High-intensity interval aerobic exercise
On an electronic bicycle, for an average of 30 min, every HIIAE was conducted. The exercise was initiated with an average 5-min warming-up phase (DE participant performed this phase at 60% of maximal heart rate, abbreviated as MHR). High-intensity interval aerobic bicycling (HIIAB) was allowed after the warm-up ended for 2 min (the 2-min HIIAB was performed at 90% of MHR and this was considered as one interval exercise phase). After the end of one interval exercise phase, the DE patient is allowed to rest in the form of an active moderate-intensity continuous bicycling phase (active rest phase) at 60% MHR for 1 min. The cycle of interval and active rest phases was repeated 7 times with an average time of 21 min. The exercise session ended with a cool-down phase which was similar to the criteria of warming up.The elderly’s heart rate was monitored during every HIAB session using a heart rate monitor that was worn at the elderly’s wrist during bicycling.