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Figures
- Fig. 1.
Position of the iliotibialis lateralis pars postacetabularis (ILPO) in the guinea fowl hindlimb. Black circles indicate the position of the sonomicrometry crystals. EMG electrodes were placed along the fascicles at the approximate mid-point of each pair of sonomicrometer transducers. Dashed lines indicate the divisions used to calculate the weight average strain and velocity. Figure drawn by Dr David Ellerby.
- Fig. 2.
Mean length of the ILPO as a function of stride duration from foot-down to foot-down when guinea fowl walked or ran on the treadmill with a slope of 0% (black) and 20% (red) at speeds of 0.5 (A) or 2.0 (B) m s–1. Horizontal black and red bars indicate the duration of EMG activity at 0.5 and 2.0 m s–1, respectively, assuming an electromechanical delay of 25 ms. Black arrows indicate toe-off. Shaded bands indicate ±1 s.e.m.
- Fig. 3.
Strain in the ILPO as a function of speed during active lengthening (positive values) and active shortening (negative values) when guinea fowl ran on the level (black), 10% incline (blue), 15% incline (green) and 20% incline (red) as a function of speed. A significant effect of speed and incline was demonstrated for both active lengthening and active shortening. Values are offset on the speed axis for clarity. Error bars indicate ±1 s.e.m.
- Fig. 4.
Velocity during active shortening (positive values: level, black; 10% incline, blue; 15% incline, green; 20% incline, red) and active lengthening (negative values) in the ILPO as a function of speed. A significant effect of speed and incline was demonstrated for active shortening velocity. The velocity during active lengthening was not significantly different across slopes, but there was a significant effect of speed. Error bars indicate ±1 s.e.m.
- Fig. 5.
Estimated mean sarcomere lengths of the ILPO during treadmill exercise at different speeds and slopes. The values at the start of active lengthening varied with slope but not with speed, and thus the mean values across all speeds are plotted as single upward-directed triangles. The mean maximum sarcomere lengths (the values at the end of lengthening and start of shortening) are indicated by closed circles, and values at the end of active shortening by inverted triangles. Treadmill slope is indicated by color: level, black; 10% incline, blue; 15% incline, green; 20% incline, red. Some values are offset on the speed axis for clarity. Error bars indicate ±1 s.e.m. Shaded areas indicate the calculated plateau and ascending limb of guinea fowl ILPO length–tension curve, based on filament lengths.
- Fig. 6.
The period of electromyographic (EMG) activity in the ILPO at different speeds and slopes. Zero time indicates foot-down. The mean start and stop times for the EMG burst are connected with a thick bar, with thin error bars at the ends indicating ±1 s.e.m. Values are grouped by speed on the vertical axis with the slope indicated by color (0%, black; 10%, blue; 15%, green, 20%, red). The thin bars on the right indicate the mean stance times ± 1 s.e.m.
- Fig. 7.
Mean values for average EMG per burst (A) and average EMG values per stride (B) in the ILPO on the level (black), 10% incline (blue), 15% incline (green) and 20% incline (red) as a function of speed. Values are offset on the speed axis for clarity. Error bars indicate ±1 s.e.m.
- Fig. 8.
Relative changes in blood flow (red) and average EMG amplitude (green) in the ILPO under various exercise conditions. Values are expressed relative to the values measured during level, unloaded running at 1.5 m s–1. Error bars indicate ±1 s.e.m.
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