Physiological Response and Sports Injury Risk Relevant Biomechanics in Endurance Obstacle Course Races  
[PERSON]  
1 Faculty of Sports Sciences, Universidad Europea de Madrid, Tajo Street, s/n, 28670 Madrid, Spain; [EMAIL_ADDRESS] ([PERSON]-M.); [EMAIL_ADDRESS] (V.J.C.-S.)  
[PERSON]  
2 Teledo Physiotherapy Research Group (GIFTO), Faculty of Physiotherapy and Nursing of Toledo, Universidad de Castilla-La Mancha, 45071 Toledo, Spain; [EMAIL_ADDRESS]  
[PERSON]  
2 Teledo Physiotherapy Research Group (GIFTO), Faculty of Physiotherapy and Nursing of Toledo, Universidad de Castilla-La Mancha, 45071 Toledo, Spain; [EMAIL_ADDRESS]  
[PERSON]  
3 Faculty of Education and Social Sciences, Universidad Andres Bello, Vina del Mar 2520000, Chile; [EMAIL_ADDRESS]  
Crupo de Investigacion en Cultura, Educacion y Sociedad, Universidad de la Costa, Barranquilla 080002, Colombia 3  
Footnote 13  
highly correlated with aerobic performance, especially when they involve passing through obstacles and carrying heavy loads [2; 3] because it allows individuals to keep a greater running pace and recover quickly after the obstacles [2; 3; 4]. The VO2 max is also a performance indicator for lactic anaerobic efforts [4]. This is important because lactic and phosphocreatine organic systems are challenged when passing obstacles. Running economy and lactate threshold are also well correlated with endurance performance, so it is important to include specific training sessions in their development [5; 6]. Thus, muscular strength (both lower and upper body), speed, and endurance, added to the high demands of balance and coordination, which are all related to the maintenance of optimal cortical arousal [7], are determinant factors related to OCR performance [1]. Other crucial factors are optimal hydration levels, since this OCR probe could take more than 1 h to complete, and the nitrates, pH, protein, and glucose in the urine, which can be very influenced by the requirements of the race [8].  
To successfully complete an OCR, athletes must undergo highly intense and cross-training programs [1]. It has been demonstrated that large training loads make competitors vulnerable to injuries [9], and experienced athletes are less affected by injuries [10]. The most predominant occur in the lower limbs because of overuse and/or altered biomechanics during running, and the risk of suffering them can be predicted by conducting some simple field tests such as one-leg standing test [11], navicular drop test [12], Jack's test [13], and active straight leg raise test [14]. But, upper extremities injuries can also be present in this sports modality because of the suspension obstacles, so the assessment of scapular kinematics [15] and isometric hand grip strength could be interesting [16; 17].  
When analysing the previous literature on OCR, we found little evidence to support specific training for them based on the real physiological requirement of these special probes. Thus, we propose the present research to study the physiological and psychological demands and injury risk in OCR with the following objectives: i. to study the physiological response in a Sprint (5 km) and Super (13 km) obstacle course race; ii. to analyse the differences in the physiological response between Sprint and Super OCR; iii. to analyse injury patterns in Sprint and Super OCR; iv. to analyse the correlation between the physiological and injury risk variables with performance in Sprint and Super OCR. The initial hypothesis was that Sprint OCR would achieve a higher anaerobic metabolism activation, and Super OCR would achieve higher degrees of stress manifestations and dehydration. This information could be used by trainers and health care professionals to improve the efficient design of training programs and injury prevention plans.