The main purpose of this study was to examine the relationship between controlled levels of effort induced in the nonplegic forearm and the associated reactions (ARs) elicited in the plegic forearm of poststroke patients. Twenty hemiplegic patients, eight women and 12 men, were asked to isometrically contract their forearm flexors, on the unaffected side, at levels equal to 100%, 75% and 50% of the maximal effort. Exerting submaximal effort was accomplished by monitoring the digitally displayed force levels which were measured by dynamometer. The ARs were measured using a goniometer. Findings revealed a direct relationship between the effort level and severity of the ARs, namely, contracting the flexors at 50%, 75% and 100% was associated with an average increase in the elbow angle of 13°, 29° and 47° respectively. Owing to the large inter-trial variations in the ARs, this trend did not reach statistical significance. The implications of the technique are discussed.