# Muscular Adaptations to Concurrent Resistance Training and High-Intensity Interval Training in Adults with Type 2 Diabetes: A Pilot Study

PMID: 37754606
Journal: International journal of environmental research and public health
Published: 2023 Sep 11
Authors: Orlando G, Pugh J, Faulkner S, Balducci S, Sacchetti M, Pugliese G, Bazzucchi I, Haxhi J, Martinez-Valdes E, Falla D, Manolopoulos K, Nimmo MA

## Question

Does adding HIIT after resistance training improve or interfere with muscle performance, muscle size, and muscle quality adaptations in adults with type 2 diabetes?

## Summary

In sedentary men with uncomplicated type 2 diabetes, eight weeks of supervised resistance training plus cycling HIIT improved VO2max, quadriceps volume, knee power, and some strength outcomes. Compared with resistance training alone, adding HIIT produced larger VO2max gains but smaller improvements in lower-limb muscle quality.

## Population

- Sedentary overweight/obese men with uncomplicated type 2 diabetes
- Sample size: 12
- Age: 30-50 years by inclusion criteria
- Sex: Male
- Fitness level: Sedentary/physically inactive for at least 12 months
- Health status: Type 2 diabetes; complications and contraindications excluded

## Methodology

- Open-label parallel randomized clinical trial pilot analysis
- 8 weeks
- Three supervised exercise centres in the UK and Italy
- Randomized and controlled study design.

## Protocol

- RT plus cycling HIIT.
- Modality: Resistance training plus cycle ergometer.
- Work intervals: 1-min cycling at workload designed to elicit 90% HRmax.
- Recovery: 1-min low-intensity cycling at 30-40% HRmax.
- Sets or repetitions: 10 intervals after RT.
- Intensity: 90% HRmax target.
- Session duration: 75 min total, 25 min HIIT portion.
- Frequency: 3 sessions/week.
- Program length: 8 weeks.
- Progression: Workload increased when average HR across intervals fell below 85% HRmax.
- Resistance training alone.
- Modality: Resistance training.
- Recovery: 2 min passive recovery between sets.
- Sets or repetitions: 3 x 10 at 70-80% 1RM plus fourth set to failure for six exercises.
- Intensity: 70-80% 1RM.
- Session duration: 50 min.
- Frequency: 3 sessions/week.
- Program length: 8 weeks.
- Progression: Weight increased when >=12 reps were completed on two consecutive sessions.

## Outcomes

### VO2max
Status: improved
Both groups improved VO2max, with larger gains in RT+HIIT.

RT +12%, p=0.034; RT+HIIT +27%, p<0.001; between-group change p=0.023.

### Muscle volume
Status: improved
Quadriceps volume increased in both groups.

RT +5.9%, p=0.035; RT+HIIT +6%, p=0.004.

### Strength
Status: mixed
RT improved multiple 1RM tests; RT+HIIT significantly improved lat pulldown but not all lower-body 1RM outcomes.

RT leg extension p=0.021, step-up p<0.001, lat pulldown p=0.005, chest press p=0.041; RT+HIIT lat pulldown p=0.003.

### Muscle quality
Status: worse/safety concern
Lower-limb muscle-quality improvements were smaller with RT+HIIT than RT alone.

Between-group leg step-up p=0.035; leg extension p=0.015.

### Glycaemia
Status: no clear change
Body composition, HbA1c, and fasting glucose did not change in either group.

## Practical Insights

- Adding HIIT after RT can increase fitness but may reduce the relative muscle-quality benefit of RT alone.
- For T2DM, screen carefully and supervise progression.

## Limitations

- Very small pilot sample
- Male-only early-stage T2DM
- Baseline group imbalance
- Diet not controlled
- RT+HIIT had higher total exercise volume than RT

## Safety And Adherence

- No exercise-related adverse events, including hypoglycaemia, were reported.

## Original Sources

- [PubMed](https://pubmed.ncbi.nlm.nih.gov/37754606/) (pubmed)
- [DOI](https://doi.org/10.3390/ijerph20186746) (doi)
- [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10530856/) (full text)

## Agent Guidance

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