Influence of training status and exercise modality on pulmonary O2 uptake kinetics in pubertal girls

The influence of training status on the oxygen uptake ( O2) response to heavy intensity exercise in pubertal girls has not previously been investigated. We hypothesised that whilst training status-related adaptations would be evident in the O2, heart rate (HR) and deoxyhemoglobin ([HHb]) kinetics of pubertal swimmers during both lower and upper body exercise, they would be more pronounced during upper body exercise. Eight swim-trained (T; 14.2±0.7 years) and eight untrained (UT; 14.5±1.3 years) girls completed a number of constant-work-rate transitions on cycle and upper body ergometers at 40% of the difference between the gas exchange threshold and peak O2. The phase II O2 time constant (τ) was significantly shorter in the trained girls during both cycle (T: 21 ± 6 vs. UT: 35 ± 11 s; P<0.01) and upper body exercise (T: 29 ± 8 vs. UT: 44 ± 8 s; P<0.01). The O2 slow component was not influenced by training status. The [HHb] τ was significantly shorter in the trained girls during both cycle (T: 12 ± 2 vs. UT: 20 ± 6 s; P<0.01) and upper body exercise (T: 13 ± 3 vs. UT: 21 ± 7 s; P<0.01), as was the HR τ (cycle, T: 36 ± 5 vs. UT: 53 ± 9 s; upper body, T: 32 ± 3 vs. UT: 43 ± 2; P<0.01). This study suggests that both central and peripheral factors contribute to the faster O2 kinetics in the trained girls and that differences are evident in both lower and upper body exercise

Aerobic Fitness and Trainability in Healthy Youth: Gaps in Our Knowledge

Peak oxygen uptake (V̇O2) is widely recognized as the criterion measure of young people’s aerobic fitness. Peak V̇O2 in youth has been assessed and documented for over 75 years but the interpretation of peak V̇O2 and its trainability are still shrouded in controversy. Causal mechanisms and their modulation by chronological age, biological maturation and sex remain to be resolved. Furthermore, exercise of the intensity and duration required to determine peak V̇O2 is rarely experienced by most children and adolescents. In sport and in everyday life young people are characterized by intermittent bouts of exercise and rapid changes in exercise intensity. In this context it is the transient kinetics of pulmonary V̇O2 (pV̇O2), not peak V̇O2, which best describe aerobic fitness. There are few rigorously determined and appropriately analyzed data from young people’s pV̇O2 kinetics responses to step changes in exercise intensity. Understanding of the trainability of pV̇O2 kinetics is principally founded on comparative studies of trained and untrained youth and much remains to be elucidated. This paper reviews peak V̇O2, pV̇O2 kinetics, and their trainability in youth. It summarizes “what we know,” identifies significant gaps in our knowledge, raises relevant questions, and indicates avenues for future research

The influence of training and maturity status on girls’ responses to short-term, high-intensity upper- and lower-body exercise

A maturational threshold has been suggested to be present in young peoples’ responses to exercise, with significant influences of training status only evidenced above this threshold. The presence of such a threshold has not been investigated for short term, high intensity exercise. To address this, we investigated the relationship between swim-training status and maturity on the power output, pulmonary gas exchange and metabolic responses to upper (UP) and lower body (LO) Wingate Anaerobic Test (WAnT). Girls at three stages of maturity: pre-pubertal (Pre: 8 trained (T) 10 untrained (UT)); pubertal (Pub: 9 T, 15 UT); and post-pubertal (Post: 8 T, 10 UT) participated. At all maturity stages, T exhibited higher peak power (PP) and mean power (MP) during UP (PP: Pre, T, 163±20 vs. UT, 124±29; Pub, T, 230±42 vs. UT, 173±41; Post, T, 245±41 vs. UT, 190±40 W; MP: Pre, T, 130±23 vs. UT, 85±26; Pub, T, 184±37 vs. UT, 123±38; Post, T, 200±30 vs. UT, 150±15 W; all P<0.05) but not LO exercise, whilst the fatigue index was significantly lower in T for both exercise modalities. Irrespective of maturity, the oxidative contribution, calculated by the area under the O2 response profile, was not influenced by training status. No interaction was evident between training status and maturity, with similar magnitudes of difference between T and UT at all three maturity stages. These results suggest there is no maturational threshold which must be surpassed for significant influences of training status to be manifest in the ‘anaerobic’ exercise performance of young girls

