Methodological considerations in measuring specific force in human single skinned muscle fibres
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Methodological considerations in measuring specific force in human single skinned muscle fibres. / Kalakoutis, Michaeljohn; Di Giulio, Irene; Douiri, Abdel; Ochala, Julien; Harridge, Stephen D.R.; Woledge, Roger C.
In: Acta Physiologica, Vol. 233, No. 3, e13719, 2021, p. 1-18.Research output: Contribution to journal › Review › Research › peer-review
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TY - JOUR
T1 - Methodological considerations in measuring specific force in human single skinned muscle fibres
AU - Kalakoutis, Michaeljohn
AU - Di Giulio, Irene
AU - Douiri, Abdel
AU - Ochala, Julien
AU - Harridge, Stephen D.R.
AU - Woledge, Roger C.
N1 - Publisher Copyright: © 2021 Scandinavian Physiological Society. Published by John Wiley & Sons Ltd
PY - 2021
Y1 - 2021
N2 - Chemically skinned fibres allow the study of human muscle contractile function in vitro. A particularly important parameter is specific force (SF), that is, maximal isometric force divided by cross-sectional area, representing contractile quality. Although SF varies substantially between studies, the magnitude and cause of this variability remains puzzling. Here, we aimed to summarize and explore the cause of variability in SF between studies. A systematic search was conducted in Medline, Embase and Web of Science databases in June 2020, yielding 137 data sets from 61 publications which studied healthy, young adults. Five-fold differences in mean SF data were observed. Adjustments to the reported data for key methodological differences allowed between-study comparisons to be made. However, adjustment for fibre shape, swelling and sarcomere length failed to significantly reduce SF variance (I2 = 96%). Interestingly, grouping papers based on shared authorship did reveal consistency within research groups. In addition, lower SF was found to be associated with higher phosphocreatine concentrations in the fibre activating solution and with Triton X-100 being used as a skinning agent. Although the analysis showed variance across the literature, the ratio of SF in single fibres containing myosin heavy chain isoforms IIA or I was found to be consistent across research groups. In conclusion, whilst the skinned fibre technique is reliable for studying in vitro force generation of single fibres, the composition of the solution used to activate fibres, which differs between research groups, is likely to heavily influence SF values.
AB - Chemically skinned fibres allow the study of human muscle contractile function in vitro. A particularly important parameter is specific force (SF), that is, maximal isometric force divided by cross-sectional area, representing contractile quality. Although SF varies substantially between studies, the magnitude and cause of this variability remains puzzling. Here, we aimed to summarize and explore the cause of variability in SF between studies. A systematic search was conducted in Medline, Embase and Web of Science databases in June 2020, yielding 137 data sets from 61 publications which studied healthy, young adults. Five-fold differences in mean SF data were observed. Adjustments to the reported data for key methodological differences allowed between-study comparisons to be made. However, adjustment for fibre shape, swelling and sarcomere length failed to significantly reduce SF variance (I2 = 96%). Interestingly, grouping papers based on shared authorship did reveal consistency within research groups. In addition, lower SF was found to be associated with higher phosphocreatine concentrations in the fibre activating solution and with Triton X-100 being used as a skinning agent. Although the analysis showed variance across the literature, the ratio of SF in single fibres containing myosin heavy chain isoforms IIA or I was found to be consistent across research groups. In conclusion, whilst the skinned fibre technique is reliable for studying in vitro force generation of single fibres, the composition of the solution used to activate fibres, which differs between research groups, is likely to heavily influence SF values.
KW - fibre types
KW - methods
KW - muscle contraction
KW - muscle force
KW - skinned fibres
KW - specific force
U2 - 10.1111/apha.13719
DO - 10.1111/apha.13719
M3 - Review
C2 - 34286921
AN - SCOPUS:85112659786
VL - 233
SP - 1
EP - 18
JO - Acta Physiologica
JF - Acta Physiologica
SN - 1748-1708
IS - 3
M1 - e13719
ER -
ID: 279128576