# Reliability of a New Portable Dynamometer for Assessing Hip and Lower Limb Strength
## 2 Materials and Methods
### Study Protocol  
Anthropometrical variables were assessed with a stadiometer and a multi-frequency bio-impedance scale (Tanita MC-980 MA, Tanita, Tokyo, Japan). Participants then performed a standardized warm-up, consisting of: (a) 6 min stepping on/off a 25 cm high box, changing the lead leg every minute; (b) dynamic stretching exercises (8 repetitions of hip circles; forward, backward, and side hip bending; leg swings in frontal and sagittal plane); and (c) bodyweight strength exercises with emphasis on the trunk and lower limb muscles (10 repetitions of squats, heel raises, hip bridges, Jackknife sit-ups, and hip extensions). After the warm-up, the participants underwent isometric strength measurements with the dynamometer MuscleBoard(r), as previously described by [PERSON] et al. [16] on an earlier version of the device. Two \"U\"-shaped and padded aluminum braces (Figure 1), attached to uniaxial load cells (FL34-100 kg; Forsentek Co., Shenzhen, China), were used to measure forces (N), separately for each limb. Nine tests (shown and described in Figure 2 and Table 1) were performed in a randomized order within a single session. Each test was repeated three times (maximal voluntary isometric contraction for 5 s) with 45-60 s break between repetitions. The break between the tests was set at 180 s. Three sessions were performed as follows: first and second sessions were performed on the same day, separated by a 45-60 min break (to analyze intra-session reliability), while the third session was performed one week after the first visit at the same hour (to analyze inter-session reliability). Hip abduction (HABD), hip induction (HADD), hip internal rotation (HIR), hip external rotation (HER) were performed unilaterally and bilaterally, while knee extension (KEXT) and plantar flexion (PFLX) were performed only unilaterally. Nordic hamstring exercise (NHE) was performed bilaterally. In all unilateral variations, participant's non-measured leg was next to the dynamometer to avoid any contact with the sensors. Unilateral contractions of the KEXT and PFLX were measured using a rigid bar that connected both sensor braces, so that a sum of forces from both load cells presented one (unilateral) measurement (shown in Figure 3). Figure 1: Portable dynamometer MuscleBoard®. (**A**) = the device from above: measurement scales, tablet with software; (**B**) = sensor braces with load cells in position for measuring horizontal movement (left or right); (**C**) = sensor braces with load cells in position for measuring vertical movement (up or down). Figure 2: Test positions for measuring peak torque in hip, knee or ankle. (**A**) = hip flexion, abduction, and adduction; (**B**) = hip extension; (**C**) = hip internal and external rotation; (**D**) = knee extension; (**E**) = ankle plantar flexion; (**F**) = Nordic hamstring exercise. For all isometric strength measurements, participants were instructed to place the measured limb(s) onto the appropriate side of the sensor braces or under the non-elastic stray (see Table 1 for more details) and asked to perform a maximum repetition by pushing their distal part of the lower leg against the brace/strap as hard as possible and holding it with maximum force for 5 s. For the NHE, participants were instructed to maintain straight knee-shoulder line during the descent, to hold arms and hands in front of the body, and to brake the forward fall for as long as possible. Standardized loud verbal encouragement was given during all measurements: \"touch, get ready, push, push, push, relax\".