To observe the differences in motor unit recruitment in healthy individuals versus those in stroke survivors, Mottram, et al. (2014) studied if the motor unit firing rates were impaired, when firing rates become constant even with an increasing force, during a voluntary contraction of the elbow flexor muscles in stroke survivors while increasing the motorneuron pool. Their subjected consisted of those who survived strokes and the control, healthy individuals and they performed two tests, one for the spastic-paretic lib and one for the contralateral limb. This study, Mottram, et al. (2014), found several differences in the motor unit recruitment between their healthy subjects and the stroke survivors. First, the threshold recruitment in spastic-paretic was lower than those in the healthy control when they performed the initial firing rates for both lower and higher threshold motor units. Secondly, they found that peak firing rates were lowering in the spastic-paretic for the lower threshold units.
Third, the spastic-paretic showed a longer duration of the impaired modulation in the firing rate for a lower and higher threshold motor unit in comparison to the contralateral muscle.