Bioelectrical impedance analysis (BIA)-derived phase angle (PhA) has been used to assess cellular health in various populations, but its usefulness as a tool for measuring muscular performance in adult athletes has not been extensively investigated. Our investigation examined the association of whole-body (WB) PhA with muscular performance in 117 adult athletes from different sports and additionally assessed whether regional PhA was a better indicator of muscular performance compared to WB, while accounting for lean soft tissue (LST). Muscular performance was assessed with handgrip strength and countermovement jump power. WB and regional PhA and LST were obtained by BIA and dualenergy x-ray absorptiometry, respectively. Multiple linear regression was used to model outcomes, while adjusting for LST. WB PhA was positively associated with relative power and relative and absolute strength (p < 0.05), irrespective of LST. Regional PhA measures explained similar amounts of variance in absolute and relative power and strength as that of WB PhA after accounting for age, sex, height, and sport type (lower limb adj R 2 = 0.42, 0.60 for power; upper limb adj R 2 = 0.38, 0.74 for strength; WB adj R 2 = 0.44, 0.63 and 0.38, 0.75 for power and strength, respectively). Only upper limb PhA was related with strength (p < 0.05) after accounting for upper limb LST. PhA may have the potential to be used as a marker of functional muscle mass, which is important when it comes to assessing muscular performance of athletes. Regional measures of PhA do not provide a better indicator of regional strength or power when compared to WB PhA.

Background: Habituation is a response decrement resulting from repeated stimuli.Reduced habituation to noxious stimuli is considered to be a proxy for central sensitization in subjects with chronic pain. Despite numerous investigations of pain habituation in relation to central sensitization, there is no consensus on the most sensitive and reliable readout, as well as analysis approach. Therefore, this study compared the usability and reliability of different readouts and habituation analysis approaches to measure pain habituation in response to repetitive heat simulation.Methods: Three blocks of 20 contact heat stimuli were applied on the volar forearm of 20 healthy subjects on two separate visits. Habituation was assessed by three different readouts: pain ratings, contact heat evoked potentials (CHEPs) and heat-induced sympathetic skin responses (SSRs). In addition, two different habituation analysis approaches were used: between the three stimulation blocks (between-block) and within the first stimulation block (within-block).Results: Significant between-block habituation for SSRs (p < 0.001), but not for pain ratings (p = 1.000) and CHEPs (p = 0.078) was found. There was significant within-block habituation for pain ratings (p = 0.012) and SSRs (p < 0.001), but not for CHEPs (p = 0.246). Only the between-block habituation of heat-induced SSR was reliable between the two visits (first to second block: intraclass correlation coefficient [ICC] = 0.58, p = 0.030; first to third block: ICC = 0.64, p = 0.015). Conclusion: Heat-induced SSR as a measure of pain-autonomic interaction revealed the strongest pain habituation and showed the highest test-retest reliability.