Title : The effects of isokinetic lower limb strength training on motor function in patients with stroke-related sarcopenia
Abstract:
Objective: To compare the effects of bilateral versus paretic lower limb isokinetic strength training on motor function and balance in patients with stroke-related sarcopenia.
Methods: Fifty-four hemiplegic patients with stroke-related sarcopenia admitted to Nanjing First Hospital from May to December 2025 were randomly assigned to an experimental group 
and a control group . After two dropouts per group, 25 patients in each group completed the study. All participants received conventional rehabilitation. The control group additionally performed isokinetic training of the paretic lower limb, while the experimental group performed bilateral lower limb isokinetic training. Knee flexion and extension were trained at 60°/s, 90°/s, and 120°/s, 4 sets of 10 repetitions per velocity, once daily, 5 days/week for 4 weeks. Primary outcomes were bilateral grip strength; isokinetic parameters (relative peak torque/body weight [PT/BW], total work, average power) at 60°/s and 120°/s; quadriceps and triceps surae muscle thickness measured by musculoskeletal ultrasound; and the Short Physical Performance Battery (SPPB). Secondary outcomes included the Fugl-Meyer Assessment–Lower Extremity (FMA-LE), modified Barthel Index (MBI), Berg Balance Scale (BBS), center of pressure (COP) parameters (sway length and area with eyes open/closed), and gait parameters (stride length, gait speed, fall risk).
Results: Within-group comparisons showed that after treatment, paretic grip strength, all isokinetic parameters, muscle thickness, SPPB, MBI, FMA-LE, BBS, COP parameters, and gait parameters improved significantly in both groups (P<0.05), whereas unaffected-side grip strength did not change significantly (P>0.05). Between-group comparisons revealed that the experimental group achieved significantly better outcomes in primary outcomes (isokinetic parameters, muscle thickness, SPPB) and all secondary outcomes 
compared with the control group (P<0.05), with no significant difference in bilateral grip strength between groups (P>0.05). Specifically, in the experimental group, unaffected-side knee flexor PT/BW at 60°/s was (67.61±9.50) N·m/kg and extensor PT/BW (117.47±19.24) N·m/kg, while affected-side knee flexor PT/BW was (40.34±6.96) N·m/kg and extensor PT/BW (82.91±11.60) N·m/kg—all significantly higher than those in the control group. Similar superiority was observed for total work, average power, and muscle thickness (e.g., unaffected quadriceps: 2.65±0.30 cm). The experimental group also had significantly higher SPPB [9(9,10)], FMA-LE (25.48±3.66), MBI (74.64±13.90), and BBS (47.12±6.95) scores, shorter COP sway length and area, longer stride length (0.76±0.13 m), faster gait speed 
, and lower fall risk (16.58±5.66%) (all P<0.05).
Conclusion: Bilateral lower limb isokinetic strength training is superior to paretic-side-only training in improving lower limb muscle strength, muscle thickness, physical function, activities of daily living, balance, and gait ability in patients with stroke-related sarcopenia. Grip strength gains did not differ between the two training strategies.
