The reliability and validity of gas exchange kinetics, maximal aerobic power, anaerobic threshold and sport specific protocols as determinants of fitness in elite athletes.

The aim of this research was to produce reliable and valid new fitness assessments utilising both gas exchange kinetics and sport specific field testing for the determination of fitness in elite athletic groups. A series of studies were conducted on both track runners and soccer players to examine the usefulness of maximal, submaximal and sport specific procedures. The physiological measurements utilisedin this research were: gas exchange kinetics, maximum aerobic power (VO2 max), anaerobic threshold and a soccer specific fitness test. The research developed new procedures and modified existing protocols to challenge athletes appropriately in the examination of relevant athletic performance indicators. For the determination of test reliability and validity, test-retest analysis was performed and cross-sectional comparisons were made between performers of both different standards of performance and event specialisms. The submaximal gas exchange kinetics test enabled the differentiation of elite sprinters from elite endurance runners. A test-retest reliability study of that procedure revealed high test variability (measurement error range: 18 - 35%), possibly due to breath-by-breath fluctuations. The development of a mean response time through a mathematical modelling technique improved the confidence in this procedure (test-retest measurement error: 16%) and produced a single, overall, measurement to enhance the future application of the procedure for the assessment of aerobic fitness in different population groups. Nevertheless, relatively high test-retest variability remains a feature of the test. Further research examined the validity of standard laboratory and sport specific measurements in the determination of training status in professional soccer players. Maximal aerobic power was shown to be unaffected by short-term (5 weeks) changes in training status (63.3 +/-5.8 ml-kg-1min-1 and 62.1 +/-4.9 ml-kg-1min-1) , questioning the relevance of this measurement to routine assessment of fitness and training status. Conversely, the soccer specific fitness test enabled the differentiation between soccer players performing at differentstandards where there was no difference in estimated VO2 max, however there was norelationship between V02 max and the soccer test which questions the validity of the new field test. Nevertheless, it is possible that this result reflects a greater sensitivity of the new test to detect soccer specific differences in the fitness of soccer players. In conclusion, the research has demonstrated that gas exchange kinetics test has limited use for the identification of aerobic fitness in elite athletes. Future investigations might clarify the relationship between the soccer specific fitness test and match performance.