Clinical and Functional Outcomes at Least 2 Years After Hamstring Muscle Repair

Health questionnaires to assess scores concerning pain and function of the treated leg and overall health

Muscle strength will be measured bilaterally using a dynamometer (Biodex System 4 Pro: Biodex Medical Systems, Shirley, NY, USA). For the knee, maximum isokinetic flexion and extension torques will be collected between full extension and full flexion at a movement speed of 60°/s (5 repetitions) and 240°/s (15 repetitions). Maximum joint torques in each movement direction will be recorded for each joint and normalized to body weight.

Instrumented gait analysis on a treadmill with an embedded plantar pressure plate (h/p/cosmos, Zebris FDM-T, Isny, Germany; 7168 sensors; area, 1.5 \* 0.5 m; range, 1-120 N/cm2; precision, 1-120 N/cm2 ± 5%; sampling rate, 120 Hz) and on an overground walkway with two embedded force plates (Kistler force plate 9260AA6, Kistler AG, Winterthur, Switzerland; sampling rate 2400 Hz). Simultaneously with the plantar pressure or force data, kinematic and electromyographic (EMG) data will be collected. Participants will then walk for 1 minute at their preferred walking speed (0% slope and at 15% slope) and at 1.2 m/s (0% slope). For all conditions, kinematic, EMG and pressure data will be recorded for 1 minute. Subsequently, the treadmill speed will be increased to preferred running speed and 2.3 m/s (0% slope), and data for 1 minute running will be recorded. Subjects will then complete overground walking and running trials on the walkway with embedded force plates.

Participants perform three jumps on a force plate. Maximum jump length, Maximum flexion and extension angles and joint moments will be identified. Subsequently, participants perform three squats onto two force plates (one per foot). On- and off times will be computed for each muscle and condition.

The length of the centre of pressure path will be measured during two 30-second unipedal stance trials using a force plate.