12 min/week of high-intensity interval training reduces aortic reservoir pressure in individuals with metabolic syndrome

Joyce S. Ramos, Lance C. Dalleck, Maximiano V. Ramos, Fabio Borrani, Llion Roberts, Sjaan Gomersall, Kassia S. Beetham, Katrin A. Dias, Shelley E. Keating, Robert G. Fassett, James E. Sharman, Jeff S. Coombes

Decreased aortic reservoir function leads to a rise in aortic reservoir pressure that is an independent predictor of cardiovascular events. Although there is evidence that high-intensity interval training (HIIT) would be useful to improve aortic reservoir pressure, the optimal dose of high-intensity exercise to improve aortic reservoir function has yet to be investigated. Therefore, this study compared the effect of different volumes of HIIT and moderate-intensity continuous training (MICT) on aortic reservoir pressure in participants with the metabolic syndrome (MetS). Fifty individuals with MetS were randomized into one of the following 16-week training programs: MICT [n = 17, 30 min at 60-70% peak heart rate (HRpeak), five times/week]; 4 × 4-min high-intensity interval training (4HIIT) (n = 15, 4 × 4 min bouts at 85-95% HRpeak, interspersed with 3 min of active recovery at 50-70% HRpeak, three times/week); and 1 × 4-min high-intensity interval training (1HIIT) (n = 18, 1 × 4 min bout at 85-95% HRpeak, three times/week). Aortic reservoir pressure was calculated from radial applanation tonometry. Although not statistically significant, there was a trend for a small-to-medium group × time interaction effect on aortic reservoir pressure, indicating a positive adaptation following 1HIIT compared with 4HIIT and MICT [F (2,46) = 2.9, P = 0.07, η = 0.06]. This is supported by our within-group analysis wherein only 1HIIT significantly decreased aortic reservoir pressure from pre to postintervention (pre-post: 1HIIT 33 ± 16 to 31 ± 13, P = 0.03; MICT 29 ± 9-28 ± 8, P = 0.78; 4HIIT 28 ± 10-30 ± 9 mmHg, P = 0.10). Three sessions of 4 min of high-intensity exercise per week (12 min/week) was sufficient to improve aortic reservoir pressure, and thus may be a time-efficient exercise modality for reducing cardiovascular risk in individuals with MetS.