Measurement of maximal oxygen uptake from two different laboratory protocols in runners and squash players.

PURPOSE: The aims of the study were to assess whether different test protocols used to elicit maximal oxygen uptake values (VO2max) attain similar results, whether different VO2max protocols were preferable for different athletic groups, and to assess whether the noninvasive criteria used to indicate the attainment of VO2max are achieved similarly in different VO2max testing protocols. METHODS: This study evaluated the attainment of either VO2max or peak VO2 (VO2peak) during two treadmill VO2max protocols: a progressive speed protocol (PSP) and a progressive incline protocol (PIP). Ten runners and 10 squash players were studied to assess whether achievement of VO2max criteria was either sport-specific or protocol-specific, or both. RESULTS: There were no significant differences in the VO2peak values reached in either PSP or PIP protocol (64.4 +/- 5.9 vs 66.5 +/- 6.0 mLO2 x kg(-1) x min(-1)). But HRmax (196 +/- 5 vs 189 +/- 5 beats x min(-1); PSP vs PIP; P < 0.01) and RER (1.14 +/- 0.05 vs 1.07 +/- 0.04; PSP vs PIP; P < 0.01) were significantly higher during the PSP test. Fifty percent of the subjects reached a plateau in either test, and of these subjects, 90% satisfied the three noninvasive criteria for VO2max in the PSP group, compared with 10% in the PIP group. CONCLUSIONS: The indirect criteria used to assess the attainment of VO2max may be limited, as the VO2peak values were higher in the PIP protocol compared with the PSP protocol, although not significantly different, whereas the HR and RER values were significantly lower in the PIP than PSP protocol. Furthermore, only 50% of subjects demonstrated the plateau phenomenon in oxygen uptake with either protocol. It may be concluded that the measured physiological variables coinciding with VO2peak may differ when different protocols are used to elicit VO2max.

Effect of growth hormone on height, weight, and body composition in Prader-Willi syndrome.

AIMS: To evaluate the effect of the administration of growth hormone on stature, body weight, and body composition in children aged between 4 and 10 years with Prader-Willi syndrome. METHODS: Height, weight, and skinfold thickness were recorded in 25 children using standard anthropometric techniques at recruitment, and six months later, shortly before the start of daily subcutaneous injections of growth hormone. Body composition was assessed via a measurement of total body water using stable isotopes. Measurements were repeated at the end of the six months of growth hormone administration. Measurements of height, weight, and skinfold thickness were expressed as standard deviation scores (SDSs). RESULTS: There was a significant reduction in the percentage of body fat after growth hormone treatment; height velocity doubled during treatment; body weight did not change significantly when expressed as an SDS. Skinfold thickness at both the triceps and subscapular site decreased in absolute terms and when expressed as an SDS. CONCLUSIONS: These results indicate sufficient potential benefit to justify a more prolonged trial of growth hormone treatment and an exploration of different dosage regimens in children with Prader-Willi syndrome.

Prediction of maximal oxygen uptake from a 20-m shuttle run as measured directly in runners and squash players.

The aim of this study was to assess the validity of the multistage shuttle run test in predicting maximal oxygen uptake (VO2 max) in athletes trained in sports with different physical demands. Over a 14-day period, 10 male long-distance runners (continuous high-intensity exercise) and 10 male squash players (intermittent high-intensity exercise) performed, in random order, the multistage shuttle run test and a maximal treadmill protocol of increasing elevation which elicited VO2 max. Compared with direct measurement of VO2 max, the shuttle run test significantly underpredicted the VO2 max of the group of runners (n = 10; P < 0.01) and of the athletes as a whole (n = 20; P < 0.01). The correlation (r) between VO2 max determined by the shuttle run test and by the treadmill protocol was 0.61 (P < 0.05) for the squash players, 0.71 (P < 0.05) for the runners and 0.67 (P < 0.01) for the athletes as a whole. As the subjects represented athletes trained specifically in sports with different physical demands, this may explain why the correlations between the shuttle run test and direct measurement of VO2 max are less robust than those reported in previous studies. Furthermore, our results indicate that there are sport-specific differences when predicting VO2 max from the multistage shuttle run test.