Aerobic Function and Muscle Deoxygenation Dynamics during Ramp Exercise in Children

McNarry, Melitta A.; Farr, Colin; Middlebrooke, A. R.; Welford, Deborah; Breese, Brynmor C.; Armstrong, Neil; Barker, Alan R.

doi:10.1249/mss.0000000000000609

Cited by 26 publications

(50 citation statements)

References 43 publications

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“…A poorer matching of muscle oxygen delivery to oxygen utilization in girls was reported in a study that used near-infrared spectroscopy to measure microcirculatory changes in deoxygenated hemoglobin and myoglobin. The authors concluded that this phenomenon may contribute to girls' lower peakVO 2 (28). However, although the physiologic mechanisms underlying sex differences in youth aerobic fitness are emerging, they have yet to be fully elucidated (5).…”

Section: Discussionmentioning

confidence: 99%

Sex-Specific Longitudinal Modeling of Youth Peak Oxygen Uptake

Armstrong

Welsman

2019

Pediatric Exercise Science

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Purpose: To investigate peak oxygen uptake (VO 2) in relation to sex, age, body mass, fat-free mass (FFM), maturity, and overweight status. Methods: Multiplicative, allometric models of 10-to 18-year-olds were founded on 1057 determinations of peakVO 2 supported by anthropometry and estimates of maturity status. Results: Baseline models with body mass controlled for showed age to exert a positive effect on peakVO 2 , with negative estimates for age 2 , sex, and a sex-by-age interaction. Sexspecific models showed maturity status to have a positive effect on peakVO 2 in addition to the effects of age and body mass. Introducing skinfold thicknesses to provide, with body mass, a surrogate for FFM explained maturity effects and yielded a significantly (P < .05) better statistical fit in all models compared with those based on FFM estimated from youth-specific skinfold equations. With girls only, the introduction of overweight, defined by body mass index, resulted in a small but significant (P < .05) negative effect, with an age-by-overweight status interaction. Conclusions: FFM has a powerful influence on peakVO 2 in both sexes. Interpretation of the development of youth aerobic fitness and its application to health should reflect the sex-and maturity-associated variation in FFM.

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Section: Discussionmentioning

confidence: 99%

Sex-Specific Longitudinal Modeling of Youth Peak Oxygen Uptake

Armstrong

Welsman

2019

Pediatric Exercise Science

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“…Boys’ peak VO 2 may be further supplemented by an increase in blood haemoglobin concentration during late teens 73–75. The prepubertal sex difference in peak VO 2 has been attributed to boys’ greater stroke index,76–78 boys’ higher maximal arterial-venous oxygen difference79 and differences in the balance between oxygen delivery to and utilisation in the muscles 80…”

Section: Maximal (Or Peak) Aerobic and Anaerobic Performancementioning

confidence: 99%

Muscle metabolism changes with age and maturation: How do they relate to youth sport performance?

2015

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Aim: To provide an evidence-based review of muscle metabolism changes with sex-age-and maturation with reference to the development of youth sport performance. Methods:A narrative review of data from both invasive and non-invasive studies, from 1970-2015, founded on personal databases supported with computer searches of PubMed and Google Scholar.Results: Youth sport performance is underpinned by sex-age-and maturation-related changes in muscle metabolism. Investigations of muscle size, structure and metabolism; substrate utilization; pulmonary oxygen uptake kinetics; muscle phosphocreatine kinetics; peak anaerobic and aerobic performance; and fatigue resistance; determined using a range of conventional and emerging techniques present a consistent picture. Age-related changes have been consistently documented but specific and independent maturation-related effects on muscle metabolism during exercise have proved elusive to establish. Children are better equipped for exercise supported primarily by oxidative metabolism than by anaerobic metabolism. Sexual dimorphism is apparent in several physiological variables underpinning youth sport performance. As young people mature there is a progressive but asynchronous transition into an adult metabolic profile. Conclusion:The application of recent developments in technology to the laboratory study of the exercising child and adolescent has both supplemented existing knowledge and provided novel insights into developmental exercise physiology. A sound foundation of laboratorybased knowledge has been established but the lack of rigorously designed child-and sportspecific testing environments has clouded the interpretation of the data in real life situations.The primary challenge remains the translation of laboratory research into the optimisation of youth sports participation and performance. Abstract: 249 wordsText: 3997 words

