Reliability of the muscle strength measurement and effects of the strengthening by an innovative exercise device for the abdominal trunk muscles.

Abstract

We developed an innovative exercise device for the abdominal trunk muscles (ATMs) that has a built-in system to measure muscle strength. We aimed to examine the reliability of the strength measurement as well as the effect of strengthening using the device. Twenty healthy adults participated in a reliability study of the muscle strength measurement. The first and second measurement were done in one day with an hour rest interval by raters 1 and 2, and the third by rater 1 following a one-week interval. We calculated the intraclass correlation coefficient (ICC). Another seven healthy men participated in a training program using the device, consisting of strengthening twice a week for 5 weeks. ATM strength was measured before and after the training period, and a positron emission tomography (PET) scan series was performed, consisting of examinations during rest before training (control condition) and during exercise after training (training condition). The intra-rater (ICC = 0.95) and inter-rater (ICC = 0.99) reliability of the strength measurement were excellent. ATM strength was significantly higher after training than before. 18F-fluorodeoxyglucose accumulation within the diaphragm, abdominal rectus, abdominal external and internal oblique, transverse abdominal, and levator ani muscles was significantly higher in the training condition than in the control. Our innovative device showed excellent reliability to quantify ATM strength. Strengthening using the device increased strength and activated the abdominals, diaphragm, and pelvic floor muscles.