Myonuclear addition is associated with sex-specific fiber hypertrophy and occurs in relation to fiber perimeter not cross-sectional area
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Myonuclear addition is associated with sex-specific fiber hypertrophy and occurs in relation to fiber perimeter not cross-sectional area. / Moesgaard, Lukas; Jessen, Søren; Mackey, Abigail L; Hostrup, Morten.
I: Journal of Applied Physiology, Bind 133, Nr. 3, 2022, s. 732-741.Publikation: Bidrag til tidsskrift › Tidsskriftartikel › Forskning › fagfællebedømt
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T1 - Myonuclear addition is associated with sex-specific fiber hypertrophy and occurs in relation to fiber perimeter not cross-sectional area
AU - Moesgaard, Lukas
AU - Jessen, Søren
AU - Mackey, Abigail L
AU - Hostrup, Morten
N1 - CURIS 2022 NEXS 221
PY - 2022
Y1 - 2022
N2 - It is unclear whether resistance training-induced myofiber hypertrophy is affected by sex, and whether myonuclear addition occurs in relation to the myonuclear domain and can contribute to explaining a potential sex-specific hypertrophic response. This study investigated the effect of 8 weeks of resistance training on myofiber hypertrophy and myonuclear addition in 12 males (28±7 years; mean±SD) and 12 females (27±7 years). Muscle biopsies were collected from m. vastus lateralis before and after the training intervention and analyzed by immunohistochemistry for fiber type and size, satellite cells, and myonuclei. Hypertrophy of type I fibers was greater in males than females (P < 0.05), whereas hypertrophy of type II fibers was similar between sexes (P = 0.158‒0.419). Expansion of the satellite cell pool (P = 0.132‒0.667) and myonuclear addition (P=0.064‒0.228) did not differ significantly between sexes, irrespective of myofiber type. However, when individual responses to resistance training were assessed, myonuclear addition was strongly correlated with fiber hypertrophy (r = 0.68‒0.85, P < 0.001). While myofiber hypertrophy was accompanied by an increase in myonuclear domain (P < 0.05), fiber perimeter per myonucleus remained constant throughout the study (P = 0.096‒0.666). These findings indicate that myonuclear addition occurs in relation to the fiber perimeter per myonucleus, not the myonuclear domain, and has a substantial role in muscle hypertrophy, but does not fully explain greater hypertrophy of type I fibers in males than females.
AB - It is unclear whether resistance training-induced myofiber hypertrophy is affected by sex, and whether myonuclear addition occurs in relation to the myonuclear domain and can contribute to explaining a potential sex-specific hypertrophic response. This study investigated the effect of 8 weeks of resistance training on myofiber hypertrophy and myonuclear addition in 12 males (28±7 years; mean±SD) and 12 females (27±7 years). Muscle biopsies were collected from m. vastus lateralis before and after the training intervention and analyzed by immunohistochemistry for fiber type and size, satellite cells, and myonuclei. Hypertrophy of type I fibers was greater in males than females (P < 0.05), whereas hypertrophy of type II fibers was similar between sexes (P = 0.158‒0.419). Expansion of the satellite cell pool (P = 0.132‒0.667) and myonuclear addition (P=0.064‒0.228) did not differ significantly between sexes, irrespective of myofiber type. However, when individual responses to resistance training were assessed, myonuclear addition was strongly correlated with fiber hypertrophy (r = 0.68‒0.85, P < 0.001). While myofiber hypertrophy was accompanied by an increase in myonuclear domain (P < 0.05), fiber perimeter per myonucleus remained constant throughout the study (P = 0.096‒0.666). These findings indicate that myonuclear addition occurs in relation to the fiber perimeter per myonucleus, not the myonuclear domain, and has a substantial role in muscle hypertrophy, but does not fully explain greater hypertrophy of type I fibers in males than females.
KW - Faculty of Science
KW - Myonuclear addition
KW - Fiber hypertrophy
KW - Sex
KW - Resistance training
KW - Myonuclear domain
U2 - 10.1152/japplphysiol.00235.2022
DO - 10.1152/japplphysiol.00235.2022
M3 - Journal article
C2 - 35952346
VL - 133
SP - 732
EP - 741
JO - Journal of Applied Physiology
JF - Journal of Applied Physiology
SN - 8750-7587
IS - 3
ER -
ID: 316118104