title: Atrophy/hypertrophy cell signaling in muscles of young athletes trained with vibrational-proprioceptive stimulation.
abstract: OBJECTIVE
  To compare the effects of isokinetic (ISO-K) and vibrational-proprioceptive (VIB) trainings on muscle mass and strength.
  
  
  METHODS
  In 29 ISO-K- or VIB-trained young athletes we evaluated: force, muscle fiber morphometry, and gene expression  of muscle atrophy/hypertrophy cell signaling.
  
  
  RESULTS
  VIB training increased the maximal isometric unilateral leg extension force by 48·1%. ISO-K training improved the force by 24·8%. Both improvements were statistically significant (P⩿0·01). The  more functional effectiveness of the VIB training in comparison with the ISO-K training was shown by the statistical significance changes only in VIB group in: rate of force development in time segment 0-50 ms (P<0·001), squat jump (P<0·05) and 30-m  acceleration running test (P<0·05). VIB training induced a highly significant increase of mean diameter of fast fiber (+9%, P<0·001), but not of slow muscle fibers (-3%, not significant). No neural cell adhesion molecule-positive (N-CAM(+))  and embryonic myosin heavy chain-positive (MHC-emb(+)) myofibers were detected. VIB induced a significant twofold increase (P<0·05) of the skeletal muscle isoform insulin-like growth factor-1 (IGF-1) Ec mRNA. Atrogin-1 and muscle ring finger-1 (MuRF-1) did not change,  but myostatin was strongly downregulated after VIB training (P<0·001). Peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α) expression increased in post-training groups, but only in VIB reached statistical significance  (+228%, P<0·05).
  
  
  CONCLUSIONS
  We demonstrated that both trainings are effective and do not induce muscle damage. Only VIB-trained group showed statistical significance increase of hypertrophy cell signaling pathways (IGF-1Ec and PGC-1α upregulation, and  myostatin downregulation) leading to hypertrophy of fast twitch muscle fibers.
authors.affiliation: Department of Physical Medicine and Rehabilitation, Wilhelminenspital, Wien, Austria.
authors.forename: Helmut
authors.initials: H
authors.lastname: Kern
authors.forename: Laura
authors.initials: L
authors.lastname: Pelosi
authors.forename: Luisa
authors.initials: L
authors.lastname: Coletto
authors.forename: Antonio
authors.initials: A
authors.lastname: Musarò
authors.forename: Marco
authors.initials: M
authors.lastname: Sandri
authors.forename: Michael
authors.initials: M
authors.lastname: Vogelauer
authors.forename: Lukas
authors.initials: L
authors.lastname: Trimmel
authors.forename: Jan
authors.initials: J
authors.lastname: Cvecka
authors.forename: Dusan
authors.initials: D
authors.lastname: Hamar
authors.forename: Josef
authors.initials: J
authors.lastname: Kovarik
authors.forename: Stefan
authors.initials: S
authors.lastname: Löfler
authors.forename: Nejc
authors.initials: N
authors.lastname: Sarabon
authors.forename: Feliciano
authors.initials: F
authors.lastname: Protasi
authors.forename: Nicoletta
authors.initials: N
authors.lastname: Adami
authors.forename: Donatella
authors.initials: D
authors.lastname: Biral
authors.forename: Sandra
authors.initials: S
authors.lastname: Zampieri
authors.forename: Ugo
authors.initials: U
authors.lastname: Carraro
mesh_terms: D000328:Adult; D006801:Humans; D006984:Hypertrophy / Q000209:etiology / Q000473:pathology; D008297:Male; D018485:Muscle Fibers, Skeletal / Q000166:cytology / Q000378:metabolism*; D009124:Muscle Proteins / Q000235:genetics / Q000378:metabolism*; D009133:Muscular Atrophy / Q000209:etiology / Q000473:pathology*; D055070:Resistance Training / Q000379:methods*; D015398:Signal Transduction / Q000502:physiology*; D013177:Sports / Q000502:physiology*; D055815:Young Adult
chemical_list: D009124:Muscle Proteins