Bioengineering of American Football: A Review

American Football is one of the sports with the highest rates of injuries and head traumas. Additionally, there is epidemiological evidence that most American Football players are affected by hypertension. Linemen are subjects at risk of developing cardiovascular disease due to their weight and the isometric training. They appear to have hypertrophic cardiac adaptations and the consensus in the literature seems that this is not a positive adaptation as in the case of the common Athlete’s heart. Given this premises, the main two lines of research are the biomechanics of football specific movement and in vivo cardiac monitoring. Studies regarding the biomechanics aims at understanding how to improve the movement of the player or how to prevent injuries during the specific movement. An important subset of these studies includes the biomechanics of concussion with the aim of prevention and recognition of concussive events. For what concerns in vivo cardiac monitoring, the number of studies on population of American football players is limited and the aim of these studies is to improve the training protocol of athletes, to monitor their recovery status or even to monitor their temperature during the training. This thesis expands the research of in vivo cardiac monitoring in American Football by recording with a Zephyr Bioharness 3.0 the electrocardiogram signal and the heart rate of fifteen players. The participants had an average age of 23.67 ± 3.42, an average weight of 94.67 kg ± 14.69 kg and an average height of 1,82 m ± 0.07m. The aim of the experimental study was to understand the effect of repeated short maximal sprints on the sympathetic and parasympathetic activity of each subject by analyzing the tachogram extracted from the recorded electrocardiogram. After each sprint, a PLATEAU phase was recognized, and a symbolic analysis was applied to the PLATEAU sequence during the training session and to pre-training and post-training sequences. Eventually, the median and interquartile range was computed for each one of the symbols. In 14 subjects the median value of the 2UV% in the PLATEAU phase was higher than the one found in pre-training sequences suggesting an early vagal reactivation after each sprint. Additionally, during the post-training sequences 11 subjects had lower values of 2UV% and 10 subjects had higher values of 0V% when compared to pre-training sequences, which respectively suggest a suppression of vagal tone and an increase in sympathetic tone, which could be explained by the intensity of the training session.