Various studies suggest the important role of physical activity and exercise in reducing the prevalence of metabolic syndrome.

At present, chronic and non-communicable diseases (NCD) are a major challenge to global health. The World Health Organization states that non-communicable diseases (including obesity and diabetes), which are components of the metabolic syndrome, have increased significantly globally.

The metabolic syndrome is a complex condition and has various definitions from various health organizations. Its components (wide waist circumference, dyslipidemia, hypertension, and insulin resistance) are generally associated with a sedentary lifestyle.

Various studies have shown that increasing physical activity has a beneficial effect on individual metabolic syndrome components. Physical activity is also classified as cost-effective so that many people can apply it.

What is Metabolic Syndrome?

Metabolic syndrome is a collection of conditions resulting from increased insulin resistance and abnormalities in fat deposition. According to the National Cholesterol Education Program (NCEP) Adult Treatment Panel III (ATP III), metabolic syndrome can be enforced if there are 3 of the following five criteria:
  1. Waist circumference  > 120 cm in men and > 89 cm in women
  2. Blood pressure  > 130/85
  3. Fasting triglycerides  > 150 mg / dL,
  4. High-density lipoprotein (HDL) cholesterol <40 mg / dL in men and  <50 mg / dL in women
  5. Fasting blood glucose> 100 mg / dL

It is unsure how metabolic syndrome occurs or how the different components can be related to a particular causal effect. However, insulin resistance is strongly suspected to be common pathophysiology. There is a positive correlation between body weight and insulin resistance and the risk of developing all the metabolic disorders associated with insulin resistance.

What are Physical Activity and Exercise?

According to WHO, physical activity is any movement of the body produced by skeletal muscles, which requires energy expenditure. The terminology of physical activity must be distinguished from 'exercise.'

Physical activity involves body movement and is performed as part of daily activities, such as playing, working, traveling, doing housework, and recreational activities.

Meanwhile, exercise, which is a sub-category of physical activity, is an activity that is planned, structured, repetitive, and aims to maintain or improve physical fitness.

Physical activity intensity refers to the difficulty of effort required to carry out an activity, such as moderate and heavy intensity. However, the sample intensity may vary from individual to individual because it also depends on previous physical activity habits and relative fitness levels.

The Metabolic Equivalent (MET) is the ratio of activity's relative metabolic rate to the resting metabolic rate. MET is generally used to determine the intensity of physical activity.

Effectiveness of Physical Activity in Preventing and Treating Metabolic Syndrome

Decreased physical activity has the potential to reduce life expectancy. However, its effects are difficult to be measured because the types and intensities of physical activity studied are varied.

This article will discuss the effects of physical activity on metabolic syndrome without focusing on specific physical activity types or intensity. 

Effectiveness of Physical Activity in Preventing Metabolic Syndrome

A meta-analysis study by Zhang et al. measured the dose and response relationship between leisure-time physical activity (LTPA) and metabolic syndrome. This study found there was an inverse relationship between LTPA and the incidence of metabolic syndrome. Compared with inactive individuals, the risk of metabolic syndrome was reduced by 8% every time there was an increase in LTPA by 10 MET (metabolic equivalent of task) hours/week.

This increase in LTPA is comparable to the recommended baseline LTPA (150 minutes per week). When the LTPA intensity is doubled, the risk of metabolic syndrome is reduced by another 20%. At the higher intensity, i.e., 70 MET-hours/week, the risk of metabolic syndrome was reduced by 53%.

Thus, this study shows that regardless of the duration/degree of LTPA is still better than nothing. An increase in LTPA substantially exceeded the recommendations associated with an additional reduction in metabolic syndrome risk.

In a cross-sectional study, Xu et al. examined the association between physical activity and metabolic syndrome in obese elderly individuals. This study assessed three domains of physical activity, namely: work, travel, and recreation. Of the 613 participants, 72% (431 participants) met the metabolic syndrome criteria, and 44.3% (263 participants) did not meet the physical activity recommendations.

Compared with low physical activity participants, participants with high levels of physical activity had a lower risk of metabolic syndrome and better HDL levels, fasting blood glucose levels, and blood pressure. However, cross-sectional research methods cannot determine a causal relationship between physical activity and metabolic syndrome.

Effectiveness of Physical Activity as Management of Metabolic Syndrome

A meta-analysis conducted by Ostman et al. examined 16 studies with a total of 77,000 participants diagnosed with metabolic syndrome. The duration of exercise studied varied between 8 weeks - 1 year. Compared with the sedentary group, the aerobic exercise group showed a decrease in body mass index (BMI), waist circumference, systolic blood pressure, fasting blood glucose, triglycerides, and low-density lipoprotein (LDL).

Also, maximal VO2 (maximal volume of oxygen processed by the body during intense activity) was significantly increased in patients randomly assigned to the exercise group. Thus, this study concludes that exercise produces better cardiovascular and metabolic outcomes in patients with metabolic syndrome. For some clinical outcomes, the only aerobic exercise group showed optimal results.

Several studies have assessed the metabolic syndrome's adverse effects on the blood vessels' integrity and the physical activity's role in reducing them. They suggest that a sedentary lifestyle in individuals with metabolic syndrome is associated with a worse arterial stiffness profile. Regular physical activity and exercise can reduce metabolic syndrome's adverse effects on blood vessels and the brain.

Therefore, doctors should pay special attention to patients with metabolic syndrome, including patients who have impaired the arteries' structure and function to increase their physical activity.

Physical Activity Recommendations for Adults

Because the prevalence of the metabolic syndrome and its components has increased significantly in recent decades and the association of physical activity with metabolic risk factors has been demonstrated, several health organizations have issued physical activity recommendations.

American Heart Association and World Health Organization recommend that adults aged 18-64 do:
  1. Moderate-intensity aerobic physical activity at least 150 minutes per week, 
  2. High-intensity physical activity at least 75 minutes per week, 
  3. Combination of the equivalent between moderate and strenuous intensity physical activity. 
Aerobic exercise should be carried out for at least 10 minutes in 1 training session.

For additional health benefits, adults should increase moderate-intensity aerobic physical activity to 300 minutes per week, vigorous-intensity aerobic physical activity to 150 minutes per week, or an equivalent combination of moderate and vigorous-intensity physical activity. Muscle strengthening exercises should be performed that engage the major muscle groups for two or more days per week.

These recommendations are relevant for all healthy adults aged 18-64 years unless specific medical conditions contraindicate physical activity. This recommendation also applies to individuals with chronic conditions, such as hypertension and diabetes, and people with disabilities.