Alterations in self-regulation of perceived effort after hypertonic versus isotonic saline injection administration

Citation

Fullerton C (2022) Alterations in self-regulation of perceived effort after hypertonic versus isotonic saline injection administration. Europhysiology 2022, Copenhagen, 16.09.2022-18.09.2022. https://doi.org/10.1111/apha.13875

Abstract
Introduction: Perceived effort is a crucial determinant of any voluntary physical action [1]. Likewise, exercise-induced pain (EIP) is believed to markedly influence task performance [2]. As perceived effort and EIP appear to involve similar neurophysiological pathways [3,4], identifying how perceptions of EIP can influence self-regulation of perceived effort may be of interest to further understand task performance across contexts. Methods: This single-blind study involved ten healthy participants (8 male, 2 female) conducting three laboratory visits. Visit 1 involved an initial cardiorespiratory testing and familiarisation, whilst Visits2 and 3 involved randomised 30-minute fixed effort cycling trials in the presence of 1.0 mL bilateral hypertonic (5.85%) or isotonic (0.9%) saline injections in the Vastus Lateralis muscle. During, performance (e.g., power output) cardiorespiratory (e.g., heart rate, pulmonary gas exchange),psychometrics (e.g., pain ratings, self-efficacy, affective valence) and neurological (cerebral oxygenation flow rates) markers were measured. After completion, the McGill Pain and Pain Catastrophising Scale were administered to identify added indices of experienced pain [5]. Data were averaged over six five-minute time zones (e.g., time zone 1 = Minute 0–5) and analysed in SPSS v.26 using a 2 x 6 repeated measures ANOVA with follow-up Bonferroni equations and Cohen’s d effect sizes being calculated. Non-parametric equivalents were used when data violated normality. Results: Participants rated pain significantly higher in the first half of the fixed-effort cycle during the hypertonic versus isotonic condition (P = .001-.044). No significant condition-time effects were identified between for power output or cardiorespiratory markers at any time zone (P =.235 -.390).Equally, cerebral oxygenation flow rates of oxyhaemoglobin, deoxyhaemoglobin and total haemoglobin did not differ between conditions and remained stable over time. However, significant differences existed between conditions in affective valence ratings at time zones 1 – 4 with large effect sizes (P = .001-.022, d = .84-.85) with more a more positive feel in the isotonic (no pain)condition than hypertonic (painful) condition. Yet, no differences in self-efficacy were observed between conditions or over time. Participants acknowledged higher dimensions of sensory pain in the hypertonic condition compared to the isotonic condition as well as higher ratings of pain catastrophising (P = .024).Conclusion: Notably, this study’s results demonstrate that experience of perceptions of EIP do not impact the self-regulation of performance or neurophysiological aspects of a fixed effort cycling task. Alternately, perceptions of pain do appear to alter psychological state (e.g., affective valence, pain catastrophising). Thus, neurophysiological factors may be less susceptible to change than psychological factors during prolonged self-regulated exercise when pain is present.

Journal
Acta Physiologica: Volume 236, Issue S725