High impact exercise programmes can improve bone strength, but little is known about whether this type of trainingfurther benefits fracture risk by improving physical function in older people. Objectives: This study investigated the influenceof high impact exercise on balance, muscle function and morphology in older men. Methods: Fifty, healthy men (65-80years) were assigned to a 6-month multidirectional hopping programme (TG) and twenty age and physical activity matchedvolunteers served as controls (CG). Before and after training, muscle function (hop performance, leg press and plantar- anddorsiflexion strength) and physiological determinants (muscle thickness and architecture) as well as balance control (swaypath, one leg stance duration) were measured. Resting gastrocnemius medialis (GM) muscle thickness and architecturewere assessed using ultrasonography. Results: Significant improvements in hop impulse (+12%), isometric leg-pressstrength (+4%) and ankle plantarflexion strength (+11%), dorsiflexor strength (+20%) were found in the TG compared tothe CG (ANOVA interaction, P