title: VO2 responses to running speeds above VO2max.
abstract: This study compared VO2, heart rate (HR) and electromyographic (iEMG) responses to speeds above the velocity associated with VO2max (v-VO2max). Eight male, middle-distance runners performed a graded exercise test to determine VO2max and v-VO2max and runs to fatigue at 100 % and 110 % v-VO2max. Breath-by-breath VO2 and HR were continuously recorded; lactate [La (-)] measured pre- and post-run and iEMG measures of rectus femoris (RF) and vastus lateralis were recorded during the first and last 20 s of each run. Analysis indicated longer time to fatigue in the 100 % v-VO2max run with no differences between conditions for VO2 or HR amplitudes or post-run [La (-)] (p > 0.05). There were significantly faster tau values (p < 0.05) in the 110 % condition in VO2 and HR. No significant correlations were observed between VO2 or HR tau values and time to fatigue. RF iEMG was significantly larger in 110 % compared to 100 % run in the first 20 s (p < 0.05). While no association between treadmill performance and VO2 response was evident, faster running speeds resulted in faster VO2 and HR responses, with no difference in amplitude or % VO2max attained. This may potentially be as a result of an increased muscle fibre recruitment stimulus during the faster running velocity resulting in faster cardiodynamic responses.
authors.affiliation: School of Human Movement, Charles Sturt University, Bathurst, Australia. rduffield@csu.edu.au
authors.forename: R
authors.initials: R
authors.lastname: Duffield
authors.forename: D
authors.initials: D
authors.lastname: Bishop
mesh_terms: D000328:Adult; D004576:Electromyography; D005080:Exercise Test; D017079:Exercise Tolerance; D005221:Fatigue / Q000503:physiopathology*; D006801:Humans; D008297:Male; D009119:Muscle Contraction; D018482:Muscle, Skeletal; D010101:Oxygen Consumption; D052097:Quadriceps Muscle; D012420:Running / Q000502:physiology*; D013997:Time Factors