5 In addition, the skin was prepared and the skin resistance was decreased to lower than 5 kilo-ohms. Prior to processing the raw EMG data, a

customized quality control program in conjunction with visual inspection was used on all the channels in order to detect and eliminate the possible contamination of the EMG signal by heartbeat and other artifacts. The EMG data were amplified Inhibitors,research,lifescience,medical and fully rectified with a band-pass filter at 5-500 Hz and then sampled at 1000 Hz. Thereafter, the data were recorded onto a hard disk and transferred to floppy disks for offline processing. The electrode sites were validated using manual muscle testing and doing maximal voluntary contraction (MVC) to isolate each instance of muscle activation and decrease cross-talk.15 Each channel had an isolated ground electrode in order to minimize the noise, and the electrodes were well taped in order to prevent the artifact. To AP24534 in vivo ensure a stable temperature and impedance, no recording was made within 10 minutes Inhibitors,research,lifescience,medical of electrode placement. The subjects were asked to relax completely in the supine position, and the noise of the channels was kept at less than 5 kilo-ohms. Data Collection Each subject performed three different trials in order that the mean of the maximal effort of the target muscle could be determined. To evaluate MVC for the TrA,

all the subjects were asked Inhibitors,research,lifescience,medical to be in the crook-lying position with flexed knees, flat feet, and hips flexed to 70° (as measured with a goniometer). Then, they were instructed to hollow in and elevate their umbilicus toward

the spine and maintain this position for 5 seconds. The exercise performance was closely monitored to ensure that the subjects were not tilting the pelvis Inhibitors,research,lifescience,medical backward or inhaling and elevating the rib cage to make the abdomen look flat. The subjects performed three successive trials of each exercise with a short rest of approximately one minute between each trial to prevent fatigue. In order to measure the MVC of IO muscles in the sitting position, the hips and the chest were fixed with two straps and the subjects were asked to produce maximal rotation Inhibitors,research,lifescience,medical without flexion toward right and left sides. Three trials of this exercise were subsequently performed. A pause of one minute was allowed between the trials.15 The MVC of multifidus muscles in the prone position was until determined by fixing the lower extremities and the chest with two straps. The subjects performed maximal trunk extension against resistance three times. A one-minute pause was also allowed between the trials.21 After the measurement of MVC, all the subjects performed the four-point kneeling exercise. Correct performance of the exercise was ensured by providing the subjects with appropriate training in two sessions. These exercises were performed in the quadruped position, with the movements of the extremities being executed in a random sequence.