A single-spring model predicts the majority of variance in impact force during a fall onto the outstretched hand

Test-retest reliability of the FALL FIT system for assessing and training protective arm reactions in response to a forward fall

“…In the present study, the maximum vGRF was 63%BW and 72%BW, for older and younger adults respectively, which was observed at the high initial lean angle with no counterweight. The difference in maximum vGRF between the studies may be attributed to the increased thickness of the foam used in the present study [25 , 26 , 55] . This suggests that the cushioning material used in the present study may be on an overly conservative safety measure.…”

“…Some of the earliest investigations of protective arm reactions involved self-induced forward falls where participants were instructed to fall, at an instant of their choosing, with the body held straight and the arms extended [20 , 21] . More recent studies of forward falls have used an externally released cable restraint that initially supported participants in a forward leaning position, allowing for an unpredictable onset of perturbation [22] , [23] , [24] , [25] , [26] , [27] , [28] , [29] , [30] .…”

“…Experiments investigating protective arm reactions generally fall into two categories, where the fall is constrained (e.g. [20] , [21] , [22] , [23] , [24] , [25] , [26] , [27] , 30] ) and where there are no (or few) constraints (e.g. [11 , 12 , [14] , [15] , [16] , [17] , 19 , 33] ).…”

Protective arm movements are modulated with fall height

“…Additionally, it is not clear how or if muscle activity is modulated to fall height/velocity, or in other words it is not clear how pre-impact EMG activity is modified in time or magnitude with fall height/velocity. Previous investigations of protective arm reactions, pre-positioned the hands and arms in an orientation that was either prepared to accept weight prior to falling (Burkhart and Andrews, 2013;Chiu and Robinovitch, 1998;Chou et al, 2001;Dietz et al, 1981;Johnston et al, 2019;Lattimer et al, 2018Lattimer et al, , 2016Lo et al, 2003;Sran et al, 2010), and/or the reaction was instructed to be volitional rather than occurring spontaneously (Dietz et al, 1981;Dietz and Noth, 1978). There have been a few studies of rapid orientation of the hands and arms in forward falls, however the landing position did not require body weight to be fully supported (DeGoede et al, 2001;Kim and Ashton-Miller, 2003;Robinovitch et al, 2005).…”

A method for simulating forward falls and controlling impact velocity

“…While these approaches do allow focused study on a particular set of fall dynamics or evoked protective reactions, the perturbation leading to a fall is generally more predictable and less likely to elicit natural reactive responses to fall provoking circumstances. For example, studies of forward falls do not allow for protective stepping responses and make balance recovery options more limited [ 18 , 21 , 26 , 27 , [31] , [32] , [33] ]. Additionally, the impact velocity, which increases with increasing fall heights, is controlled by limiting the fall height to a pre-determined distance which may allow participants to pre-plan a protective response [ 18 , 21 , 26 , 27 , [31] , [32] , [33] ].…”