Metabolic Syndrome and Physical Activity Levels in College Students

Abstract

Background:

It is estimated that >30% of young adults attending college are overweight or obese and do not participate in enough physical activity (PA) to maintain a healthy body mass. Many of the known risk factors that are often associated with obesity also place an individual at risk for developing metabolic syndrome (MetS). The purpose of this study was to examine the prevalence of MetS and the magnitude and rate of PA levels in college students.

Methods:

Seventy-six college-aged students participated in the study. The following information was obtained from each participant: body anthropometrics, fasting glucose and lipoproteins, and accelerometer-measured activity levels. Participants wore, at the waist, the wireless activity monitor (wGT3X-BT; ActiGraph, Pensacola, FL) for seven consecutive days to monitor PA levels. MetS was determined if the participant met three of the five criteria utilizing the National Cholesterol Education Program guidelines.

Results:

More than half of the participants had at least one criterion, with the overall prevalence of MetS being 9.2%. MetS participants were more sedentary (84.8% vs. 91.0%, P < 0.001) and engaged in less light activities (8.9% vs. 6.0%, P < 0.001).

Conclusions:

Current activity levels in college students do not meet the established guidelines for total steps per day, elevating the risk of acquiring metabolic disorders.

Introduction

Between 1991 and 1997, the greatest increase in obesity (body mass index >30 kg/m²) was found among 18- to 29-year-olds (7.1%–12.1%).¹ The American College Health Association (ACHA) reported that the percentage of overweight and obese college students has increased from 27.4% in 2006 to 29.2% in 2011.² Obesity can be a serious medical health problem that can cause complications such as high blood pressure (BP), atherosclerosis, heart disease, diabetes, high blood cholesterol, cancers, and sleep disorders.^3
–5 Metabolic syndrome (MetS) is a grouping of cardiovascular disease risk factors that include (1) central or general obesity (WC; increased waist circumference); (2) hypertension (HTN; elevated or high BP); (3) glucose intolerance, insulin resistance (diabetes), or some level of poor glucose control; (4) a reduced level of high-density lipoprotein cholesterol (HDL-C); and (5) elevated levels of triglycerides (TG) (hypertriglyceridemia). An estimated 36% of the U.S. adult population meet the criteria for MetS⁶ and several studies have reported rates of MetS in college students ranging from 3% to 10% across the genders.^7
–9

Physical activity (PA) levels have been shown to elicit an inverse relationship with MetS.^10
–12 Cho et al. reported that participation in any kind of leisure-time PA was associated with a reduction in the odds for MetS by 15% in men and by 35% in women.¹⁰ However, previous research suggests that in the United States young adults are not engaging in PA levels, at least 150 weekly minutes of moderate intensity or 75 weekly minutes of vigorous intensity, that meet the standards established by the Centers for Disease Control and Prevention (CDC) for PA.¹³ Thus, the aims of this study were to investigate the gender differences in the prevalence of MetS, individual criteria, and amount and intensity of PA levels in college students with and without MetS.

Materials and Methods

Participants

This cross-sectional study design recruited college-aged students. The Institutional Review Board at California State University Bakersfield approved the study. The sample was 79 college students (mean ± standard deviation: 23.9 ± 5.3 years, 169.6 ± 8.4 cm, 76.7 ± 16.4 kg, 26.5 ± 5.0 kg/m²) who met the inclusion criteria: (1) attended the Student Health Center after an overnight fast (minimum of 8 hr); (2) if female, not pregnant; (3) had complete data on all study variables (i.e., glucose, lipoproteins, BP, and WC); and (4) no previous diagnosis of diabetes. All data were collected by trained staff and included the standardized medical examinations. Exclusion criteria included women who were or thought to be pregnant, incomplete blood values, inability to complete an 8-hr fast, and previous diagnosis of diabetes. Three subjects were excluded from analysis due to missing blood values.

