THE EFFECT OF MEASUREMENT TECHNIQUE AND LOAD ON LOWER LIMB KINEMATICS IN CYCLE ERGOMETRY

Abstract

Many studies involving cycle ergometry often provide a description of lower limb kinematics. This description has been used top provide information regarding: body position and configuration that maximizes aerobic energy expenditure, optimal seat to pedal distance for anaerobic and aerobic work, and simulations of lower limb kinematics. However, joint angle measurements are often done statically and may not reflect the actual joint kinematics during the assigned task. This is a possible limitation of studies involving a description of lower limb kinematics, and presents a specific question that needs to be addressed. Do measurements of lower limb joint angles vary when determined with different measurement techniques under various conditions? Based on the tensionlength curve; a muscle will generate it's largest force/tension at 100% of (or slightly greater than) its resting length. As the muscle length deviates from resting length, and/or with the onset of fatigue, force/tension production decreases. To compensate for a decrement in force, it is speculated that joint angle measured statically may be different when measured dynamically and with different conditions of resistance and fatigue. It may be important to measure joint angles during the performance of assigned test conditions. Therefore, the purpose of this study is to determine whether joint kinematics change with different measurement technique, conditions of loading, and with fatigue. Nine males with recreational cycling experience participated in this study. Their average age, height, and weight were 26.9 years (S.D.=3.11), 180.4 cm (S.D.=8.01), and 77.37 kg (S.D.=6.82), respectively. Informed consent and anthropometric measurements were obtained. A cycle ergometer with a basket, plate-loaded resistance mechanism was used in this study. Seat to pedal distance was adjusted to 109% of each subject's leg length as measured from the symphysis pubis to the ground (+I-lcm). Pedal toeclips were worn; and each subject's upper body was kept perpendicular to the ground. Four joint angle measurement conditions were examined. In the first condition, the maximum and minimum hip, knee, and ankle joint angles were determined with a hand-held goniometer. In the three other test conditions joint angles were determined with an Ariel Performance Analysis System (APAS). A video camera positioned perpendicular to the ergometer was used to record joint angles in the unloaded, loaded-non fatigued (maximum power output), and loaded fatigued (minimum power output) conditions. Maximum and minimum power output were determined by an SMI Power Program (Sports Medicine Industries, Inc.) synchronized with the video record. Digitizing points were attached to the right side of the subjects at the following anatomical sites: distal end of the foot, lateral malleolus, centre of rotation of the knee, greater trochanter of the femur; and a point attached to a plumb line located on the deltoid, intersecting the marking on the greater trochanter, as viewed through the camera. During the unloaded condition each subject pedaled at a self selected cadence. The 30-second Wingate Anaerobic Cycling Test was used with a resistance of 85 mdka of body mass to induce the loaded-non fatigued and loaded fatigued joint angles. - - DBMANOVA's and ~ost-hocte sts revealed significant differences (~<0.05)in the (1) minimum ankle hgle; and (2) maximum Lgle ofthe hip, knee,'8nd ankle when determined with different measurement techniques (goniometer vs film) and in different test conditions (loaded vs unloaded, fatigue vs non-fatigue). It is concluded that: (1) different measurement techniques and conditions of loading will result in different hip, knee, and ankle joint kinematics; and (2) whether joint angles should be measured during the actual test condition would be dependant on the degree of accuracy required.