Designing a study to examine acute cross-over effects of lower limb muscle fatigue during upright standing

Research Question: Are there acute cross-over effects of lower limb muscle fatigue on movement strategies of young adults during upright standing? Background: Our study will make use of three major concepts: the cross-education phenomenon, muscle fatigue, and postural control. The cross-education phenomenon is a theory that dates as far back as 1898 in which it was first coined by Walter Davis in his work and it pertains to the effects of training one side of the body to the untrained contralateral or opposite side. Cross-education experiments have since been expanding in various other aspects of physiology, such as its effects in strength training, muscle size preservation, hip flexor stretching, speed of voluntary effort, and flexibility to name a few. Looking at these various research studies, we can see evidence of cross-education phenomenon in various physiological aspects regardless if it's upper extremity or lower extremity. This leads us to ask if cross-education can be seen in movement strategies and postural control as well. Muscle fatigue, our second concept, is the decrease in maximal force as a response to contractile activity. It can be described in various ways, such as central vs peripheral or global vs local. Finally, Postural control is the ability to control one's body position in space for stability and orientation. Simply put, it is the ability to be able to maintain upright standing. Looking at these three components-the cross-education phenomenon, muscle fatigue, and postural control-that have been studied over the last century, we have developed a research idea that uses the influence these three have on each other. Our research will generate a quantitative analysis of the cross-educational phenomenon on postural control by observing contralateral muscle fatigue. Materials and Methods: Twenty individuals are expected to enroll in the study. Participants will be healthy young (18-35 years old) adults, with no known balance disorder, neuromuscular disorder/impairment, or lower extremity injuries. Postural control data will be collected with a force plate. Participants will perform pre- and post-fatigue balance tasks on a force plate that includes single-legged standing with variations of the right and left foot and stable and unstable surface types. Following initial balance assessment a fatigue task of single leg standing calf raises will be performed until exhaustion. Data from pre-fatigue balance tasks and post-fatigue balance tasks will be analyzed and compared. Anticipated Results, Conclusions, and Impact: We anticipate that acute fatiguability on one of the lower limbs in our subjects will influence contralateral postural stability and control during upright standing. We expect this to be supported objectively by measurements of the muscle activity from the force plate device. As for impact, we want to increase our understanding on postural control training through cross-education and be able to provide evidence via objective data. We also hope this study can provide new insight for various applications, such as physical rehabilitation or performance training.