PMID- 27899900
OWN - NLM
STAT- PubMed-not-MEDLINE
LR  - 20200930
IS  - 1664-042X (Print)
IS  - 1664-042X (Electronic)
IS  - 1664-042X (Linking)
VI  - 7
DP  - 2016
TI  - Fiber Type-Specific Satellite Cell Content in Cyclists Following Heavy Training 
      with Carbohydrate and Carbohydrate-Protein Supplementation.
PG  - 550
LID - 550
AB  - The central purpose of this study was to evaluate the fiber type-specific 
      satellite cell and myonuclear responses of endurance-trained cyclists to a block 
      of intensified training, when supplementing with carbohydrate (CHO) vs. 
      carbohydrate-protein (PRO). In a crossover design, endurance-trained cyclists (n 
      = 8) performed two consecutive training periods, once supplementing with CHO (de 
      facto "control" condition) and the other with PRO. Each training period consisted 
      of 10 days of intensified cycle training (ICT-120% increase in average training 
      duration) followed by 10 days of recovery (RVT-reduced volume training; 33% 
      volume reduction vs. normal training). Skeletal muscle biopsies were obtained 
      from the vastus lateralis before and after ICT and again following RVT. 
      Immunofluorescent microscopy was used to quantify SCs (Pax7+), myonuclei (DAPI+), 
      and myosin heavy chain I (MyHC I). Data are expressed as percent change +/- 90% 
      confidence limits. The 10-day block of ICT(CHO) increased MyHC I SC content (35 +/- 
      28%) and myonuclear density (16 +/- 6%), which remained elevated following RVT(CHO) 
      (SC = 69 +/- 50% vs. PRE; Nuclei = 17 +/- 15% vs. PRE). MyHC II SC and myonuclei were 
      not different following ICT(CHO), but were higher following RVT(CHO) (SC = +33 +/- 
      31% vs. PRE; Nuclei = 15 +/- 14% vs. PRE), indicating a delayed response compared 
      to MyHC I fibers. The MyHC I SC pool increased following ICT(PRO) (37 +/- 37%), but 
      without a concomitant increase in myonuclei. There were no changes in MyHC II SC 
      or myonuclei following ICT(PRO). Collectively, these trained endurance cyclists 
      possessed a relatively large pool of SCs that facilitated rapid (MyHC I) and 
      delayed (MyHC II) satellite cell proliferation and myonuclear accretion under 
      carbohydrate conditions. The current findings strengthen the growing body of 
      evidence demonstrating alterations in satellite cell number in the absence of 
      hypertrophy. Satellite cell pool expansion is typically viewed as an advantageous 
      response to exercise. However, when coupled with our previous report that PRO 
      possibly enhanced whole muscle recovery and increased MyHC I and II fiber size, 
      the limited satellite cell/myonuclear response observed with carbohydrate-protein 
      seem to indicate that protein supplementation may have minimized the necessity 
      for satellite cell involvement, thereby suggesting that protein may benefit 
      skeletal muscle during periods of heavy training.
FAU - McKenzie, Alec I
AU  - McKenzie AI
AD  - Human Performance Laboratory, James Madison University Harrisonburg, VA, USA.
FAU - D'Lugos, Andrew C
AU  - D'Lugos AC
AD  - Human Performance Laboratory, James Madison University Harrisonburg, VA, USA.
FAU - Saunders, Michael J
AU  - Saunders MJ
AD  - Human Performance Laboratory, James Madison University Harrisonburg, VA, USA.
FAU - Gworek, Keith D
AU  - Gworek KD
AD  - Human Performance Laboratory, James Madison University Harrisonburg, VA, USA.
FAU - Luden, Nicholas D
AU  - Luden ND
AD  - Human Performance Laboratory, James Madison University Harrisonburg, VA, USA.
LA  - eng
PT  - Journal Article
DEP - 20161116
PL  - Switzerland
TA  - Front Physiol
JT  - Frontiers in physiology
JID - 101549006
PMC - PMC5110549
OTO - NOTNLM
OT  - endurance-trained cyclists
OT  - intensified training
OT  - myogenesis
OT  - protein supplementation
EDAT- 2016/12/03 06:00
MHDA- 2016/12/03 06:01
PMCR- 2016/11/16
CRDT- 2016/12/01 06:00
PHST- 2016/09/22 00:00 [received]
PHST- 2016/11/01 00:00 [accepted]
PHST- 2016/12/01 06:00 [entrez]
PHST- 2016/12/03 06:00 [pubmed]
PHST- 2016/12/03 06:01 [medline]
PHST- 2016/11/16 00:00 [pmc-release]
AID - 10.3389/fphys.2016.00550 [doi]
PST - epublish
SO  - Front Physiol. 2016 Nov 16;7:550. doi: 10.3389/fphys.2016.00550. eCollection 
      2016.