# High-Intensity Interval Training Versus Moderate-Intensity Continuous Training in Middle-Aged and Older Patients with Type 2 Diabetes: A Randomized Controlled Crossover Trial of the Acute Effects of Treadmill Walking on Glycemic Control

PMID: 31661946
Journal: International journal of environmental research and public health
Published: 2019 Oct 28
Authors: Mendes R, Sousa N, Themudo-Barata JL, Reis VM

## Question

Does one treadmill-walking HIIT session lower acute blood glucose more than duration- and intensity-matched moderate continuous walking or seated rest in middle-aged and older adults with type 2 diabetes?

## Summary

In 15 middle-aged and older adults with type 2 diabetes, one supervised treadmill-walking HIIT session lowered blood glucose more than a matched moderate continuous walk during exercise and short lab recovery. The protocol used incline walking, medical screening, glucose and cardiovascular checks, and had no acute adverse events in this selected group.

## Population

- Middle-aged and older adults with type 2 diabetes treated with metformin and/or gliptins
- Sample size: 15
- Age: 60.25 +/- 3.14 years
- Sex: 8 women and 7 men
- Fitness level: No supervised exercise program in prior 6 months
- Health status: Type 2 diabetes, HbA1c 7.03 +/- 0.33%, medically screened for vigorous exercise

## Methodology

- Randomized controlled crossover trial
- Three acute experimental visits one week apart
- Laboratory treadmill walking after standardized breakfast
- Randomized and controlled study design.

## Protocol

- Treadmill walking HIIT.
- Modality: Incline treadmill walking.
- Work intervals: 3 minutes at 70% HRR.
- Recovery: 3 minutes at 30% HRR.
- Sets or repetitions: 5.
- Intensity: High bouts averaged 71.83 +/- 2.04% HRR.
- Session duration: 40 minutes including 5-minute warm-up and 5-minute cool-down.
- Frequency: Single acute visit.
- Program length: Single session.
- Progression: None.
- Treadmill walking MICT.
- Modality: Treadmill walking.
- Work intervals: 30 minutes continuous.
- Sets or repetitions: 1 continuous bout.
- Intensity: 50% HRR; achieved 50.25 +/- 1.55% HRR.
- Session duration: 40 minutes including 5-minute warm-up and 5-minute cool-down.
- Frequency: Single acute visit.
- Program length: Single session.
- Progression: None.

## Outcomes

### Lab glucose
Status: improved
Both exercise sessions reduced blood glucose during exercise and lab recovery compared with seated control, and HIIT had a greater effect than MICT.

Time*condition interaction p<0.001; HIIT vs MICT p=0.017.

### Ambulatory glucose
Status: no clear change
The lab glucose advantage did not persist as a significant ambulatory follow-up difference.

Ambulatory time*condition interaction F=0.348, p=0.944.

### Acute safety
Status: improved
The screened and monitored protocol was completed without recorded acute exercise-related adverse events.

Adherence 100%; no listed acute adverse events.

### Exercise intensity
Status: no clear change
Average global exercise intensity was matched between HIIT and MICT.

Global HIIT 50.50 +/- 1.93% HRR vs MICT 50.25 +/- 1.55% HRR; p=0.742.

## Practical Insights

- Incline walking can create vigorous intervals at modest walking speeds, which may be safer than running for some older adults.
- For diabetes-related features, pair interval recommendations with medication, glucose, foot, and cardiovascular safety boundaries.
- The acute glucose benefit should not be presented as a durable next-day glycemic improvement from one session.

## Limitations

- Small sample.
- Acute session only.
- Clinically screened sample using metformin and/or gliptins, not insulin or secretagogues.
- No continuous glucose monitoring.
- Ambulatory diet was not quantitatively controlled.

## Safety And Adherence

- No symptomatic hypoglycemia, asymptomatic level 2 hypoglycemia, hyperglycemia, foot injuries, musculoskeletal pain/discomfort, or chest angina were recorded during exercise or lab recovery.
- Sessions had cancellation thresholds for abnormal glucose, blood pressure, or heart rate.
- The authors recommend clinical evaluation and stress testing before vigorous exercise in people with T2D.

## Original Sources

- [PubMed](https://pubmed.ncbi.nlm.nih.gov/31661946/) (pubmed)
- [DOI](https://doi.org/10.3390/ijerph16214163) (doi)
- [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6862460/) (full text)

## Agent Guidance

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