title: Oxygen uptake and heart rate kinetics during heavy exercise: a comparison between arm cranking and leg cycling.
abstract: This study examined the oxygen uptake (VO(2)) and heart rate (HR) kinetics during arm cranking and leg cycling at work rates above the anaerobic threshold (AT). Ten untrained male subjects [21.6 (1.3) years] completed two 7 min 15 s constant-load arm cranking and two leg cycling tests at a power output halfway between the mode-specific AT and peak VO(2). The time constants for phase II VO(2) (tau) and HR (tau) kinetics were determined by fitting a monoexponential curve from the end of phase I until 3 min of exercise. VO(2) tau and HR tau values were significantly (P < 0.001) slower in arm cranking [VO(2) tau = 66.4 (3.0) s; HR tau = 74.7 (4.4) s] than in leg cycling [VO(2) tau = 42.0 (1.9) s; HR tau = 55.6 (3.5) s]. The VO(2) slow component (VO(2SC)) accounted for a significantly (P < 0.001) greater percentage of the total exercise response during arm cranking [23.8 (1.6)%] than during leg cycling [14.2 (1.5)%]. The greater relative VO(2SC) and the slower VO(2) tau with arm exercise are consistent with a greater recruitment of metabolically inefficient type II muscle fibres during arm cranking than during leg cycling.
authors.affiliation: School of Physiotherapy and Exercise Science, Griffith University, Gold Coast, 9726 Queensland, Australia. D.Schneider@mailbox.gu.edu.au
authors.forename: Donald A
authors.initials: DA
authors.lastname: Schneider
authors.forename: Andrew N
authors.initials: AN
authors.lastname: Wing
authors.forename: Norman R
authors.initials: NR
authors.lastname: Morris
mesh_terms: D000328:Adult; D015308:Anaerobic Threshold; D001132:Arm / Q000502:physiology*; D001642:Bicycling; D015444:Exercise / Q000502:physiology*; D006339:Heart Rate; D006801:Humans; D007700:Kinetics; D007866:Leg / Q000502:physiology*; D008297:Male; D010101:Oxygen Consumption; D010807:Physical Endurance