Department of Health and Exercise Science, Colorado State University, Fort Collins, USA.
Department of Health and Exercise Science, Colorado State University, Fort Collins, USA.
Neuropsychologia. 2022 Apr 15;168:108186. doi: 10.1016/j.neuropsychologia.2022.108186. Epub 2022 Feb 18.
The majority of tasks we perform every day require coordinated use of both hands. Following a stroke, the paretic hand contribution to bimanual tasks is often impaired, leading to asymmetric hand use. Grip strength is a commonly used clinical indicator of progress towards stroke motor recovery. The extent to which the paretic hand's contribution to bimanual tasks improves with increasing grip strength is not known. The purpose of this study is to determine how grip strength capacity of the paretic hand influences its contribution to bimanual tasks.
Twenty-one chronic stroke participants and ten older control participants volunteered to take part in this study. The individuals with stroke were recruited in two distinct groups based on the grip strength capacity of paretic hand, i.e., paretic hand strength/non-paretic hand strength, expressed as a percentage. The low strength-capacity group was identified as individuals with grip strength capacity less than 60% and the high strength-capacity group was individuals with grip strength capacity greater than or equal to 60%. All groups performed isometric, grip force contractions in two bimanual tasks - a maximum force production (MVC) task and a submaximal force control task. We quantified the magnitude of force contributed by the paretic and non-paretic hands during both tasks. Additionally, in the force control task we quantified the amount and structure of force variability using coefficient of variation (CV) and approximate entropy (ApEn) for both hands.
The amount of force contributed by the paretic hand increased in bimanual tasks with an increase in its grip strength capacity, (maximal force production: r = 0.85, p < 0.01; submaximal force control: r = 0.62, p < 0.01). In the bimanual MVC task and bimanual force control task, both hands contributed equal magnitudes of force in the high strength-capacity group but unequal forces in low strength-capacity group. Surprisingly, the amount and structure of force variability in bimanual force control tasks did not change with the increase in grip strength capacity, (CV of force: r = - 0.07, p = 0.77; ApEn: r = - 0.23, p = 0.31). Both low and high strength-capacity stroke groups showed significantly higher CV of force and heightened ApEn compared with the control group.
With the increase in grip strength capacity, the paretic hand contributes greater magnitude of force but continues to show persistent deficits in force modulation in bimanual tasks. Therefore, stroke rehabilitation should emphasize retraining of the paretic hand for force modulation to maximize its use in bimanual tasks.
我们每天执行的大多数任务都需要双手协调使用。中风后，瘫痪手在双手任务中的贡献通常会受到损害，导致手使用不对称。握力是衡量中风运动康复进展的常用临床指标。瘫痪手在双手任务中的贡献随握力增加而提高的程度尚不清楚。本研究的目的是确定瘫痪手的握力能力如何影响其在双手任务中的贡献。
21 名慢性中风参与者和 10 名老年对照组自愿参加了这项研究。根据瘫痪手的握力能力，即瘫痪手/非瘫痪手的力量百分比，将中风患者分为两组。低强度能力组的定义是握力能力小于 60%的个体，高强度能力组的定义是握力能力大于或等于 60%的个体。所有组均进行等长、握力收缩，在两项双手任务中进行：最大力产生（MVC）任务和次最大力控制任务。我们量化了在这两项任务中瘫痪手和非瘫痪手贡献的力的大小。此外，在力控制任务中，我们使用变异系数（CV）和近似熵（ApEn）对手的力变异性的幅度和结构进行了量化。
随着握力能力的增加，瘫痪手在双手任务中贡献的力增加（最大力产生：r=0.85，p<0.01；次最大力控制：r=0.62，p<0.01）。在双手 MVC 任务和双手力控制任务中，高强度能力组双手贡献的力相等，但低强度能力组双手贡献的力不相等。令人惊讶的是，力控制任务中力变异性的幅度和结构随握力能力的增加而没有变化（力的 CV：r=-0.07，p=0.77；ApEn：r=-0.23，p=0.31）。低强度和高强度能力的中风组与对照组相比，力的 CV 和 ApEn 明显更高。
随着握力能力的增加，瘫痪手贡献的力更大，但在双手任务中仍然存在力调节的持续缺陷。因此，中风康复应强调对瘫痪手进行力调节再训练，以最大限度地提高其在双手任务中的使用。
