Muscle Excitation During A Weighted And Unweighted Supine Bridge (a Pilot Study)

Abstract

Previous studies have examined the relationship between muscle activities during a single leg bridge (SLB) without including the gluteus maximus muscle (Gmax). Similarly, few studies have evaluated the influence of additional loading during a SLB. PURPOSE: To examine muscle activation levels of the Gmax, semitendinosus (ST), and the biceps femoris long-head (BFL) during SLB, and weighted single leg bridge (wSLB). METHODS: Two recreationally active college students (1 male;1 female) were recruited for the study and were free of any muscle or orthopedic injuries. Surface electromyography (sEMG) were used to collect muscle activities. Maximal voluntary contractions (MVC) were collected for each muscle group prior to testing. Each participant performed three repetitions of both SLB and wSLB, following a pattern of 60 beats per minute (~2 beats up, ~3 beat hold, and ~2 beats down) which was verified using an electronic metronome. Data was collected and analyzed using a commercially available sEMG package. MVCs of each muscle were used to normalize the observed peak sEMG during the exercise. Peak root mean square (RMS) was obtained for each muscle and the peak RMS in SLB was set to 100% to provide a means of comparison. Burst threshold was defined as 10% of the observed peak value. This value determined the onset and offset of the muscle excitation. RESULTS: There was a 37.0 +/- 1.7 average difference in magnitude between the two exercises. The duration of activity of the Gmax, BFL, and ST during the unweighted trials were 4.0 +/- 1.25 seconds, 3.5 +/- 0.75s and 4.2+/- 0.45s, respectively. Muscle activity duration remained unchanged in the wSLB in the Gmax and STN. However, there was an increase in BFL activity during the wSLB trials (4.0 +/- 0.7s). CONCLUSION: In the male participant, it was concluded that the main muscle activated during the original single leg bridge and the weighted single leg bridge was BFL. However, for the female participant, the main muscle was the STN. Muscle activation of the hamstring muscles increased as a whole from the unweighted exercises to the weighted exercise. As well as the duration of BFL activity.This study is preliminary and will be conducted at a larger scale in the future to enhance credibility and reliability.