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A number of studies have indicated that exercise is associated with alterations in pain perception. In general, investigators have typically found a hypoalgesic response (i.e. diminished pain perception) to occur during and following exercise. It is currently unclear why exercise alters pain perception but some research indicates that there is an interaction between pain modulatory and cardiovascular systems. Elevated resting blood pressure (BP), such as hypertension, has been associated with reduced sensitivity to noxious stimulation. In addition, acute elevations in BP (pharmacologically) have also been associated with alterations in pain perception. Exercise elevates BP due to the physiological demands of the activity, but only a limited amount of research has been conducted examining the interaction between exercise, hypoalgesia and BP. Results from this research indicate that exercise significantly alters cardiovascular responses, and these alterations appear to be associated with alterations in pain perception. However, the interaction between exercise, pain perception and BP has been primarily examined indirectly. The mechanisms underlying the interaction between BP and pain perception are currently not entirely understood. It has been suggested that endogenous opioids may be involved in the interaction between BP and pain perception; however, results appear to be equivocal in the human research that has been conducted in this area. It has also been suggested that baroreceptor activation may play a role in the interaction between BP and pain perception.

Fibromyalgia syndrome (FMS) is a widespread musculoskeletal pain condition with unclear physiologic mechanisms. The purpose of this investigation was to compare the responsiveness of nociceptive flexion reflex (NFR) pathways between women with and without FMS. A secondary purpose was to examine the influence of depression, fibromyalgia symptom severity, and cardiovascular health on NFR responses among women with FMS. Fifteen women with FMS and 14 healthy controls participated in an experimental session to assess NFR responses to sural nerve stimulation, resting mean arterial pressure (MAP) and heart rate (HR), and scores on the Beck Depression Inventory (BDI) and Fibromyalgia Impact Questionnaire (FIQ). NFR responses were successfully elicited from all healthy individuals, but only eight (53 %) of the women with FMS. These women did not differ in the minimum stimulus intensity required to elicit an NFR response compared to healthy controls (p ≥ 0.35). Further, these women had lower BDI (p = 0.04) and FIQ (p = 0.02) scores compared to women with FMS from whom NFR responses could not be elicited. Resting HR was higher in both groups of women with FMS compared to healthy individuals (p <0.05), and MAP was strongly associated with NFR thresholds only among women with FMS (r = 0.88, p <0.01). Findings from this preliminary investigation suggest that NFR pathways are impaired in women who are more severely impacted by symptoms of depression and fibromyalgia, potentially due to desensitization of NFR pathways with chronic autonomic arousal.

Background Adolescence is a vulnerable period for experiencing poor sleep health. Growing studies have demonstrated lifestyle behaviors including physical activity (PA), screen time (SCT), and sedentary behaviors (SED) as the potential factors associated with sleep health in adolescents; yet, the evidence is inconclusive and the directionality of temporal associations across school days are not well understood. This study examined the day-today bidirectional associations of lifestyle behaviors with sleep health parameters in adolescents. Methods A total of 263 adolescents (58% boys) in 6 th-8 th grades wore an accelerometer for 24-hour across the three consecutive school days and completed recording SCT in time-diary and answering sleep quality (SQ) questions for each day. Sleep-wake patterns as well as time spent in moderate-and vigorous-intensity PA (MVPA) and SED were objectively quantified from the wrist-worn accelerometry data across the two segments of the day (during and after school hours). Mixed model analyses were conducted to test bidirectional associations between lifestyle factors and sleep health parameters in each temporal direction across the days. Additionally, indirect associations across the days were tested using an autoregressive cross-lagged model analysis in the framework of path analysis. Results MVPA minutes in a day did not predict sleep health parameters that night. The bidirectional associations were partially observed between SED and sleep health, but the significance and direction of the associations largely varied by the time segment of a day as well as types of sleep health parameters. Additionally, greater SCT during the day was associated with