title: Influence of work-interval intensity and duration on time spent at a high percentage of VO2max during intermittent supramaximal exercise.
abstract: The purpose of this study was to examine the effect of work-interval duration (WID) and intensity on the time spent at, or above, 95% VO2max (T95 VO2max) during intermittent bouts of supramaximal exercise. Over a 5-week period, 7 physically active men with a mean (+/-SD) age, height, body mass, and VO2max of 22 +/- 5 years, 181.5 +/- 5.6 cm, 86.4 +/- 11.4 kg, and 51.5 +/- 1.5 ml.kg-1.min-1, respectively, attended 7 testing sessions. After completing a submaximal incremental test on a treadmill to identify individual oxygen uptake/running velocity relationships, subjects completed a maximal incremental test to exhaustion to VO2max and subsequently (from the aforementioned relationship) the minimum velocity required to elicit VO2max (vVO2max). In a random order, subjects then carried out 3 intermittent runs to exhaustion at both 105% and 115% vVO2max. Each test used a different WID (20 s, 25 s, or 30 s) interspersed with 20-second passive recovery periods. Results revealed no significant difference in T95 vVO2max for intermittent runs at 105% versus 115% vVO2max (p = 0.142). There was, however, a significant effect (p < 0.001) of WID on T95 VO2max, with WIDs of 30 seconds enabling more time relative to WIDs of 20 seconds (p = 0.018) and 25 seconds (p = 0.009). Moreover, there was an interaction between intensity and duration such that the effect of WID was magnified at the lower exercise intensity (p = 0.046). In conclusion, despite a number of limitations, the results of this investigation suggest that exercise intensities of approximately 105% vVO2max combined with WIDs greater than 25 seconds provide the best way of optimizing T95 VO2max when using fixed 20-second stationary rest periods.
authors.affiliation: School of Human Sciences, St. Mary's University College, Twickenham, United Kingdom. wakefield@smuc.ac.uk
authors.forename: Benjamin R
authors.initials: BR
authors.lastname: Wakefield
authors.forename: Mark
authors.initials: M
authors.lastname: Glaister
mesh_terms: D000328:Adult; D015308:Anaerobic Threshold / Q000502:physiology; D000704:Analysis of Variance; D054874:Athletic Performance / Q000502:physiology*; D005080:Exercise Test; D005081:Exercise Therapy / Q000379:methods*; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D019344:Lactic Acid / Q000097:blood; D008297:Male; D018763:Muscle Fatigue / Q000502:physiology*; D010101:Oxygen Consumption / Q000502:physiology*; D010807:Physical Endurance / Q000502:physiology*; D012146:Rest / Q000502:physiology; D012420:Running / Q000502:physiology*; D013997:Time Factors
chemical_list: D019344:Lactic Acid