“…For example, wearable health trackers can be used to monitor gait speed, sleep time, heartbeats, daily diet, and energy consumption, etc. Most existing studies involve chronic conditions [ 4 , 5 , 6 ], rehabilitation [ 7 , 8 ], cardiovascular disease [ 9 , 10 , 11 ], fall [ 12 , 13 , 14 ], and general wellness [ 15 , 16 , 17 , 18 ].…”