title: Low-volume high-intensity swim training is superior to high-volume low-intensity training in relation to insulin sensitivity and glucose control in inactive middle-aged women.
abstract: OBJECTIVE
  We tested the hypothesis that low-volume high-intensity swimming has a larger impact on insulin sensitivity and glucose control than high-volume low-intensity swimming in inactive premenopausal women with mild hypertension.
  
  
  METHODS
  Sixty-two untrained premenopausal women were randomised to an inactive control (n = 20; CON), a high-intensity low-volume (n = 21; HIT) or a low-intensity high-volume (n = 21; LIT) training group. During the 15-week intervention period, HIT performed 3 weekly 6-10 × 30-s all-out swimming intervals (average heart rate (HR) = 86 ± 3 % HRmax) interspersed by 2-min recovery periods and LIT swam continuously for 1 h at low intensity (average HR = 73 ± 3 % HRmax). Fasting blood samples were taken and an oral glucose tolerance test (OGTT) was conducted pre- and post-intervention.
  
  
  RESULTS
  After HIT, resting plasma [insulin] was lowered (17 ± 34 %; P < 0.05) but remained similar after LIT and CON. Following HIT, 60-min OGTT plasma [insulin] and [glucose] was lowered (24 ± 30 % and 10 ± 16 %; P < 0.05) but remained similar after LIT and CON. Total area under the curve for plasma [glucose] was lower (P < 0.05) after HIT than LIT (660 ± 141 vs. 860 ± 325 mmol min L(-1)). Insulin sensitivity (HOMA-IR) had increased (P < 0.05) by 22 ± 34 % after HIT, with no significant change after LIT or CON, respectively. Plasma soluble intracellular cell adhesion molecule 1 was lowered (P < 0.05) by 4 ± 8 and 3 ± 9 % after HIT and CON, respectively, while plasma soluble vascular cell adhesion molecule 1 had decreased (P < 0.05) by 8 ± 23 % after HIT only.
  
  
  CONCLUSIONS
  These findings suggest that low-volume high-intensity intermittent swimming is an effective and time-efficient training strategy for improving insulin sensitivity, glucose control and biomarkers of vascular function in inactive, middle-aged mildly hypertensive women.
authors.affiliation: Sport and Health Sciences, College of Life and Environmental Sciences, University of Exeter, Exeter, UK.
authors.forename: Luke J
authors.initials: LJ
authors.lastname: Connolly
authors.affiliation: Department of Nutrition, Exercise and Sports, Section of Integrative Physiology, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Nikolai B
authors.initials: NB
authors.lastname: Nordsborg
authors.affiliation: Department of Nutrition, Exercise and Sports, Section of Integrative Physiology, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Michael
authors.initials: M
authors.lastname: Nyberg
authors.affiliation: Department of Occupational Medicine and Public Health, The Faroese Hospital System, Tórshavn, Faroe Islands.|Faculty of Natural and Health Sciences, University of the Faroe Islands, Tórshavn, Faroe Islands.
authors.forename: Pál
authors.initials: P
authors.lastname: Weihe
authors.affiliation: Sport and Health Sciences, College of Life and Environmental Sciences, University of Exeter, Exeter, UK.|Department of Nutrition, Exercise and Sports, Section of Integrative Physiology, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Peter
authors.initials: P
authors.lastname: Krustrup
authors.affiliation: Faculty of Natural and Health Sciences, University of the Faroe Islands, Tórshavn, Faroe Islands. magnim@setur.fo.|Department of Food and Nutrition, and Sport Sciences, Center for Health and Human Performance, University of Gothenburg, Gothenburg, Sweden. magnim@setur.fo.
authors.forename: Magni
authors.initials: M
authors.lastname: Mohr
mesh_terms: D000328:Adult; D001786:Blood Glucose / Q000378:metabolism*; D005260:Female; D000072696:High-Intensity Interval Training / Q000379:methods*; D006801:Humans; D007328:Insulin / Q000097:blood*; D008875:Middle Aged; D010807:Physical Endurance / Q000502:physiology*; D005082:Physical Exertion / Q000502:physiology*; D017697:Premenopause / Q000502:physiology; D057185:Sedentary Behavior; D013550:Swimming / Q000502:physiology*
chemical_list: D001786:Blood Glucose; D007328:Insulin
keywords: Blood glucose; Body composition; Metabolic health; Type 2 diabetes; Upper body exercise