title: Neuromuscular and metabolic responses to high-intensity intermittent cycling protocols with different work-to-rest ratios.
abstract: OBJECTIVE
  To investigate the effects of work-to-rest-ratio manipulation on neuromuscular and metabolic responses during 2 high-intensity intermittent training (HIT) protocols to exhaustion. Since different exercise durations were expected, the authors hypothesized that the protocol registering a longer duration would have a more pronounced effect on neuromuscular responses, while the other would challenge the cardiopulmonary system more.
  
  
  METHODS
  Thirteen competitive cyclists (age 19 ± 2 y) performed a preliminary incremental test to identify their maximal power output and 2 intermittent protocols to exhaustion (40:20s and 30:30s) at a fixed work rate of 135%Pmax interspersed by passive recovery. Surface electromyographic (sEMG) parameters (including muscle-fiber conduction velocity), cardiopulmonary parameters, and blood lactate concentration [La-] were recorded.
  
  
  RESULTS
  Time to exhaustion and total work were significantly higher for the 30:30s (38 ± 13 min, 495 ± 161 kJ) than for the 40:20s (10 ± 3 min, 180 ± 51 kJ). No differences were found in sEMG parameters for the 2 protocols. Mean and peak values of VO2, heart rate, ventilatory parameters (except for the peak value of respiratory frequency), and [La-] were significantly higher in the 40:20s than in the 30:30s.
  
  
  CONCLUSIONS
  These results do not support the hypothesis that a longer time spent at high intensity has a more pronounced effect on neuromuscular responses, as no differences in EMG parameters were found in the 2 HIT protocols. Regarding metabolic responses, while the 40:20s led to maximal values of VO2, [La-], and ventilatory parameters within a few minutes, the 30:30s allowed maintenance of moderately high values for a considerably longer period, especially for [La-] and ventilatory parameters.
authors.affiliation: Dept of Human Movement and Sport Sciences, University "Foro Italico", Rome, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Nicolò
authors.forename: Ilenia
authors.initials: I
authors.lastname: Bazzucchi
authors.forename: Mauro
authors.initials: M
authors.lastname: Lenti
authors.forename: Jonida
authors.initials: J
authors.lastname: Haxhi
authors.forename: Alessandro
authors.initials: A
authors.lastname: Scotto di Palumbo
authors.forename: Massimo
authors.initials: M
authors.lastname: Sacchetti
mesh_terms: D001642:Bicycling / Q000502:physiology*; D004576:Electromyography; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D019344:Lactic Acid / Q000097:blood; D009431:Neural Conduction / Q000502:physiology; D010101:Oxygen Consumption / Q000502:physiology; D005082:Physical Exertion / Q000502:physiology*; D011659:Pulmonary Gas Exchange / Q000502:physiology; D012123:Pulmonary Ventilation / Q000502:physiology; D055815:Young Adult
chemical_list: D019344:Lactic Acid