A system for coordinating a rhythmic musculoskeletal activity of a user with a rhythmic cardiac cycle of the user, comprising: a prompt device for providing a recurrent prompt to the user to thereby provide a timing indication for performance of the rhythmic musculoskeletal activity; a first detector (64, 74, 76) for detecting a selected recurrent aspect of the user's cardiac cycle that repeats at a heart rate of the user; a second detector (70, 78) for detecting a selected recurrent component of the user's rhythmic musculoskeletal activity that repeats at a cadence of the user; and a processor, responsive to said detection of said selected recurrent aspect of the cardiac cycle of the user, the system characterized in that the processor is further responsive to the detection of said selected recurrent component of the rhythmic musculoskeletal activity of the user, and is configured to adaptively time the recurrent prompt so as to coordinate timing of the selected recurrent component of the rhythmic musculoskeletal activity of the user to occur with a targeted timing relationship relative to the timing of the selected recurrent aspect of the cardiac cycle of the user, wherein adaptively timing the recurrent prompt comprises: determining a target timing of the selected recurrent component of the rhythmic musculoskeletal activity of the user relative to the timing of the selected recurrent aspect of the cardiac cycle of the user, evaluating the timing of the selected recurrent component of the rhythmic musculoskeletal activity of the user relative to the target timing, and automatically adjusting timing of the prompt so as to guide the user to substantially align the timing of the selected recurrent aspect of the rhythmic musculoskeletal activity with the target timing. a prompt device for providing a recurrent prompt to the user to thereby provide a timing indication for performance of the rhythmic musculoskeletal activity; a first detector (64, 74, 76) for detecting a selected recurrent aspect of the user's cardiac cycle that repeats at a heart rate of the user; a second detector (70, 78) for detecting a selected recurrent component of the user's rhythmic musculoskeletal activity that repeats at a cadence of the user; and a processor, responsive to said detection of said selected recurrent aspect of the cardiac cycle of the user, the system characterized in that the processor is further responsive to the detection of said selected recurrent component of the rhythmic musculoskeletal activity of the user, and is configured to adaptively time the recurrent prompt so as to coordinate timing of the selected recurrent component of the rhythmic musculoskeletal activity of the user to occur with a targeted timing relationship relative to the timing of the selected recurrent aspect of the cardiac cycle of the user, wherein adaptively timing the recurrent prompt comprises: determining a target timing of the selected recurrent component of the rhythmic musculoskeletal activity of the user relative to the timing of the selected recurrent aspect of the cardiac cycle of the user, evaluating the timing of the selected recurrent component of the rhythmic musculoskeletal activity of the user relative to the target timing, and automatically adjusting timing of the prompt so as to guide the user to substantially align the timing of the selected recurrent aspect of the rhythmic musculoskeletal activity with the target timing.