Cardiovascular disease (CVD) is the leading cause of mortality worldwide [1
]. In 2005 there was a reported 17.5 million deaths related to the disease, representing 30% of the global population [2
]. Risk factors for CVD including obesity, blood pressure, blood lipids and lipoproteins have shown to track from childhood through to adulthood [3
]. Metabolic syndrome (MetS) is the co-existence of multiple risk factors including hyperinsulinaemia, glucose intolerance, hypertension, decreased levels of high-density lipoprotein cholesterol (HDL-C) and elevated triglycerides (TG) [5
]. At least one MetS risk factor was evident in one third of children (12-19 years) from the Third National Health and Nutritional Survey [6
]; whereas one in ten was diagnosed with the syndrome itself when using the National Cholesterol Education Programme - Third Adult Treatment Panel definition. The prevalence of overweight and obesity for children (4-18 years) in the UK is reported to be 15 and 4% respectively [7
]. Furthermore, in comparison to England (2.9%) obesity was more prevalent for those living in Scotland (7.6%) and Wales (6.5%).
For many, overweight and obesity is the result of the combined effect of excess energy consumption and inadequate physical activity (PA) [8
]. Previously, for children and adolescents PA has correlated negatively with body fatness and insulin resistance [9
]. Conclusions regarding associations with blood lipids and lipoproteins are less clear. Although a recent meta-analysis reported no effect of aerobic exercise on non-high-density lipoprotein cholesterol, further studies are warranted [12
]. Despite this, significant inverse relationships between PA and metabolic risk scores have recently been reported [13
], highlighting the importance of PA on childhood health. Schools are thought to be the ideal setting to implement PA interventions to combat CVD risk factors, with access to large populations from a variety of social classes, coinciding with a monitoring structure already in place [15
The association between psychosocial variables and obesity is complex. Research findings in this area indicate that there is a relationship between depression in youth and subsequent obesity [17
]. The stigma attached to being overweight may affect peer relationships and may result in children and adolescents feeling less able to participate in PA and more likely to suffer from psychological distress [19
The impact of PA on psychological health and well being has been noted for some years. Biddle et al. [21
] reported that PA was associated with reduced levels of anxiety and depression and improved self-esteem, mood and cognitive function. In addition, epidemiological evidence suggests that PA is associated with a decreased risk of developing depression [22
]. Exercise programmes have consistently been found to be as effective in reducing levels of depression in adult samples as a variety of standard psychotherapeutic treatments [23
The relationship between PA and psychological well-being needs further investigation. Physical activity can have a positive effect on self-esteem and physically active children tend to suffer from fewer mental health problems [24
]. In a review of PA in children and adolescents, Biddle et al. [25
] suggest that a lack of PA in children has been associated with a number of psychosocial variables and perceived barriers. Positive effects on self-esteem are evident for all people participating in PA however the impact on self-perceptions is particularly strong for children [26
]. A different pattern of psychosocial variables seems to be important for adolescents including perceived competence, and achievement orientation.
Previous school-based interventions targeting both children and adolescents have demonstrated modest improvements to CVD risk factors, including obesity, insulin resistance, blood pressure, and blood lipids [15
]. Many of these school-based interventions have also looked to improve diet. Most school-based PA interventions have looked to improve physical education (PE) lessons or to provide extra-curricular activities [15
]; few studies have sought to increase PA levels by integrating exercise into what would normally be classroom delivered subjects.
Recently an intervention by Reed et al. [32
] used a whole school approach targeting six action zones to increase elementary school children's (9-11 years) PA. The only prescriptive component was to introduce three 15-minute periods per week of classroom PA. This allowed participants to carry out activities including skipping, dancing and resistance exercises. Sixteen months into the programme, improvements in aerobic fitness and blood pressure were evident, but no effect was observed for blood lipids, apolipoprotein B, C-reactive protein, and fibrinogen. Despite detail pertaining to the duration of time provided for participants to perform PA, there was no information regarding the amount of actual PA performed. It is evident that more population-based prevention programs are needed [33
]. Targeting class-room based curriculum subjects with an increase in PA, may display favourable outcomes in child CVD risk status.