Fatigue after stroke is a widely observed phenomenon. Unfortunately, the mechanisms underlying the causes of post stroke fatigue are largely unknown. Using Transcranial Magnetic Stimulation (TMS), we can look at the conduction of the motor pathways via current stimulation delivered through a coil placed on the scalp. TMS is a widely accepted measure of both central nervous system excitation and inhibition. Using EMG recording on the muscle itself and TMS, we can see muscle and central nervous system measures simultaneously. In addition to TMS, in this project we are using force transducers designed for measuring grip strength. We can see how much force the participant can biomechanically produce by performing maximal voluntary contractions (MVCs). MVCs are generated by having the participant squeeze the transducer as hard as possible for 6 seconds. We take 3 trials and average the results. Since stroke participants can vary widely in force production on the affected side as compared with healthy controls, for this project we have chosen to have all participants use the same grip norms. We are using a paper by Virgil Mathiowetz (1985) as a reference. In this paper, Mathiowetz has a table in age increments of 5 years with corresponding normative grip strength information for both men and women and for the left and right hand. We decided to use this normative information so that each stroke participant and his/her age and sex-matched control would be performing at the same biomechanical level. This allows us to control the variable of differing force levels affecting the results. For this experiment, we have the participant perform 3 MVCs at baseline for the right, left, and both hands (bimanual task) with transducers, each with 1 min rest between. We also have a bimanual force control component that involves taking the bimanual MVC and scaling a trajectory for 50% and having the participant hold that force for 30 second increments, 3 times with 1 min rest between. Next, we perform baseline TMS measures, looking at motor evoked potentials (excitation measures) and silent periods (inhibition measures). Then, we perform the fatiguing task. This includes a trajectory of 7 seconds hold, 3 seconds rest for 10 blocks based on 30% of the normative data (Mathiowetz) for that participant. After each 10 block trial, the participant must perform 1 MVC with no rest. We keep doing the fatigue task until the participant fails to reach the guideline of 30% half the block time (3.5 seconds)for 3 consective blocks. Immediately following task failure, we take one more MVC and another bimanual force control task. We then take the TMS measures again (both MEP and silent periods). Then, TMS is repeated at 30 minutes and 60 minutes afterwards in order to look at how the nervous system recovers. In this project, we are looking at how both force production and central nervous system measures are affected by fatigue. We want to look at both the fatigued hand and how the other hand compensates for this reduction in the bimanual force control task. With the TMS measures, we want to look at the inhibitory measures (silent period) to see how it is affected immediately following a fatiguing task and how long it the differences persist over time.