According to the statistics, 50% of the world population is over 20 years old and
they have a body mass index (BMI) of ≥ 25. Worldwide, at least 2.8 million people die each year as a result of
rate of diseases is caused by overweight or obesity (Halliwill
et al., 2013).
Obesity is a complex condition characterized by excessive accumulation of adipose tissue. According to various studies and statistics, obesity has been identified as one of the negative factors for
people's health and longevity and is
associated with many health issues, such as cardiovascular diseases, diabetes, blood pressure, and lipids. The
World Health Organization (WHO) refers to the rapid increase in the prevalence of obesity as an epidemic of obesity (obesity epidemic) and
associates obesity and its implications with one of the main health risks in the world today (Zar
et al., 2017). Recognizing the factors that can help reduce this problem is of high importance.
Obesity is result of the imbalance between energy intake and energy expenditure. Sport activities play an important role in reducing and maintaining body weight (Mohammadi Moghaddam
et al., 2014). Weight is associated with the hormonal changes in the plasma level, which can affect the physiological function of the body.
Weight gain can change the hormone orexin and leptin levels.
Orexin is an appetite-stimulating hormone produced by posterior hypothalamus that secretes into the blood.
It can increase the appetite by affecting the appetite centers in the brain. Orexin production in obese individuals is generally less than the normal ones.
It has an inverse relationship with BMI (King
et al., 2009).
In a study conducted on the animals, the researchers found that although orexin-deficient animals ate less, they were heavier than the non-orexin-deficient ones. According to their findings, obesity in orexin-deficient animals may be due to the inability of
brown preadipocytes to be differentiated from brown fat, which reduces the brown fat thermogenesis and leads to dampening of energy expenditure (Sellayah
et al., 2011). On the other hand, a study investigated the effects of orexin on sleep and wakefulness,
energy homeostasis, and intestinal secretion among a newly created mouse line overexpressing human prepro-orexin gene. The results showed that orexin inhibited the animals' rapid eye movement sleep. In addition, it increasingly affected the metabolic heat production independent of uncoupling protein mediated thermogenesis in
brown fat (Mäkelä, 2010). The deficiency of this hormone in the human body is largely responsible for the development of obesity, since it reduces
the body's ability to burn fats and calories.
Therefore, doing exercises can improve the individuals' quality of life and health (Messina
et al., 2014).
On the other hand, one of the important hormones that play role in obesity is
leptin, which disorder can trigger the abnormal increase and decrease of the body weight. A close relationship was found between serum leptin, fat percentage, and BMI
; so that elevated body fat increased leptin secretion and
caused gradual resistance to leptin’s activity. In recent years, the effect of leptin on
arterial blood pressure and heart rate was demonstrated. Researchers believe that in obese participants, increased levels of leptin in the blood (as an indicator of leptin's resistance)
affects the obesity-associated diseases, cardiovascular diseases, type 2 diabetes, insulin resistance, and high blood pressure (Keller
et al., 2005). In this regard,
doing physical exercises can
boost the quality of one’s health.
In physical education, combined exercise training is a combination of aerobic and weight training that increases muscle mass and
reduces fat simultaneously.
A lot of studies have investigated the role of aerobic exercises on leptin secretion; however, some contradictions exist in the results. For example, Khorshidi (Khorshidi
et al., 2012) observed that 12 weeks of aerobic training reduced serum leptin levels and increased serum testosterone, which is contrary to the results reported by Ara (Ara
et al., 2006) and Sari (Sari
et al., 2007), who found that aerobic exercise did not affect the leptin secretion.
The fruit of the almond is a drupe weighing between 20 and 80 grams.
Research shows that diets consisting of almonds increase blood lipoprotein levels.
Dietary consumption of almonds reduces the coronary heart diseases and has antioxidant properties. Peanuts, like other nuts, have high levels of unsaturated fats and low levels of saturated fat. Therefore, its consumption is effective in reducing fats, notably cholesterol and reduces the risk of cardiovascular diseases (Esfahlan
et al., 2010).
In the study by Stephens et al., consuming almond and its oil reduced the risk of cardiovascular diseases by lowering blood cholesterol levels. Almond consumption also led to a significant increase in high density lipoprotein cholesterol (HDL-c) and a significant decrease in total cholesterol (TC) and low density lipoprotein cholesterol (LDL-c) (Stephens
et al., 2010). In another study, Spiller et al. found that TC and LDL-c levels in the almond-consuming group were significantly lower than those who did not consume almonds. However, the role of almond consumption besides physical activity has been underestimated (Spiller
et al., 1998).
In general, considering the importance of identifying strategies for improving the physiological conditions of overweight women, controversial results over the effect of aerobic training on plasma levels of leptin and orexin, lack of research on combined exercise trainings, and absence of continuous and sufficient research on sweet almond supplementation, this study was conducted. The purpose was to investigate the effect of eight weeks of combined exercise training with sweet almond supplementation on plasma levels of leptin and orexin in overweight women
.
Materials and Methods
Design and participants: This study was carried out with a quasi-experimental design in terms of the applied purpose and data collection. The statistical population of this study consisted of overweight women in Ardakan city, Yazd province, Iran.
To conduct the study, 60 participants with a BMI 25-30 were randomly selected and randomly divided into four groups of training, training-sweet almond supplement, supplement, and control (n = 15 in each group). The inclusion criteria for the participation in the study were personal consent, women with a BMI 25-30,
absence of movement disorders, not participating in any sport programs except the current research program, and lack of food supplements consumption that affected the research process.
The exclusion criteria were the participants' withdrawal, taking drugs, smoking, and not implementing the protocols thoroughly. Training and training-sweet almond supplement groups went through the combined exercise training program during three training sessions of about 45 minutes, carried out weekly for eight consecutive weeks.
Intervention: Aerobic exercises involved 10 minutes of warm-up, 25 to
45 minutes of walking/running at 65-75% of the maximum heart rate on the treadmill, and 5 minutes of cool-down, which were performed in two sessions each week. Resistance exercises consisted of
chest presses, underhand cable pulldowns, front and back biceps curls, leg presses, as well as knee bending and straightening at 55 to 65% of
one repetition maximum during three-time periods with an interval of two to three minutes (
Table 1). Each session of resistance training involved 10 minutes of warm-up and five minutes of cool-down. Prior to the exercises, participants' one repetition maximum was estimated
for each seven movements using the
lifted weight formula (30/ number of repetitions)+1 (Maud and Foster, 2006). With regard to the previous research, the training-sweet almond supplement and supplement groups consumed a pack of 50 grams of sweet almond as an afternoon snack
three times a week for eight weeks. The blood samples were taken 24 hours before the first session and after the last session in a 12-hour fasting state.
To simulate the sampling time and to control the circadian rhythm,
the sampling was carried out at the beginning and end of the study at eight o'clock in the mornings. To control the daytime rhythm, sampling at the beginning and end of the study was performed at eight o'clock in the morning.
Measurements: Five ml of blood was taken from the right arm vein of the participants. Leptin concentrations were measured using human-specific kits of Pishtaz Teb Inc. Orexin levels were measured through enzymatic method using the Virro Inc. kit.
Ethical considerations: All stages of this research Has been approved by Ethics Committee of Islamic Azad University Bafgh Branch with Code IR.IAU.B. 1397,28-14-5/1127
Data analysis: Descriptive statistical methods including
central tendency and dispersion indices were used to analyze the data.
For the inferential statistics, Shapiro-Wilk test was used to test the normal distribution of data in pre-test and post-test. A two-way repeated measures ANOVA
was run thereafter. The significance level was preset at P-value ≤ 0.05 and all statistical analyses were conducted using SPSS 22.
Results
The means' comparisons showed that simultaneous use of sweet almond supplements and combined exercise training did not have a significant effect on serotonin elevation and reduction of leptin compared to the sweet almond supplement and combined exercise training groups. In other words, training and of sweet almond supplementations did not have a synergistic effect on each other (P ≤ 0.05)