Unilateral Versus Bilateral Upper Limb Training After Stroke

#045 – Unilateral Versus Bilateral Upper Limb Training After Stroke

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Unilateral Upper Limb Training

  • Unilateral upper limb training (UULT) is a training method where only the affected limb is trained, including repetitive task-related training and constraint-induced movement training (CIMT).
  • The hypothesis behind UULT is restricting the use of non-paretic upper limb and encouraging the use of the paretic upper limb could reduce the inhibitory flow from the contralesional M1 to the ipsilesional M1, therefore improving the functional recovery of the hemiplegic upper limb.
  • However, UULT is debated, as some studies suggest that UULT is only effective for patients with high hemiplegic arm functions and cannot improve bimanual coordination.

Bilateral Upper Limb Training

  • Bilateral upper limb training (BULT) is performed with both limbs. BULT includes bilateral functional task training, bilateral robotic-assisted training, and bilateral arm training with rhythmic cueing.
  • Studies found that BULT can promote re-balancing of the abnormal IHI caused by stroke, as indicated by the decrease of excessive inhibition from the contralesional to ipsilesional primary motor cortex (M1). Also, fMRI studies revealed that BULT could increase the interhemispheric coupling (the sensorimotor areas) as well as intra-hemisphere coupling (ipsilesional SMA to M1).

Hypotheses behind the positive effect of BULT

  1. BULT may facilitate positive neural interactions among sensorimotor-related areas of the ipsilesional and contralesional hemispheres to enhance inter-/intra-hemispheric coupling in stroke survivors.
  2. BULT may promote motor recovery in stroke patients through decreased SICI over the impaired hemisphere.
  3. A more symmetric IHI has been shown to be correlated with the improvement in motor functions of the paretic upper extremity following BULT.
  4. Increased activity in the sensorimotor related areas (M1, SMA, PMC, and S1) that might contribute to functional reorganization and neuroplasticity was associated with BULT.

Recent Evidence on Unilateral versus Bilateral Upper Limb Training

The modulatory effects of bilateral arm training (BAT) on the brain in stroke patients

A systematic review, 2019. (Restricted Access)


  • Explore the brain modulatory effects of BAT in patients with stroke as measured by neuroimaging and neurophysiological outcomes.

Interventions in the included the studies

  • Robot-assisted bilateral training, by 4 studies.
  • EMG-triggered electrical muscle stimulation with BAT by 1 study.
  • Synchronous BAT by 4 studies.
  • BAT with rhythmic auditory cueing (BATRAC).


  • 11 studies including 225 stroke participants.
  • The motor-related areas are activated, especially M1, SMA, and S1, in the affected hemisphere, which facilitated plastic reorganization in the brain following BAT;
  • Increased short-interval intracortical inhibition (SICI) in the contralesional hemisphere is seen with BAT, and such an increase indicates BAT may enhance the contralesional M1 as a functionally integrated area used to reorganized cortical network.
  • BAT may promote brain connectivity and increase both the inter-hemispheric (SMA-SMA, SMA-M1) and intra-hemispheric (S1-SMA, S1-M1) coupling when performing motor-related tasks.

SMA: supplementary motor area; S1 primary somatosensory cortex; M1: primary motor cortex;


  • BAT may be more effective for improving the upper extremity motor recovery in stroke patients compared with UAT by inducing positive inter- and intra-hemispheric coupling and enhanced activation in the ipsilesional primary motor area (M1), supplementary motor area (SMA), and primary sensory cortex (S1).
  • BAT may increase cortical network reorganization by inducing an increase in SICI in the unaffected hemisphere, thus contributing to motor recovery.

Comparison of bilateral and unilateral upper limb training in people with stroke

A systematic review and meta-analysis, 2019. (Open Access)


  • Compare the improvements in motor impairment and functional performances of people with stroke after bilateral upper limb training (BULT) and unilateral upper limb training (UULT).


21 full-text articles with 842 subjects.


