Table 2 Difference in timing of peak activation for each muscle in the co-activation indices (mean ± SD)
|  | Vastus Medialis – Semimembranosus (msec) | Vastus Lateralis – Biceps Femoris (msec) | Semimembranosus – Biceps Femoris (msec) |
|---|---|---|---|
Low level co-activation step-up | 0.55 ± 2.48 | −2.53 ± 5.75 | −1.57 ± 3.27 |
95% Confident Interval | |||
 Upper Limit | 3.63 | 4.62 | 2.49 |
 Lower Limit | −2.53 | −9.67 | −5.63 |
Step-up with deliberate co-activation | −0.18 ± 8.52 | −1.96 ± 11.04 | −0.70 ± 5.34 |
95% Confidence Interval | |||
 Upper Limit | 10.39 | 11.74 | 5.93 |
 Lower Limit | −10.76 | −15.67 | −7.32 |