Exercise as medicine – but not always at the right dose

Physical activity is often promoted as a universal solution to health problems, and for good reason: regular exercise reduces disease risk and improves both physical and mental function. However, one critical nuance is often overlooked in public messaging – exercise is only beneficial when dose, timing, and context are properly matched to the individual.

Exercise follows the same principles as medication

In medicine, it is self-evident that a drug can be beneficial at one dose and harmful at another. Exercise works in the same way. Its effects are determined by:

• Intensity

• Duration

• Frequency

• The individual’s capacity and load history

When these factors are poorly matched, exercise may increase symptoms rather than improve health.

When exercise produces the opposite effect

For individuals with a high overall load, exercise can become an additional stressor. This is particularly relevant in the presence of:

• Persistent pain

• Sleep deprivation

• High psychosocial stress

• Reduced recovery capacity

In such cases, increasing training volume may lead to:

• Worsening pain

• Prolonged recovery time

• Reduced motivation

• Increased risk of dropout

The adaptive window

Training adaptations occur when the load falls within the body’s adaptive window – a level of stimulus sufficient to provoke adaptation without exceeding recovery capacity.

Factors that narrow this window include:

• Stress

• Sleep loss

• Energy deficiency

• Previous injury

This explains why two individuals can respond very differently to the same training program.

The role of low-intensity activity

During periods of reduced tolerance, low-intensity activity may be more appropriate than structured exercise. Examples include:

• Easy walking

• Light circulation-promoting activity

• Movement without performance targets

Such approaches can support health without overstimulating the system.

Clinical implications

Recommending exercise indiscriminately can be just as problematic as recommending inactivity. An individualized approach, where exercise is considered in relation to total load and life context, leads to better and more sustainable outcomes.

Summary

Exercise is a powerful health intervention, but its effects depend on correct dosing. When load exceeds the body’s capacity to adapt, exercise can lose its therapeutic value. Adjusting dose – not just motivation – is often the key.

Sources

• Garber, C. E., et al. (2011). Quantity and quality of exercise for developing and maintaining fitness. Medicine & Science in Sports & Exercise, 43(7), 1334–1359.

• Meeusen, R., et al. (2013). Prevention, diagnosis and treatment of overtraining syndrome. European Journal of Sport Science, 13(1), 1–24.

• Halson, S. L. (2014). Monitoring training load to understand fatigue in athletes. Sports Medicine, 44(2), 139–147.