Relationship between physical activity, body mass index (BMI) and lipid profile of students in Ghana

Introduction In Ghana, there is no data regarding physical activity habits and lipid profiles of students. Therefore, the aim of this study was to investigate the relationship between physical activities, Body Mass Index (BMI) and lipid profile of students in Ghana. Methods Cluster and systematic sampling techniques were employed to recruit 120 students, aged 18 years and above. This cross-sectional study was carried out among students from the University of Ghana. Biochemical analysis was conducted analysing total cholesterol (TC), high density lipoprotein (HDL), low density lipoprotein (LDL) and triglycerides (TG) in serum samples. Anthropometry measurements were also taken and BMI calculated. The physical activities, undertaken over a 7-day period, by the students were assessed using the International Physical Activity Questionnaire (IPAQ). Results 31.7% and 21.7% of the students were overweight and obese respectively. 61.5% of the obese students were engaged in high level physical activity as compared to 45.5% and 36.8% of the normal and overweight students, respectively. Normal weight students and overweight students showed significant differences in means of TC; [(4.56 ± 0.930 mmol/L) and (5.06 ± 0.93 mmol/L), respectively] and also between normal weight group (4.54 ± 0.93 mmol/L) and the obese students (5.24 ± 1.18 mmol/L). Significant correlations were also observed between TG, TC and BMI; and TC and TG, HDL and a strong correlation between LDL and TC (r=0.967). Conclusion Strong correlations between BMI, physical activity and lipid profile indices among students in Ghana. Comprehensive efforts should be applied to reduce the incidence of CVDs among students.


Introduction
Globally, the leading cause of death are non-communicable diseases (NCDs) [1]. These have impacted greatly on the burden of the management of diseases around the globe. The incidence of cardiovascular diseases (CVD), a NCD, is on the rise [2]. In Ghana, CVDs are the leading cause of death [3]. Lifestyle behaviours known to increase CVDs risks include high alcohol consumption, poor eating habits, physical inactivity, extended sitting time and smoking [4][5][6].
In Ghana, adolescents have poor eating habits; often eating nutritionally unbalanced and unhealthy diet that is low in dietary fibre and high in simple sugars, fats and sodium [7]. The onset of CVDs is also linked to serum concentrations of the various categories of lipids in the body. Higher levels of high density lipoproteins (HDL) and low levels of low density lipoproteins (LDL) are cardio protective [8]. Diets rich in saturated fats increase the serum concentration level of LDL, whereas the dietary approach to stop hypertension (DASH) diet which is rich in fruits, vegetables and monounsaturated fatty acids increases HDL levels thereby protecting the heart against CVDs [9]. In addition to the effect of diet on cardiovascular health, the level of physical activity is important in protecting against CVDs [10]. It is recommended that healthy adults engage in about 150 minutes of physical activity every week [11]. However, this cannot be said to be the norm among Ghanaians [12,13]. University education can be stressful for students and can have negative impact on lifestyle behaviours such as poor eating habits and low physical activity [14].
This can increase the risk of CVDs. The American College Health Association reported an increase in the risk of developing CVDs among university students [15]. Anecdotally, one would have been expected that university students would be more active and engage in healthy lifestyles due to their educational background and the fact that they may be privy to the important link between high levels of physical activity and good health. This position is supported by a study that found that non-university students were found to have a greater risk of developing chronic diseases than those in university [16]. In Ghana, there is no data regarding physical activity habits and lipid profiles of students and their risk of developing CVDs. Therefore, the aim of this study was to investigate the relationship between physical activities, Body Mass Index (BMI) and lipid profile of students in Ghana in order to investigate the risk of developing CVDs among Ghanaian students.

