title: Load knowledge reduces rapid force production and muscle activation during maximal-effort concentric lifts.
abstract: OBJECTIVE
  Rapid force development is a key factor influencing performance and injury risk in movements where little time is available for force production; thus there is a need to develop interventions that enhance this ability. In the present study, the influence of load knowledge on mechanical output [rate of force development; (RFD) and power] and muscle activation [electromyographic (EMG) responses] in the concentric-only bench press throw exercise was studied.
  
  
  METHODS
  Fifteen strength-trained individuals performed 6 sets of 6 maximal explosive repetitions in a single test session after extensive familiarization. In three of these sets the subjects were given knowledge about the load before each repetition (known condition; KC), whereas in the other three sets they were given no information (unknown condition; UC). In both conditions the loads were 30, 50 and 70 % of maximum, but condition and load orders were randomized.
  
  
  RESULTS
  RFD (24-50 %) and power output (20-39 %) were significantly higher in UC in the early time intervals from movement onset (<150 ms). In addition, UC elicited greater EMG amplitudes in anterior deltoid both prior to movement onset (pre50-0 ms) and in the early time intervals (<100 ms) after movement onset, and in pectoralis major after movement onset (<100 ms).
  
  
  CONCLUSIONS
  UC resulted in a greater initial activation of the muscles and both a higher RFD and mechanical power output in the early phase of the movement under all loading conditions (30-70 % of maximum). UC appears to offer a novel neuromuscular stimulus, and further research on the effects of continued exposure is warranted.
authors.affiliation: Sports Research Centre, Miguel Hernández University, Elche, Avda. De la Universidad s/n., 03202, Elche, Alicante, Spain. jlhdez43@gmail.com.
authors.forename: J L
authors.initials: JL
authors.lastname: Hernández-Davó
authors.affiliation: Sports Research Centre, Miguel Hernández University, Elche, Avda. De la Universidad s/n., 03202, Elche, Alicante, Spain.
authors.forename: R
authors.initials: R
authors.lastname: Sabido
authors.affiliation: Sports Research Centre, Miguel Hernández University, Elche, Avda. De la Universidad s/n., 03202, Elche, Alicante, Spain.
authors.forename: M
authors.initials: M
authors.lastname: Moya-Ramón
authors.affiliation: Centre for Exercise and Sports Science Research, Edith Cowan University, 270 Joondalup Drive, Joondalup, WA, 6027, Australia.
authors.forename: A J
authors.initials: AJ
authors.lastname: Blazevich
mesh_terms: D000328:Adult; D006801:Humans; D008297:Male; D009119:Muscle Contraction; D018482:Muscle, Skeletal / Q000502:physiology*; D011597:Psychomotor Performance; D014891:Weight Lifting / Q000502:physiology* / Q000523:psychology
keywords: Neuromuscular adaptation; Power; Rate of force development; Strength