Changes in leg movements and muscle activity with speed of locomotion and mode of progression in humans

Abstract

Knowledge of adaptations to changes in speed and mode of progression (walking-running) in human locomotion is important for an understanding of underlying neural control mechanisms and allows a comparison with more detailed animal studies. Leg movements and muscle activity patterns were studied in ten healthy males (19-29 yr) during level walking (0.4-3.0 m X s-1) and running (1.0-9.0 m X s-1) on a motor-driven treadmill. Movements were recorded in the sagittal plane with a Selspot optoelectronic system. Recordings of EMG were made from seven different muscles of one leg by means of surface electrodes. Durations, amplitudes and relative phase relationships of angular displacements and EMG activity were analysed in relation to different phases of the stride cycle (defined by the leg movements). The durations of the entire stride cycle and of the support phase were found to decrease curvilinearly with velocity. Swing and support phase durations were linearly related to cycle duration in walking, and curvilinearly related in running. The characteristic occurrence of double support phases in walking was also seen in very slow running. Support length increased with speed up to about 1.2 m both in walking and running, but was longer in walking at the same velocity. Increases in net angular displacements were largest for hip movements and for knee flexion-extension during the swing phase in running. With increasing velocity a clear shift in relative rectus femoris activity occurred from knee extension to hip flexion. Gastrocnemius lateralis (LG) was co-activated with the other leg extensors prior to foot contact in running, whereas in walking LG was not turned on until later in the support phase. The ankle flexor tibialis anterior had its main peak of activity after touch-down in walking and before touch-down in running. The same basic structure of the stride cycle as in other animals suggests similarities in the underlying neural control. Human speed adaptation is distinguished primarily by an increase in both frequency and amplitude of leg movements and by a possibility of changing between a walking and a running type of movement pattern.

Treadmill walking in incomplete spinal-cord-injured subjects: 1. Adaptation to changes in speed

“…This pattern can adapt easily to different speeds, 15,17 inclines, [30][31] surfaces such as overground versus treadmill [32][33][34][35] and uneven surfaces. 36 The main objective of the present study was to measure how SCI subjects adapt to changes in the walking speed.…”

“…This adaptation is generally obtained by increasing the cadence (stride frequency) and the stride length simultaneously, [11][12][13][14][15][16][17] although it is possible to adapt somewhat by modifying only one aspect. 15 The adaptation to higher walking speeds also includes greater joint angular excursions, [17][18][19][20][21] and changes in the timing or in the amplitude of the activity of muscles controlling lower limb joints. 17,[22][23] Gait impairments resulting from neurological injuries or disorders are usually determined by comparing the gait of neurologically impaired subjects to that of normal subjects walking at their preferred speed.…”

“…15 The adaptation to higher walking speeds also includes greater joint angular excursions, [17][18][19][20][21] and changes in the timing or in the amplitude of the activity of muscles controlling lower limb joints. 17,[22][23] Gait impairments resulting from neurological injuries or disorders are usually determined by comparing the gait of neurologically impaired subjects to that of normal subjects walking at their preferred speed. However, in SCI subjects that were observed in the laboratory, the preferred speed was usually two to 10 times slower than the preferred speed of the average normal subject.…”

Influence of M. tibialis anterior fatigue on the walk-to-run and run-to-walk transition in non-steady state locomotion

“…One of the most remarkable differences between walking and running at speeds in proximity of the transition-speed was the touch-down angle of the foot that was smaller during running (Table 5, literature [18,26]). It is expected that this would introduce a less demanding situation for TA.…”

“…Therefore, Prilutsky and Gregor [3] suggested that RWT might be controlled by other muscle groups, namely the muscles active during stance (soleus, gastrocnemius and vastus lateralis). The perception of increased effort in these support-related muscles is likely to be required for the acceleration and deceleration of the body's centre of mass and the larger peaks of vertical ground reaction forces [3,18].…”