No abstract

There is a decline in the EEG response to exercise in the PFC following the RCP, whilst alpha activity in the MC is preferentially maintained; therefore, changes within the PFC appear to play a role in exercise termination.

We examined the effects of a single 2.5-mg dose of melatonin on the thermoregulatory and circulatory responses to intermittent exercise at a room temperature of 27.2+/-0.4 degrees C (mean+/-S.D.), a relative humidity of 55+/-3% (mean+/-S.D.), and a light intensity of 200-300 lux. In a double-blind cross-over study, six male participants ingested either melatonin or placebo at 11:45 hr. Participants then rested in a semi-supine position for 75 min and completed an intermittent running protocol for 66 min at alternating intensities of 40, 60 and 80% of maximal oxygen uptake. Rectal and mean skin temperature, heart rate, blood pressure, skin blood flow, subjective alertness and sleepiness, ratings of perceived exertion (RPE) and thermal strain were recorded. No effects of melatonin were found on these variables measured during the resting period (P>0.10). During exercise, melatonin was found to moderate the increase in rectal temperature by approximately 0.25 degrees C (P=0.050) and magnify the increase in skin blood flow (P=0.047). Postexercise systolic blood pressure was 7.8+/-2.5 mmHg (mean+/-S.D.) lower than before the exercise in the melatonin trial; a change which differed significantly to that in the placebo trial (P=0.018). Melatonin did not influence subjective alertness and sleepiness before or after exercise and did not change the responses of mean skin temperature, RPE and thermal strain during the exercise (P>0.10). In summary it is apparent that a 2.5-mg dose of melatonin has hypothermic, but not soporific, effects during 66 min of intermittent exercise performed under moderate heat stress. Whether such effects improve endurance athletic performance in hot conditions remains to be confirmed. Our data also suggest that postexercise systolic hypotension is more marked after ingestion of melatonin.

BackgroundPhysicians are frequently confronted with complex health situations of patients, but knowledge of intensive forms of multimorbidity and their development during life is lacking.This study explores patterns and trajectories of chronic health problems of patients with multimorbidity particularly those with more than ten conditions and type and variety of organ systems involved in these patterns during life.MethodLife time prevalence patterns of chronic health problems were determined in patients with illness trajectories accumulating more than ten chronic health problems during life as registered by general practitioners in the South of the Netherlands in the Registration Network Family Practices (RNH).ResultsOverall 4,560 subjects (5%) were registered with more than ten chronic health problems during their life (MM11+), accounting for 61,653 (20%) of the 302,808 registered health problems in the population (N = 87,837 subjects). More than 30% accumulates 4 or more chronic health conditions (MM4-5: 4–5 conditions (N = 14,199; 16.2%); MM6-10: 6–10 conditions (N = 14,365; 16.4%).Gastro-intestinal, cardiovascular, locomotor, respiratory and metabolic conditions occur more frequently in the MM11+ patients than in the other patients, while the nature and variety of body systems involved in lifetime accumulation of chronic health problem clusters is both generic and specific. Regarding chronic conditions afflicting multiple sites throughout the body, the number of neoplasms seems low (N = 3,592; 5.8%), but 2,461 (49%) of the 4,560 subjects have registered at least one neoplasm condition during life. A similar pattern is noted for inflammation (N = 3,537, 78%), infection (N = 2,451, 54%) and injury (N = 3,401, 75%).ConclusionThere are many challenges facing multimorbidity research, including the implementation of a longitudinal, life-time approach from a family practice perspective. The present study, although exploratory by nature, shows that both general and specific mechanisms characterize the development of multimorbidity trajectories. A small proportion of patients has a high number of chronic health problems (MM11+) and keeps adding health problems during life. However, GP’s need to realise that more than one third of their patients accumulate four or more chronic health problems (MM4-5 and MM6-10) during life.

Rationale: Exogenous cortisol is a modulator of behavior related to increased motivated decision making (Putman et al., 2010), where risky choices yield potentially big reward. Making risk based judgments has been shown to be important to athletes in optimizing pacing during endurance events (Renfree et al., 2014; Micklewright et al., 2015).Objectives: Therefore, the aims of this study were to examine the effect of 50 mg exogenous cortisol on neurophysiological responses and risk taking behavior in nine healthy men. Further to this, to examine the effect of exogenous cortisol on exercise performance.Methods: Using a double blind counterbalanced design, cyclists completed a placebo (PLA), and a cortisol (COR) trial (50 mg cortisol), with drug ingestion at 0 min. Each trial consisted of a rest period from 0 to 60 min, followed by a risk taking behavior task, a 30 min time trial (TT) with 5 × 30 s sprints at the following time intervals; 5, 11, 17, 23, and 29 min. Salivary cortisol (SaCOR), Electroencephalography (EEG) and Near Infrared Spectroscopy (NIRs) were measured at 15, 30, 45, and 60 min post-ingestion. Glucose and lactate samples were taken at 0 and 60 min post-ingestion. During exercise, power output (PO), heart rate (HR), EEG, and NIRS were measured. SaCOR was measured 10 min post-exercise.Results: Cortisol increased risk taking behavior from baseline testing. This was in line with significant neurophysiological changes at rest and during exercise. At rest, SaCOR levels were higher (P < 0.01) in COR compared to PLA (29.7 ± 22.7 and 3.27 ± 0.7 nmol/l, respectively). At 60 min alpha slow EEG response was higher in COR than PLA in the PFC (5.5 ± 6.4 vs. −0.02 ± 8.7% change; P < 0.01). During the TT there was no difference in total km, average power or average sprint power, although Peak power (PP) achieved was lower in COR than PLA (465.3 ± 83.4 and 499.8 ± 104.3; P < 0.05) and cerebral oxygenation was lower in COR (P < 0.05).Conclusion: This is the first study to examine the effect of exogenous cortisol on exercise performance. These results are in line with previous research showing altered risk taking behavior following exogenous cortisol, however the altered behavior did not translate into changes in exercise performance.