Elevated muscle pain induced by a hypertonic saline injection reduces power output independent of physiological changes during fixed perceived effort cycling.

Pain is a naturally occurring phenomenon that consistently inhibits exercise performance by imposing unconscious, neurophysiological alterations (e.g., corticospinal changes) as well as conscious, psychophysiological pressures (e.g., shared effort demands). Although several studies indicate that pain would elicit lower task outputs for a set intensity of perceived effort, no study has tested this. Therefore, this study investigated the impact of elevated muscle pain through a hypertonic saline injection on the power output, psychophysiological, cerebral oxygenation, and perceptual changes during fixed perceived effort exercise. Ten participants completed three visits (1 familiarization + 2 fixed perceived effort trials). Fixed perceived effort cycling corresponded to 15% above gas exchange threshold (GET) [mean rating of perceived effort (RPE) = 15 "hard"]. Before the 30-min fixed perceived effort exercise, participants received a randomized bilateral hypertonic or isotonic saline injection in the vastus lateralis. Power output, cardiorespiratory, cerebral oxygenation, and perceptual markers (e.g., affective valence) were recorded during exercise. Linear mixed-model regression assessed the condition and time effects and condition × time interactions. Significant condition effects showed that power output was significantly lower during hypertonic conditions [t107 = 208, P = 0.040, ß = 4.77 W, 95% confidence interval (95% CI) [0.27 to 9.26 W]]. Meanwhile, all physiological variables (e.g., heart rate, oxygen uptake, minute ventilation) demonstrated no significant condition effects. Condition effects were observed for deoxyhemoglobin changes from baseline (t107 = -3.29, P = 0.001, ß = -1.50 ΔµM, 95% CI [-2.40 to -0.61 ΔµM]) and affective valence (t127 = 6.12, P = 0.001, ß = 0.93, 95% CI [0.63 to 1.23]). Results infer that pain impacts the self-regulation of fixed perceived effort exercise, as differences in power output mainly occurred when pain ratings were higher after hypertonic versus isotonic saline administration.NEW & NOTEWORTHY This study identifies that elevated muscle pain through a hypertonic saline injection causes significantly lower power output when pain is experienced but does not seem to affect exercise behavior in a residual manner. Results provide some evidence that pain operates on a psychophysiological level to alter the self-regulation of exercise behavior due to differences between conditions in cerebral deoxyhemoglobin and other perceptual parameters.

Relationship between food perceptions and health-related quality of life in a prospective study with breast cancer patients undergoing chemotherapy

OBJECTIVE: To correlate the perceptions related to dietary intake with the domains and subscales of health-related quality of life (HRQL) in women with breast neoplasms receiving chemotherapy. METHODS: In this prospective study, 55 women with breast cancer were followed up during chemotherapy at three different times (T0, T1, T2). Before chemotherapy, perceptions related to food consumption were evaluated. HRQL was analyzed with the EORTC QLQ-C30 and Br23 instruments 21 days after each investigated cycle. The differences (T2-T0) in the subscales and HRQL domains were correlated with the differences (T2-T0) in the appetite scores. Spearman's correlation was used to verify a possible correlation between differences in functional and overall HRQL domains (T2-T0) and differences in appetite scores for certain foods and between the differences in some subscales of EORTC QLQ-C30 and Br23 (T2-T0) and differences in appetite scores for certain food groups (T2-T0). RESULTS: Correlations between pain and appetite for bitter taste and between an increased appetite for juices and pain intensification or fatigue were identified, and pain was correlated with an appetite for starchy foods. An appetite for vegetables, legumes and meat/eggs was correlated with physical function. The only significant correlation with social functions occurred between the appetite for sweet foods and these functions. We found a correlation between overall health, emotional function, social function and physical function and the appetite for juices. CONCLUSION: Chemotherapy alters the individual's relationship with food and, consequently, the individual's HRQL.