19 randomized controlled trials examining the effects of physical exercise in frail older adults were included in this review. The purpose was to determine whether exercise influenced performance-based measures of physical function, using a definition of frailty which takes into account the individual level of physical function and ability to perform activities of daily living. Results indicated that exercise significantly improved gait speed and scores on the Short Physical Performance Battery [SPPB], however its effects on endurance, balance, and functional status were inconsistent. Due to limited evidence in this respect, it remains unclear which type, frequency, intensity, duration and setting are most effective.