Effects of concurrent strength and endurance training on genes related to myostatin signaling pathway and muscle fiber responses

J Strength Cond Res. 2014 Nov;28(11):3215-23. doi: 10.1519/JSC.0000000000000525.


Concurrent training (CT) seems to impair training-induced muscle hypertrophy. This study compared the effects of CT, strength training (ST) and interval training (IT) on the muscle fiber cross-sectional area (CSA) response, and on the expression of selected genes involved in the myostatin (MSTN) signaling mRNA levels. Thirty-seven physically active men were randomly divided into 4 groups: CT (n = 11), ST (n = 11), IT (n = 8), and control group (C) (n = 7) and underwent an 8-week training period. Vastus lateralis biopsy muscle samples were obtained at baseline and 48 hours after the last training session. Muscle fiber CSA, selected genes expression, and maximum dynamic ST (1 repetition maximum) were evaluated before and after training. Type IIa and type I muscle fiber CSA increased from pre- to posttest only in the ST group (17.08 and 17.9%, respectively). The SMAD-7 gene expression significantly increased at the posttest in the ST (53.9%) and CT groups (39.3%). The MSTN and its regulatory genes ActIIb, FLST-3, FOXO-3a, and GASP-1 mRNA levels remained unchanged across time and groups. One repetition maximum increased from pre- to posttest in both the ST and CT groups (ST = 18.5%; CT = 17.6%). Our findings are suggestive that MSTN and their regulatory genes at transcript level cannot differentiate muscle fiber CSA responses between CT and ST regimens in humans.

Publication types

  • Randomized Controlled Trial

MeSH terms

  • Adolescent
  • Adult
  • Exercise Test
  • Forkhead Box Protein O3
  • Forkhead Transcription Factors / genetics
  • Gene Expression*
  • Humans
  • Intercellular Signaling Peptides and Proteins
  • Male
  • Muscle Fibers, Fast-Twitch / cytology
  • Muscle Fibers, Slow-Twitch / cytology
  • Myostatin / genetics
  • Myostatin / metabolism*
  • Oxygen Consumption
  • Physical Conditioning, Human / methods
  • Physical Conditioning, Human / physiology
  • Proteins / genetics
  • Quadriceps Muscle / cytology
  • Quadriceps Muscle / metabolism*
  • RNA, Messenger / metabolism
  • Resistance Training*
  • Running / physiology*
  • Signal Transduction / genetics
  • Smad7 Protein / genetics
  • Young Adult


  • FOXO3 protein, human
  • Forkhead Box Protein O3
  • Forkhead Transcription Factors
  • Intercellular Signaling Peptides and Proteins
  • MSTN protein, human
  • Myostatin
  • Proteins
  • RNA, Messenger
  • Smad7 Protein
  • WFIKKN2 protein, human