This study was designed to evaluate the effect of an intensive after-school freestyle dance and lifestyle education program on risk factors for CVD and T2DM. The high attendance rate (85.6%) of our intervention is likely related to the fact that classes and counseling took place at the school after school hours. It is our belief that program convenience makes higher attendance more likely.
Interventions that are culturally tailored have been shown to be most effective for children of racial or ethnic minorities (28
). Our participants were predominantly Hispanic, and the program incorporated dances that were familiar to the Hispanic culture. Culturally familiar heart-healthy recipes and food were also integrated into the program. Together, these components of our intervention encourage lifelong, shared activity, and long-term sustainable lifestyle changes for children and their families.
The outreach approach used in our study exemplified the benefit of incorporating more families into a lifestyle intervention program. Furthermore, most children in the study engaged in dancing because they enjoyed the activity. We used random HR monitoring to gauge the exercise intensity and consistency, thus ensuring the validity of our dance intervention as providing MVPA. Together with lifestyle interventions, at the end of the 16-week period, an improvement was seen in a variety of risk factors, with the greatest improvement seen among children in overweight and obese BMItile categories.
is used to evaluate overweight and obesity in children. BMI levels are shown to correlate with an increase in BF and CVD risk levels (29
). Studies have shown that obese children tend to be less active than their non-obese peers (22
), and decreased activity is known to lead to low levels of fitness and increased adiposity (32
). MVPA impacts BF and muscular fitness (32
), and longer durations of PA seems to be more effective in changing BF (34
). Our study showed that a 16-week after-school dance and lifestyle education program aimed at parents and children, with 4 h of weekly PA, had a positive impact on BMI and body composition among children who are obese and overweight. Statistically significant changes occurred in BMItile
and FFM primarily in children classified as overweight and obese. Exercise interventions in adults were shown to reduce the percentage of weight lost as FFM in some studies (35
), whereas in others, mainly aerobic type of exercise resulted in an increase in FFM (36
). The increase of FFM that we found in our participants is also consistent with the findings from a study of a school-based PA program aiming to enhance endurance, flexibility, and strength in children (38
). The changes in BMItile
in a positive direction suggest that interventions of significant duration, similar to our program, are likely to bring about clinically significant changes. Seven children had improvements in percentile category, whereas one child's BMI category worsened.
However, an increase in FFM accounted for the increased BMItile
. A decrease in %BF among overweight children in our study is an expected outcome, according to previous data (20
). There was no significant difference found in BMI and BF changes in children in the normal weight group. Furthermore, these data show that our intervention is foremost successful in high-risk-category participants, such as those who are overweight and obese. Therefore, we advocate for similar future studies to specifically target this group of children. Moreover, in addition to improvements in body composition, the observed improvements in HOMA-IR and lipid profile support the benefits of an after-school program providing MVPA and lifestyle education to children and their parents.
The HOMA-IR is a validated method to assess insulin resistance, a key component in the pathogenesis of the metabolic syndrome (40
). Overweight and obese children are at risk for this metabolic consequence. Our results of improved serum glucose and HOMA-IR among overweight children after participation in the program support previous findings of the positive effects of exercise and healthy diet on insulin sensitivity (8
) and therefore may also suggest decreased CVD and T2DM risks.
CVD is one of the biggest contributors to morbidity and mortality in industrialized nations (46
). The American Academy of Pediatrics states that elevated cholesterol levels in children increase the risk for coronary heart disease (CHD) later in life (46
), and the American Heart Association emphasizes the importance of exercise in childhood as a way of preventing heart disease (48
). Stoedefalke (47
) reviewed 14 studies looking at the effect of PA on lipid profiles in children; six studies showed a positive correlation. Effects of time, intensity, and duration of exercise regimen may have played a role in these results. Our study provided aerobic exercise in the form of freestyle dance for a period of 16 weeks, three times weekly plus a once weekly practice session, for an average duration of 50 min per class, with participants having an average HR of 130 bpm. This is considered moderate to vigorous activity that approaches aerobic threshold (49
). The significant reductions found in TC, LDL, and non-HDL may be the result of the combination of changes made in dietary habits and participating in the after-school dance activity. Nevertheless, the combination of lifestyle education and a moderate to vigorous exercise regimen improves the CVD risk factors of overweight and obese children, consistent with the findings of some previous studies (50
HR decreases with aerobic training, and a decrease in RHR is indicative that the heart is working more efficiently (52
). Optimal physical fitness and regular training is assumed to induce adaption of the autonomic nervous system and is often observed as a decrease in resting basal HR thought to be mediated by an increase in cardiac vagal tone (53
). Data support that good aerobic fitness may have protective cardiovascular effects through enhancing the cardiac vagal function during exercise (49
). Various activities may have different physiological effects on children at different ages. This needs to be taken into account when designing MVPA programs to optimize cardiovascular benefits (54
). In our study, children were engaged in MVPA for 50 min on average, which was 83% of class time. This resulted in a statistically significant decrease in RHR suggesting an improvement in cardiovascular fitness. Higher levels of PA have also been reported to be associated with lower BP (51
). BP was only slightly decreased in our study without reaching statistical significance. This finding may well be explained by the fact that the majority of our participants were normotensive at baseline. Therefore, the improvement may have been too small to be detected. Others have reported similar results among children and adolescents (34
The questionnaire offered child-reported information on changes in lifestyle behaviors. Some of the children reported positive changes reflecting healthy eating habits, improvements in PA, and in sedentary behavior at the end of our intervention. This finding is considered important because children who watch more than 4 h of TV have been shown to have higher BMI and % BF than those who watch 2 h or less (55
). The improvement was maintained 6 months after the intervention in many of the children. These findings are very encouraging and suggest possible long-term effects of programs providing dance activity and lifestyle education. We do not have repeat blood lipids and other study parameters at 6 months, which will allow us to document a persistent improvement in our participants. As questionnaires have limitation in reflecting what really occurs, our follow-up questionnaire results should be interpreted with this caveat in mind. Nonetheless, our results justify future studies to understand the long-term impact of exercise and lifestyle programs.