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longer and relative transport duration with the object
was shorter, compared with without glove.
So far, few studies have investigated functional
performance with and without support from a soft-
robotic glove (13–16, 31, 32). Polygerinos’ group as-
sessed the direct effect of a soft-robotic glove on the
Jebsen-Taylor Hand Function Test in 1 healthy subject,
and reported that it took longer to perform several
tasks with the glove compared with normative per-
formance times of healthy subjects without the glove
(32). Although this finding is in line with previous
studies performed with former versions of the current
ironHand glove within the elderly population with or
without age-related diseases (13–16), the longer time
needed to perform a task with the glove was not seen
in the current study.
Although some studies assessed movement execu-
tion during ADL in older adults (26), to our knowledge
no study has assessed the direct influence of a wearable
assistive technology of the hand for older adults on
movement execution during a functional task. The light
condition was well within the performance range of the
subjects. It is possible that it is unnatural to perform a
task, which can be performed without support, while
wearing a glove that provides unnecessary grasp sup-
port and decreases sensation. Therefore, compensa-
tion for an unknown situation or decreased sensation
because of wearing a glove might have affected the
performance in the light condition. Peak velocity of
the hand during the task was lower and elbow excur-
sion was larger with the glove in the light condition
compared with without the glove.
On the other hand, when participants had to perform
a task closer to the upper limits of their functional ca-
pacity, the disadvantageous influence regarding peak
velocity was absent. Moreover, transport of the heavy
object, the phase in which the glove supports the user
most, was faster with the glove compared with without
the glove. This suggests that grasp support can be be-
neficial for older adults while performing a task close
to the limits of their functional capacity. The partici-
pants might have felt more confident when using the
glove with the heavy object, enabling them to increase
their movement speed when holding the object. The
high usability score and positive attitude towards the
ironHand glove observed in previous studies with the
glove (13) might support this improved confidence
experienced when grasping and lifting objects.
Although participants needed relatively less time
to transport the heavy object with the assistance of a
soft-robotic glove compared with without, a relatively
longer time was needed to grasp the heavy object
with glove support. It is likely that the observed posi-
tive effects (relative shorter transporting phase) were
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counterbalanced by the negative influences (relative
longer grasping time), resulting in no differences in
total movement time, as observed in the present study.
This might also play a role in the lack of improved per-
formance time on the functional level with the glove,
as was found in previous studies (13, 15, 16). One
plausible explanation for the relatively longer grasping
phase is that the participants waited for feedback from
the system, in the form of noticeable force exerted
on their hand, before they felt confident enough to
lift the object. In this case, the time it takes between
registration by the glove’s control system that support
is needed and actual force exertion being perceived by
the participant is represented as a delay during grasping
of the object. Therefore, it is beneficial to explore pos-
sibilities to reduce the time between grasp initiation
and actual force transfer of the glove on the hand. One
option is to detect grasping movements before actual
contact with the object is made. To realize this, reach
must be distinguished from reach-to-grasp movements.
Possible ways for exploration of earlier grasp intention
detection are with the use of electromagnetic sensors,
inertial measurement units, bend sensors and pressure
sensors (33–35).
A factor that might have contributed to the extent
to which effects were (not) observed in the present
study is the time dedicated to familiarization. Although
participants used the glove for approximately 10 min
before starting the reach-and-grasp tasks until they
felt comfortable with it, it is possible that they did not
reach its full potential (36). Radder et al. (16) reported
that functional performance time of older adults with
hand function problems with a previous version of
the ironHand glove increased during no more than 3
repetitions up to the level of unsupported movements,
despite an initial slower performance with the glove.
Nevertheless, in the study of Radder et al. (16) no pla-
teau in performance was reached yet after 3 repetitions,
suggesting that performance time may have improved
further beyond the familiarization time applied in the
present study. Although, so far, no studies have as-
sessed the effect of prolonged use of an orthosis that
supports grip function in older adults, it is known that
training is essential to improve the performance of ol-
der adults with declined hand function (10). Therefore,
prolonged low-intensity training with an assistive soft-
robotic glove in a home setting might enhance hand
function in older adults. Additional research, in which
the ironHand glove is used for a prolonged period in
ADL, is planned to obtain more insight into its possible
effects on functional performance.
A few limitations of this study should be taken into
account when interpreting the results and generaliza-
tion towards ADL. First, this study is only performed