Procedure for diagnosing MetS

Physiological biomarkers included measurement of WC measured to the nearest 0.1 cm at the end of a normal expiration with a steel tape measure placed at the highest point of the iliac crests while in a standing position. BP was measured after 5 min of rest in the sitting position using the left arm. Measurements were taken up to three times with an automated BP cuff (E-Sphyg2; American Diagnostics Corporation, Hauppauge, NY); the mean of the measurements taken was used in the analysis. Glucose concentration was determined by a hexokinase method, TG concentration was measured enzymatically using a series of coupled reactions, and HDL-C concentration was measured directly. Participants were classified as having MetS if they had three or more of the following criteria: (1) WC women ≥35 inches, men ≥40 inches; (2) BP ≥130/85 mmHg; (3) TG concentration >110 mg/dL; (4) HDL-C concentration women <50 mg/dL, men <40 mg/dL; and (5) fasting glucose concentration >100 mg/dL. The criterion used to define MetS was the same by Grundy et al.¹⁴ and Nelson et al.¹⁵

Biochemical tests

Participants were escorted to the campus Student Health Center to provide a venous blood sample (after an overnight fast of at least 8 hr) to measure their blood lipids [total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), HDL-C, and serum TG] and fasting blood glucose. The volume of the venous blood sample that was taken from each participant was 5 mL. All samples were analyzed through direct enzymatic methods for serum glucose, TC, TG, and HDL-C. Low-density lipoprotein cholesterol was calculated through the Friedwald equation.^16,17 Interassay variability from in-house quality control results were within 5%–10%. Intra-assay variability was ∼2%–3%.

Diagnostic criteria for MetS

A metabolic syndrome risk score (MSRS) was calculated for each study participant.⁶ The MSRS ranged from a score of 0–5. Those participants who scored two or fewer risk factors were determined not to have MetS; in contrast, participants who had three to five risk factors were determined to have MetS.

PA measurement

On completion of blood collection, participants were fitted with a wireless activity monitor (wGT3X-BT; ActiGraph, Pensacola, FL) and were asked to wear the device for seven consecutive days. The ActiGraph wGT3X-BT monitor is a triaxial accelerometer (dimensions: 4.6 × 3.3 × 1.5 cm; weight 19 grams), which was worn on the waist using an elastic belt to secure at the level of the umbilicus for quantifying the amount and rate of PA. The monitor was initialized at a sample rate of 30 Hz to record activities of free-living conditions. They were allowed to remove the ActiGraph while bathing or immersing in water, or during sleeping hours. ActiGraph data were downloaded using ActiLife (6.13.3) software (ActiGraph LLC). The raw acceleration data was converted into activity counts based on the Freedson criteria algorithm.¹⁸ Existing cutoff points were used for the vertical axis of the accelerometer. To determine the intensity of the activity, the following standards were used: time spent in sedentary time (<100 counts/min), light- (100–2019 counts/min), moderate- (2020–5998 counts/min), and vigorous-intensity PA (≥5999 counts/min).

Statistical analysis

Descriptive statistics (mean, standard deviation) were reported for all variables of interest. Independent t-tests were performed for comparison between groups for the accelerometer-measured activity variables. A chi-squared test for independence analysis was used to determine the influence of gender. The statistical software package used for analysis was SPSS version 21 (IBM, Armonk, NY). Alpha was set at P < 0.05.

Results

The demographic characteristics of the study population of eligible (n = 76) participants are presented in Table 1. Women comprised 55.2% of the sample. Significant differences were found in HDL (P = 0.01), WC (P < 0.01), and systolic BP (P < 0.01) between the genders.

Table 1.

Demographics of Participants and Individual Criteria for Metabolic Syndrome

Variable	Women (n = 42)	Men (n = 34)
Age (years)	23.3 ± 4.3	24.6 ± 6.4
Height (cm)	165.0 ± 7.1	175.7 ± 5.7
Weight (kg)	69.8 ± 13.8	85.6 ± 15.4
Body mass index (kg/m²)	25.7 ± 5.5	27.6 ± 4.2
HDL-C (mg/dL)	62.6 ± 16.9^a	53.0 ± 14.4
FG (mg/dL)	101.6 ± 7.4	103.2 ± 15.4
WC (cm)	75.9 ± 11.4	87.6 ± 10.2^a
Triglycerides (mg/dL)	77.3 ± 42.4	83.4 ± 53.4
SBP (mmHg)	118.7 ± 12.6	132.0 ± 13.8^a
DBP (mmHg)	76.0 ± 8.1	78.2 ± 9.5
TC (mg/dL)	164.5 ± 29.9	165.3 ± 28.3
LDL-C (mg/dL)	87.7 ± 23.7	93.6 ± 23.7

Significant differences (P < 0.01).

DBP, diastolic blood pressure; FG, fasting glucose; HDL-C, high-density lipoprotein cholesterol; LDL-C, low-density lipoprotein cholesterol; MetS, metabolic syndrome; SBP, systolic blood pressure; TC, total cholesterol; WC, waist circumference.

