European Journal of Applied Physiology

, Volume 114, Issue 9, pp 1875–1888

Irisin and FNDC5: effects of 12-week strength training, and relations to muscle phenotype and body mass composition in untrained women

  • S. Ellefsen
  • O. Vikmoen
  • G. Slettaløkken
  • J. E. Whist
  • H. Nygaard
  • I. Hollan
  • I. Rauk
  • G. Vegge
  • T. A. Strand
  • T. Raastad
  • B. R. Rønnestad
Original Article

DOI: 10.1007/s00421-014-2922-x

Cite this article as:
Ellefsen, S., Vikmoen, O., Slettaløkken, G. et al. Eur J Appl Physiol (2014) 114: 1875. doi:10.1007/s00421-014-2922-x



To investigate the effects of strength training on abundances of irisin-related biomarkers in skeletal muscle and blood of untrained young women, and their associations with body mass composition, muscle phenotype and levels of thyroid hormones.


Eighteen untrained women performed 12 weeks of progressive whole-body heavy strength training, with measurement of strength, body composition, expression of irisin-related genes (FNDC5 and PGC1α) in two different skeletal muscles, and levels of serum-irisin and -thyroid hormones, before and after the training intervention.


The strength training intervention did not result in changes in serum-irisin or muscle FNDC5 expression, despite considerable effects on strength, lean body mass (LBM) and skeletal muscle phenotype. Our data indicate that training affects irisin biology in a LBM-dependent manner. However, no association was found between steady-state serum-irisin or training-associated changes in serum-irisin and alterations in body composition. FNDC5 expression was higher in m.Biceps brachii than in m.Vastus lateralis, with individual expression levels being closely correlated, suggesting a systemic mode of transcriptional regulation. In pre-biopsies, FNDC5 expression was correlated with proportions of aerobic muscle fibers, a relationship that disappeared in post-biopsies. No association was found between serum-thyroid hormones and FNDC5 expression or serum-irisin.


No evidence was found for an effect of strength training on irisin biology in untrained women, though indications were found for a complex interrelationship between irisin, body mass composition and muscle phenotype. FNDC5 expression was closely associated with muscle fiber composition in untrained muscle.


Irisin FNDC5 Lean body mass Fat mass Muscle fiber Skeletal muscle Strength training Thyroid hormones Exercise Myosin heavy chain MHC MyHC mRNA Real-time RT-PCR qRT-PCR Metabolism 


18S rRNA

18S ribosomal RNA






musculus Biceps brachii


Dual-energy X-ray absorptiometry


Enzyme immunoassay


Fat mass


Fibronectin type III domain-containing protein 5


Free triiodothyronine


Free thyroxine


Glyceraldehyde-3-phosphate dehydrogenase


Lean body mass


Myosin heavy chain


Peroxisome proliferator-activated receptor gamma coactivator 1-alpha


Polymerase (RNA) II (DNA directed) polypeptide A


Peptidylprolyl isomerase A (cyclophilin A)


Quantitative reverse transcriptase-polymerase chain reaction


Repetition maximum


Ribosomal protein L32 (RPL32)


Serum concentrations of irisin


TATA box binding protein


Thyroid-stimulating hormone


Ubiquitin C


musculus Vastus lateralis

Supplementary material

421_2014_2922_MOESM1_ESM.docx (15 kb)
Supplementary material 1 (DOCX 15 kb)
421_2014_2922_MOESM2_ESM.tif (227 kb)
Figure s1. Expression stability (M) of nine selected reference genes in A) musculus Vastus lateralis (VL) and B) musculus Biceps brachii (BB) following 12 wks of strength training in 17 previously untrained women. M was calculated using GeNorm, as described by Vandesompele et al. (2002). In both VL and BB, B2m and PPIA were found to be the most stably expressed reference genes, ranking them as most suitable for normalization of target gene qRT-PCR data. (TIFF 227 kb)
421_2014_2922_MOESM3_ESM.tif (73 kb)
Figure s2. Per-mg-tissue expression of PPIA in untrained (pre, black columns) and trained (post, white columns) musculus Vastus lateralis (VL) and musculus Biceps brachii (BB). Data were normalized to the external reference gene mw2060, an approach developed by Ellefsen et al. (2008). The effect of training on gene expression was tested using a paired t test. No differences were found between groups. Values are mean ± S.D. (TIFF 72 kb)
421_2014_2922_MOESM4_ESM.tif (742 kb)
Figure s3. Effects of 12 weeks of progressive heavy strength training on steady-state expression of FNDC5, PGC1α splice variants 1 and 4 (s1 and s4), TBP, GAPDH and MyHC2X in A, C) musculus Vastus lateralis (VL) and B, D) musculus Biceps brachii (BB) of 17 previously untrained young women. Strength training was performed as either 3L1U (three sets lower body - one set upper body; n = 7; in A-B) or 1L3U (one set lower body - three sets upper body; n = 10; in C-D). Muscle biopsies were sampled before (pre) and after (post) the training period. Data were normalized to PPIA and are presented as post-training expression relative to pre-training expression, measured as log2-fold change. Effects of training on gene expression were tested on log2-transformed data using paired t tests. * = p<0.05, *** = p<0.001. Data are presented as box plots, with the central line marking the data set median.(TIFF 742 kb)

Copyright information

© Springer-Verlag Berlin Heidelberg 2014

Authors and Affiliations

  • S. Ellefsen
    • 1
  • O. Vikmoen
    • 1
  • G. Slettaløkken
    • 1
  • J. E. Whist
    • 2
  • H. Nygaard
    • 1
  • I. Hollan
    • 3
  • I. Rauk
    • 2
  • G. Vegge
    • 1
  • T. A. Strand
    • 2
  • T. Raastad
    • 4
  • B. R. Rønnestad
    • 1
  1. 1.Lillehammer University CollegeLillehammerNorway
  2. 2.Innlandet Hospital TrustLillehammerNorway
  3. 3.Hospital for Rheumatic DiseasesLillehammerNorway
  4. 4.Norwegian School of Sport ScienceOsloNorway