(73) VARIATION IN LUMBOSACRAL MUSCLE FUNCTION THROUGHOUT THE RESPIRATORY CYCLE AS MEASURED BY TENSIOMYOGRAPHY

Purpose: Tensiomyography (TMG) has significant utility in the examination of muscle functionality as it evades limitations found in other methods of analyzing muscle function. TMG measures muscle displacement (Dm), delay time (Td), contraction time (Tc), half-relaxation time (Tr), and sustain time (Ts). Of these parameters, the most reliable and evaluated are Dm, Td, and Tc. Specifically, functioning of the erector spinae and other lumbosacral muscles can be analyzed via TMG with little challenge. However, stiffness of the lumbar spine and lumbosacral muscles fluctuates throughout the respiratory cycle. Such fluctuations may pose an issue when examining the functionality of these muscles. This study aims to understand how such fluctuations alter the parameters measured via TMG and aid in understanding differences that arise from increased muscle contractility throughout the respiratory cycle. Methods: Thirty students at the University of Central Florida [10 males, 20 females, mean age: 21.067 ± 1.552, mean body mass: 64.818 kg ± 14.503, mean height: 168.063 cm ± 9.940] were examined under four breathing conditions. First, a baseline amplitude for electrical stimulation was found using the TMG. Muscle function at end-tidal inspiratory volume (ETIV), end-tidal expiratory volume (ETEV), total lung capacity (TLC), and residual volume (RV) were analyzed. Visual cues were utilized as signals of inhalation (ETIV) and exhalation (ETEV), when the diaphragm expanded and contracted, respectively. Participants were instructed to inhale as much air as possible (TLC) and to exhale all the air from their lungs (RV). Measurements were taken twice at all breathing conditions and the highest of two measurements was utilized for data analysis. This procedure was completed on both the erector spinae (ES) and latissimus dorsi (LD). Paired samples t-tests were run to compare data sets from the four respiration levels. Results: When comparing measurements for ES taken at ETIV and ETEV, differences Dm (p < 0.001), Tr (p = 0.010), and Ts (p < 0.001) were statistically significant. For comparisons between ETIV and TLC, Dm (p = 0.017) differences were statistically significant. ETEV and TLC analyses showed Dm (p < 0.001), Tr (p = 0.024), and Ts (p < 0.001) were statistically significant. Comparisons for ETEV and RV illustrated significantly different Dm (p < 0.001), Tr (p = 0.011), and Ts (p = 0.002) values. For LD, no comparisons were statistically significant. Conclusions: The erector spinae functions differently at various points of respiration. When utilizing tools like tensiomyography, it is important to understand that data collected on erector spinae may be skewed based on the respiratory conditions of a participant at a given time. Practical Applications: This is the first study to explicitly examine how respiratory conditions can skew TMG measurements. This data serves to illustrate that muscle function is different throughout the respiratory cycle. Therefore, data collected using TMG on muscles that are affected by respiration may not be accurate to the true functioning of the muscle. This finding should be built upon to create a standardized protocol for analyzing muscles such as the erector spinae. Acknowledgements: N/A