Reasons for performing the study: It is unknown if different locomotor activities are equally effective at meeting the stabled horse's need for exercise and if they attenuate unwanted behaviour.Hypothesis: Alternative forms of exercise influence the intensity of locomotor activities during a period of turn-out (the so-called rebound effect), and the occurrence of unwanted or undesirable activities during standard handling situations.Method: Twenty-four horses kept in stables were randomly assigned to one of four exercise regimes ' walker, treadmill, turn-out and riding - for four consecutive days. Because these forms of exercise provide additional environmental stimulation, beyond that provided by exercise, each horse served as its own control in four corresponding (no exercise) control treatments presented in a balanced order. Unwanted behaviour was tested by taking horses to weighing scales and loading and unloading them onto a four-horse float by an experienced handler, and the rebound effect was tested by releasing them into a large arena for a period of 15 minutes at the end of the exercise and control treatments.Results: Locomotor activities made up a large part of their behaviour in the large arena following control treatments and all exercise regimes were sufficient to reduce the intensity of walking (P<0.05), trotting (P<0.01) and cantering (P<0.001) on release into a large arena. Exercise regime reduced the number of bucks (P<0.01) and rolling (P<0.05) during rebound tests suggesting that turn-out was having a stronger effect than the other three exercise regimes. Exercise regimes significantly reduced the amount of unwanted behaviour and the number of commands given by the handler during weighing (both P<0.05) but had no effect on these behaviours during loading onto a float.Conclusion: Providing stabled horses with one hour per day of exercise on a walker, treadmill, turn-out or by being ridden are all effective at allowing expression oflocomotor activities in stabled horses.Potential relevance: Providing stabled horses with regular exercise is likely to provide positive effects on horse welfare, training ability and handler safety.