Martin Anderson

The Relationship of Hypercapnic Ventilatory Responses to Age, Gender and Athleticism

SummaryWhen a gas mixture containing carbon dioxide (CO2) is inhaled by an individual, alveolar ventilation is increased. This ventilatory response to CO2 highlights the relationship between the increase in exercise ventilation and the increase in alveolar CO2 pressure (paCO2). This response is mediated centrally by brainstem chemoreceptors in the medulla and, to a lesser extent, peripherally by the carotid and aortic bodies. However, the response of increased breathing to rising paCO2 varies markedly among individuals.The responses to CO2 rebreathing have been investigated by a variety of research groups for different reasons. The range of responses by children and adults including: gender differences; responses by athletes; the relationship between age and body size; and whether it is an acquired or inherited response have been studied.The following is a summary of these different aspects of CO2 rebreathing has been complied to assist researchers studying any single or multiple facets of the area.

Recreational patterns, body composition and socioeconomic status of Western Australian secondary school students.

A study of 4672 secondary school students was carried out in order to assess the relationship between body composition, recreational patterns, and socioeconomic status as indicated by parental occupation and the school attended. Results indicated that there were more girls than boys participating in organized sport, and health and fitness activities; and more boys than girls involved in informal recreational activities and home-based passive pursuits. A higher proportion of participants came from the higher socioeconomic status (SES) group. More high-SES students revealed weight appropriate to their height.

The relationship between carbon dioxide sensitivity and sprint or endurance performance in young swimmers.

There has been some evidence that extremes of CO2 sensitivity can indicate an individuals potential for sprint or endurance athletic performance. This study examined the responses to CO2 rebreathing, and previously validated sprint and endurance tests by subjects who were involved in regular, but not intensive, swimming training. The aim was to determine whether subjects with low CO2 sensitivity might perform better on endurance tests, whilst those subjects with high CO2 sensitivity would be more successful in the sprint tests. Initially, 168 young (mean mean(s.d.) age = 12.4(2.1) years) swimmers were measured using a modified version of the Read CO2 rebreathing technique. From this sample, 17 high (mean means(s.d.) = 2.24(0.39) 1 min-1 mmHg-1) CO2 responders were matched by gender, age, height, weight and FVC with 17 low (mean means(s.d.) = 0.57(0.19) 1 min-1 mmHg-1) responders. Each of these 17 pairs underwent two sprint tests (10 s Tri-level alactic power, 50 m run) and two endurance tests (PWC170, 1.6 km run) in order to determine whether any differences existed between the two groups and the sprint and endurance parameters. The subjects remained unaware of their results of the rebreathing test throughout testing. A dependent t test was then used to compare the results collected from each group. The low CO2 responders recorded a significantly faster 1.6 km run time, but were not superior on the PWC170 ergometer test, than the high CO2 responders. The high CO2 responding group recorded significantly higher results on the 10 s alactic power test, but not the 50 m sprint run, than the low responders. Hence, further study is required to ascertain underlying causes as to why significant differences occurred with CO2 rebreathing, the 1.6 km run and the 10 s alactic power test, but not with the PWC170 and the 50m sprint run.