Abstract
The purpose of this study was to examine models of coordination in short-term acute adaptations to inclined treadmill walking. Coordination was evaluated by examining the step-by-step changes in walking joint kinematics (ankle, knee, and elbow joints), kinetics (under foot pressures and contact timings), and muscle activity (medial gastrocnemius and tibialis anterior). Twelve participants (6 males and 6 females; 23.4 (±2.9) years old, 68.7 (±14.9) kg, 169.2 (±11.6) cm), who gave written informed consent, were involved in this study. Walking was performed on a motorized treadmill and participants walked in random conditions where treadmill grade changed from 0deg to 5deg, -5deg to 0deg, 0deg to -5deg and 5deg to 0deg, at a rate of 0.1deg/sec. Trials lasted 1-2 minutes generating approximately 50 steps per condition. Belt speed was kept constant at the participant's self-selected speed. Variables were quantified as the peak or mean value within a step and subjected to time series analysis to examine step-by-step rates of change. Temporal and spatial parameters were used to examine coordination between the limbs. Kinetic and kinematic data more clearly show adaptation compared to muscle data (based on the rates of change across steps), consistent with the idea of motor equivalence. In terms of coordination, despite each trial containing the same task demands (changes in 5deg of slope), interlimb spatial coordination varied while temporal coordination remained consistent. Taken together, these results suggest that coordination and control depend strongly on the nature of the specifics of the task.
