Physical activity is increasingly recognized as an important modifying factor for physical fitness and health markers in people (Pate 2013). Physical activity is likewise essential for children and adults with congenital heart disease (ConHD) (Takken 2011; Tikkanen 2012; Duppen 2013; Longmuir 2013). Despite the growing body of literature on the benefits of physical activity, a large number of patients with ConHD do not adhere to recommendations (Reybrouck 2005; McCrindle 2007).
Physical activity refers to any bodily movements that result in an increase in energy expenditure above baseline resting energy expenditure (Caspersen 1985). Physical activity can be habitual and a part of daily living, as well as part of a structured exercise program. Physical exercise is defined as a subset of physical activity that is planned, structured and repetitive, and has as a final or an intermediate objective the maintenance or improvement of physical fitness (Caspersen 1985). Physical activity can be assessed by self-report or objective measures. However, physical activity is difficult to assess and interpret as no method is accurate. Interventions to increase physical activity are therefore also evaluated by health outcomes mediated by physical activity such as exercise capacity, health-related quality of life and risk markers for metabolic syndrome.
Children and adults with ConHD have reduced exercise capacity across the different heart defects, in comparison with healthy people (Kempny 2012). The low level of physical activity in this population may explain this reduced exercise capacity, along with restrictions for unknown reasons (Lunt 2003; McCrindle 2007; Buys 2012a; Buys 2012b; Buys 2013).
The American Heart Association and the European Society of Cardiology recommend that children and adults with ConHD should be encouraged to be normally active and to participate in recreational sport activities (Takken 2011; Longmuir 2013). However, so far those recommendations are primarily based on expert opinion (Evidence level 5) rather than scientific evidence (Klausen 2012). The effects of interventions to increase physical activity in people with ConHD need to be further investigated and summarized.
Description of the condition
ConHD can be defined as "a gross structural abnormality of the heart or intrathoracic great vessels that is actually or potentially of functional significance" (Mitchell 1971). The reported birth prevalence worldwide has increased from 0.6 per 1000 live births in 1934 to 9.1 per 1000 live births after 1995 (van der Linde 2011). This corresponds to 1.35 million live births with ConHD each year, representing a major public health issue (van der Linde 2011). Before the end of the 1970s, less than 20% of children born with ConHD survived into adulthood (Warnes 2001). Today, 85% are expected to live until adulthood (Moons 2010). Their children are at increased risk of having a congenital abnormality (van der Bom 2011).The complexity of the disease varies and is reflected in survival rates, comorbidity and health-related quality of life (Warnes 2001). Genetic syndromes, gestational age and birth weight, as well as complications after surgery, add to comorbidity and contribute to the long-term outcomes (Wernovsky 2008).
Description of the intervention
Interventions can be facility based, home based or both. Promotion of and incentives to increase exercise and physical activity can be undertaken in a multitude of ways and situations. Exercise-based interventions for people with ConHD may take place at any relevant time from early childhood to adulthood. The type of intervention directed at people with ConHD should be adjusted to age, developmental stage and disease progression.
The first interventions for people with ConHD in the 1980s examined whether maximal oxygen uptake and exercise capacity could be safely improved by facility based exercise-based interventions (Goldberg 1981). As this seemed to be the case, it has been suggested that exercise-based interventions should become a part of the routine care of patients with ConHD (Tikkanen 2012; Duppen 2013).
Interventions to promote physical activity in children and adults have been encouraged and described (Hirth 2006; Baumgartner 2010; Takken 2011; Longmuir 2013). It is suggested that practitioners should promote physical activity in all medically-stable children and adults, according to the frequency and intensity recommended in general population guidelines. Moreover, sedentary time should be reduced, as prolonged sedentary time has been associated with negative health outcomes (Thorp 2011). Physical activity counselling should be based on a clinical assessment at every patient interaction. Social, cognitive and motivational theories should be used to guide a patient-centred approach, to identify personal relevant goals and develop an individual action plan (Longmuir 2013). The evidence for the recommendations is low (Evidence level 5), mainly based on expert opinion, as the body of knowledge is limited (Hirth 2006)
From research in other populations with cardiac disease, we know that exercise-based rehabilitation can lead to increased physical fitness, increased physical activity levels in daily life and a healthier lifestyle, which persist after termination of the exercise program (Vanhees 2012). Also, in individuals with ConHD, rehabilitation programmes can have persistent beneficial effects, although more evidence in this population is needed (Longmuir 1990; Rhodes 2005).
