A physiological review of American football.

American football has been one of the most popular sports in North America within the past century and has recently received support and increased participation from European nations. Two of the biggest concerns regarding participation in American football are the high incidence of injury and the physical demand for preparation. A basic understanding of the physiological systems utilised in the sport of football is necessary in order to develop optimal training programmes geared specifically for preparation as well as the requirements of individual field positions. Previously, it has been assumed that football relies primarily on an anaerobic source of energy for adenosine triphosphate (ATP) resynthesis with approximately 90% coming from the phosphocreatine (PCr) energy system. In lieu of research conducted specifically with football players, it appears that the energy contribution from the anaerobic glycolytic pathway in this sport has been underestimated. The elevated blood lactate levels observed in football players following game participation cast doubt on this hypothesis. Identifying position specific characteristics may also enhance the development of training programmes based on the requirements of the different positions. It appears that offensive and defensive linemen are generally larger, have higher levels of percent body fat and have greater absolute strength scores than all other positions. Offensive backs, defensive backs and wide receivers tend to display the lowest percentages of body fat, lower absolute strength scores, fastest times over 5, 10, 40 and 300m and the highest relative VO2max values. Linebackers appeared to represent a transition group mid way between the backs and linemen for size, body composition, strength, speed and endurance as well as positional duties. Findings within the literature suggest that a lack of cardiovascular development of university and professional football players may prove to be a hindrance to performance with specific regards to thermal regulation. Additional aerobic conditioning as well as the reduction of percent body fat would not only enhance performance, but might play a key role in preventing injuries and allowing a smoother transition into life after football.

Mechanical efficiency of the elbow flexors in rowing.

Biomechanical and especially kinesiological investigations of the mechanical efficiency of rowers are rarely found in today's literature. The coach frequently relates to skills or technical movements in terms of their aesthetic appearance rather than their mechanical effectiveness. The force output of the elbow flexors appears to be a function of the forearm position. The literature referring to the mechanical efficiency of the elbow flexors seems to favor both semiprone and supine positions, whereas the prone position appears to be discredited. It is the latter grip position that is actually employed and traditionally accepted in the sport of rowing. In fact, this technique was never challenged or scientifically researched to see whether a modified one might lead to better efficiency. Consequently, the purpose of this investigation was to analyze whether athletes' force output differed if the gripping technique was changed from pronation to a semiprone grip (one arm prone, the other semiprone). Under the specific conditions of this investigation, it was demonstrated that the semiprone position was generating greater force output and higher electrical activity, thus being superior to the classical prone grip.

Force analysis of the rowing stroke employing two differing oar grips.

The velocity of the rowing boat appears to depend on the force which the athlete applies at the handle of the oar. Although force is generated by legs, upper body, and arms, the latter are the only limbs which actually transmit and apply the force against the oar. The force output of the arms seem to be a function of the forearm position used by the athlete while gripping the oar. The traditional gripping technique is with the forearms in pronation. This technique was never challenged or scientifically researched to see whatever a modified one might lead to better efficiency. Consequently, the purpose of this investigation was to analyze whether athletes' force output differed if the gripping technique was changed from pronation to a semiprone grip (one arm prone, the other semiprone). Under the specific conditions of this investigation it was demonstrated that the semiprone position was generating greater force output, thus being superior to the classical prone grip.

Technique and muscle force.

In the sport of rowing, as may be the case in other sports, the coach frequently tends to relate to skills or technical movement in terms of their aesthetic appearance rather than to their kinesiological requirements, or muscular effectiveness. Maximal isometric strength was tested (N = 18) in three components of the rowing stroke: height of sagittal pull; angle of pull in sagittal plane; and the power position in both the catch and the finish. The results of this investigation suggest that certain technical parameters commonly utilized by rowing coaches seem to be less efficient when discussing muscular effectiveness. Thus one might conclude, that slight alterations in the cycle of the rowing stroke are desirable.