Prevalence of MetS between the genders and individual criteria

The overall prevalence of MetS in participants was 9.2% in the sample (Table 2). It was more common in men (9.4%) than in women (7.2%). Abnormal fasting glucose (46.1%) and resting BP (27.6%) were the most common individual criteria; in contrast, abnormal TG (2.6%) and WC (1.2%) were the least common criteria across genders. Women had the highest rates of abnormal fasting glucose levels (34.0%) and HDL (9.6%), whereas men had the highest abnormal BP (20.2%).

Table 2.

Prevalence of Individual Criterion in Women and Men with Metabolic Syndrome

	0	1	2	3	4	5
Women	33.3%	52.4%	7.1%	2.4%	4.8%	0.0%
Men	15.6%	59.4%	15.6%	5.2%	3.1%	1.1%

Metabolic Risk Stratification Score 0 = no individual criteria met; 5 = all individual criterion met.

Prevalence of risk factor combinations

More than half (53.2%) of the participants had at least one metabolic abnormality, and overall 9.2% met the criteria for the diagnosis of MetS (Table 2). Four or more criteria were found in four participants (4.3%); one participant had all five criteria (1.1%). Men had at least one metabolic abnormality when compared with women (59.4% vs. 52.4%) and, 9.4% of men compared with 7.2% of women had three or more criteria components for MetS.

PA levels

Participants that were in the non-MetS group were less sedentary (84.8% vs. 91.0%, t ₇₄ = 8.061, P < 0.001) and performed more light activities (8.9% vs. 6.0%, t ₇₄ = 5.433, P < 0.001) than those with MetS. Moderate intensity (2.1% vs. 1.9%, t ₇₄ = 1.121, P = 0.071) and vigorous activities (0.1% vs. 0.1%, t ₇₄ = 0.783, P = 0.093) were not significantly different comparing non-MetS versus MetS. In addition, the total number of steps for the 7-day period (60,500 vs. 38,000, t ₇₄ = 6.561, P < 0.001) and steps per minute (5.7 vs. 3.1, t ₇₄ = 5.706, P = < 0.001) were significantly different between those without MetS and those with MetS (Table 3).

Table 3.

Participant Measured Activity Levels with Metabolic Syndrome and Nonmetabolic Syndrome

Variable	Metabolic	Syndrome	Statistic
Variable	No	Yes	Statistic
Sedentary, %	84.8 ± 3.8	91.0 ± 2.0	t ₇₄ = 8.061, P < 0.001^a
Light activity, %	8.9 ± 3.5	6.0 ± 2.0	t ₇₄ = 5.433, P < 0.001^a
Moderate activity, %	2.1 ± 1.1	1.9 ± 1.1	t ₇₄ = 1.121, P = 0.071
Vigorous activity, %	0.1 ± 0.07	0.1 ± 0.1	t ₇₄ = 0.783, P = 0.093
Total steps/1000	60.5 ± 14.6	38.0 ± 9.9	t ₇₄ = 6.561, P < 0.001^a
Steps per minute	5.7 ± 1.7	3.1 ± 0.8	t ₇₄ = 5.706, P < 0.001^a

Statistically significant (P < 0.001).

Discussion

Findings from this study show that nearly 10% of the participants met the criteria for MetS, which is less than the national average of 34% in individuals between 18 and 24 years, but similar to previously reported data on MetS and college-aged adults.¹⁹ In addition, participants were more sedentary and on average took <6000 steps per day with the criteria for MetS, which is considered to be “active” by researchers.²⁰ The combination of increased sedentary time and risk factors for MetS demonstrate that PA is needed to reduce the risk of cardiovascular and metabolic diseases later in life.

