# Reliability of a New Portable Dynamometer for Assessing Hip and Lower Limb Strength
## 4 Discussion  
The purpose of this study was to evaluate inter- and intra-session reliability of the new, portable, and externally fixated dynamometer MuscleBoard(r) for assessing strength of hip and lower limb muscles. Overall, the results demonstrate high to excellent intra- and inter-session reliability with low to acceptable within-individual variation for average and maximal peak torques in all bilateral strength tests. Furthermore, the calculated agonist:antagonist ratios for bilateral strength tests also had good to high intra- and inter-session reliability. Conversely, the peak torques and calculated agonist:antagonist ratios for unilateral tests had lower intra- and inter-session reliability. The results of strength assessments can be reported with different units of measurements (N, Nm, Nm/kg, N/kg, % of bodyweight, etc. ), which makes the direct comparison of peak torques/forces from different studies difficult. Nevertheless, [PERSON] et al. (2013) [18] used externally fixated load cells to measure hip strength of ice hockey players and found similar results for HADD and HABD (157.5 \(\pm\) 48.9 Nm vs. 158.8 \(\pm\) 48.2 Nm and 155.7 \(\pm\) 51.4 Nm vs. 154.8 \(\pm\) 40.3 Nm from our study, respectively), higher HFLX (174.1 \(\pm\) 66.9 Nm vs. 146.8 \(\pm\) 40.8 Nm from our study) and lower HEXT (146.7 \(\pm\) 56.7 Nm vs. 199.8 \(\pm\) 52.6 Nm from our study). Furthermore, HADD:HABD ratio of \(\sim\)103% from bilateral measurement and HFLX:HEXT ratio of \(\sim\)75% from unilateral measurement is in agreement with previous studies using the GroinBar device on football players [13,15], while measured HIR:HER ratio of \(\sim\)96% from unilateral and 124% from bilateral measurement in our study is comparable to bilaterally measured the HIR:HER ratio of 108% from the study by [PERSON] et al. (2019) [15]. In addition, peak torques during the NHE showed high intra-session reliability, which is comparable to other similar devices for measuring forces during the NHE--namely, [PERSON] et al. (2015) [19], who tested the NordBord device, and [PERSON] et al. (2020) [20], who recently tested the Hamstring Solo Elite device. This is a particularly important measurement characteristic of dynamometers since eccentric strength of the hamstrings (measured during the NHE but not on the isokinetic  
\begin{table}
\begin{tabular}{l c c c c c c c c c} \hline \hline \multirow{2}{*}{**Parameter**} & \multirow{2}{*}{**S1 Mean (SD)**} & \multirow{2}{*}{**S1 95\% CI**} & \multirow{2}{*}{**S3 Mean (SD)**} & \multirow{2}{*}{**S3 95\% CI**} & \multirow{2}{*}{**\% CV**} & \multirow{2}{*}{**ICC2,k**} & \multirow{2}{*}{**Sig**} & \multirow{2}{*}{\(d\)} \\ \cline{1-1} \cline{5-1  
-dynamometer) [21,22] is a significant risk factor for the occurrence of hamstring strain injuries [23]. Another important measurement characteristic of the device in the context of prevention/rehabilitation of hamstring injuries is the ability to measure forces for each limb separately since inter-limb strength asymmetry during the NHE is another risk factor for hamstring injuries [24]. We observed high to excellent intra- and inter-session reliability for bilateral tests of HADD, HADD, HIR, and HER and moderate to good intra-session reliability results for unilateral tests of HFLX and HEXT. This is comparable to the results of the study by [PERSON] et al. (2019) [15], in which they used the GroinBar device, a similar externally fixated dynamometer.