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High-intensity interval training improves autonomic, vascular function in adolescents

Novel cardiovascular disease risk factors improved in adolescents after 2 weeks of high-intensity interval training, according to data published in the American Journal of Physiology - Heart and Circulatory Physiology.

Bert Bond, PhD, MSc, associate lecturer and associate research fellow, department of sport and health sciences, University of Exeter, United Kingdom, and colleagues reported traditional CVD risk factors did not improve after high-intensity interval training (HIIT).

The researchers evaluated 13 adolescents over a 3-week period in which they completed six HIIT sessions lasting 8 to 10 minutes. They measured traditional CVD risk factors such as triglycerides, glucose, insulin, cholesterol and blood pressure and novel CVD risk factors such as heart rate variability (HRV) and flow-mediated dilation (FMD). These measures were taken in a fasted state as well as in a postprandial state before (PRE), 1 day and 3 days after training.

Bert Bond

Results showed fasted FMD improved 1 day after training (P = .003, effect size = 0.7) but not 3 days after training (P = .32, effect size = 0.22) compared with PRE. Postprandial FMD was greater 1 day after training (P < .001, effect size = 1.01) and 3 days after training (P = .01, effect size = 0.6) compared with PRE.

Additionally, fasted HRV was greater 1 day after training (P = .001, effect size = 0.71) and 3 days after training (P = .02, effect size = 0.44). Results demonstrated a lower HRV following the test meal in all visits (P < .001, effect size = 0.59).

Bond and colleagues stated that the HIIT program had no effect on traditional CVD risk factors or aerobic fitness.

"The present study identifies that improvements in autonomic and vascular functions are achievable in asymptomatic adolescents following 2 [weeks] of HIIT and that these may occur in the absence of changes in traditional CVD risk factors," Bond and colleagues wrote. "Additionally, most of these improvements were lost 3 days after the last HIIT session."

"Considering that few adolescents meet the current guideline of a minimum of 60 [minutes] of daily exercise, HIIT may offer an attractive, low-volume alternative to moderate-intensity exercise interventions for the primary prevention of CVD," they continued."

In a press release, Bond stated that while adolescents may be more successful in improving their health with HIIT, more research is necessary.

"This is an important finding, but more work is needed to inform existing physical activity guidelines for health," he said in the release. "The next step is to confirm these results on more participants, especially groups who are at greater risk of future cardiovascular disease, and to address the impact of longer high-intensity interventions." – by Chelsea Frajerman Pardes

Disclosures: The authors report no relevant financial disclosures.