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In acute whiplash injuries, early physiotherapy has been shown to reduce pain and increase cervical movement, but the cost-effectiveness of this treatment has been questioned. It is unclear whether the benefits result from manipulative physiotherapy or from the patient's ability to perform the accompanying home exercise programme when instructed about its importance. In a single blind prospective randomized trial 71 patients who received out-patient physiotherapy were shown to have significant improvement in severity of neck pain (P< 0-01) and cervical movement (P< 0-01) at 1 and 2 months post-injury when compared with 33 patients who received analgesia and a cervical collar. Sixty-six patients who were offered comprehensive advice for home mobilization by a physiotherapist showed a similar improvement. There appears to be no difference in effectiveness between outpatient physiotherapy and home mobilization.

It has been hypothesized previously that because a strong correlation was found between the difference in electromyographic activity (EMG) of rectus femoris (RF) and hamstrings (HA; EMG(RF)-EMG(HA)) and the difference in the resultant moments at the knee and hip (Mk-Mh) during exertion of external forces on the ground by the leg, input from skin receptors of the foot may play an important role in the control of the distribution of the resultant moments between the knee and hip by modulating activation of the two-joint RF and HA. In the present study, we examined the coordination of RF and HA during the swing phase of walking and running at different speeds, where activity of foot mechanoreceptors is not modulated by an external force. Four subjects walked at speeds of 1.8 m/s and 2.7 m/s and ran at speeds of 2.7 m/s and 3.6 m/s on a motor-driven treadmill. Surface EMG of RF, semimembranosus (SM), and long head of biceps femoris (BF) and coordinates of the four leg joints were recorded. An inverse dynamics analysis was used to calculate the resultant moments at the ankle, knee, and hip during the swing phase. EMG signals were rectified and low-pass filtered to obtain linear envelopes and then shifted in time to account for electromechanical delay between EMG and joint moments. During walking and running at all studied speeds, mean EMG envelope values of RF were statistically (P<0.05) higher in the first half of the swing (or at hip flexion/knee extension combinations of joint moments) than in the second half (or at hip extension/knee flexion combinations of joint moments). Mean EMG values of BF and SM were higher (P<0.05) in the second half of the swing than in the first half. EMG and joint moment peaks were substantially higher (P<0.05) in the swing phase of walking at 2.7 m/s than during the swing phase of running at the same speed. Correlation coefficients calculated between the differences (EMG(RF)-EMG(HA)) and (Mk-Mh), taken every 1% of the swing phase, were higher than 0.90 for all speeds of walking and running. Since the close relationship between EMG and joint moments was obtained in the absence of an external force applied to the foot, it was suggested that the observed coordination of RF and HA can be regulated without a stance-specific modulation of cutaneous afferent input from the foot. The functional role of the observed coordination of RF and HA was suggested to reduce muscle fatigue.

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