Effect of exercise on pain processing and motor output in people with knee osteoarthritis: a systematic review and meta-analysis.

OBJECTIVE: Guidelines recommend exercise as a core treatment for knee osteoarthritis. However, it is unclear how exercise affects measures of pain processing and motor function. The aim was to evaluate the effect of exercise on measures of pain processing and motor function in people with knee osteoarthritis. METHODS: We searched five electronic databases (MEDLINE, EMBASE, CINAHL, SCOPUS and Cochrane Central Register of Controlled Trials) for studies on knee osteoarthritis, of any design, evaluating pain processing and motor function before and after exercise. Data were pooled with random-effects meta-analysis. Study quality was assessed using the Downs and Black and quality of evidence was assessed using the GRADE. RESULTS: Eighteen studies were eligible and 16 were included. Following acute exercise, pressure pain threshold increased local to the study limb (standardised mean difference [95% confidence interval (CI)] 0.26, [0.02, 0.51], n = 159 from 5 studies), but there was no statistically significant change remote from the study limb (0.09, [-0.11, 0.29], n = 90 from 4 studies). Following an exercise program (range 5-12 weeks) there were no statistically significant changes in pressure pain threshold (local 0.23, [-0.01, 0.47], n = 218 from 8 studies; remote 0.33 [-0.13, 0.79], n = 76 from 4 studies), temporal pain summation (0.38 [-0.08, 0.85], n = 122 from 3 studies) or voluntary quadriceps muscle activation (4.23% [-1.84 to 10.30], n = 139 from 4 studies). CONCLUSION: Very-low quality evidence suggests that pressure pain threshold increases following acute exercise. Very-low quality evidence suggests that pressure pain threshold, temporal pain summation or voluntary quadriceps activation do not change statistically significantly following exercise programs.

Brain control of volitional ankle tasks in people with chronic stroke and in healthy individuals.

This study explored the relationships between motor cortical control of ankle dorsiflexors and clinical impairments of volitional ankle dorsiflexion in people with chronic stroke. Eighteen persons with stroke and 14 controls were evaluated. Clinical tools were used to assess ankle dorsiflexion amplitude and isometric strength. Transcranial magnetic stimulation (TMS) of the primary motor cortex (M1) tested the functional integrity of cortical circuits controlling the tibialis anterior (TA). All clinical scores and most TMS outcomes were impaired in people with chronic stroke. The lower clinical scores were related to the reduction of the strength of corticospinal projections onto spinal motoneurons. Concurrent TMS and clinical testing in chronic stroke provided original data demonstrating relationships between the integrity of cortical and corticospinal components of TA motor control and volitional ankle tasks. Our study proposes that volitional ankle mobilization in chronic stroke may be explained by the residual abnormal M1 circuits which may be responsive for rehabilitation intervention. This should be confirmed in longitudinal studies with larger samples to determine whether TMS outcomes associated with lower limb muscles are predictive of clinical changes or vice versa.

[Cerebral reorganization in chronic low back pain and neurostimulation to improve motor control]. / Réorganisation cérébrale en lombalgie chronique et neurostimulation pour l'amélioration du contrôle moteur.

Chronic recurrent pain results in brain reorganization for cortical sensory and motor representation of muscles. This review supports the hypothesis that maladaptive plasticity in chronic low back pain patients could be associated with disorders of volitional activation of trunk/pelvis muscles and alterations of their anticipatory motor patterns for postural control. This is actually observed for the transversus abdominis muscle, an abdominal muscle that stabilizes the lumbosacral spine against external and internal postural perturbations. Indeed, voluntary activation of this muscle is more difficult in low back pain and a posterolateral translation of its cortical motor representation is observed in association with a delay of its anticipatory activation (usually observed in any focal limb movement). During physiotherapy, low back pain patients are trained to hollowing for contracting the transversus abdominis muscle, which normalizes both activation delays and cortical motor representation. This motor rehabilitation could be potentiated by peripheral repetitive magnetic stimulation directly over the nerves/muscles. This review introduces the magnetic stimulation technique and proposes to combine peripheral theta-burst stimulation to conventional therapy for increasing the functional gain. This may facilitate the activation of sensory afferents and modulate cortical plasticity to improve (or even re-activate) the sensorimotor control and possibly influence pain. Peripheral magnetic stimulation as an ancillary treatment adjuvant for promoting motor control in low back pain might also be relevant in any other neurological or musculoskeletal disorder with underlying maladaptive brain reorganization.