# High-intensity interval training combining rowing and cycling efficiently improves insulin sensitivity, body composition and VO(2)max in men with obesity and type 2 diabetes

PMID: 36387850
Journal: Frontiers in Endocrinology
Published: 2022 Nov 01
Authors: Petersen MH, de Almeida ME, Wentorf EK, Jensen K, Ørtenblad N, Højlund K

## Question

Does an 8-week supervised HIIT program combining rowing and cycling improve insulin sensitivity, body composition, and VO2max in men with obesity and type 2 diabetes compared with obese and lean glucose-tolerant men?

## Summary

This supervised 8-week rowing-and-cycling HIIT study in middle-aged men found improved insulin sensitivity, VO2max, body composition, and selected glycemic markers in men with type 2 diabetes, with similar relative improvements in obese and lean glucose-tolerant men. The trial had excellent adherence and no injuries, but it was not randomized, included only men, and used a highly supervised equipment-based protocol.

## Population

- Middle-aged men in lean glucose-tolerant, obese glucose-tolerant, and obese type 2 diabetes groups.
- Sample size: 44
- Age: Eligible age 40-65 years.
- Sex: Men only.
- Health status: Lean or obese glucose-tolerant, or obese with type 2 diabetes; non-smokers.

## Methodology

- Non-randomized supervised intervention study comparing responses across lean glucose-tolerant, obese glucose-tolerant, and obese type 2 diabetes groups.
- 8 weeks.
- Specialized diabetes and university research setting in Denmark.
- Controlled study design.

## Protocol

- Combined rowing/cycling HIIT.
- Modality: Rowing ergometer and cycle ergometer.
- Work intervals: 1 min high-intensity intervals.
- Recovery: 1 min active/rest recovery; 4 min break between modality blocks.
- Sets or repetitions: Blocks of 5 intervals; progressed from 2 to 5 blocks.
- Intensity: Cycling at 100-110% maximal cycling capacity; HR about 86-88% max.
- Session duration: 32-71 min depending on progression phase.
- Frequency: 3 sessions/week.
- Program length: 8 weeks.
- Progression: 2 blocks weeks 1-2, 3 blocks weeks 3-4, 4 blocks weeks 5-6, 5 blocks weeks 7-8.
- Across-group comparison without no-exercise control.
- Modality: All groups completed the same rowing/cycling HIIT.
- Work intervals: Same as intervention.
- Recovery: Same as intervention.
- Sets or repetitions: Same as intervention.
- Intensity: Same as intervention.
- Session duration: Same as intervention.
- Frequency: Same as intervention.
- Program length: 8 weeks.
- Progression: Same as intervention.

## Outcomes

### Insulin sensitivity
Status: improved
Glucose disposal rate improved in all groups, including a large increase in the type 2 diabetes group.

GDR +42% in type 2 diabetes p<0.001, +27% in obese glucose-tolerant p=0.001, +29% in lean p<0.001.

### VO2max
Status: improved
VO2max increased in all metabolic groups.

Approximately +15% in type 2 diabetes (p<0.001), +8% in obese glucose-tolerant (p=0.002), and +10% in lean glucose-tolerant (p=0.001).

### Body composition
Status: improved
Weight, BMI, waist, waist-hip ratio, and fat mass decreased slightly, while lean body mass increased.

Fat mass decreased about 1.6-2.3 kg and lean body mass increased about 0.6-1.5 kg across groups, all p<0.05.

### Glycemic biomarkers in type 2 diabetes
Status: improved
HbA1c and fasting glucose decreased in the type 2 diabetes group.

HbA1c -4 +/- 2 mmol/mol p=0.017; fasting glucose -1.0 +/- 0.4 mmol/L p<0.001.

### Safety and adherence
Status: improved
Adherence was very high and no injuries were reported.

>95% adherence in all groups; no injuries.

## Practical Insights

- A 1 min on / 1 min off protocol can be progressed by adding blocks, but the late-stage sessions were long for consumer app use.
- Low-impact equipment-based HIIT may be useful for obesity and diabetes populations under supervision.
- Do not translate the insulin-sensitivity findings directly to unsupervised bodyweight HIIT.

## Limitations

- Non-randomized design without no-exercise control.
- Men only.
- Short intervention and no follow-up.
- No actual food-intake data.
- Protocol required rowing/cycling equipment and close supervision.
- Insulin-treated type 2 diabetes was not included.

## Safety And Adherence

- No injuries were reported.
- One lean participant developed knee problems before training and did not complete.
- The protocol was supervised and HR-monitored.

## Original Sources

- [PubMed](https://pubmed.ncbi.nlm.nih.gov/36387850/) (pubmed)
- [DOI](https://doi.org/10.3389/fendo.2022.1032235) (doi)
- [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9664080/) (full text)

## Agent Guidance

Preserve the paper-level scope of this note. Do not generalize beyond the population, protocol, measured outcomes, and limitations above.