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“…Although peak aerobic fitness significantly increased, in line with Baquet et al (2001), GET appeared to be unaffected by the HIIT intervention for both those with and without asthma, suggesting that training above the GET for short intermittent periods may not elicit improvements. The GET%V̇O2 were similar at baseline to previous studies (McNarry et al, 2015a), however, contrary to HIIT in normal weight children (McNarry et al, 2015b), GET significantly increased in both intervention and control groups within the present study. This suggest that increases in GET are possibly due to the maturational changes in both those in the intervention and control during a period of rapid growth that may have occurred during that time (Breese et al, 2010), although a larger study is required to confirm this suggestion.…”

Section: Discussionsupporting

confidence: 87%

“…Previously, techniques to investigate changes in O2 delivery and muscle blood flow were costly, invasive and not ethically sound for use in paediatric populations, for example muscle biopsy, tissue O2 microelectrodes and myoglobin O2 saturation by spectrophotometric analysis. NIRS is used in recent research (McNarry et al, 2015a and the current thesis as it is relatively cheap, portable, non-invasive and most importantly provides a continuous measure to provide measures of the dynamic changes in tissue oxygenation.…”

Section: Oxygen Uptake Kineticsmentioning

confidence: 99%

Influence of high-intensity interval training in adolescents with asthma

Winn¹

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Low levels of fitness are associated with increased body mass index (BMI), both of which are related to quality of life (QoL) and the occurrence and severity of asthma. Therefore, the purpose of this thesis was to co-develop and implement a six-month high-intensity interval training (HIIT) intervention targeting aerobic fitness, BMI and QoL improvements in adolescents with asthma. Six-hundred and sixteen adolescents (13.0±1.1years; 155 asthma; 85% mild asthma as defined by medication-step) participated in the study, with 223 enrolled in the school based HIIT intervention (50 asthma), consisting of 10-30second bouts at >90%age-predicted maximum heart-rate with equal rest, 3x30minutes/week. Formative group interviews to elicit the views of adolescents with and without asthma on asthma and exercise were used to inform the design of the intervention. Anthropometrics, aerobic fitness, lung function and QoL were measured at baseline, mid-point and post-intervention to evaluate the intervention's impact; follow-up measures were also taken to evaluate sustainability. Focus groups revealed participants with asthma had a fear of asthma attack through exercise, although fear did not act as a barrier, and that the intervention should be varied to circumvent activity-specific anxieties. Participants with asthma were found to have higher BMI and lower physical activity in comparison to their peers, but no difference in cardiorespiratory fitness. The intervention elicited significant improvements in peak cardiorespiratory fitness, irrespective of asthma, while maintaining BMI which increased in the controls; no changes were observed in the sub-maximal exercise parameters, QoL or lung function. The present findings suggest that HIIT may be effective at increasing peak cardiorespiratory fitness and preventing increases in BMI in adolescents, irrespective of asthma status. Overall, the series of studies show that asthma does not deleteriously influence maximal and sub-maximal aerobic fitness, or trainability in adolescents, and that HIIT is a safe exercise modality for adolescents with asthma.

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Aerobic Function and Muscle Deoxygenation Dynamics during Ramp Exercise in Children

Abstract: The sex difference in peak V˙O2 in 9- to 10-yr-old children is, in part, related to sex-specific changes in muscle O2 extraction dynamics during incremental exercise.

Cited by 26 publications

References 43 publications

Sex-Specific Longitudinal Modeling of Youth Peak Oxygen Uptake

Sex-Specific Longitudinal Modeling of Youth Peak Oxygen Uptake

Muscle metabolism changes with age and maturation: How do they relate to youth sport performance?

Influence of high-intensity interval training in adolescents with asthma

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