Prevalence of MetS between the genders and individual criteria

When reviewing previous research, the findings of this study reveals that the prevalence of MetS was either lower than^7
–9 or greater than^14,21,22 the students recruited as participants. There is still variability between criteria used to define MetS in college students. Our overall prevalence of MetS in college students was 9.2%. The overall prevalence of MetS was greater in men than in women, which is similar to previously reported findings.^14,21,22 The average daily step count was lower compared with Bailey et al.²³ More than 80% of the waking hours our participants were spent sedentary. The prevalence of MetS in this study in men and women was 7.2% versus 9.8%, compared with Tope and Rogers⁹ (12% vs. 7.3%), Dalleck and Kjelland²¹ (6.8% vs. 7.3%), Morrell et al.⁸ (6.45% vs. 7.3%), Fernandes and Lofgren¹⁴ (3.7% vs. 7.3%), de Freitas et al.²⁴ (1.7% vs. 7.3%), and Morrell et al.²⁵ (6.0% vs. 7.3%). Previous research has reported the range of MetS in college students of 3.0%–10%.^{7
–9,21,24,25}

Prevalence of risk factor combinations

The prevalence of MetS among U.S. adults and adolescent populations was previously reported to be 34.3% and 10.1%, respectively.^26,27 The prevalence of MetS in our study is similar to Mattsson et al. who reported 7.5% of 24-year old Finnish men and women had MetS, and Dalleck and Kjelland who reported 6.8% of college students had MetS using National Cholesterol Education Program Adult Treatment Panel III criteria.^21,28 However, Tope and Rogers and Keown et al. reported the prevalence of MetS in their studies of 12.1% and 10%, respectively.^7,9 In our population, the overall prevalence of MetS was 9.2% of college-aged students, which is between the previous studies. Our findings support the idea that increasing PA can reduce the risk factors associated with increased risk of cardiovascular disease (CVD).

PA levels

This study suggests that those students with low activity, as determined by steps per day, have a greater number of MetS criteria than those who are more physically active. The greatest amount of time the students spent in this study was sedentary and spent a very small percentage of their time performing moderate PA, 84.8% versus 91.0% and 2.1% ± 1.1% versus 1.9% ± 1.1% in those participants without MetS, respectively. This sedentary time may be described as sitting in the classroom, studying in the library, or driving to campus. Moderate activity may be described as performing some type of PA (jogging, cycling, swimming, etc.). Previous studies have reported total steps taken per day of nearly 10,000.^29,30 However, in this study our participants took 7982.6 ± 2209.6 steps per day, which is less than the goal of 10,000 steps per day that the American Heart Association suggests to reduce CVD risk factors.³¹ Bailey et al. reported that the odds of having a body fat >32% were reduced by 21.9% for every increase of 1000 steps per day (P ≤ 0.05).²³ The authors concluded that a recommendation of 10,000–12,000 steps per day is associated with lower body mass index and body fat percentages.²³ Increasing the total number of steps per day will also reduce the increased risk of CVD risk factors.

The study has a few limitations that must be considered when interpreting the results. The study design was cross-sectional; therefore, we were unable to determine the relationship between MetS and PA. All of our participants were recruited from the same college campus, which can limit the generalizability of the results. However, it should be noted that the subjects that volunteered for the study were similar to the demographics of the community on campus. It is also possible that the PA patterns may have been increased due to the monitoring of PA. To account for this, we told the students not to change their current activity levels or monitor diet while they were participating in the study. The accelerometers did not collect heart rate values, so we cannot compare results with cardiorespiratory fitness. In addition, the biochemical tests did not test for inflammatory markers or insulin levels. Finally, many of the students who participated in this study were from the kinesiology department and may have participated in more PA compared with students in different majors.

The findings of this study suggest the prevalence of MetS has not changed over the previous years. Abnormal fasting glucose and resting BP are the most prevalent issues among college-aged students today. The study also demonstrates that college-aged students do not meet the guidelines established of 10,000 steps per day. These findings have important public health implications due to the well-known CVD risk factors associated with MetS that may be carried on it to adulthood, as well as, the amount of PA is determined during their early adulthood years. To reduce the potential future risk of CVD in these young adults with a current diagnosis of MetS should reduce energy intake, increase PA, and limit sedentary behaviors.

Footnotes

Acknowledgments

This research was supported by grants awarded from the Grants, Research, and Sponsored Programs (GRASP) at California State University Bakersfield (RCU Mini-Grant). We gratefully thank these individuals who contributed to data collection: Mr. Guanrong Cai, Ms. Eryn Chang, Ms. Natali Contreras, Ms. Sydney Haynes, Mr. Andrew Hudson, Ms. Kristen Morgan, Mr. Daniel Serrano, and Mr. Nick Slinkard. We also thank Dr. Oscar Rico and Ms. Erika Delamar at the California State University Bakersfield Student Health Center for collecting and analysis of our blood samples.

Author Disclosure Statement

No conflicting financial interests exist.

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