IntroductionHand grip strength (HGS) is an important measure in a physiotherapy assessment
and for this purpose it is necessary to have valid and reliable instruments to measure
it. In this study we aimed at investigating the reliability, validity, and agreement
of the new hand-held dynamometer NOD (OT-Bioelettronica, To-Italy) compared to Jamar
(R) hydraulic dynamometer (JD), the gold standard.MethodsFifty healthy subjects were
selected; 9 trials for the dominant hand and 9 trials for the non-dominant hand were
administrated to each of them: 3 trials of HGS with the JD in rung #3, 3 trials with
the JD-adapted-grip (like the NOD one), and 3 trials with NOD. To verify the reliability
of NOD, the Intraclass Correlation Coefficient (ICC 3,1) was calculated with a mixed
effects model with the addition of adjustment variables (age, gender, dominant / non-dominant
limb, trials). The model used single HGS measurements to estimate variance components,
so reflecting both degree of correspondence and agreement among devices.To assess
concurrent validity NOD was compared to the "gold standard" JD, in terms of ICCs and
through Pearson correlation. The agreement between the methods of measurement was
calculated with the Limits of Agreement (LoA) and the plots of Bland-Altman.MethodsFifty
healthy subjects were selected; 9 trials for the dominant hand and 9 trials for the
non-dominant hand were administrated to each of them: 3 trials of HGS with the JD
in rung #3, 3 trials with the JD-adapted-grip (like the NOD one), and 3 trials with
NOD. To verify the reliability of NOD, the Intraclass Correlation Coefficient (ICC
3,1) was calculated with a mixed effects model with the addition of adjustment variables
(age, gender, dominant / non-dominant limb, trials). The model used single HGS measurements
to estimate variance components, so reflecting both degree of correspondence and agreement
among devices.To assess concurrent validity NOD was compared to the "gold standard"
JD, in terms of ICCs and through Pearson correlation. The agreement between the methods
of measurement was calculated with the Limits of Agreement (LoA) and the plots of
Bland-Altman.ResultsAll ICCs show high inter-reliability; the results are very similar
for both dynamometers. The value of the adjusted ICC of NOD was 0.90. For validity,
Pearson correlations of NOD towards JD and JD-adapted-grip were high (r = 0.87 and
0.88). However, the LoA and the plots of Bland-Altman demonstrated that there is no
agreement between NOD and JD and between NOD and JD-adapted-grip, with NOD showing
lower mean scores than JD.ConclusionsNOD is a reliable and valid instrument for HGS.
However, even if it cannot be considered interchangeable with JD because there is
no agreement between them in free-living adults, NOD is easier to carry than other
dynamometers, it has a Bluetooth (R) connection with a free App and it is a multi-purpose
tool that should be considered both in daily practice and in clinical settings.
