Electromyography of spinal and abdominal muscles during garden raking with two rakes and rake handles.

Fifteen young normal subjects (4 males, 11 females) participated in the study. They were required to assume a staggered upright posture with left leg leading in front of a 75 x 75 cm raking box with 20-cm deep evenly distributed dry and wet sand and dirt. The subjects raked using a pulling and pushing action and a 60 cm stroke length at a self-selected optimum pace with a normal straight handled rake and with a rake with a modified handle. The handle modification consisted of three curvatures of 50, 60 and 50 degrees, with an effective rake length of 150 cm. While the subjects performed the raking their EMG was recorded from erectores spinae at L1 and L3 levels, external obliques and rectus abdominis bilaterally. The pulling activities with both rakes generated significantly different EMGs from pushing (p < 0.01). The normal rake generated marginally higher activity compared to the modified rake. However, in pushing the modified rake generated much higher EMG activity than the normal rake (p < 0.01). The medium being raked and the moisture in it also had a significant effect on EMG (p < 0.02). On the basis of the results of this study, the normal rake was concluded to be a better rake.