Intensity and physiological strain of competitive ultra-endurance exercise in humans

• Published in: Journal of sports sciences 2008-03, Vol.26 (5), p.477-489
• Main Authors: Lucas, Samuel J. E., Anglem, Nat, Roberts, Warren S., Anson, J. Greg, Palmer, Craig D., Walker, Robert J., Cook, Christian J., Cotter, James D.
• Format: Article
• Language: English
• Subjects: Adult; adventure racing; Arginine Vasopressin - blood; Biological and medical sciences; Body Temperature - physiology; Exercise - physiology; exercise intensity; Female; Fundamental and applied biological sciences. Psychology; Heart Rate - physiology; Humans; Leukocytes - metabolism; Male; Middle Aged; Physical Endurance - physiology; Physical Exertion - physiology; Physiological strain; Plasma Volume - physiology; Reticulocyte Count; sleep deprivation; Sodium - blood; Sports - physiology; Vertebrates: body movement. Posture. Locomotion. Flight. Swimming. Physical exercise. Rest. Sports
• ISSN: 0264-0414; 1466-447X
• DOI: 10.1080/02640410701552872

The aim of this study was to determine the magnitude and pattern of intensity, and physiological strain, of competitive exercise performed across several days, as in adventure racing. Data were obtained from three teams of four athletes (7 males, 5 females; mean age 36 years, s = 11; cycling [Vdot]O 2 peak 53.9 ml · kg −1  · min −1 , s = 6.3) in an international race (2003 Southern Traverse; 96 - 116 h). Heart rates (HR) averaged 64% (95% confidence interval: ± 4%) of heart rate range [%HRR = (HR − HR min )/(HR max  − HR min ) × 100] during the first 12 h of racing, fell to 41% (±4%) by 24 h, and remained so thereafter. The level and pattern of heart rate were similar across teams, despite one leading and one trailing all other teams. Core temperature remained between 36.0 and 39.2°C despite widely varying thermal stress. Venous samples, obtained before, during, and after the race, revealed increased neutrophil, monocyte and lymphocyte concentrations (P