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.

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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. 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 1h at low intensity (average HR=73±3% HRmax). Fasting blood samples were takenand an oral glucose tolerance test (OGTT) was conducted pre- and post-intervention. 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±325mmolminL(-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. 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.