Exercise training principles
| Principle | Criteria for this review | Example |
|---|---|---|
| Specificity: Training adaptations are specific to the system or muscles trained with exercise | Appropriate population targeted and intervention given based on primary outcome | Aerobic exercise such as brisk walking is more appropriate for an intervention aimed at increasing cardiovascular fitness than strength training |
| Progression: Over time, the body adapts to exercise. For continued improvement, the volume or intensity must be increased | Stated exercise programme was progressive and outlined training progression | A walking intervention 2×/week at 60% of maximum heart rate for 30 min, adds 5 min/week over 6 weeks |
| Overload: For an intervention to improve fitness, it must be greater than what the individual is already doing | Rationale provided that programme was of sufficient intensity/exercise prescribed relative to baseline fitness | An individual currently cycles 30 min 2×/week; the exercise intervention must be of greater volume to see a significant improvement in fitness |
| Initial values: Improvements in the outcome of interest will be greatest in those with lower initial values | Selected population with low level of primary outcome measure and/or baseline physical activity levels | Those with lowest levels of fitness have greatest room for improvement. A sample with high fatigue levels will be more likely to see a significant change than a sample with low baseline fatigue |
| Reversibility: Once a training stimulus is removed, fitness levels will eventually return to baseline | Performed follow-up assessment on participants who decreased or stopped exercise training after conclusion of intervention | 'Use it or lose it'. Strength gains achieved over 1 year of resistance exercise may completely reverse within a number of months of inactivity |
| Diminishing returns: The expected degree of improvement in fitness decreases as individuals become fit, thereby increasing the effort required for further improvements | Performed follow-up assessment of primary outcomes on participants who continued to exercise after conclusion of intervention | Non-exercisers who begin an exercise programme are likely to experience large initial gains, but the magnitude of change will decrease over time. Also known as the 'ceiling effect' |