Muscle metabolism during exercise

Armstrong, Neil; Barker, Alan R.; McManus, Alison M.

doi:10.1093/med/9780198757672.003.0006

Cited by 10 publications

(8 citation statements)

References 88 publications

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“…A poorer matching of muscle oxygen delivery to oxygen utilization in 9–10-year-old girls than similar-aged boys has been reported from a study using near infra-red spectroscopy to estimate microcirculatory changes in deoxygenated Hb and myoglobin (McNarry et al 2015), but this has not been confirmed. Methodological and ethical challenges leave it unclear whether there are meaningful sex differences in the ratio of active muscle mass to FFM, or in muscle structure, or in aerobic enzyme activity, or in muscle fibre types, or in muscle activation (Armstrong et al 2017; Dotan et al 2012; Malina et al 2004). For the physiological mechanisms underlying sex differences in the development of aerobic fitness to be fully elucidated further development and application of non-invasive technology to developmental exercise physiology is required.…”

Section: Discussionmentioning

confidence: 99%

Multilevel allometric modelling of maximal stroke volume and peak oxygen uptake in 11–13-year-olds

Armstrong

Welsman

2019

Eur J Appl Physiol

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Purpose To investigate (1) whether maximal stroke volume (SV max ) occurs at submaximal exercise intensities, (2) sex differences in SV max once fat-free mass (FFM) has been controlled for, and, (3) the contribution of concurrent changes in FFM and SV max to the sex-specific development of peak oxygen uptake V O 2 . Methods The peak V O 2 s of 61 (34 boys) 11-12-year-olds were determined and their SV determined during treadmill running at 2.28 and 2.50 m s −1 using carbon dioxide rebreathing. The SV max and peak V O 2 of 51 (32 boys) students who volunteered to be tested treadmill running at 2.50 m s −1 on three annual occasions were investigated using multilevel allometric modelling. The models were founded on 111 (71 from boys) determinations of SV max , FFM, and peak V O 2 . Results Progressive increases in treadmill running speed resulted in significant (p < 0.01) increases in V O 2 , but SV levelledoff with nonsignificant (p > 0.05) changes within ~ 2-3%. In the multilevel models, SVmax increased proportionally to FFM 0.72 and with FFM controlled for, there were no significant (p > 0.05) sex differences. Peak V O 2 increased with FFM but after adjusting for FFM 0.98 , a significant (p < 0.05) sex difference in peak V O 2 remained. Introducing SV max to the multilevel model revealed a significant (p < 0.05), but small additional effect of SVmax on peak V O 2 . Conclusions Fat-free mass explained sex differences in SV max , but with FFM controlled for, there was still a ~ 5% sex difference in peak V O 2 . SV max made a modest additional contribution to explain the development of peak V O 2 , but there remained an unresolved sex difference of ~ 4%.

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Section: Discussionmentioning

confidence: 99%

Multilevel allometric modelling of maximal stroke volume and peak oxygen uptake in 11–13-year-olds

Armstrong

Welsman

2019

Eur J Appl Physiol

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“…Within the models small but significant age effects for PP and MP, independent of, and additional to, changes due to FFM were observed for both boys and girls. In combination with the increases in FFM it is likely that these reflect not only increases in total muscle volume but also changes in maturity status–related factors such as muscle activation (i.e., the decline in activation deficit) (36), muscle structure (34), muscle fiber type (37), and muscle metabolism (37) which were not investigated herein. These factors have been comprehensively reviewed elsewhere in relation to the ethical and methodological challenges of exploring their influence on maximal-intensity exercise in youth but there is a paucity of empirical evidence on their relative contributions to short-term power output in 11- to 18-yr-olds (9,36,37).…”

Section: Discussionmentioning

confidence: 99%

Sex-Specific Longitudinal Modeling of Short-Term Power in 11- to 18-Year-Olds

Armstrong

Welsman

2019

Medicine &Amp; Science in Sports &Amp; Exercise

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Purpose To investigate, longitudinally, short-term power output in relation to sex and concurrent changes in age, body mass, fat-free mass (FFM), and maturity status. Methods Multiplicative multilevel modeling which enables the effects of variables to be partitioned concurrently within an allometric framework was used to analyze the peak power (PP) and mean power (MP) of 388 11- to 18-yr-olds. Multilevel models were founded on 763 (405 from boys; 358 from girls) determinations of PP and MP from Wingate anaerobic tests, supported by anthropometric measures and maturity status. Results In both sexes, PP and MP were significantly ( P < 0.001) correlated with age, body mass, and FFM. After controlling for body mass, initial models showed positive effects for age on PP and MP, with negative effects for sex and a sex by age interaction. Sex-specific models showed maturity status to have no additional effect on either PP or MP once age and body mass had been controlled for. Skinfold thicknesses in addition to body mass to provide a surrogate for FFM, yielded a significantly ( P < 0.05) better statistical fit in all models compared with those based on either body mass or FFM estimated from youth-specific skinfold equations. Models founded on estimated FFM provided a significantly ( P < 0.05) better fit than those based on body mass. Conclusions With body mass controlled for boys’ PP and MP are higher than those of girls and sex differences increase with age from 11 to 18 yr. A multilevel modeling approach has showed that in both sexes the most powerful influences on short-term power output are concurrent changes in age and FFM as reflected by the combination of body mass and skinfold thicknesses.

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“…the decline in activation deficit), and muscle metabolism. These factors have been reviewed elsewhere in relation to the ethical and methodological challenges of exploring their effects on exercise performance but empirical evidence is sparse (Armstrong et al 2017 ; Barker and Armstrong 2010 ; Dotan et al 2012 ; Malina et al 2004 ).…”

Section: Discussionmentioning

confidence: 99%

Development of 11- to 16-year-olds’ short-term power output determined using both treadmill running and cycle ergometry

2019

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Purpose To investigate the development of peak power output (PP) and mean power output (MP) during two different modes of exercise in relation to sex and concurrent changes in age, body mass, fat-free mass (FFM), maturity status and, in the case of MP, peak oxygen uptake ( ). Methods PP and MP were determined cycling against a fixed braking force (Wingate anaerobic test) and running on a non-motorized treadmill. Peak was determined using cycle ergometry and treadmill running. 135 (63 girls) students initially aged 11–14 years were tested over 2 days on three annual occasions. The data were analysed using multiplicative allometric modelling which enables the effects of variables to be partitioned concurrently within an allometric framework. Multiplicative models were founded on 301 (138 from girls) determinations of PP and MP on each ergometer. Results With body mass controlled for, both PP and MP increased with age but maturity status did not independently contribute to any of the multiplicative allometric models. Boys’ PP and MP were significantly ( p < 0.05) higher than girls’ values on both ergometers. On both ergometers in both sexes, the most powerful morphological influence on PP and MP was FFM. Ergometer-specific peak had a significant ( p < 0.05), additional effect in explaining the development of MP. Conclusions The development of short-term power output is sex specific but within sex multiplicative allometric models of running- and cycling-determined PP and MP were similar, suggesting that either mode of exercise can be used in future studies of short-term power output in youth.

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Muscle metabolism during exercise

Cited by 10 publications

References 88 publications

Multilevel allometric modelling of maximal stroke volume and peak oxygen uptake in 11–13-year-olds

Multilevel allometric modelling of maximal stroke volume and peak oxygen uptake in 11–13-year-olds

Sex-Specific Longitudinal Modeling of Short-Term Power in 11- to 18-Year-Olds

Development of 11- to 16-year-olds’ short-term power output determined using both treadmill running and cycle ergometry

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