title: Effect of Plyometrics on the Energy Cost of Running and MHC and Titin Isoforms.
abstract: Several training strategies such as plyometrics have been shown to improve running economy; however, its physiological basis remains elusive.
  
  
  OBJECTIVE
  To examine the effect of plyometric training on the energy cost of running (ECR, J · kg(-1) · min(-1)), titin, and myosin heavy chain (MHC) isoforms.
  
  
  METHODS
  Subjects were randomly assigned to a 6-wk plyometric treatment (P; n = 11) or control group (C; n = 11). Preintervention and postintervention outcomes included body composition, vertical jump, sit-and-reach, maximal oxygen consumption (VO2max), speed at onset of blood lactate, 3-km time trial performance, ECR, and a vastus lateralis muscle biopsy for protein analysis.
  
  
  RESULTS
  Plyometric intervention resulted in improved time trial (P, 2.6% faster, P = 0.04; C, 1.6%, P = 0.17). VO2max improved in the P group (5.2%, P = 0.03), whereas the C group increased by 3.1% (P = 0.20). The ECR decreased in the P group as the result of 6 wk of plyometric training (P = 0.02 for stage 3), whereas it increased in the C group (P = 0.02 for stage 3). The ECR correlated strongly with performance at stages 2, 3, and 4 (r > 0.8, P < 0.001) independent of group. There was no significant main effect of group, time, or interaction on any of the protein isoforms analyzed. A negative correlation was found between the ECR at stage 7 and MHC IIa (r = -0.96, P < 0.001), and the ECR at stage 6 with titin isoform 1 (T1)/T2 ratio (r = -0.69, P = 0.007) independent of group.
  
  
  CONCLUSIONS
  Six weeks of plyometric training improved running performance and the ECR despite no measurable changes in MHC and titin isoforms. However, higher MHC IIa and lower T1/T2 isoform ratios correlated to lower ECR.
authors.affiliation: 1Department of Nutritional Sciences, Rutgers University, New Brunswick, NJ; and 2Department of Health and Human Performance, Montana Center for Work Physiology and Exercise Metabolism, University of Montana, Missoula, MT.
authors.forename: Joseph
authors.initials: J
authors.lastname: Pellegrino
authors.forename: Brent C
authors.initials: BC
authors.lastname: Ruby
authors.forename: Charles L
authors.initials: CL
authors.lastname: Dumke
mesh_terms: D000328:Adult; D054874:Athletic Performance / Q000502:physiology; D064211:Connectin / Q000378:metabolism*; D004734:Energy Metabolism; D005260:Female; D006801:Humans; D019344:Lactic Acid / Q000097:blood; D008297:Male; D018995:Myosin Heavy Chains / Q000378:metabolism*; D010806:Physical Education and Training / Q000379:methods*; D059385:Plyometric Exercise; D020033:Protein Isoforms; D052097:Quadriceps Muscle / Q000378:metabolism*; D012420:Running / Q000502:physiology*
chemical_list: D064211:Connectin; D020033:Protein Isoforms; D019344:Lactic Acid; D018995:Myosin Heavy Chains