Kinematic and electromyographic analysis of the legs, torso, and arms during an exhaustive run

Distance running performance is dependent on the integration of the complex mechanisms of neuromuscular control, central and peripheral cardiovascular performance, and fatigue resistance. The end result of these interactions is movement, as defined by running mechanics. During high-intensity running, specific muscles may demonstrate signs of neuromuscular fatigue, which may alter running local and whole-body running mechanics. There are few published studies specific to running which describe neuromuscular fatigue of torso and arm muscles, how fatigue affects the kinematics of the upper body, and how neuromuscular fatigue relates to kinematic changes. Fifteen trained male distance runners were recruited to participate in this study. Each subject performed an exhaustive run at an intensity approximating 95% of maximal oxygen consumption. Electromyographic data were collected from thirteen muscles unilaterally and kinematic data were collected from key joints of the upper and lower body during the exhaustive run. Increased motor unit recruitment was observed in nearly all muscles studied, many demonstrating statistically significant linear trends. Torso muscles demonstrated similar levels of recruitment to the leg muscles. Statistically significant models of neuromuscular fatigue were observed during the exhaustive run for two leg muscles and one torso muscle. None of the arm muscles demonstrated statistically significant changes indicative of fatigue. A number of statistically significant kinematic changes were observed throughout the run for all regions of the body. Some kinematic changes were significantly correlated to changes in motor unit recruitment patterns or neuromuscular fatigue. These results confirm that runners develop neuromuscular fatigue during high intensity running and this may limit performance. Based on these results, general recommendations for muscle-specific training programs may be made for groups of athletes similar to the population studied. However, there are many individual differences within this population and therefore personalized training recommendations require a thorough neuromuscular and kinematic evaluation. Groups of runners with different demographics may also show different trends in fatigue patterns. Therefore, further research is needed to investigate the effect of exhaustive running on various populations. Additionally, research is needed to validate training programs which aim to delay or prevent neuromuscular fatigue as a means of enhancing running performance