Biodex system 3 pro

Regarding isokinetic strength registration, peak concentric torque values in quadriceps and hamstring muscles were recorded using an isokinetic dynamometer (Biodex System Pro 3™, Biodex Medical Systems, Inc., New York, NY, USA). From a seated position (80° hip flexion), two sets of concentric/concentric knee flexion–extension movements were performed, with a range of motion ranging from 0° (full extension) to 90° of knee flexion [3 (link),39 (link)]. In the first set, three sub-maximal concentric contractions at 60°/s were performed as a familiarization. In the second set, three maximal concentric contractions at 120°/s were carried out to determine peak concentric torque values. Peak concentric torque values in quadriceps (QTORQ) and hamstrings (HTORQ) were registered, considering the highest value for analysis, and expressed as a percentage of the body weight. The angles at which QTORQ and HTORQ were reached were also recorded (QANG-TORQ and HANG-TORQ, respectively). The hamstrings/quadriceps strength ratio (H/Q ratio) was also calculated.

Height was measured in metres (m) using a stadiometer.^{[14 ]} Weight (kg) was measured using a calibrated scale with a beam and moveable weights.^{14 ]} Isokinetic concentric trunk extension and flexion were measured using a Biodex System 3 PRO isokinetic system (Biodex Medical Systems, Inc., New York, USA). The isokinetic system was calibrated before testing. The participants were requested to be seated at 90 degrees and a range of motion for trunk flexion and extension was set at 70 degrees. Axis of rotation used the anterior superior iliac spine. Results were measured in newton metres (N·m).^{[10 (link)]} The Biodex Isokinetic System 3 PRO is a reliable and valid method for measuring muscle torque recorded during isolated joint exercise when angular velocity remains constant.^{[9 (link)]} Isokinetic dynamometers provide an accommodating resistance equal and opposite to the muscular forces applied for maximum external force output with changing positions of the joint.
The data collection was conducted by a biokineticist, trained in using the isokinetic device. The data were collected in a controlled environment, entered directly into the computer and data station of the isokinetic system.

The participants were familiarized with the experimental testing and stretching protocols one week prior to data collection and visited the laboratory on four further occasions under experimental conditions, performed in a randomized order with each trial separated by 48 hours. During the experimental trials, the participants performed a 5‐minute warm‐up on a Monark cycle at 60 rpm with a 1‐kg resistance load. The participants were then positioned in the fully reclined chair of an isokinetic dynamometer (Biodex System 3 Pro, IPRS) laying on their right side. The right leg was placed in the anatomical position (0°) at the hip and knee with non‐elastic strappings across the hips and right thigh to minimize pelvic rotation and anterior pelvic tilt, respectively. The left shank was strapped in the dynamometer's leg attachment with the left hip flexed to 120° and knee flexed to 90°, with the medial femoral epicondyle aligned over the center of rotation of the dynamometer (see Figure 1D). The position and strappings were adopted from methods employed in previous studies examining knee flexor moment and stiffness17, 18 to ensure that gravitational effects on the shank could not influence passive moment during ROM trials.

The Biodex™ (Shirley, NY, United States) isokinetic dynamometer system (Biodex System 3 Pro) was used to measure the muscle strength of the knee extensor muscle (quadriceps femoris). This device is reliable and accurate for measuring muscle strength (Drouin Joshua et al., 2004 (link)). Participants sat with their hands folded in front of their chests, hips flexed to 90°, and waists restrained with system-equipped straps. The axis of rotation of the knee joint was kept aligned with the axis of rotation of the isokinetic dynamometer system by placing an immobilization pad over the ankle joint. The measured angular velocity was set to 60°/s (Chang et al., 2019 (link)). Each participant took two pretest values before the start of muscle strength measurements. At the beginning of the analysis, the participants were directed to repeat the flexion and extension of the knee joint five times continuously at a speed of 60°/s, using their maximum muscle strength. Muscle strength was represented by normalized mean peak torque (Nm) divided by body weight (Kg), with higher values indicating greater muscle strength. The entire measurement process was conducted in a standardized manner for all participants under the same directions and encouragement. The results were collected in a duplicate manner and presented as mean values.

Quadriceps and hamstring strength was assessed for both sides with an isokinetic dynamometer (Biodex System 3 Pro, Biodex Medical Systems, Inc, Shirley, NY) using previously reported methods [35 (link)]. The participant was in a seated position and performed five reciprocal concentric contractions for the knee extensors (quadriceps) and flexors (hamstrings) at 60°/s. The Biodex System 3 DBM (Version 1.7) system software was used to process peak torque for the quadriceps and the hamstrings for the injured and the uninjured sides.