PMID- 31785108
OWN - NLM
STAT- MEDLINE
DCOM- 20210728
LR  - 20210728
IS  - 1469-445X (Electronic)
IS  - 0958-0670 (Linking)
VI  - 105
IP  - 2
DP  - 2020 Feb
TI  - Muscle cross-sectional area and motor unit properties of the medial gastrocnemius 
      and vastus lateralis in normal weight and overfat children.
PG  - 335-346
LID - 10.1113/EP088181 [doi]
AB  - NEW FINDINGS: What is the central question of this study? Are differences in 
      muscle size and motor unit properties between normal weight and overfat children 
      muscle specific? What is the main finding and its importance? Muscle 
      cross-sectional area and motor unit action potential amplitudes and firing rates 
      were similar between overfat and normal weight children for both the medial 
      gastrocnemius and vastus lateralis muscles. There was no evidence that the 
      chronic mechanical overload provided by the greater body mass resulted in 
      significant hypertrophy of contractile tissue or motor units that would be used 
      during lower-to-moderate intensity activities. ABSTRACT: This study examined the 
      possible differences in muscle cross-sectional area (mCSA), motor unit action 
      potential amplitudes (MUAP(AMPS) ) and interspike intervals (ISIs) of the firing 
      instances of the medial gastrocnemius (MG) and vastus lateralis (VL) between 
      normal weight (NW) and overfat (OF) children aged 7-10 years. Fourteen NW 
      (age = 8.6 +/- 1.1 years, BMI = 15.8 +/- 1.4 kg m(-2) ) and 12 OF 
      (age = 8.8 +/- 0.9 years, BMI = 21.8 +/- 2.4 kg m(-2) ) children performed isometric 
      trapezoidal muscle actions at 40% of maximal voluntary contraction of the plantar 
      flexors and knee extensors. Surface electromyography was recorded from the MG and 
      VL and decomposed into the firing events of motor units (MUs). Statistical 
      procedures were performed on the composite recruitment thresholds (RTs), ISIs and 
      MUAP(AMPS) of recorded MUs collapsed across subjects and the y-intercepts and 
      slopes calculated from each subject's ISI and MUAP(AMP) vs. RT relationships. 
      Ultrasound was used to assess mCSA, echo intensity (mEI), and subcutaneous fat 
      (sFAT) of the MG and VL. The OF had greater mCSAs, mEI and sFAT 
      (P = 0.004-0.024), but there were no differences in mCSA when accounting for mEI 
      for the MG (P = 0.506) and VL (P = 0.326). The NW children had significantly 
      greater composite MUAP(AMPS) for the VL and MG (P < 0.001), but only 
      significantly larger MUAP(AMPS) of the VL remained for the NW (P < 0.001) when 
      subjects were matched for sFAT. There were no differences between groups for the 
      ISI or MUAP(AMP) vs. RT relationships (P > 0.05). These findings suggest that the 
      OF children did not undergo significant muscle or MU hypertrophy that would be 
      routinely activated during activities of daily living.
CI  - (c) 2019 The Authors. Experimental Physiology (c) 2019 The Physiological Society.
FAU - Herda, Trent J
AU  - Herda TJ
AUID- ORCID: 0000-0002-5555-5156
AD  - Neuromechanics Laboratory, University of Kansas, Lawrence, KS, USA.
FAU - Ryan, Eric D
AU  - Ryan ED
AUID- ORCID: 0000-0001-9589-4534
AD  - Neuromuscular Research Laboratory, Department of Exercise Science and Sport 
      Science, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
AD  - Human Movement Science Curriculum, University of North Carolina at Chapel Hill, 
      Chapel Hill, NC, USA.
FAU - Kohlmeier, Martin
AU  - Kohlmeier M
AD  - Department of Nutrition, School of Medicine, University of North Carolina at 
      Chapel Hill, Chapel Hill, NC, USA.
AD  - Nutrigenetics Laboratory, University of North Carolina at Chapel Hill, 
      Kannapolis, NC, USA.
FAU - Trevino, Michael A
AU  - Trevino MA
AD  - Applied Neuromuscular Physiology Laboratory, Department of Health and Human 
      Performance, Oklahoma State University, Stillwater, OK, USA.
FAU - Gerstner, Gena R
AU  - Gerstner GR
AD  - Department of Human Movement Sciences, Old Dominion University, Norfolk, VA, USA.
FAU - Roelofs, Erica J
AU  - Roelofs EJ
AD  - School of Kinesiology, University of Minnesota Twin Cities, Minneapolis, MN, USA.
FAU - Miller, Jonathan D
AU  - Miller JD
AD  - Neuromechanics Laboratory, University of Kansas, Lawrence, KS, USA.
LA  - eng
GR  - University of North Carolina at Chapel Hill Nutrition Research 
      Institute/International
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
DEP - 20200109
PL  - England
TA  - Exp Physiol
JT  - Experimental physiology
JID - 9002940
SB  - IM
MH  - Action Potentials/physiology
MH  - Body Weight/physiology
MH  - Child
MH  - Exercise/*physiology
MH  - Female
MH  - Humans
MH  - Male
MH  - Muscle, Skeletal/*physiology
MH  - Pediatric Obesity/diagnosis/*physiopathology
MH  - Quadriceps Muscle/*physiology
MH  - Recruitment, Neurophysiological/*physiology
OTO - NOTNLM
OT  - action potential amplitudes
OT  - children
OT  - firing rates
OT  - motor unit
OT  - obesity
EDAT- 2019/12/01 06:00
MHDA- 2021/07/29 06:00
CRDT- 2019/12/01 06:00
PHST- 2019/09/17 00:00 [received]
PHST- 2019/11/27 00:00 [accepted]
PHST- 2019/12/01 06:00 [pubmed]
PHST- 2021/07/29 06:00 [medline]
PHST- 2019/12/01 06:00 [entrez]
AID - 10.1113/EP088181 [doi]
PST - ppublish
SO  - Exp Physiol. 2020 Feb;105(2):335-346. doi: 10.1113/EP088181. Epub 2020 Jan 9.