Moreover, {HEAD ~ the “second leg}” corresponds to the standing leg in {TAIL ~ the next single leg grounded period} 
Moreover , { HEAD ~ the “ second leg } ” corresponds to the standing leg in { TAIL ~ the next single leg grounded period }
OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL