Since 1990, several hormones (adipokines) have been identified in relation to obesity, type 2 diabetes, metabolic syndrome, cardiovascular disease (CVD), nervous, endocrine, and immune systems (
Akbarzadeh et al., 2012). Adipose tissue is an endocrine organ that secretes different components including hormones, growth factors, cytokines, and complement factors. These factors play role in fat cell differentiation and metabolism, regulation of vascular blood flow, and fat metabolism (
Haider et al., 2006). Physical exercise affects the adipose tissue and can influence the health process. Furthermore, adipose tissue secrets different adipokines such as vaspin. Vaspin seems to cause insulin sensitivity and metabolic homeostasis reactions. However, the mechanism of this process is unknown. Nevertheless, physical activity can cause a change of vaspin in the blood circulation (
Seeger et al., 2008). Vaspin plays role in different metabolic processes, such as fat tissue activity, changes in body mass index (BMI), blood glucose tolerance, metabolic syndrome, diabetes, and CVD (
Chtara et al., 2005,
Klöting et al., 2006,
Youn et al., 2008). Exercise training influences adipose tissue, which leads to release of vaspin. It was reported that 12 weeks of aerobic interval activity could decrease total cholesterol and low-density lipoprotein (LDL) (Pedersen et al., 2016). Moreover, physical fitness is determined by measuring indicators such as body composition, body fat percentage, BMI, and waist to hip ratio (WHR) (
Saghebjoo et al., 2011). Regular exercise training, including endurance and resistance activities, improves physical condition and health promotion. For example, endurance training increases energy expenditure and fat oxidation, while strength training increases body mass and muscle strength (
Kang et al., 2009). Increase of adipose tissue is related to the low level of serum vaspin and physical activity can increase serum levels of vaspin among non-athletes (
Youn et al., 2008). Furthermore, it was reported that modification of life style and increase of physical activity decreased the vaspin level, body weight, and resistance to insulin among the overweight and obese adolescents (
Lee et al., 2010). Another study demonstrated that the increase in serum vaspin was related to obesity and caused a decrease in insulin sensitivity. It was also reported that the association between increased serum levels of vaspin and weight gain were associated with decreased levels of insulin sensitivity in diabetic patients (
Youn et al., 2008). On the contrary, another study revealed that aerobic training did not change the vaspin level significantly (
Khademosharie et al., 2014). It seems that physiological beneficial changes can be achieved by endurance activities, resistance training, or a combination of them, which can balance the energy metabolism and fitness in body composition, insulin sensitivity, and regulation of energy metabolism to establish health (
Youn et al., 2008). Meanwhile, it is probable that combination of exercise training has more beneficial effect than individual training methods (
Klöting et al., 2006). Considering different results about the effect of exercise training on the levels of vaspin, body composition, and lipid profile, this study aimed to evaluate the effect of endurance exercise training on the serum vaspin, lipid profiles, and some anthropometric indices in young people.
Material and Methods
Design and participants: This semi-experimental study was carried out on 40 male students (19.2 ± 2
.1 y), who were selected using the randomize method. The participants were selected from physical education students in Sistan & Baluchistan University, Zahedan, Iran. Of the 40 students, 14 were excluded since they were not able to keep up with the study conditions and recommendations. The remaining 26 participants completed the study without any problem; so, they were randomly divided into the endurance or aerobic (n = 13) and control (n = 13) groups.
The inclusion criteria were having 18-25 years of age, using the university's self-service restaurant, having no professional training and physical illnesses, residing in dorms with no medical histories, having a stable weight for at least three months, and having confirmation certificate of public health provided by a physician from the university clinic. The exclusion criteria included smoking, failing to adhere to exercises regularly, not using the university's self-service restaurant, and consuming medications or supplements that affect the laboratory test results.
Exercise training program: Aerobic activities, which involved walking and running were supervised by an exercise physiologist in 60 min/d and 3d/wk for 10 weeks. At every training session, the participants completed the warm up activities during the first 6 min, performed stretching and flexibility exercises during the next 4 min (taking a total of 10 minutes). In the following, they conducted a 15-50 min walking-running at 55 - 85% of HRmax. Relaxation exercises were performed 10 min at the end of the period. The cold-up exercises, performed at the end of the process, lasted 3 to 4 minutes and included jogging and walking. After every workout session, 5 min of stretching were performed by all participants. This phase was considered to last less than 10 min. The participants' heart rates were checked and recorded by a manometer. Furthermore, all trainings and activities were performed and checked by an exercise physiologist.
