Exercising harder may matter more than total exercise time
A large prospective study suggests that how hard you move may matter more than how long, and that the answer differs depending on which disease you're trying to prevent.
A prospective study involving nearly 100,000 UK Biobank participants has revealed that the proportion of daily movement spent at vigorous intensity predicts disease risk more effectively than exercise volume alone across eight serious conditions, including dementia, type 2 diabetes and immune-mediated inflammatory diseases (IMIDs).
For the study participants wore wrist accelerometers for one week and were followed for roughly seven years.
The researchers discovered that the threshold for getting meaningful benefit was quite low: those who devoted more than four per cent of their total daily movement to vigorous activity, defined as effort intense enough to cause breathlessness, had 29 to 61 per cent lower risk across all eight outcomes. The more interesting finding was that this was condition-specific:
- For dementia and inflammatory conditions like rheumatoid arthritis and psoriasis, exercise intensity was the dominant driver, independent of volume.
- For type 2 diabetes, cardiovascular disease, and all-cause mortality, the combination of intensity and duration of activity produced the biggest risk reduction.
| Condition | Risk Reduction* | Key Driver |
|---|---|---|
| Dementia | 63% lower risk | Intensity |
| IMIDs (arthritis, psoriasis) | Significant reduction | Intensity |
| Type 2 diabetes | 60% lower risk | Intensity + Volume |
| All-cause mortality | 46% lower risk | Intensity + Volume |
| Major cardiovascular disease | Significant reduction | Intensity + Volume |
| Atrial fibrillation | Significant reduction | Intensity + Volume |
| Liver disease | Significant reduction | Intensity + Volume |
| Chronic kidney disease | Significant reduction | Intensity + Volume |
| Chronic respiratory disease | Significant reduction | Intensity + Volume |
The authors note that current physical activity recommendations treat moderate and vigorous activity as interchangeable on a per-minute basis. This new data suggests that framing may need revisiting, and that the answer depends considerably on which condition you are trying to prevent.
