*3.1. Effects of Detraining*

From the originally identified papers, only nine clearly described the effects of detraining on the postural control system. The duration of the detraining or retention period ranged from 4 weeks (*n* = 1 paper) to 6 weeks (*n* = 1), 8 weeks (*n* = 3), 12 weeks (*n* = 2), 60 days (*n* = 1), and the highest reported duration of detraining was half a year (*n* = 1). One included study did not report on detraining from an intervention, but rather "detraining from everyday life" by administering 60 days of bed rest. All of the other papers provided details of an intervention with a length of 8 weeks (*n* = 1), 10 weeks (*n* = 1), 12 weeks (*n* = 2), 16 weeks (*n* = 3) or 40/80 weeks (*n* = 1, in this particular study, participants could choose their own intervention length to increase adherence; [19]). Details of the interventions' main focus are displayed in Table 1.

Due to the differences in outcome measures and lengths of detraining, it is futile to quantify exact effects of detraining on a week-by-week basis. This is further complicated by studies that did not report on their effects directly post intervention, so it is unclear whether their detraining values later on indicate significant declines after the exercises were ceased (i.e., [17]). The first clear sign of detraining in all studies was after 4 weeks, at which point the improved plantar flexion proprioception after an 8-week brisk walking program had disappeared [23]. Further, at 6 weeks, the effects of an 8-week whole body vibration training program seemed to have returned to baseline [15]. More exercise effects seemed to disappear between 8 and 12 weeks, after which most benefits from a low-intensity balance program [21] and from seated or weight-bearing resistance training [22] had significantly digressed.

Exercises for which lasting benefits were reported after specified detraining periods were, firstly, an 8-week aquatic balance training (both with and without combining it with vibration training; outcome measures: 5 times sit-to-stand (STS) and timed up and go (TUG) performance; after 8 weeks of detraining [15]). Second, 16 weeks of Tai Chi still had positive effects on one-leg stance performance (strongest effects on eyes open condition [20] and on ankle plantar and dorsal flexion proprioception [23]) after 8 weeks of detraining. Additionally, third, 12 weeks of functional weightbearing exercise still had a positive effect on "coordinated stability" (the ability to draw a line within the lines of a track, using a pen fixed by a rod to the person at waist level) after 12 weeks of detraining [22]. However, in terms of this last result, it should be noted that outcomes for a more common indicator of fall risk, the "Physiological Profile Assessment", no longer showed differences compared to controls after 12 weeks of detraining [22].

In terms of long-term effects, it is interesting to note the benefits of a strength training protocol reported by Sherk et al. [19] on maximum strength outputs. They showed that, after 6 months of detraining, improvements were better retained if participants had been engaged with the program for a longer period of time (80 vs. 40 weeks of training). Finally, the results of Ritzmann et al. [18] are of relevance. They showed that the effects of detraining due to bed rest can be offset by the introduction of 3-min high-intensity jumping workouts.
