Neuromechanics of the Cycling Task

Journal of Biomechanics

Prilutsky

Gregor

2014

Self Cite

The neuromusculoskeletal system interacts with the external environment via end-segments, e.g. feet. A person with trans-tibial amputation (TTAmp) has lost a foot and ankle; hence the residuum with prosthesis becomes the new end-segment. We investigated changes in kinetics and muscle activity in TTAmps during cycling with this altered interface with the environment. Nine unilateral TTAmps and nine subjects without amputation (NoAmp) pedaled at a constant torque of 15Nm and a constant cadence of 90rpm (~150watts). Pedal forces and limb kinematics were used to calculate resultant joint moments. Electromyographic activity was recorded to determine its magnitude and timing. Biomechanical and EMG variables of the amputated limb were compared to those of the TTAmp sound limb and to the dominant limb in the NoAmp group using a one-way ANOVA. Results showed maximum angular displacement between the residuum and prosthesis was 4.8 ± 1.8deg. The amputated limb compared to sound limb and NoAmp group produced lower extensor moments averaged over the cycle about the ankle (13 ± 2.3, 20 ± 5.7, and 19 ± 5.3Nm, respectfully) and knee (8.4 ± 5.0, 15 ± 4.5, and 12.7 ± 5.9Nm, respectfully) (p<0.05). Gastrocnemius and rectus femoris peak activity in the TTAmps shifted to later in the crank cycle (by 36° and 75°, respectfully; p<0.05). These data suggest gastrocnemius was utilized as a one-joint knee flexor in combination with rectus femoris for prosthetic socket control and highlight prosthetic control as an interaction between the residuum, prosthesis and external environment.

Section: Introductionmentioning

confidence: 99%

Motor adaptation to prosthetic cycling in people with trans-tibial amputation

Journal of Biomechanics

Prilutsky

Gregor

2014

Self Cite

“…The cycling task was chosen because it requires effective integration of human neuromuscular control and bicycle systems thus providing a unique environment for the investigation of motor control. 8 Cycling is a rhythmic task similar to gait and one that includes upper body support by the saddle minimizing the need to stabilize the torso during propulsion. The cycling task also provides a well controlled mechanical environment allowing for easy manipulation of the imposed load and cadence to the human system.…”

Section: Introductionmentioning

confidence: 99%

Effectiveness of force production in persons with unilateral transtibial amputation during cycling

Prosthetics &Amp; Orthotics International

Gregor

2011

Individuals with a unilateral transtibial amputation have lost the structure of the ankle joint and the muscles and connective tissues controlling the joint. In addition, sensory input from the joint and surrounding tissues has also been lost. These individuals must now adapt to structural and physiological changes related to the amputation and interact with their environment via a prosthetic limb on one side and via an intact limb on the other. 1 Changes that occur after amputation include: the sound limb becomes the dominate limb for locomotion [2][3][4][5][6] ; atrophy of the residual limb with possible hypertrophy of the sound limb 7 ; and alterations in movement strategies. 1,4,5 All of these changes are interrelated and will affect the person's ability to generate and effectively direct forces to interact with their environment. It remains unclear how these distinct, yet integrated, changes relate to the control of task performance. The purpose of this study was to investigate the pedaling technique employed by transtibial Effectiveness of force production in persons with unilateral transtibial amputation during cycling Walter Lee Childers and Robert J Gregor Abstract Background: Few published reports exist regarding the control of the human/prosthesis interface in persons with unilateral transtibial amputation. Objective: To investigate strategies employed by prosthetic users in controlling the human/prosthesis interface to highlight challenges associated with either the amputation or the design of the prosthesis. Study Design: Randomized controlled trial. Methods: Cycling was used as the locomotor task to allow for better control of task mechanics compared to walking. A group of nine cyclists with intact limbs were compared to eight cyclists with transtibial amputation (CTA) during a simulated cycling time trial. The CTA group pedaled with a stiff and flexible prosthetic foot. Reaction forces between the foot and the pedal were measured using an instrumented pedal system. The force effectiveness (FE) ratio was used as the measure of task performance. The FE ratio is the force component normal to the bicycle crank arm divided by the resultant force for both limbs and is commonly used to analyze pedaling technique. Results: The CTA group was equally as effective at applying forces as the intact group. Conclusions: These data suggest that individuals with lower limb loss are able to compensate for their amputation to utilize a similar pedaling technique for locomotor performance. As global strategies, e.g. force effectiveness, appear similar between groups future research should focus on local strategies, e.g. individual joint kinematics and kinetics. Clinical relevanceResearch involving local strategies, e.g. individual joint kinematics and kinetics and their relationship to net output of the human/prosthesis system, will enhance our understanding of this system while allowing for better clinical application of the research.

Symmetrical kinematics does not imply symmetrical kinetics in people with transtibial amputation using cycling model

Kogler

2014

J Rehabil Res Dev

Abstract-People with amputation move asymmetrically with regard to kinematics (joint angles) and kinetics (joint forces and moments). Clinicians have traditionally sought to minimize kinematic asymmetries, assuming kinetic asymmetries would also be minimized. A cycling model evaluated locomotor asymmetries. Eight individuals with unilateral transtibial amputation pedaled with 172 mm-length crank arms on both sides (control condition) and with the crank arm length shortened to 162 mm on the amputated side (CRANK condition). Pedaling kinetics and limb kinematics were recorded. Joint kinetics, joint angles (mean and range of motion [ROM]), and pedaling asymmetries were calculated from force pedals and with a motion capture system. A one-way analysis of variance with Tukey post hoc compared kinetics and kinematics across limbs. Statistical significance was set to p