PMC

Visual feedback provided during cycling tests and training sessions. Participants are asked to cycle at a target power level or cadence which is represented by the white box on the screen. If the participant is successful, the ball stays within the box and turns green (a). If the participant cycles at a higher (b) or lower (c) power level or cadence, the ball moves out of the box and turns red.

Coefficient of variance of cycling cadence and power output during a constant load cycling test in an individual with CP who is adept at cycling (Participant 1). The coefficient of variance for each variable was calculated over 1-minute periods in which FES assistance to the quadriceps muscles was either turned on (red shaded areas) or off (areas of the graph without red shading).

Cycling performance during the initial application of FES in a child for whom cycling was a novel task (participant 2). The top trace (a) illustrates his power output and the bottom trace (b) illustrates his cadence. The red vertical bars at 240 s indicate when FES assistance began and FES remained on during the red-shaded portion of the graph. Data were smoothed for analysis using a second-order lowpass Butterworth filter with a cutoff frequency of 0.1 Hz.

Cycling performance during incremental cycling tests with and without FES assistance in a child who is well adept at cycling (participant 1). The graphs illustrate peak cadence (a), peak heart rate as a percentage of resting heart rate (b), average power output (c), and average heart rate (d) during the tests. For average power output (c) and average heart rate (d) standard deviation values are shown. The blue bars represent volitional cycling and the red bars represent FES-Assisted cycling trials.

Tricycle components and participant set-up for FES-assisted cycling study []. The tricycle-based system is instrumented with a torque sensor and shaft encoder to allow for collection of torque, crank position and cadence, and consequentially the calculation of instantaneous power output, during the cycling session. The stimulator provides surface stimulation to bilateral quadriceps. The auxiliary hub motor was used for subjects 3 and 4 (please see text for details). A laptop computer is used for data acquisition, control of the stimulation timing, and control of the hub motor and to provide visual feedback on cycling performance to the cyclist.

Power output during constant load cycling tests with (red line) and without (blue line) FES assistance. This data are from a child without cycling experience (participant 3) and the auxiliary hub motor was required for testing. The vertical black line at 120 seconds denotes the transition from a passive cycling phase (in which the motor moved the child's legs while he rested) to an active phase (in which the motor continued to control cadence, and the participant assisted with the cycling effort). In the FES assistance condition, the stimulation was applied only during the active cycling phase. Data were smoothed for analysis using a second-order lowpass Butterworth filter with a cutoff frequency of 0.1 Hz.