Physical Activity and Sedentary Time Patterns in Children and Adolescents with Cystic Fibrosis and Age- and Sex-Matched Healthy Controls

Background:Regular physical activity (PA) is increasingly recognised as important in the care of patients with Cystic Fibrosis (CF) but there is a dearth of evidence regarding physical activity levels (PAL) or how these are accrued in those with CF.Methods:Physical activity was measured by a hip-worn accelerometer for seven consecutive days by eighteen children (10 boys; 12.4 ± 2.8 years) with mild to moderate CF and eighteen age- and sex-matched controls (10 boys; 12.5 ± 2.7 years).Results:Both CF and healthy children demonstrated similar PAL and patterns of accumulation across the intensity spectrum, with higher levels of PA during weekdays in both groups. FEV1 was predicted by high-light PA in CF compared to low-light PA in healthy children.Conclusion:These findings highlight weekends and light PA as areas warranting further research for the development of effective intervention strategies to increase PA in the youth CF population

Promotion of physical activity for adolescents with cystic fibrosis: A qualitative study of UK multi-disciplinary cystic fibrosis teams

BackgroundThe Cystic Fibrosis Trust recently published a standards of care document which stated that patients should be given a physical activity (PA) programme based on their motivations, fitness, and willingness to be active. However, there remains much debate regarding the roles and responsibilities for PA promotion, as well as “optimal” recommendations and advice. This study aimed to qualitatively explore cystic fibrosis (CF) multidisciplinary teams (MDTs) advice, recommendations and practices relating to PA promotion for adolescents with CF.MethodSemi-structured interviews were conducted with fifteen members of CF MDTs (11 physiotherapists, two dieticians and two paediatricians). Thematic analysis was used to analyse the data.ResultsMajor themes identified were: 1) structure of MDTs, 2) recommendations relating to intensities, durations and types of PA, and 3) use of exercise testing. Participants reported variation between MDTs in terms of who is responsible for promoting and supporting PA, the nature of advice given to patients, and the use of exercise testing. Participants consistently lacked confidence in their own or others’ knowledge to provide standardised recommendations to patients and highlighted that PA promotion and support was often overlooked during busy periods.ConclusionsDespite its importance, PA support and promotion is not always prioritised. MDTs lack confidence in their ability to promote PA. Standardised advice and training relating to optimal intensities, durations and types of PA would provide a baseline from which to individualise advice to each patient and could increase confidence in PA promotion among MDTs

Investigating the Modulatory Role of Chronological and Biological Age on Performance Predictors in Youth Swimmers

The aim of this study was to determine the modulatory roles of biological maturity and age on the predictors of performance in youth swimmers and their stability over a six-month training cycle

Influence of training status and maturity on pulmonary O2 uptake recovery kinetics following cycle and upper body exercise in girls

The influence of training status on pulmonary VO2 recovery kinetics, and its interaction with maturity, has not been investigated in young girls. Sixteen prepubertal (Pre: trained (T, 11.4 ± 0.7 years), 8 untrained (UT, 11.5 ± 0.6 years)) and 8 pubertal (Pub: 8T, 14.2 ± 0.7 years; 8 UT, 14.5 ± 1.3 years) girls completed repeat transitions from heavy intensity exercise to a baseline of unloaded exercise, on both an upper and lower body ergometer. The VO2 recovery time constant was significantly shorter in the trained prepubertal and pubertal girls during both cycle (Pre: T, 26 ± 4 vs. UT, 32 ± 6; Pub: T, 28 ± 2 vs. UT, 35 ± 7 s; both p < .05) and upper body exercise (Pre: T, 26 ± 4 vs. UT, 35 ± 6; Pub: T, 30 ± 4 vs. UT, 42 ± 3 s; both p < .05). No interaction was evident between training status and maturity. These results demonstrate the sensitivity of VO2 recovery kinetics to training in young girls and challenge the notion of a “maturational threshold” in the influence of training status on the physiological responses to exercise and recovery