Investigating The Sensitivity Of Phase Angle To Eccentric Exercise

Phase Angle (PhA) is a tool used in clinical practices typically collected during bioelectrical impedance analysis (BIA) scans. PhA is a measure of cellular integrity and body water distribution and is thus sensitive to inflammation and fluid shifts. Muscular damaging exercise can cause both, however whether PhA is sensitive to muscular damage from eccentric exercise is unknown. PURPOSE: The purpose of this project was to determine if PhA is sensitive to muscular damage to be used as a tool for tracking recovery. METHODS: Participants (n = 12, 4 females; Age: 21 ± 3 years; Height: 169 ± 20 cm; Body mass: 76 ± 13 kg) underwent a maximal voluntary isometric contraction (MVIC) for both arms and then completed sets of 10 eccentric bicep curls at 45°s-1 using the non-dominant arm. After each set, MVIC was remeasured; once MVIC values were reduced to 60% or less of the original measurement, exercise was concluded. BIA scans were conducted before and after the exercise protocol to measure segmental PhA. Pressure-pain threshold test (PPT) and pain tolerance (VAS) were also conducted pre and post exercise. Participants returned to the lab at 24 h, 48 h & 72 h for MVIC, BIA, PPT and VAS assessment. RESULTS: There was a significant difference in MVIC values in participants pre to post exercise (p = 0.001; mean difference (md) = -9%) and post exercise compared to 24 h (-9%), 48 h (-3%) and 72 hours (4%, p < 0.01 for all). Extracellular water (ECW; p = 0.04, md = 0.06 kg), intracellular water (ICW; p = 0.002, md = 0.07 kg), and total body water (TBW; p = 0.004, md = 0.09 kg) were all significantly different in the arm used in the exercise protocol. However, there was no significant difference in PhA (p = 0.78), the participant’s PPT (p = 0.08) or VAS (p = 0.58) over the three days following exercise. CONCLUSION: While the protocol resulted in significant muscular force production decrements, as evidenced by reduced MVIC up to 72 h post exercise and significant body water shifts, there was no difference in PhA, pain tolerance or soreness in the arm used following the exercise protocol and through 72 h recovery. Therefore, it remains to be seen if PhA is sensitive to muscular damage or if it can be used to track recovery following muscular damage.