# High-intensity interval training as an efficacious alternative to moderate-intensity continuous training for adults with prediabetes PMID: 25918728 Journal: Journal of diabetes research Published: 2015-01-01 Authors: Jung ME, Bourne JE, Beauchamp MR, Robinson E, Little JP ## Question Can adults with prediabetes adhere to independently performed HIIT over one month after a brief supervised intervention, and how does adherence and short-term cardiometabolic response compare with traditional moderate-intensity continuous training? ## Summary This randomized feasibility study compared short-term adherence to HIIT versus moderate-intensity continuous training in inactive adults with prediabetes. Participants first completed 10 exercise sessions over 12 days, mostly supervised, then were asked to continue their assigned exercise independently three times weekly for four weeks. HIIT used progressive 1-minute intervals at about 90% peak heart rate with 1-minute easy recovery; after training, the independent prescription was 10 x 1-minute intervals plus warm-up and cool-down for 25 minutes per session. Self-reported adherence over follow-up was higher for HIIT than MICT, vigorous activity by accelerometer was higher in HIIT, and both groups improved VO2peak and systolic blood pressure. The authors emphasized feasibility rather than definitive safety or long-term cardiometabolic benefit. ## Population - Inactive adults aged 30-60 years with prediabetes who were cleared for vigorous activity. - Sample size: 32 - Age: Mean 51 (SD 10) years overall. - Sex: 5 male and 27 female overall. - Fitness level: Inactive; baseline relative VO2 20.23 (SD 4.48) mL/kg/min. - Health status: Prediabetes; mean BMI 32.9 kg/m2 and mean waist circumference 107.3 cm. ## Methodology - Randomized feasibility trial with a 2-week supervised exercise introduction followed by 4 weeks of independent exercise. - 10 exercise sessions over 12 days plus 4 weeks of independent follow-up. - Initial laboratory and home training with research-assistant supervision for most introductory sessions, followed by independent free-living exercise. - Randomized and controlled study design. ## Protocol - HIIT. - Modality: Participant-selected walking outdoors, elliptical, treadmill walking, or stationary cycling. - Work intervals: 1 minute at about 90% HRpeak. - Recovery: 1 minute low-intensity/easy recovery. - Sets or repetitions: Progressed from 4 to 10 intervals during 10-session introduction; independent follow-up prescribed 10 intervals. - Intensity: Intervals at about 90% HRpeak; supervised-phase average including rest, warm-up, and cool-down was 82 +/- 3% HRpeak. - Session duration: 25 minutes for the follow-up HIIT prescription, including 3-minute warm-up, 10 x 1-minute intervals, 1-minute recoveries, and 2-minute cool-down. - Frequency: 3 sessions per week during independent follow-up; 10 sessions over 12 days during introduction. - Program length: 2-week introduction plus 4-week independent follow-up. - Progression: Interval count increased from 4 x 1-minute intervals to 10 x 1-minute intervals by day 10. - MICT. - Modality: Participant-selected walking outdoors, elliptical, treadmill walking, or stationary cycling. - Work intervals: Continuous exercise. - Intensity: About 65% HRpeak; supervised-phase average was 67 +/- 5% HRpeak. - Session duration: Progressed from 20 minutes to 50 minutes by day 10; follow-up prescribed 50 minutes. - Frequency: 3 sessions per week during independent follow-up; 10 sessions over 12 days during introduction. - Program length: 2-week introduction plus 4-week independent follow-up. - Progression: Continuous exercise duration increased from 20 minutes to 50 minutes by day 10. ## Outcomes ### Exercise adherence Status: improved HIIT adherence by training log was higher than MICT over one-month follow-up: 89 +/- 11% versus 71 +/- 31%. t(18.96)=2.08, p=0.05, Cohen's d=0.75. ### Vigorous physical activity Status: improved HIIT participants accumulated more weekly vigorous activity at follow-up than MICT participants. HIIT 23.7 +/- 18.0 min/week versus MICT 10.7 +/- 9.7 min/week; F(1,20)=4.41, p=0.049, Cohen's d=0.92. ### Cardiorespiratory fitness Status: improved Absolute VO2peak, relative VO2peak, and peak power increased over time across groups, with no group or group-by-time differences. Absolute VO2peak F(1,24)=20.96, p<0.001; relative VO2peak F(1,24)=14.82, p<0.001; peak power F(1,24)=14.08, p<0.001. ### Systolic blood pressure Status: improved Systolic blood pressure decreased over time across both exercise groups. F(1,24)=17.36, p<0.001, Cohen's d=1.75. ### Body mass and waist circumference Status: no clear change Body mass and waist circumference did not change significantly from baseline to one-month follow-up in either group. Reported p values >0.05. ## Practical Insights - A 1-minute on, 1-minute off HIIT structure may be feasible for screened inactive adults with prediabetes after a short supervised introduction. - Progressive exposure, behavioral counselling, heart-rate monitoring, and RPE education were part of the intervention context and should not be stripped from safety interpretation. - Shorter HIIT sessions may support adherence where lack of time is a barrier, but long-term adherence and safety still need stronger evidence. ## Limitations - Small feasibility study. - Independent exercise was only observed for one month. - More HIIT participants than MICT participants lacked one-month follow-up data. - Not powered to evaluate safety or injury risk. - Clinical population and screening requirements limit generalizability to broad unscreened consumer users. ## Safety And Adherence - All 32 participants completed the short-term supervised intervention with no complications. - The study excluded multiple higher-risk conditions and required clearance for vigorous exercise. - The authors state that the study was not designed to examine safety and musculoskeletal injuries in response to HIIT versus MICT. ## Original Sources - [PubMed](https://pubmed.ncbi.nlm.nih.gov/25918728/) (pubmed) - [DOI](https://doi.org/10.1155/2015/191595) (doi) - [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4396724/) (full text) ## Agent Guidance Preserve the paper-level scope of this note. Do not generalize beyond the population, protocol, measured outcomes, and limitations above.