Pain, discomfort, and enjoyment during moderate exercise: Relationships to weight status and diet quality

More than two-thirds of the population in the United States have overweight or obesity and the comorbidities associated with excess weight further compound the issue. It is clear that this issue will not be solved without innovative approaches to understanding which personal barriers interfere with adherence to recommended treatment elements. Exercise is among the strategies included in the multidimensional management of obesity. Our previous research has suggested that pain may be a factor that is associated with physical activity in people with obesity. Given that little is known of the relationships among weight status, pain, and exercise-related pain/discomfort/enjoyment, we are seeking to examine these as they relate to overweight/obesity compared to normal weight individuals. In addition, some preliminary studies in animals demonstrated that increased pain sensitivity and susceptibility to pain occurred following exposure to a ‘Western’ diet. This relationship needs to be examined in humans. As such we will explore whether diet quality measured via select biomarkers is associated with pain severity and tolerance at baseline. A case-controlled design with prospective outcome measurements was used. Generally healthy adults with BMI above 18.5 kg/m2 were recruited for the study. In the single study session, height, weight, body composition, and health history were first taken, followed by assessing subjective pain via 4 validated pain questionnaires (subjective pain rating scale, SPRS; short form McGill Pain Questionnaire, SFMPQ; West Haven-Yale Multidimensional Pain Inventory, WHYMPI; short form Brief Pain Inventory, SFBPI), and objective pain test via dolorimetry. Diet quality was assessed via 5 biomarkers obtained via blood (i.e., plasma alkylresorcinol, Omega-3 Index, serum fatty acid composition, serum carotenoids, and serum selenium). Then an exercise session (maximum duration 42 minutes) was conducted to examine affective responses (i.e., pain, overall feeling, enjoyment, and discomfort) during exercise. Blood samples were stored in -80 °C until analyses in TTU and external accredited labs were conducted. Statistical analysis was conducted as follows: 1) imputation of missing data via multiple imputation using the mice package in R; 2) group comparisons via Welch’s independent samples t-tests for variables without missing data and multiple imputation Student’s t-tests for variables with missing data using the MKmisc package in R; 3) the logrank test comparing the discontinue time of exercise between groups; 4) constructing linear regression analyses to examine relationship of each of 5 diet quality-related biomarkers with pain severity and pain tolerance. Twenty-two normal weight adults (F = 14) and 33 adults with obesity (F = 16) were enrolled in the study (mean age of whole sample = 27.09 ± 10.09 years). There were no differences in pain prevalence (whole sample: 3.6%), pain severity (whole sample: SPRS, 0.44 ± 0.74; PPI of SFMPQ, 0.29 ± 0.50; WHYMPI, 0.46 ± 0.66; SFBPI, 0.61 ± 0.84), pain interference (whole sample: WHYMPI, 0.46 ± 0.66; SFBPI, 0.49 ± 1.45), pain sensitivity (whole sample: 3373.82 ± 1376.54 gf/cm2), and pain tolerance (whole sample: 4703.82 ± 1614.24 gf/cm2) between groups. Moreover, no group differences were detected for affective responses to exercise (whole sample: feeling scale, 1.53 ± 2.15; SPRS, 1.71 ± 1.59; enjoyment scale, 1.18 ± 2.01; discomfort scale, 0.69 ± 2.33). In the exploratory analysis, we did not find any relationship between objective diet quality and pain severity and pain tolerance after adjusting for multiple comparisons (all Ps > 0.05). Taken together, these results suggest that weight status is not associated with pain sensation and affective responses to exercise in a generally healthy population. Also, diet quality measured via biomarkers does not predict pain severity and pain tolerance in a population with low pain prevalence.