Methods
Ethical considerations: ethical clearance for the study was obtained from the Ethics and Protocol Review Committee (EPRC) of the School of Biomedical and Allied Health Sciences of the University of Ghana. All subjects provided information regarding the study and their consent sought before participating in the study. Participants' confidentiality and anonymity were protected.
Study design and sampling: this cross-sectional study was carried out among students from the University of Ghana (UG). The UG is located in the Greater Accra Region of Ghana with an estimated student population of over 38,000. The students included in this study were 18 years and above. Since the UG is a very large geographical area, a cluster sampling method was used because it is the most timeefficient and cost-efficient probability design for large geographical areas [17]. Cluster sampling technique ensures an increased level of accessibility of perspective sample group members [17]. Additionally, a systematic sampling method was used to add a degree of system or process into the random selection of subjects and also to ensure that the population was evenly sampled [17]. Going by the widely quoted Cohen's effect size classification for one-way between groups analysis of variance (ANOVA), an expected large effect size will correspond to an effect size of 0.49 or more [18]. Hence a power analysis using the GPower computer software was conducted. The GPower software has been shown to have excellent accuracy and has been used in sample size calculations for many studies [19,20]. The results from the power analysis conducted using the Gpower software showed that a sample of 120 volunteers would be needed to determine a large effect, 0.49 with 80% power, using one way repeated measures ANOVA between means with alpha at 0.05.
Data collection: socio-demographic information of the students was obtained by the use of a self-administered semi-structured questionnaire. Information obtained included their ages, programmes of study and their marital status. The data for biochemical analysis, anthropometry measurements and assessment of physical activity were taken by the authors with the assistance of two experienced biomedical scientist with over ten years work experience between them.
Biochemical analysis: three (3ml) of venipuncture blood was drawn from students into gel separator tubes. These were then centrifuged at 3000 rpm for 10 minutes and stored in Eppendorf tubes  Correlations between the different variables tested are presented in Table 5. Strong, significant and positive correlation was observed between LDL and TC and negative significant low correlations was also seen between HDL and TG. It is also important to note that there were negative correlations between LDL and Physical activity and TG and physical activity level even though the test was not significant.

Discussion
Physical activity, BMI and lipid profile are important indicators of an individual's cardiovascular health [23]. Regular physical activity and BMI within acceptable ranges are cardio protective and have an enormous positive impact in reducing the risk of CVDs [24]. Also, blood concentrations of the various lipids also provide important information on an individual's cardiovascular health [25]. Therefore undertaking a research to investigate the relationship between BMI and lipid profile among students in Ghana will provide a baseline data in addressing the high incidence rate of CVDs in Ghana. The study reported majority of the obese students (61.5%) engaged in high level physical activity compared to the rest of the categories. This finding is not surprising because obese students may be motivated to indulge in high levels of physical activity in order to lose weight compared to the rest. However a study indicated that obesity rather leads to physical inactivity [26]. Earlier studies suggested that high BMI is strongly associated with cardiovascular biomarkers rather than physical inactivity [27]. Furthermore, a study conducted by Dudina [28] postulated that any 5-unit increase in BMI was associated with increased CVD risk. The results obtained in this study contrasts the results of a study [29] carried out among Ghanaian civil servants in which high levels of physical activity was rather observed in only 3.4% of those who were obese and 4.3% in those who were overweight.
The contradiction between the results of this study and previous studies may be due to the method used to assess physical activity.
The international physical activity questionnaire (IPAQ) relied on selfreported data, rather than more objective methods for assessing physical activity, and this method of physical activity assessment is subject to over-reporting which may well be the case with the obese group. This is further supported by the fact that physical activity data showed no significant association with any measure of blood lipids which is contrary to much published research.
A recent study have showed associations between BMI and lipid profile indices in obese people [30]. Greater level of obesity which is exhibited in high BMI has also been linked to higher TC and lower HDL levels [31]. Post hoc test revealed significant differences between TG levels of overweight, obese and normal weight students.
Significant differences were also observed in TC levels between normal weight students and overweight students. In addition, differences were also seen between normal weight students and obese students. where abnormal lipid profile were related to obesity, it should not be encouraged as it increases the risk of the onset of CVDs.

Conclusion
In conclusion, the results of this study showed correlations between BMI, physical activity and lipid profile indices among students in Ghana. Comprehensive efforts should be applied to reduce the incidence of CVDs among students.
What is known about this topic  No study conducted on this topic in Ghana;  No data available indicating the relationship between BMI, physical activity and lipid profile among students in Ghana.

What this study adds
 This study shows that correlations exist between BMI, physical activity and lipid profile indices among university students in Ghana;  Provides baseline data on the relationship between BMI, physical activity and lipid profile indices among students in Ghana.

Competing interests
The authors declare no competing interests.

Authors' contributions
All the authors were involved in the conceptualisation, design, data collection, analyses and writing up the manuscript. Table 1: results of chi square tests comparing the demographics between male and female students