Physiological responses to a five-day adventure race: Continuous blood glucose, hemodynamics and metabolites the 2012 GODZone field-study.

BACKGROUND/OBJECTIVE: Adventure racing is an ultra-endurance activity that imposes a unique multifaceted stress on the human body. The purpose of this field study was to examine the physiological responses to a 5-day adventure race. METHODS: Eight competitors, two teams (1 female each) in the 2012 GODZone adventure race volunteered. Competitors trekked, cycled and paddled ∼326 km in ∼116 hours. Continuous glucose was measured the day before and throughout. Body mass, urinary solutes, and blood pressure and heart rate during resting, standing, and repeated squat-stand conditions, were assessed pre and post. RESULTS: Despite no changes in mean blood glucose levels, there was increased glycemic variability (Standard deviation glucose; Pre: 0.5 ±â€¯0.1 vs Race: 1.0 ±â€¯0.2 mmol/L, p = 0.02) and periods of hypoglycemia (i.e., Min glucose Pre: 4.1 ±â€¯0.3 vs Race: 3.6 ±â€¯0.5 mmol/L, p = 0.05) during the race. After the race, the blood pressure during resting, standing and squat-stand conditions was significantly lower, by 14 ±â€¯14 mmHg, 16 ±â€¯15 mmHg and 18 ±â€¯15 mmHg (all p < 0.05), respectively, with no change in heart rate. During five-days of adventure racing there is increased glycemic variability and more frequent periods of low blood glucose levels. Additionally, following the race pronounced hypotension is observed in competitors. CONCLUSION: We observed more frequent glucose fluctuations, lower glucose levels and significant perturbations in blood pressure control. Further research is warranted to examine the long-term impact of adventure racing on metabolic and cardiovascular function.

Fluid and electrolyte balance during two different preseason training sessions in elite rugby union players.

The purpose of this study was to compare fluid balance between a resistance and an aerobic training sessions, in elite rugby players. It is hypothesized that resistance exercise will result in a higher prevalence of overdrinking, whereas during the aerobic session, underdrinking will be more prevalent. As with previous fluid balance studies, this was an observational study. Twenty-six players completed the resistance training session, and 20 players completed the aerobic training session. All players were members of an elite rugby union squad competing in the southern hemisphere's premier competition. For both sessions, players provided a preexercise urine sample to determine hydration status, pre- and postexercise measures of body mass, and blood sodium concentration were taken, and the weight of drink bottles were recorded to calculate sweat rates and fluid intake rates. Sweat patches were positioned on the shoulder of the players, and these remained in place throughout each training session and were later analyzed for sodium concentration. The percentage of sweat loss replaced was higher in the resistance (196 ± 130%) than the aerobic training session (56 ± 17%; p = 0.002). Despite this, no cases of hyponatremia were detected. The results also indicated that more than 80% of players started training in a hypohydrated state. Fluid intake seems to differ depending on the nature of the exercise session. In this group of athletes, players did not match their fluid intakes with their sweat loss, resulting in overdrinking during resistance training and underdrinking in aerobic training. Therefore, hydration strategies and education need to be tailored to the exercise session. Furthermore, given the large number of players arriving at training hypohydrated, improved hydration strategies away from the training venue are required.