Exercise as it relates to Disease/Enhancing aerobic and anaerobic fitness in asthmatic children

Counil F, Varray A, Matecki S, Beurey A, Marchal P, Voisin M et al. Training of aerobic and anaerobic fitness in children with asthma. The Journal of Pediatrics. 2003;142(2):179-184. DOI: 10.1067/mpd.2003.83

What is the background to this research?
This paper evaluates improvements in aerobic and anaerobic fitness in asthamatic children after a training protocol designed to target both energy systems. Asthma is a chronic inflammatory condition affecting the airways. In 2013, the disorder affected 1 in 7 children and 1 in 15 adults in the United States. The majority of studies looking at exercise capacity in asthmatic people published prior to 2002 have been from an aerobic energy system point of view. The authors reported that a training effect on the anaerobic component of fitness has not been demonstrated in patients with asthma, and that all current training protocols are designed to improve aerobic fitness. Tolerable exercise protocols, both aerobic and anaerobically focussed, are important for people with asthma. There is a large amount of self-limitation of physical activity (PA) in asthmatic people due to unpleasant feelings associated with exercising, such as dyspnea and exercise-induced bronchospasm (EIB). Despite this, regular PA is recognised as being beneficial for asthmatics as it improves both cardiorespiratory health and muscular conditioning. It has been reported that equal decreases in maximal aerobic and anaerobic capacity exist in this population indicating that there is a need to increase both aspects of fitness.

Where is the research from?
The article was published in The Journal of Pediatrics in 2002. The research was conducted by a team from University of France Montpellier, Faculty of Sport Science. Service de Pédiatrie (the pediatric department) and Service d'Exploration Fonctionnelle Respiratoire (the exploration of respiratory function service) at Arnaud de Villeneuve Hospital were also involved. The head author, Francois-Pierre Counil, is a part of the Department of Pediatrics at Sherbrooke University and has many publications of research in respiratory, pulmonology and sports medicine.

What kind of research was this?
The study was a randomised controlled trial (RCT). At the time of the study (2002), only a few other controlled studies were available on the effects of endurance training in children with asthma. Some studies showed improvements in VO 2 max , maximal aerobic power (MAP)  , and anaerobic threshold , other studies showed no improvements. Being a RCT, the level of evidence should be reliable as the participants were randomly placed into either an exercising group or a control group. RCTs are considered to be the gold standard for determining the efficacy of a treatment protocol and the safety for the participants. They also ensure a low level of systematic error and provide a very high level of evidence regarding the effectiveness of the proposed protocol.

What did the research involve?
The study involved 16 male children who were recruited from two inpatient pulmonary rehabilitation clinics in Font Romeu, France. The participants had 3 sessions/week over 6 weeks. Each session involved 45min of continuous cycling, and every 4min they performed a 1min sprint at load corresponding to each subject’s individual MAP (recorded during an initial VO 2 max test). All sessions were supervised by a trainer and a pulmonologist to ensure the participants performed the exercises safely and correctly. The method used in the study is sound and a similar program has been used previously. However, it may have been more advantageous to undertake two different training modalities; one directly designed to improve aerobic fitness and another to improve anaerobic fitness. As well as this, increasing the length of the program from 6 weeks to 16 weeks may yield more reliable results. The study is limited in that only 16 children were recruited. The children were aged 10-16y/o, indicating that they would have been at very different stages of development, resulting in very different responses to training. Past studies have reported inconclusive evidence about aerobic response in children pre puberty.

What were the basic results?
The training protocol resulted in significant increases from baseline in the exercise group for: No significant changes were found in the control group for any of the tested variables. The researchers reported that both aerobic and anaerobic fitness can be improved in asthmatic children by using an exercise protocol that involves bouts of both high and moderate-low intensity workloads. However, there may be an overemphasis on the improvement to the anaerobic fitness of the participants as the only anaerobic parameter that significantly increased post-intervention was peak power. Neither the maximal breaking mass the subject could theoretically handle (Fo), nor the maximal cycling velocity theoretically obtained if Fo=0 (Vo) increased after the training protocol. Therefore, it is more likely that improvements in anaerobic fitness are not as great as improvements in aerobic fitness using the protocol implemented in this study. In order to further improve anaerobic fitness above just peak power, a specific protocol should be implemented that targets anaerobic fitness directly. For example, high intensity interval training (HIIT), or a resistance-based training program.
 * VO 2 max
 * Maximal aerobic power (MAP)
 * Maximum heart rate (HR max )
 * Peak power

What conclusions can we take from this research?
From the results, it can be seen that aerobic-based training in asthmatic children makes significant improvements in their aerobic fitness. However more data is needed to assess significant improvements in anaerobic fitness as the only aspect to improve in the study was peak power. For example, evaluating lactate thresholds and implementing a resistance-based protocol may be more informative about improvements to the anaerobic capacity of asthmatic children. A study duration including both male and females would also make the findings more applicable to a wider population group. These findings align with a more recent study from 2007 that also found improvements in power outputs and VO 2 max. This study involved two exercise sessions per week for 16 weeks. Each session included 30min of aerobic exercise followed by 30min of resistance-based exercise. The study concluded that exercise improves the quality of life and EIB in asthmatic children. However, another study reported no significant improvements in lung function (measured using FEV 1 ) after a 6 week exercise intervention (3 x 40min sessions/week), but did report improvements in clinical symptoms and quality of life (measured using the Paediatric Allergic Disease Quality of Life Questionnaire).

Practical advice
Exercise Recommendations Cycling Resistance Cautions
 * For those with no or little history of PA, include a build-up period over 8 sessions of low intensity.
 * Once tolerable, increase the duration and intensity, aiming for 40-45min of moderate intensity.
 * To train both aerobic and anaerobic systems, high intensity "sprints" can be added in every 4-5min of moderate intensity cycling.
 * Upper and lower body resistance based exercise can be performed with free weights.
 * Literature suggests 3 sets of 15 repetitions per exercise.
 * Caution should be taken for those with severe asthma when considering beginning a PA program as those involved in the study were classified as having only mild-moderate asthma.

Further information/resources
Helpful links
 * What happens in your airways when you have asthma
 * Exercise and Asthma
 * Asthma Australia
 * Exercise-induced asthma
 * 11 Ways to Encourage Your Child to be more Physically Active