Progressive shoulder abduction loading is a crucial element of arm rehabilitation in chronic stroke

Abstract

Background: Total reaching range of motion (work area) diminishes as a function of shoulder abduction loading in the paretic arm in individuals with chronic hemiparetic stroke. This occurs when reaching outward against gravity or during transport of an object.

Objectives: This study implements 2 closely related impairment-based interventions to identify the effect of a subcomponent of reaching exercise thought to be a crucial element in arm rehabilitation.

Methods: A total of 14 individuals with chronic moderate to severe hemiparesis participated in the participant-blinded, randomized controlled study. The experimental group progressively trained for 8 weeks to actively support the weight of the arm, up to and beyond, while reaching to various outward targets. The control group practiced the same reaching tasks with matched frequency and duration with the weight of the arm supported. Work area and isometric strength were measured before and after the intervention.

Results: Change scores for work area at 9 loads were calculated for each group. Change scores were significantly larger for the experimental group indicating a larger increase in work area, especially shoulder abduction loads equivalent to those experienced during object transport. Changes in strength were not found within or between groups.

Conclusions: Progressive shoulder abduction loading can be utilized to ameliorate reaching range of motion against gravity. Future work should investigate the dosage response of this intervention, as well as test whether shoulder abduction loading can augment other therapeutic techniques such as goal-directed functional task practice and behavioral shaping to enhance real-world arm function.

Figures

Figure 1

Example of a Research Participant Positioned With the ACT3D

Figure 2

Example of a Top-Down View of Calculated Work Areas for Movement While Fully Supported by the Horizontal Haptic Surface (Table) and 7 Shoulder Abduction Loading Levels (0%-150% of Limb Weight) Note: Work area reduces as a function of increasing shoulder abduction loading where the 100% level is equivalent to reaching under normal gravitational loading conditions.

Figure 3

Work Area Change Scores (m2) for Both the Experimental and Control Groups Following the Intervention Period Note: Change scores in the experimental group are positive indicating improvement and are significantly greater than the control group at shoulder abduction levels experienced during everyday reaching and retrieval tasks. Change scores at 100% to 175% are clinically meaningful* in that they equate to improvements of >20% of work area while supported on the haptic table or >60% of the work area at the respective loading level. *A 0.10 m2 (1000 cm2) change score is equivalent to the average length of the upper limb segment squared (32 cm × 32 cm).