To investigate the impact of various intensities of modified constraint-induced movement therapy (mCIMT) on the morphology and surface electromyography of upper limb muscles in stroke patients.

A total of 128 stroke patients who received treatment in the Department of Rehabilitation Medicine of our hospital from October 1, 2021, to June 1, 2023, were randomly divided into an observation group (n=64) and a control group (n=64) using numerical randomization. Both groups of patients received routine rehabilitation treatment, while the control group received mCIMT with daily sling restrictions on the healthy side for 3 hours, and underwent shaping training and self-training for 2 hours per day. The observation group was restricted to the healthy side with a daily sling for 3 hours, and the time for shaping and self-training was>3 hours/day. The EMG values of the triceps, biceps, and extensor carpi of the affected side of the two groups were compared before and 6 weeks after treatment. The muscle thickness and cross-sectional area of the triceps and biceps were measured by ultrasonic muscle, and the value of Upper Limb Fugl-Meyer assessment (UFMA) was recorded. Compare the inter-group and intra-group differences of the above values through independent sample t-test and paired sample t-test.

The average daily self-training duration of the observation group patients was (3.95±0.93) hours. After treatment, the surface electromyography (sEMG) root mean square value (RMS), cross-sectional area, and thickness of the triceps brachii, biceps brachii, and extensor carpi of both groups of patients showed significant improvements compared to previous treatment (P<0.05). After treatment, the surface electromyography (sEMG) root mean square (RMS) of the triceps brachii, biceps brachii, and extensor carpi in the observation group were significantly better than those in the control group [triceps brachii: (128.73±31.12) μV vs (119.47±17.48) μV; Biceps brachii: (138.56±37.58) μV vs (122.76±29.66) μV; Extensor carpi: (127.40±19.31) μV vs (118.24±20.68) μV]. The differences were statistically significant (t=2.075, 2.636, 2.591; P=0.041, 0.009, 0.011). The cross-sectional area and thickness of the triceps and biceps brachii in the observation group were higher than those in the control group [triceps brachii: (3.10±0.56) cm²vs (2.92±0.42) cm², (14.56±1.32) mm vs (13.88±1.37) mm; biceps brachii: (3.34±0.99) cm²vs (3.07 ± 0.35) cm², (15.15±1.54) mm vs (14.63±1.35) mm], and the differences were statistically significant (t=2.034, 2.016, 2.056, 2.054; P=0.044, 0.046, 0.042, 0.042). The FMA scores of the observation group patients after treatment were significantly higher than those of the control group [(38.10±9.51) points vs (32.64±7.32) points], and the difference was statistically significant (t=3.641, P<0.001).

Further increasing the training intensity of mCIMT (daily training>3 h) can significantly improve the sEMG performance of upper limbs and the score of FMA scale in stroke patients. It can also increase the muscle thickness and cross-sectional area of the biceps and triceps, helping patients recover upper limb function after a stroke.