What method of activity monitoring, specifically heart rate intensity and activity duration, have been used to monitor exercise in PD?  We are interested in being able to confirm that individuals are exercising at a given percentage of their HR max, and over a specific duration of time...but also want to limit the amount of "interaction" the exerciser needs to have with the monitoring device (number of buttons to push, devices to put on/take off, etc..).  We are trying to move towards a more pragmatic method of monitoring - least invasive and least amount of "in-clinic" visits required for downloading of data.  We would also like to include as many individuals as possible and therefore are also trying to be conscious of the fact that many folks won't or don't have access to a smart phone, computer, or wireless internet access.  We are interested to hear what others have found feasible yet also reliable.