Upper extremity muscle thickness and grip strength following a boccia-based intervention in hemiparetic individuals

The global prevalence of stroke is increasing, highlighting the critical importance of effective post-stroke rehabilitation. Although boccia was originally designed for individuals with special needs, its potential benefits for stroke rehabilitation, particularly regarding task-related changes in ultrasound-observed muscle characteristics, have not been thoroughly investigated. This study aimed to examine the association of an 8-week boccia-based intervention with changes in upper extremity muscle thickness and grip strength in individuals with hemiparesis following stroke. A total of 22 stroke survivors were randomly allocated to a boccia group (Boc, n = 12) or a control group (Ctrl, n = 10). While the control group received conventional physical therapy for eight weeks, the boccia group participated in both physical therapy and boccia-based intervention three times per week. Upper extremity muscle thickness and grip strength were assessed before and after the intervention. In the control group, a significant increase was observed only in the triceps brachii muscle thickness. In contrast, the boccia group demonstrated statistically detectable increases in forearm muscles (flexor digitorum profundus, flexor digitorum superficialis, pronator teres, and brachioradialis), triceps brachii muscle thickness, and grip strength. Incorporating boccia-based intervention into the rehabilitation programs of individuals with hemiparesis after stroke may be associated with broader upper extremity muscle involvement and concurrent improvements in grip strength. These findings should be interpreted as exploratory and hypothesis-generating. The trial registration number: NCT07254273 (https://clinicaltrials.gov/study/NCT07254273), Unique Protocol Id: E-15604681-100-234561 and the date of registration: 2025/11/13 (https://register.clinicaltrials.gov/prs/beta/studies/S000GEKF00000050/recordSummary). Retrospectively registered.