  • Nine studies compared the effects of bilateral functional task training (e.g., folding a towel, lifting two cups and picking up two pegs bilaterally) and unilateral task-related training.
  • Two studies compared the effects of bilateral functional task training and dose-matched neurodevelopmental therapy, weight-bearing exercises and unilateral functional task training.
  • Two studies compared the effects of bilateral functional task training and unilateral functional task training in people with chronic stroke.
  • 1 study investigated the combined effects of 30 minutes of bilateral functional arm training and 30 minutes of standardized occupational therapy, which included neurodevelopmental therapy, stretching exercises, resistance training and fine movement training of the affected upper limb. The outcomes of combined therapy were then compared with those observed after 60 minutes of standardized occupational therapy.
  • Seven studies explored the effects of bilateral robotic-assisted or resistance training on upper limb motor function after stroke.
  • Three studies compared the effects of 90 minutes of bilateral robotic-assisted training and 90 minutes of unilateral robotic-assisted training.
  • Three studies compared the effects of bilateral robotic-assisted training and dose-matched unilateral functional task training in subjects with chronic stroke.
  • 1 study compared a combination of robotic-assisted priming and task-oriented training with task-oriented training alone on the affected upper limbs of patients with sub-acute stroke.
  • Five studies compared the effects of bilateral arm training involving rhythmic auditory cueing with the effects of dose-matched unilateral upper limb training, which included neurodevelopmental therapy, upper limb mobilization, strengthening exercises and fine movement training.

Motor impairment

  • Significantly greater improvement in motor impairment in the BULT group, compared with the UULT group as measured by FMA-UE.
    • No significant improvements were observed with BULT when compared with UULT in the subgroups according to post-stroke duration.

Functional performance

  • Functional performance was assessed using the time component of WMFT and the WMFT, ARAT and BBT scores.
  • No significant difference was observed between BULT and UULT in terms of improvements in the score component of the WMFT.
    • BULT did not yield significant improvement when compared with UULT in any of the post-stroke duration subgroups
  • A comparison of BULT and UULT revealed no significant difference in the time component of the WMFT
    • BULT did not yield a no significant improvement over UULT in the subgroups.


  • Both BULT and UULT can help to improve motor impairment and functional performance after stroke.
  • Notably, BULT was superior to UULT in terms of improving motor impairment after stroke, as measured by the FMA-UE.
  • However, BULT and UULT yielded similar effects on functional performance in people with stroke, as measured by the WMFT, ARAT and BBT.

The Effects of Unilateral Versus Bilateral Motor Training on Upper Limb Function in Adults with Chronic Stroke

A Systematic Review, 2021 (Restricted Access)


Evaluate and compare the effects of unilateral and bilateral motor training on upper limb motor function in chronic stroke patients.


  • 7 randomized controlled trials included
  • Unilateral and bilateral training improved upper limb function in chronic stroke patients.
  • Improvements between interventions were equivocal.
  • Bilateral upper limb training however may be more efficacious for increasing upper limb strength and quality of movement, with unilateral training more beneficial for recovering functional ability for activities of daily living.


  • While the findings of the included studies support the use of unilateral and bilateral motor training post chronic stroke, the seven studies that were included methodologically all presented with limitations, hence strong conclusions cannot be drawn and further research is warranted.

Robot-Assisted Therapy for Upper Extremity Motor Impairment After Stroke

A Systematic Review and Meta-Analysis, 2021. (Restricted Access)


(Only the results of bilateral and unilateral training)

  • The subgroup analysis revealed that the effects of unilateral robot-assisted therapy, but not that of bilateral robot-assisted therapy, were superior to conventional rehabilitation.

How to perform mirror therapy after stroke? Evidence from a meta-analysis

Using Mirror therapy, movements executed unilaterally showed a higher effect on motor function than a bilateral execution.

What now?

  • From the articles above and previous research discussed, there is no clear superiority for either one of the treatments over the other.
  • Nonetheless, it seems that both Unilateral and Bilateral UL training are effective to improve motor impairment and function for stroke patients,
  • Unilateral UL training could be more beneficial for improving functional abilities
  • Bilateral UL training can improve strength and motor impairment
  • Unilateral upper limb training using robot-assisted training or mirror therapy could be more effective than bilateral upper limb training.

Which should I use?

  • Use both to improve UL function
  • Use bilateral UL training to promote motor recovery
  • If you’re using robot-assisted training or mirror therapy, unilateral training might be the better option.


Thank your for reading.

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