A Practical and Time-Efficient High-Intensity Interval Training Program Modifies Cardio-Metabolic Risk Factors in Adults with Risk Factors for Type II Diabetes

Abstract

IntroductionRegular physical activity (PA) can reduce the risk of developing type 2 diabetes, but adherence to time-orientated (150 min week−1 or more) PA guidelines is very poor. A practical and time-efficient PA regime that was equally efficacious at controlling risk factors for cardio-metabolic disease is one solution to this problem. Herein, we evaluate a new time-efficient and genuinely practical high-intensity interval training (HIT) protocol in men and women with pre-existing risk factors for type 2 diabetes.Materials and methodsOne hundred eighty-nine sedentary women (n = 101) and men (n = 88) with impaired glucose tolerance and/or a body mass index >27 kg m−2 [mean (range) age: 36 (18–53) years] participated in this multi-center study. Each completed a fully supervised 6-week HIT protocol at work-loads equivalent to ~100 or ~125% V˙O2 max. Change in V˙O2 max was used to monitor protocol efficacy, while Actiheart™ monitors were used to determine PA during four, weeklong, periods. Mean arterial (blood) pressure (MAP) and fasting insulin resistance [homeostatic model assessment (HOMA)-IR] represent key health biomarker outcomes.ResultsThe higher intensity bouts (~125% V˙O2 max) used during a 5-by-1 min HIT protocol resulted in a robust increase in V˙O2 max (136 participants, +10.0%, p < 0.001; large size effect). 5-by-1 HIT reduced MAP (~3%; p < 0.001) and HOMA-IR (~16%; p < 0.01). Physiological responses were similar in men and women while a sizeable proportion of the training-induced changes in V˙O2 max, MAP, and HOMA-IR was retained 3 weeks after cessation of training. The supervised HIT sessions accounted for the entire quantifiable increase in PA, and this equated to 400 metabolic equivalent (MET) min week−1. Meta-analysis indicated that 5-by-1 HIT matched the efficacy and variability of a time-consuming 30-week PA program on V˙O2 max, MAP, and HOMA-IR.ConclusionWith a total time-commitment of <15 min per session and reliance on a practical ergometer protocol, 5-by-1 HIT offers a new solution to modulate cardio-metabolic risk factors in adults with pre-existing risk factors for type 2 diabetes while approximately meeting the MET min week−1 PA guidelines. Long-term randomized controlled studies will be required to quantify the ability for 5-by-1 HIT to reduce the incidence of type 2 diabetes, while strategies are required to harmonize the adaptations to exercise across individuals.

Impact of data averaging strategies on V̇O2max assessment: Mathematical modeling and reliability

“…A similar effect was observed with time‐averaging strategies. The difference between the 6‐b and 60‐b averaging strategies was reduced from 10.1% to 8.5% following a HIT training program that increased O 2max by ~8% ( P < 0.05 and P < 0.001 for intercepts and slopes, respectively; n = 41). This effect was partially reverted following three weeks of detraining, that is, the difference between the 6‐b and 60‐b averaging strategy increased to 9.9% ( P = 0.35 and P = 0.03 for intercepts and slopes compared to pre‐training, respectively).…”

“…Forty‐one subjects belonging to subgroups 1 and 2 participated in a 6‐week high‐intensity interval training (HIT) protocol aimed at increasing O 2max . After the training period, a single O 2max test was performed. This was followed by a 3‐week detraining period after which another single O 2max test was performed.…”

“… After the training period, a single O 2max test was performed. This was followed by a 3‐week detraining period after which another single O 2max test was performed.…”

Interindividual responses to different exercise stimuli among insulin‐resistant women

“…For instance, some individuals show improvements with exercise training (eg, decrease in fasting glucose) and are considered responders , whereas others may not have such a response (eg, no change or even increases in fasting glucose) and are considered non‐responders . Individual variability has been reported mainly regarding fitness‐related variables, and in response to moderate‐intensity endurance (ET), resistance (RT), or high‐intensity interval training (HIT), and also in different age groups such as children, adults, or older populations, The existence of non‐responders for glucose homeostasis‐related variables has been confirmed more recently . In the present study, we confirmed a wide interindividual variability that is independent of the training‐induced changes after HIT, RT, or CT with regard to 20 outcomes and risk parameters, including 9 body composition, 3 cardiovascular, 3 metabolic, and 5 performance parameters.…”

“…The interindividual variability has been reported mainly in the context of fitness‐related variables, and in response to moderate‐intensity endurance (ET), resistance (RT), or high‐intensity interval training (HIT), and also in different age groups such as children, adults, or older populations . The existence of non‐responders for glucose homeostasis‐related variables has been confirmed more recently …”