Earlier onsets in internal oblique and gluteus maximus muscles during leg raising in Functional Movement Screen score 3 than score 1

Active straight leg raising (ASLR) is a fundamental test and used in the Functional Movement Screen (FMS). In the ASLR of the FMS, one subgroup performs the movement correctly without any compensation (ASLR-3), whereas another subgroup has limitations in ASLR but not the passive straight leg raising (ASLR-1-SMCD). We aimed to investigate whether abdominal muscle activities in ASLR are different between individuals with ASLR-1-SMCD and ASLR-3. The relative latency of the onset of the following muscles to the right rectus femoris muscle during the right ASLR and the amplitude of activity in the following muscles for 50 msec after the onset of rectus femoris muscle activity were compared: left rectus abdominal, bilateral external oblique, bilateral internal oblique, and left gluteus maximus muscles. Data of 17 participants with ASLR-3 and 34 participants with ASLR-1-SMCD, whose sex ratio was matched to the ASLR-3 group, were analyzed. Those with ASLR-1-SMCD had statistically significant delays in the relative latency of the right internal oblique muscle (46.32±70.83 msec) and left gluteus maximus muscle (100.36±75.40 msec) muscles compared with those with ASLR-3 (right internal oblique muscle=9.75±23.07 msec, left gluteus maximus muscle=57.50±36.89 msec). However, the difference in the amplitude of activity in any muscles was not significant. The ASLR-1-SMCD group had greater relative latency of the onset of right internal oblique muscle and left gluteus maximus muscle to the onset of the right rectus femoris muscle during the right ASLR compared with the ASLR-3 group.