Localized Bicep Tissue Bioimpedance Alterations Following Eccentric Exercise in Healthy Young Adults

Abstract

The localized bicep tissue bioimpedance was measured from participants who completed an eccentric exercise protocol with one arm and no exercise with the other arm to compare changes that occur as a result of the exercise protocol over a 96h observation period. Methods: The localized bicep bioimpedance, bicep circumference, and self-reports of bicep pain were collected from 6 volunteers at pre, post, 24h, 48h, 72h, and 96h timepoints after completing an eccentric exercise protocol of the elbow flexor muscles. Results: The unexercised bicep showed no statistically significant differences between the pre-exercise and post-exercise measures at any timepoints for all impedance measures and circumference. The exercised bicep showed statistically significant decreases (p < 0.01) for 10 kHz, 50 kHz, and 100 kHz impedance (resistance and reactance) and increases of bicep circumference at the 72h and 96h post-protocol timepoints, compared to the pre-protocol measurements. The self-reports of pain of the exercised bicep also showed statistically significant increases (p < 0.01) at the 48h and 72h timepoints compared to the baseline reports. Conclusion: Completion of the eccentric protocol resulted in increases of bicep circumference and decreases in the magnitude of resistance and reactance components of the localized tissue bioimpedance; with maximum changes of swelling and impedance occurring at the same post-protocol timepoints. These changes support that localized tissue bioimpedance is sensitive to the changes that occur as a result of the exercise protocol with the potential to quantify tissues for exercise induced changes. Significance: Localized tissue bioimpedance is sensitive to the changes that occur from eccentric exercise and may be a potential method to non-invasively quantify tissues for changes due to exercise, fatigue, injury, and recovery.

Cole-impedance parameters representing biceps tissue bioimpedance in healthy adults and their alterations following eccentric exercise

“…The bioimpedance data from the participants that was analyzed for this research was collected and reported initially by Freeborn et al in [16] . While the complete details of the study participants and exercise protocol are available in [16] , they are also summarized here for readers.…”

“…Bioimpedance is also currently being investigated as a noninvasive technique to characterize skeletal muscle tissue with a particular focus on assessing neuromuscular disorders [10] , [11] , [2] . Beyond assessing neuromuscular disorders, bioimpedance is being investigated to monitor tissue changes that result from the exercise and fatigue of skeletal muscle, with decreases in impedance magnitude reported after resistance training protocols [12] , [13] , [14] , [15] , [16] , with further results reporting decreased in impedance magnitude for acute muscle injury [17] , [18] .…”

“…Regardless of the application, when analyzing collected bioimpedance data two approaches are typically adopted: (i) analyzing a single or multiple discrete frequencies [17] , [12] , [13] , [16] or (ii) reducing a multi-frequency impedance spectra to an equivalent circuit representation [20] , [14] , [15] . While analyzing discrete frequencies is useful to identify if changes are occurring, it is difficult to link these changes to specific properties of the tissue and its structure.…”

“…Exploring this aim requires a higher stimulus exercise protocol than previous studies to induce (reversible) tissue damage and collecting measurements at further time-points post exercise. Both of which were accomplished in a follow-up study by Freeborn et al [16] .…”

“…This provides the motivation for this study, to expand on the analyses of bicep tissue bioimpedance collected by Freeborn et al in [16] that only analyzed discrete frequency impedance changes (at 10 kHz, 50 kHz, and 100 kHz) in participants for 96 h following an eccentric exercise protocol to answer the research question: Does participation in an eccentric exercise protocol alter the CPE parameters of the Cole-impedance model that represent the measured tissue bioimpedance?…”