How the intervention might work
Physical activity behaviours are affected by personal, social and environmental factors (Heath 2012). Interventions that address personal factors to encourage physical activity involving education on health benefits, motivation and physical training are likely to be successful (Pate 2013). Education on health benefits and motivation can be improved by individually-tailored programmes based on behavioural and social cognitive theories (Kahn 2002).
Interventions mediated by behaviour change techniques, goal setting, feedback and problem-solving aimed at increasing daily physical activity levels, have proven successful in other fields (Olander 2013). Physical activity can be improved by clarifying the individual's specific needs, followed by individual or group-wise guidance to overcome barriers and foster motivation (Longmuir 2013). Goal setting, social support and behavioural reinforcement through self-reward and structured problem solving are examples of components of these types of interventions. Interventions involving behaviour change techniques can be described using a taxonomy in order to structure and specify the terminology used in invention studies (Michie 2011).
Self-efficacy is considered to be an important mediator in physical activity (Bar-Mor 2000; Olander 2013). Self-efficacy is defined as the belief that one has the ability to engage in a specific behaviour, such as physical activity (Bandura 1986).
There are convincing data demonstrating that contemporary cardiac rehabilitation programmes provide direct health benefits, reduce cardiovascular risk and event rates, increase healthy behaviours and promote active lifestyles (Kwan 2012). Furthermore there is evidence that a cardiac rehabilitation programme can improve quality of life in different populations with acquired heart disease (Weberg 2013). It is possible that exercise-based interventions could induce similar benefits in participants with ConHD.
There is a great interest in the association between exercise-based interventions and health-related quality of life. Health-related quality of life can be defined as the degree of overall life satisfaction that is positively or negatively influenced by an individual’s perception of certain aspects of life that are important to them, including matters both related and unrelated to health (Moons 2004). Davies et al. have shown that exercise training that improves exercise capacity may have a clinically-important effect on health-related quality of life in people with mild to moderate heart failure (Davies 2010).The efficacy of physical activity for improving functional capacity and quality of life is clear in the short-term, but long-term effects are yet unknown (Piepoli 2013). It is unknown if exercise-based interventions can impact health-related quality of life in individuals with ConHD (Kovacs 2005). Studies have shown that self-assessed physical functioning poorly predicts actual exercise capacity in adolescents and adults with ConHD (Gratz 2009). Nevertheless, associations between physical fitness and different domains of health-related quality of life have been noted in some studies (Van De Bruaene 2011; Buys 2013). However, the way these dimensions interact and respond to exercise-based intervention programs is poorly understood.
Why it is important to do this review
Uncertainty exists as to whether exercise-based interventions are harmful or beneficial for people with congenital heart disease (ConHD), and whether current recommendations are effective. However, undue care/protection may be harmful if it restricts physical activity. By contrast, strenuous physical exercise may be harmful to individuals with ConHD due to their heart condition. There is a growing interest in the association between health-related quality of life and health-related fitness in people with ConHD. Trials have examined the effect of exercise training on physical fitness and health-related quality of life, but no consensus has been established (Duppen 2013). Thus, a systematic review of trials testing the interventions for increasing physical activity is needed to synthesize the evidence on quality of life, health-related fitness, cardiovascular risk factors and adverse events in people with ConHD.
This review aims to summarize the results of all randomized trials with an experimental intervention aiming to increase physical activity in individuals with ConHD. It is important to do this review, because it includes all interventions that intend to increase physical activity, and will not solely focus on exercise training. Habitual physical activities, such as increased leisure time activities and active transport, will also be included in the review.