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Aim: To assess the within-subject variation of thermoregulatory responses during 2 consecutive 15-km road races. Secondly, we explored whether gastrointestinal temperature (TGI) data from the first race could improve our previously established predictive model for finish TGI in the second race. Methods: We measured TGI before and immediately after both races in 58 participants and determined correlation coefficients. Finish Ta in the second race was predicted using a linear regression analysis including age, BMI, pre-race fluid intake, TGI increase between baseline and the start of the race and finish TGI in the first race. Results: Under cool conditions (WBGT 11-12°C), TGI was comparable between both races at baseline (37.6±0.4°C vs. 37.9±0.4°C; p = 0.24) and finish (39.4±0.6°C vs. 39.4±0.6°C; p = 0.83). Finish TGI correlated significantly between both races (r = 0.50; p<0.001). The predictive model (p< 0.001) could predict 32.2% of the finish TGI in the second race (vs. 17.1 % without finish TGI in race 1). Conclusion: Our findings demonstrate that the use of previously obtained thermoregulatory responses results in higher predictability of finish core body temperatures in future races, enabling better risk assessment for those athletes that are most likely to benefit from preventive measures. [ABSTRACT FROM AUTHOR]

Exercise-induced increase in core body temperature may lead to the development of hyperthermia (>40.0°C) and/or decreased performance levels. This study examined the effects of wearing a cooling vest during a 5-km time trial on thermoregulatory responses and performance. 10 male masters athletes (42±10 years) performed a 5-km time trial on a motorized treadmill in a climate chamber (25°C, 55% relative humidity) with and without a cooling vest. Split times, heart rate, core-, skin- and cooling vest temperature were measured every 500 m. Subjects also rated thermal comfort and level of perceived exertion. The cooling vest significantly decreased heart rate (p<0.05), decreased skin temperature (p<0.001) and improved thermal comfort (p<0.005) during the time trial. Time to finish the 5-km time trial and pacing strategy did not differ between the control (1 246±96 s) and cooling vest condition (1 254±98 s, p=0.85). Additionally, thermoregulatory responses, maximum core body temperature and level of perceived exertion were not different across conditions (p=0.85, p=0.49, p=0.11, respectively). In conclusion, we demonstrated that wearing a cooling vest during exercise improves thermal comfort but does not enhance performance or decrease core body temperature in male masters athletes under temperate ambient conditions. [ABSTRACT FROM AUTHOR]

Objective: To investigate whether physical fitness and/or fat distribution and inflammation profile may explain why approximately 30 % of the women with obesity are protected against obesity-related disorders. Method: 10 metabolically healthy obese women and 10 age- and weight-matched women with the metabolic syndrome were enrolled. Physical fitness (VO2max ), daily physical activity levels (METs, steps per day), insulin sensitivity (clamp), body fat distribution (DXA scan) and, inflammation markers and adipokines were determined. Results: The metabolically healthy obese women had a 17 % higher VO2max (25.1 ± 3.9 vs. 21.5 ± 3.1 ml · min -1· kg -1, p = 0.04) and tended to take more steps per day (7 388 ± 1 440 vs. 5 927 ± 1 301, p = 0.06) than women with the metabolic syndrome. Despite equivalent levels of fat mass, metabolically healthy obese women had significantly lower circulating TNF-α levels compared to women with the metabolic syndrome (3.55 ± 3.83 vs. 0.43 ± 0.97 ng/ml, p = 0.03). No differences were seen in insulin sensitivity, adipokines, and inflammatory markers between both groups. Conclusion: Metabolically healthy obese women have a higher cardio-respiratory fitness and lower TNF-α levels, which may partly explain why these women are protected from the detrimental effects of obesity compared to obese women with the metabolic syndrome. [ABSTRACT FROM AUTHOR]

Exercise training represents a successful and powerful strategy to prevent future cardiovascular disease. Paradoxically, performance of exercise is also associated with an increased risk of acute cardiac events. Accordingly, patients may present to hospital with cardiac symptoms following a bout of unaccustomed physical effort (e.g. exercise). Current guidelines for the identification of an acute myocardial infarction (AMI) importantly depend on the presence of cardiac troponin as a highly sensitive marker of cardiac damage. However, a number of studies have reported elevated cardiac troponin levels in asymptomatic, healthy subjects after endurance exercise (such as a marathon, prolonged cycling or prolonged walking). These observations indicate that elevated cardiac troponin levels can be the result of cardiac ischemia, and subsequent necrosis, but also may be related to strenuous exercise. In this paper, we present three different clinical cases of post-exercise elevations in cardiac troponins, each with a distinct clinical presentation. These case studies emphasize that a detailed assessment of all symptoms and a thorough patient-history are prerequisite for accurate interpretation of a positive cardiac troponin test following exercise.

Objective: To determine the physiological impact and health risks for walkers during the Nijmegen (the Netherlands) Four Days Marches in 2007, the largest walking event in the world with more than 45,000 participants., Design: Observational study., Methods: 66 volunteers were randomly selected and counterbalanced for distance walked and gender in this observational study. Subjects walked 30 km (n = 20; 10 men), 40 km (n = 25; 14 men) or 50 km (n = 21; 10 men) per day, for 4 consecutive days. Core body temperature, fluid intake, changes in body weight, plasma sodium concentrations and energy usage were measured before and after the marches., Results: During this event, ambient temperatures ranged from 11.0 degrees C to a maximum 25.4 degrees C expressed as 'wet bulb globe temperature' (WBGT). Heart rate (+38 beats per minute) and core body temperature (+0.8 degree C) significantly increased in all subjects during each day (about 9 hours walking per day at an average of 4.6 km/h), but hyperthermia was not diagnosed (definition: > 39.0 degrees C). Average fluid intake varied between 2.6 and 3.3 l/d with a range of 0.3-12 l/d. The relative change in body weight associated with this was -3.1 to +4.3%. Mean plasma sodium concentration decreased from 142.4 to 140.6 mmol/l over each walking day. The plasma sodium correlated negatively with fluid intake (r = -0.32; p < o.001), change in body weight (r = -0.13; p < 0.05), and walking time (r = -0.37; p < 0.001). A high prevalence of hyponatraemia (5%) and hypernatraemia (16%) was observed; extrapolating these findings to the entire field a large group (about 10,000) would have been at risk with this electrolyte imbalance., Conclusion: This study showed that walking the Four Days Marches in Nijmegen with mild ambient conditions led to one in five participants incurring disturbances in fluid and electrolyte balance. Nonetheless, the participants were well able to keep their increasing core temperature within safe limits. Apart from the frequent electrolyte imbalance, the fluid intake varied strongly between individuals.