PMID 36755928

Research
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The effects of three different low-volume aerobic training protocols on cardiometabolic parameters of type 2 diabetes patients: A randomized clinical trial

Gentil P, Silva LRBE, Antunes DE, Carneiro LB, de Lira CAB, Batista G, de Oliveira JCM, Cardoso JS, Souza DC, Rebelo ACS

Question

Do different low-volume aerobic training protocols, including short-interval HIIT, long-interval HIIT, and moderate continuous training, produce different cardiometabolic adaptations in adults with type 2 diabetes?

Summary

This randomized clinical trial compared two low-volume treadmill HIIT formats with low-volume moderate continuous training in adults with type 2 diabetes. Both HIIT protocols used only 10 minutes of high-intensity work per session, twice weekly for 8 weeks, and improved VO2max more than the moderate continuous protocol. The longer 2-minute interval protocol also significantly reduced HbA1c, triglycerides, and systolic blood pressure within group, while several other cardiometabolic markers did not significantly change.

Methodology

  • Adults with type 2 diabetes, age 40 years or older, not participating in other training programs; moderate/high cardiovascular-risk conditions and several cardiopulmonary/orthopedic exclusions applied. Fifty-two were randomized and 44 were included in final analysis.
  • 44 participants.
  • Motorized treadmill walking/running.
  • Work intervals: S-HIIT: 30 seconds; L-HIIT: 2 minutes.
  • Recovery: S-HIIT: 30 seconds passive; L-HIIT: 2 minutes passive.
  • Intensity: 100% vVO2max during HIIT work bouts; warmup/cooldown at 50% vVO2max.
  • Approximately 24 minutes including warmup and cooldown.
  • 2 sessions/week.
  • 8 weeks.
  • Parallel randomized clinical trial with three exercise groups: long-interval HIIT, short-interval HIIT, and moderate-intensity continuous training.
  • VO2max, HbA1c and fasting glycemia, Lipid profile, and Resting blood pressure and heart rate were tracked.

Outcomes

VO2max

VO2max improved significantly in both HIIT groups and improved more than MICT, with no meaningful difference between L-HIIT and S-HIIT.

L-HIIT MD +3.2 +/- 1.7 ml/kg/min, p<0.001; S-HIIT MD +3.4 +/- 1.7 ml/kg/min, p<0.001; L-HIIT vs MICT p=0.04, S-HIIT vs MICT p=0.01, L-HIIT vs S-HIIT p=0.9.

Improved

HbA1c

HbA1c significantly decreased only in the L-HIIT group, while S-HIIT and MICT did not reach significance.

L-HIIT MD -1.8 +/- 1.8%, p<0.01; S-HIIT MD -0.92 +/- 2.0%, p=0.09; MICT MD -0.59 +/- 1.7%, p=0.2.

Mixed

Triglycerides

Triglycerides significantly decreased only in the L-HIIT group; S-HIIT trended down but was not statistically significant, and MICT did not improve.

L-HIIT MD -23.80 +/- 39.6 mg/dL, p=0.04; S-HIIT MD -23.19 +/- 49.0 mg/dL, p=0.09; MICT MD +5.36 +/- 31.9 mg/dL, p=0.5.

Mixed

Resting systolic blood pressure

Resting SBP significantly decreased only in the L-HIIT group.

L-HIIT MD -12.07 +/- 15.3 mmHg, p<0.01; S-HIIT MD -7.33 +/- 17.1 mmHg, p=0.1; MICT MD +4.43 +/- 13.1 mmHg, p=0.2. L-HIIT reduced SBP more than MICT, p=0.018, d=1.56.

Mixed

Other cardiometabolic markers

Fasting glycemia, total cholesterol, HDL, LDL, resting HR, and resting DBP did not significantly change in any group.

Reported p>0.05 for all groups.

No clear change

Insights

  • A low-volume treadmill HIIT dose of 10 minutes hard work per session, 2 times per week for 8 weeks, can improve VO2max in adults with T2DM under screened, monitored conditions.
  • Short 30-second intervals and longer 2-minute intervals both improved VO2max, but the stronger HbA1c, triglyceride, and SBP signal came from the 2-minute interval protocol.
  • For app guidance, metabolic claims should be scoped tightly: this trial supports cardiorespiratory improvement more consistently than broad metabolic-marker improvement.
  • Clinical users with T2DM need screening/supervision language, especially because CPET excluded several safety-risk participants before training.

Limitations

  • No non-exercise control group, so exercise effects cannot be separated from all non-exercise conditions.
  • No dietary control beyond instructions to keep usual diet habits.
  • Small final group sizes and no a priori sample-size definition.
  • Clinical T2DM sample limits direct general-population translation.
  • Intervention was supervised and intensity was based on CPET-derived vVO2max.

Safety

  • No intervention adverse-event count was reported.
  • CPET screening excluded participants with low exercise capacity, uncontrolled arrhythmias during exertion, unstable angina, and abnormal SBP response.
  • Authors highlight that longer HIIT intervals may create greater cardiovascular stress in T2DM patients, requiring cost-benefit judgment.