Examining Intra-Individual Variability of Perceived Physical Discomfort In Young Adults: A Potential Exercise Antecedent

Abstract

Ecological Momentary Assessment (EMA) allows the observation of intra-individual variance in cognitive, perceptual, psychological, and contextual variables that may impact recurrent health behaviors such as exercise. Perceptions of physiological states (e.g. pain, illness) likely influence behaviors, but most assessments are cross-sectional. PURPOSE: To determine preliminary estimates of intra-individual variability in perceived physiological states. METHODS: A secondary analysis was conducted using data from young, healthy adults (N=29) undergoing EMA of exercise antecedents. Participants were sent four surveys per day across 14 days (56 total surveys). The extracted variables pain, stiff, and achy were scored on a seven-point Likert scale; 0= not at all, 3= moderately, 6= extremely. Individual item scores were summed to create a “physical discomfort” score (Cronbach’s alpha=0.847). Data were retained from compliers who completed >75% of EMA surveys. Compliers (n=20, 23±4 years, BMI=25.6±3.1 kg/m2, 60% female) completed 89±5% of surveys. Missing data were imputed with the participant’s daily means for that respective variable. Two-way mixed intra-class correlation coefficients (ICC) were calculated with 95% confidence intervals (CI) for pain, stiffness, achiness, and physical discomfort across all 56 time blocks and across 14 daily means. ICC≤0.5, between 0.5-0.75, between 0.75-0.9, and ≥0.9 indicate poor, moderate, good, or excellent consistency. RESULTS: Indices of physical discomfort were generally low (M±SD): pain=0.9±1.2; achy=1.3±1.4; stiff=1.5±1.5. Poor consistency was observed across time points for pain (ICC=0.32; CI=0.21-0.51), achy (0.44; 0.31-0.63); stiff (0.48; 0.34-0.67), and physical discomfort (0.49; 0.35-0.67). Poor-to-moderate consistency was observed across daily means for pain (0.46; 0.31-0.66), achy (0.57; 0.41-0.75), stiff (0.60; 0.45-0.77), and physical discomfort (0.59; 0.43-0.76). CONCLUSION: Due to the inconsistent nature of perceived pain, achiness, stiffness, and physical discomfort, more frequent assessment of physical discomfort may be necessary within EMA to capture important fluctuations. Understanding the timing, magnitude, and direction of fluctuations could expose points of vulnerability relating to exercise behavior.