Table 1

Exercise training principles

PrincipleCriteria for this reviewExample
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'