title: Concurrent transcranial direct current stimulation and progressive resistance training in Parkinson's disease: study protocol for a randomised controlled trial.
abstract: Parkinson's disease (PD) results from a loss of dopamine in the brain, leading to movement dysfunctions such as bradykinesia, postural instability, resting tremor and muscle rigidity. Furthermore, dopamine deficiency in PD has been shown to result in maladaptive plasticity of the primary motor cortex (M1). Progressive resistance training (PRT) is a popular intervention in PD that improves muscular strength and results in clinically significant improvements on the Unified Parkinson's Disease Rating Scale (UPDRS). In separate studies, the application of anodal transcranial direct current stimulation (a-tDCS) to the M1 has been shown to improve motor function in PD; however, the combined use of tDCS and PRT has not been investigated.
  
  
  
  We propose a 6-week, double-blind randomised controlled trial combining M1 tDCS and PRT of the lower body in participants (n = 42) with moderate PD (Hoehn and Yahr scale score 2-4). Supervised lower body PRT combined with functional balance tasks will be performed three times per week with concurrent a-tDCS delivered at 2 mA for 20 minutes (a-tDCS group) or with sham tDCS (sham group). Control participants will receive standard care (control group). Outcome measures will include functional strength, gait speed and variability, balance, neurophysiological function at rest and during movement execution, and the UPDRS motor subscale, measured at baseline, 3 weeks (during), 6 weeks (post), and 9 weeks (retention). Ethical approval has been granted by the Deakin University Human Research Ethics Committee (project number 2015-014), and the trial has been registered with the Australian New Zealand Clinical Trials Registry (ACTRN12615001241527).
  
  
  
  This will be the first randomised controlled trial to combine PRT and a-tDCS targeting balance and gait in people with PD. The study will elucidate the functional, clinical and neurophysiological outcomes of combined PRT and a-tDCS. It is hypothesised that combined PRT and a-tDCS will significantly improve lower limb strength, postural sway, gait speed and stride variability compared with PRT with sham tDCS. Further, we hypothesise that pre-frontal cortex activation during dual-task cognitive and gait/balance activities will be reduced, and that M1 excitability and inhibition will be augmented, following the combined PRT and a-tDCS intervention.
  
  
  
  Australian New Zealand Clinical Trials Registry ACTRN12615001241527 . Registered on 12 November 2015.
authors.affiliation: School of Exercise and Nutrition Sciences, Deakin University, Melbourne, Australia.
authors.forename: Ashlee M
authors.initials: AM
authors.lastname: Hendy
authors.affiliation: School of Exercise and Nutrition Sciences, Deakin University, Melbourne, Australia.
authors.forename: Alex
authors.initials: A
authors.lastname: Tillman
authors.affiliation: Institute for Physical Activity and Nutrition (IPAN), Deakin University, Burwood, 3125, Melbourne, VIC, Australia.
authors.forename: Timo
authors.initials: T
authors.lastname: Rantalainen
authors.affiliation: EuroMov, University of Montpellier, Montpellier, France.
authors.forename: Makii
authors.initials: M
authors.lastname: Muthalib
authors.affiliation: Clinical Exercise Science Research Program, Institute of Sport, Exercise and Active Living, Victoria University, Melbourne, Australia.|Stroke Division, The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Melbourne, Australia.
authors.forename: Liam
authors.initials: L
authors.lastname: Johnson
authors.affiliation: La Trobe Sport and Exercise Medicine Research Centre, School of Allied Health, La Trobe University, Melbourne, Australia.
authors.forename: Dawson J
authors.initials: DJ
authors.lastname: Kidgell
authors.affiliation: School of Exercise and Nutrition Sciences, Deakin University, Melbourne, Australia.|La Trobe Rural Health School, College of Science, Health and Engineering, La Trobe University, Bendigo, Australia.
authors.forename: Daniel
authors.initials: D
authors.lastname: Wundersitz
authors.affiliation: Cognitive Neuroscience Unit, School of Psychology, Deakin University, Melbourne, Australia.
authors.forename: Peter G
authors.initials: PG
authors.lastname: Enticott
authors.affiliation: School of Exercise and Nutrition Sciences, Deakin University, Melbourne, Australia. weipeng.teo@deakin.edu.au.|Institute for Physical Activity and Nutrition (IPAN), Deakin University, Burwood, 3125, Melbourne, VIC, Australia. weipeng.teo@deakin.edu.au.
authors.forename: Wei-Peng
authors.identifier: 0000-0003-3929-9778
authors.initials: WP
authors.lastname: Teo
mesh_terms: D002985:Clinical Protocols; D004311:Double-Blind Method; D005684:Gait; D006801:Humans; D017063:Outcome Assessment, Health Care; D010300:Parkinson Disease / Q000628:therapy*; D004856:Postural Balance; D055070:Resistance Training; D018401:Sample Size; D065908:Transcranial Direct Current Stimulation
keywords: Balance; Gait; Neuroplasticity; Non-invasive brain stimulation; Parkinson’s disease; fNIRS