title: Anodal tDCS applied during strength training enhances motor cortical plasticity.
abstract: OBJECTIVE
  The objective of this study was to assess the effect of anodal transcranial direct current stimulation (a-tDCS) on voluntary dynamic strength and cortical plasticity when applied during a 3-wk strength training program for the wrist extensors.
  
  
  METHODS
  Thirty right-handed participants were randomly allocated to the tDCS, sham, or control group. The tDCS and sham group underwent 3 wk of heavy-load strength training of the right wrist extensors, with 20 min of a-tDCS (2 mA) or sham tDCS applied during training (double blinded). Outcome measures included voluntary dynamic wrist extension strength, muscle thickness, corticospinal excitability, short-interval intracortical inhibition (SICI), and silent period duration.
  
  
  RESULTS
  Maximal voluntary strength increased in both the tDCS and sham groups (14.89% and 11.17%, respectively, both P < 0.001). There was no difference in strength gain between the two groups (P = 0.229) and no change in muscle thickness (P = 0.15). The tDCS group demonstrated an increase in motor-evoked potential amplitude at 15%, 20%, and 25% above active motor threshold, which was accompanied by a decrease in SICI during 50% maximal voluntary isometric contraction and 20% maximal voluntary isometric contraction (all P < 0.05). Silent period decreased for both the tDCS and sham groups (P < 0.001).
  
  
  CONCLUSIONS
  The application of a-tDCS in combination with strength training of the wrist extensors in a healthy population did not provide additional benefit for voluntary dynamic strength gains when compared with standard strength training. However, strength training with a-tDCS appears to differentially modulate cortical plasticity via increases in corticospinal excitability and decreases in SICI, which did not occur following strength training alone.
authors.affiliation: Centre for Physical Activity and Nutrition Research, Deakin University, Victoria, Australia.
authors.forename: Ashlee M
authors.initials: AM
authors.lastname: Hendy
authors.forename: Dawson J
authors.initials: DJ
authors.lastname: Kidgell
mesh_terms: D000328:Adult; D004558:Electric Stimulation; D004576:Electromyography; D019054:Evoked Potentials, Motor / Q000502:physiology; D005080:Exercise Test; D005260:Female; D006801:Humans; D007537:Isometric Contraction; D008297:Male; D009044:Motor Cortex / Q000502:physiology*; D053580:Muscle Strength; D018482:Muscle, Skeletal / Q000033:anatomy & histology / Q000502:physiology*; D009473:Neuronal Plasticity / Q000502:physiology*; D011597:Psychomotor Performance / Q000502:physiology*; D055070:Resistance Training; D013997:Time Factors; D050781:Transcranial Magnetic Stimulation; D014953:Wrist; D055815:Young Adult