Journal of Rehabilitation Medicine 51-4inkOmslag | Page 15

Grip strength after stroke
about the recovery of sustainability of grip force during
the first year after stroke.
The main aim of this observational study was to as-
sess recovery of muscle function in hand and fingers
during the first year post-stroke. The study assessed:
(i) maximum grip force in different hand positions
(wide to narrow grip) and different modalities of pinch
force, (ii) rate of force development in hand grip and
key pinch grip, and (iii) sustainability of hand and key
pinch grip force. To assess recovery, the performance
of the affected and non-affected sides was compared at
inclusion into the study and at 4 different time-points
during the 1-year follow-up period.
METHODS
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of Privacy Rights at the University Hospital of North Norway
reviewed and approved the study (reference no. 39/2008).
The participants in the current study were recruited from the
participants included at 1 of the centres (Trondheim University
Hospital). Only maximum grip force in the affected hand was
tested in the main study, in the current study additional detailed
measurements of grip strength, rate of force development and
sustainability of grip force of the affected and non-affected hand
were performed. The current study was commenced slightly
after the main study. The main study was an intervention study
with no explicit focus on strength training; no differences
between the groups were found in grip strength on the affected
side (13). Level of impairment at 2 weeks was assessed by
Fugl-Meyer Assessment and National Institutes of Health Stroke
Scale, functional independence by modified Rankin Scale. The
participants were assessed 5 times: at inclusion (2) and after 4,
28, 30 and 54 weeks after stroke; hereafter referred to as W2,
W4, W28, W30 and W54.
Participants and design Outcome measures
The participants in this longitudinal cohort study were a sub-
sample of the Norwegian Constraint-Induced Therapy Multi-
site Trial (NORCIMT) (12, 13). NORCIMT is a multicentre,
randomized controlled trial, investigating the effect of early vs
late implementation of constraint-induced movement therapy
(CIMT).
The inclusion criteria for the NORCIMT study were: more
than 5 days and less than 26 days after stroke, persistent uni-
lateral paresis (arm function 2–5 or hand motor function 2–4
on the Scandinavian Stroke Scale), ability to extend the wrist
or 2 fingers, modified Rankin Scale (MRS) score 0–2 prior
to stroke, a Mini-Mental State Examination (MMSE) score
of more than 20, and the ability to follow a 2-step command
and to sign informed consent. Exclusion criteria were: MRS
post-stroke > 4, hemispatial neglect (line bisection test more
than 2 cm deviation), life expectancy less than 1 year, injury or
other conditions affecting motor function. The North Norway
Regional Committee of Medical Ethics and the Commission All participants were examined by the same non-blinded
examiner at all 5 time-points. The outcome measures were
detailed isometric measurements of grip strength including
MVC in 5 different hand and finger positions and force-time
curves. Maximum force during grip strength measurements and
force ratios (affected/non-affected hand) can be used to reliably
examine strength impairments in patients with chronic stroke
(14). Excellent test-retest reliability for maximum grip force
measurements has also been shown < 12 weeks post-stroke (15).
A Biometrics E-LINK EP9 evaluation system (Biometrics
Ltd, Gwent, UK, 2006), with an electronic hand dynamometer
(G100) and pinchmeter (P100) were used to assess grip strength.
The dynamometer has 5 adjustable handle positions, ranging
from narrow grip (position 1 – muscles are in a shortened
range) to wide grip (position 5 – muscles are in a lengthened
position) using power grip, as shown in Fig. 1 (A–E). Force-
time curves were generated with a sampling frequency of 20
Hz. Allen & Barnett (16) demonstrated that the Biometrics
Fig 1. Overview of the 8 grips used: power grip was measured with a hand dynamometer in 5 positions from (A) narrow grip (position 1) to (E)
wide grip (position 5). Pinch grip was measured with a pinchmeter with 3 grips: Key, 3-finger and 2-finger pinch.
J Rehabil Med 51, 2019