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Walking‐mediated upregulation of follistatin‐like 3 expression is insufficient to increase muscle contractile force
Author(s) -
Blazek Alisa,
Beck Eric,
Li Jackie,
McElha Kevin,
Hewett Timothy,
Agarwal Sudha,
Weisleder Noah
Publication year - 2015
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.29.1_supplement.992.2
Subject(s) - follistatin , muscle hypertrophy , myostatin , medicine , endocrinology , downregulation and upregulation , skeletal muscle , chemistry , ex vivo , biochemistry , in vitro , gene
Molecular mechanisms coordinating muscle and bone strength and growth with exercise (EX) are undefined. EX upregulates follistatin‐like 3 (FSTL3) in mouse and human skeletal muscle, bone and serum, and FSTL3 is required for EX‐driven bone formation (Nam, 2014, in press). FSTL3 is known to bind and inhibit myostatin. Thus, our purpose was to determine if FSTL3 increases muscle hypertrophy and force generation through this mechanism to collectively regulate musculoskeletal function. Wild‐type (WT) or Fstl3‐/‐ C57/Bl6 mice (n=30) were treadmill walked for 45 min/day at 8 m/min for 6 weeks, a protocol that increases bone formation. Muscles were mounted between stimulating electrodes, equilibrated at max force, then stimulated from 1‐150 hz to generate force vs. frequency curves. No differences in force were observed in WT EX and WT NoEX, indicating that walking was not sufficiently rigorous to produce a training effect on muscle force. No force differences were observed in Fstl3‐/‐ EX and Fstl3‐/‐ NoEX. Endogenous FSTL3 may not be sufficient to alter muscle contractile force generation in response to walking. FSTL3 regulates bone health in response to walking EX; however, walking is insufficient to increase muscle force and hypertrophy. While walking may be prescribed as a treatment regimen for increasing bone growth in humans, clinicians should be aware that walking may need to be supplemented with a resistance EX program to increase muscle strength/hypertrophy.