title: The effects of work-rest duration on intermittent exercise and subsequent performance.
abstract: This study examined the effects of different work - rest durations during 40 min intermittent treadmill exercise and subsequent running performance. Eight males (mean +/- s: age 24.3 +/- 2.0 years, body mass 79.4 +/- 7.0 kg, height 1.77 +/- 0.05 m) undertook intermittent exercise involving repeated sprints at 120% of the speed at which maximal oxygen uptake (nu-VO2max) was attained with passive recovery between each one. The work - rest ratio was constant at 1:1.5 with trials involving short (6:9 s), medium (12:18 s) or long (24:36 s) work - rest durations. Each trial was followed by a performance run to volitional exhaustion at 150% nu-VO2max. After 40 min, mean exercise intensity was greater during the long (68.4 +/- 9.3%) than the short work - rest trial (54.9 +/- 8.1% VO2max; P < 0.05). Blood lactate concentration at 10 min was higher in the long and medium than in the short work - rest trial (6.1 +/- 0.8, 5.2 +/- 0.9, 4.5 +/- 1.3 mmol x l(-1), respectively; P < 0.05). The respiratory exchange ratio was consistently higher during the long than during the medium and short work - rest trials (P < 0.05). Plasma glucose concentration was higher in the long and medium than in the short work - rest trial after 40 min of exercise (5.6 +/- 0.1, 6.6 +/- 0.2 and 5.3 +/- 0.5 mmol x l(-1), respectively; P < 0.05). No differences were observed between trials for performance time (72.7 +/- 14.9, 63.2 +/- 13.2, 57.6 +/- 13.5 s for the short, medium and long work - rest trial, respectively; P = 0.17), although a relationship between performance time and 40 min plasma glucose was observed (P < 0.05). The results show that 40 min of intermittent exercise involving long and medium work - rest durations elicits greater physiological strain and carbohydrate utilization than the same amount of intermittent exercise undertaken with a short work-rest duration.
authors.affiliation: Faculty of Health and Life Sciences, Coventry University, Coventry, UK. m.price@coventry.ac.uk
authors.forename: Mike
authors.initials: M
authors.lastname: Price
authors.forename: Karl
authors.initials: K
authors.lastname: Halabi
mesh_terms: D000328:Adult; D001786:Blood Glucose / Q000378:metabolism; D001835:Body Weight / Q000502:physiology; D015444:Exercise / Q000502:physiology*; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D019344:Lactic Acid / Q000097:blood; D008297:Male; D010101:Oxygen Consumption / Q000502:physiology; D010806:Physical Education and Training / Q000379:methods*; D010807:Physical Endurance / Q000502:physiology; D012146:Rest / Q000502:physiology*; D012420:Running / Q000502:physiology*; D013647:Task Performance and Analysis; D013997:Time Factors
chemical_list: D001786:Blood Glucose; D019344:Lactic Acid