Maximal isokinetic and isometric muscle strength of major muscle groups related to age, body weight, height, and sex in 178 healthy subjects Test protocol Muscle test procedures. Prior to each test participants became familiar with the procedures by performing 5-10 submaximal contractions and 1 or 2 maximal contractions as warm-up. During the test they were guided with standardized instructions recorded and played as an audio file to encourage maximal muscle performance (An example: make use of all your effort in the full range of motion at extension as well as flexion. Furthermore during each contraction the speaker in an encouraging tone yells push... and pull... ). Participants were stabilized in the chair with shoulder and abdominal straps as well as they were informed to stabilize the body by holding tight around a seat handle when possible. The anatomical axis of rotation was aligned to the dynamometer axis using visual inspection and manual palpation. The range of motion (ROM) was set wide enough to obtain maximal speed at the isokinetic tests. Isokinetic muscle strength was tested prior to the isometric muscle strength. The isokinetic tests included eight maximal concentric reciprocal contractions, each contraction separated by a 15 seconds rest whereas isometric tests included three maximal muscle contractions each lasting five seconds separated by 40 seconds rest intervals. At least three minutes rest separated each test. For each test including all the contractions performed the coefficient of variation was calculated. To avoid sub-maximal performance or outliers, the test was redone or data discarded if the coefficient of variation exceeded 10% for ankle and knee, and 15% for hip, shoulder, elbow, and wrist. Gravity correction was used but the dynamometer was not adjusted to preload as it is not considered to affect the peak torque at the range of motions and angular speeds used in our protocols, however, the dynamometer software was set to estimate peak torque for the preset test speed only, which excluded data from the acceleration and deceleration phases. Page 1
Knee DETAILED INSTRUCTION FOR EACH TEST PROCEDURE Axes of movement. Through the most prominent part of the lateral femur condyle. Positions. Back of the chair was placed in 85 degrees and the dynamometer arm was placed just proximal to ankle. Range of motion (ROM). 80 degrees extension starting with the knee 90 degrees flexed. Movement velocity. 90 /s Position for gravity correction. The thigh and lower leg formed an angle of 170 degrees. Joint position for isometric testing. Extension with the knee in a 70 degrees flexion. Page 2
Ankle Axes of movement. Just below and posterior to the medial malleolus. Positions. Back of the chair was positioned in 85 degrees. The dynamometer arm equipped with a foot plate was placed around the ankle. The thigh was supported with a cushion and the angle between the thigh and the lower leg was 120 degrees as determined by a hand held goniometer. ROM. 48 degree extension from fully flexed position. Position for gravity correction. Ankle in neutral position (24 degrees from maximal flexion). Joint position for isometric testing. Extension with the ankle in the neutral position. Page 3
Hip Axes of movement. Anterior to the upper end of the major trochanter. Positions. Supine position on the chair with the dynamometer arm placed as distal on the thigh as possible. ROM. 60 degrees extension from hip in 90 degrees flexion. Position for gravity correction. With the lower limb in a horizontal position but without contact to the chair. Joint position for isometric testing. Flexion with the hip placed in a 130 degrees extended position. Page 4
Shoulder Axes of movement. Center of the shoulder joint. Positions. The chair was rotated 15 degrees in the direction of the test arm with the back placed in 70 degrees. The actuator was tilted 10 degrees backwards. The dynamometer arm did not support the test arm. ROM. A 70 degrees adduction starting from the horizontal position. Position for gravity correction. With the shoulder in the horizontal position. Joint position for isometric testing. Abduction with shoulder adducted 45 degrees from the horizontal position (neutral position) Page 5
Elbow Axes of movement. The most prominent part of both elbow epicondyles. Positions. The back of the chair was positioned in an 85 degrees position, the actuator was rotated 30 degrees away from the body. The dynamometer arm was equipped with a grip and the upper arm was supported by a cushion. ROM. 110 degrees flexion starting with the elbow fully extended. Position for gravity correction. With the elbow in 65 degrees flexed position. Joint position for isometric testing. Flexion with the elbow in a 90 degrees flexed position. Page 6
Wrist Axes of movement. 1.5 cm distally to the distal end of the ulna. Positions. The back of the chair was positioned in 85 degrees, the dynamometer arm was equipped with a hand grip, and a cushion was placed under the forearm for support. ROM. A 45 degrees flexion and extension from the horizontal position. Movement velocity. 90 /s Position for gravity correction. Wrist in the horizontal position. Joint position for isometric testing. Flexion with the wrist in the horizontal position. Page 7