Force control deficits in chronic stroke: grip formation and release phases

Abstract

The aim of the study was to develop a novel approach for quantifying stair-stepping in a trajectory tracking task with the goal of understanding how age and stroke-related differences in motor control contribute to force control deficits. Nine stroke participants, nine age-matched controls, and nine young healthy adults performed an isometric gripping task while squeezing, holding, and releasing a cylindrical device. The visual tracking task involved three different rates of force production (5, 10, and 20% maximal force/s). Four outcome measures determined force control deficits: (a) root mean square error, (b) standard deviation, (c) step number, and (d) mean pause duration. Our findings indicate that step number, and especially mean pause duration, differentiated force control deficits in the three groups more effectively than the traditional root mean square error. Moreover, stroke participants showed the largest force control deficits during the grip release phase compared to age-matched and young healthy controls. Importantly, step number and mean pause duration quantified stair-stepping while measuring different constructs than root mean square error. Distinct step and duration interruptions in force modulation by persons post-stroke during the grip release phase provide new information with implications for motor recovery during rehabilitation.

Motor control differs for increasing and releasing force

“…Very few studies exist that compare young and older adults during force increase and release. Specifically, there is a single study that suggests exacerbation of force variability during force release in older adults relative to young adults (Naik et al 2011). Nonetheless, the gain of visual feedback and rate of force development was not controlled in that study, which could influence the results.…”

“…For instance, participants exhibited altered force control during a power grip task while releasing force than increasing force (Naik et al 2011). This finding seemed to be independent of the participant's age or rate of force generation.…”

Deficits in motor abilities for multi-finger force control in hemiparetic stroke survivors

“…To assess these motor abilities, various submaximal force-matching tasks and computational methods have been developed (Lodha et al 2010(Lodha et al , 2012Naik et al 2011;Lindberg et al 2012;Kang and Cauraugh 2014). Recently, a hierarchical variability decomposition (HVD) model was developed for the purpose of quantifying specific motor abilities that contribute to the motor behaviors of a redundant motor system (Koh et al 2015).…”

“…Although various motor abilities are required in steady force production tasks, the motor control deficits after stroke have been typically captured through a few indexes such as the steadiness of the finger force (Kurillo et al 2004;Lodha et al 2010Lodha et al , 2012Naik et al 2011;Lindberg et al 2012;Chang et al 2013). Other motor abilities such as accuracy, reproducibility, flexibility, or multiformity are not well understood in the stroke population, although one previous study reported that stroke survivors retained multiformity in reaching tasks (Reisman and Scholz 2003) while still showing deficits in reproducibility (Reisman and Scholz 2006).…”

Quantitative assessment of hand motor function in cervical spinal disorder patients using target tracking tests

“…Its clinical effectiveness has been well studied in other conditions, such as stroke [17][18][19], Parkinson disease [18,20], brain injury [14,21], and chronic inflammatory demyelinating polyneuropathy (CIDP) [19]. The target tracking test visualizes a predefined waveform that a subject must track by adjusting handgrip force in order to minimize the error between the waveform and the subject's response.…”