Determination of anthropometric indices and body composition: Body weight and height were measured using standard methods by an athletic trainer. Body weight and height were measured by a Seca scale to the nearest 100 g and 0.5 cm, respectively. The waist circumference was measured between the lower border of the rib and the iliac crest by a non-stretchable tape. Body mass index was evaluated based on the calculation of body weight (kg)/height (m
2) (
Mahan and Raymond, 2016,
Ramírez-Vélez et al., 2017). Percentage of body fat was calculated by skinfold thickness measurements (Skinfold Fat Caliper SAEHAN, SH5020; South Korea). The body fat was also calculated based on the following formula:
Density body (DB) =1.1093800 – (0.0008267. (S) + [0.0000016 (S2) – 0.0002574]. [Age( y)]
% Body fat = (4.95/ BD + 4.5).100
Where, S = Total fat under the skin in three points, including chest, abdomen, and thigh. This formula was approved by Jackson and Pollock for men (Jackson, Pallock., et al., 1978). Three points of the participants' body were used for determination of the body fat, including pectoral, superailiac crest, and midthigh area of the body. According to the standard, body fat of 24% or greater was considered as obesity (
Jackson and Pollock, 1978). All skinfold thickness measurement was performed by the athletic trainer and supervised by a sports physiologist.
Nutritional assessment: Dietary intakes were evaluated using the 24-hr recall questionnaire. All consumed foods were recorded in the questionnaire for two days. The mean values of calorie and macro-nutrients intake were measured on one weekday and on week-end. Dietary intake data and the amount of daily
food intake were recorded in 48-hr recall questionnaires. The calorie and macro-nutrients intake were analyzed using a computer software program developed for analyzing the Iranian foods (
Mirmiran et al., 2004). The participants were educated by a nutritionist and followed up regularly. According to the recall questionnaire, all participants mentioned the type and amount of different foods consumed in two days of week.
Blood sampling and determination of lipid profile: To conduct the study, 10 ml fasting blood was taken from all participants in pre- and post-training. In the intervention group, blood samples were taken 48 hrs after the last exercise session. Serum was analyzed for lipid profiles in two steps of cholesterol and triglyceride. Moreover, HDL levels were calculated by enzymatic method, and using commercial kits, Parsazmun, Tehran, Iran, RA- 1000 (Technical publication No, UBA- 7638 – 00/USA) (Richmond et al.,1973). The LDL value was calculated employing friedwald formula (
Friedewald et al., 1972). The remained samples were stored at -70 °C till analysis.
Determination of adipokines; Vaspin: Serum levels of vaspin were measured by Enzyme-linked Immune-Sorbent Assay enzyme- linked immune-sorbent assay (ELISA) using the commercial kits: Human adipsin; Hangzhou Eastbiopharm Co, LTD, Cat.No:CK-E10968 ELISA kit).
Ethical considerations: The Ethics Committee of Zahedan University of Medical Sciences approved this study (Code number; 6992; 31. Jan. 2015).
Data analysis: The SPSS 16 was used for statistical analysis. Data were reported in mean ± SD. Kolmogorov Smirnov test was used to test normal distribution of the data. Independent sample
t-test and paired sample
t-test were also applied to compare means between and within the two groups with normal distribution, respectively. In the case that the data were not distributed normally, nonparametric test such as Mann-Whitney U and Wilcoxon were used between or within groups respectively. P-value < 0.05 was considered as the significant level.
Results
The general characteristics of participants in the two groups are shown in
Table 1. At baseline, the mean of anthropometric indices was normal in the two groups and no significant difference was observed between them in terms of BMI, WC, and WHR (
P > 0.05).
However, with regard to the body fat percentage, the intervention group's scores were significantly different before and after the exercise training (
P = 0.02). However, this difference was not significant in the control group (
P = 0.3,
Table 2). Significant difference was also observed in the body fat percent before and after the exercise training in the intervention group compared to the control group (
P = 0.009).
No significant difference was observed in the intervention group in terms of lipid profile levels before and after the exercise training. However, except to the HDL level, all other changes were significant compared to the control group (
P < 0.05,
Table 3).
According to vaspin level, no significant difference was observed before and after the exercise training between the study groups (
P = 0.1,
Table 4). Furthermore, the amount of blood vaspin reduced one month after the aerobic exercise training, but no significant difference was observed in the two groups (
P = 0.1). Moreover, a significant difference was seen in the level of vaspin in the intervention group before (
P = 0.01) and after (
P = 0.05) the endurance exercise training intervention compared to the control.
Dietary analysis showed no significant variation in the daily calorie intake between two groups. It was found that mean of the daily calorie intake was 2383.7 ± 265.7 and 2412.7 ± 285.2 kcal/d in the intervention and control groups, respectively, which was near the recommended dietary allowances. In addition, the ratio of macronutrients is similar in providing the total daily energy intake in the intervention and control groups. The average ratio of the daily calorie intake of the macronutrients in the case group included carbohydrates, proteins, and fats were 59.3 ± 1.5%, 17.6 ± 2.7%, and 23.1 ± 4.1%, respectively. These levels had no significant difference compared to the control group (
P > 0.05).