If exercise is medicine, how much do we prescribe?

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exercise is medicine

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Research has suggested exercise is medicine, so should it be prescribed as such? A recent review summarized existing evidence supporting the clinical efficacy of prescribing exercise for managing abdominal obesity.

Evidence has shown that regular and consistent exercise is one of the most important lifestyle changes that can help reduce and prevent chronic diseases. As exercise enables favourable changes to the body, it reduces the risk of developing metabolic syndrome. This suggests that exercise is medicine, which is now recognised as a medical treatment.

Those with abdominal obesity may not have an elevated BMI

Often described as a global pandemic, abdominal obesity affects more than 20% of the adult population worldwide. Obesity is defined as having a body mass index (BMI) of 30 or higher, however, individuals with abdominal obesity do not always have an elevated BMI.

Abdominal obesity is a predominant risk factor and one of five factors for metabolic syndrome. Metabolic syndrome is defined as a clustering of at least three out of five medical conditions that occur together and can increase an individual’s risk of heart disease, stroke and diabetes. Other clinical risk factors include high blood pressure, elevated cholesterol or triglyceride levels, insulin resistance or high blood sugar and low high-density lipoprotein (HDL). It has been estimated that by the year 2030, 50% of adults will be classified as obese, thereby increasing the risk of metabolic syndrome. This raises significant problems for health services and economies.

In a recent review published in BMC Sports Science, Medicine and Rehabilitation, researchers in the United Kingdom evaluated the current evidence supporting the clinical efficacy of prescribing exercise to manage abdominal obesity. The study also explores the relationship between adiposopathy or “sick fat”, which is adipose tissue dysfunction caused by high-calorie diet combined with a sedentary lifestyle, and metabolic syndrome. It also reviews the optimal type and dose of exercise required for improving one’s health status. To understand how abdominal obesity, a reversible condition, contributes significantly to metabolic syndrome, researchers must first recognise the association between the disease and condition.

Abdominal fat is associated with insulin resistance

When ectopic fat (storage of triglycerides in non-fatty tissue) accumulates in the tissue surrounding the abdomen, it is directly related to the development of insulin resistance, another hallmark of metabolic syndrome. These fat deposits are associated with dysfunctional fat tissue (or adiposopathy), which secretes pro-inflammatory molecules such as prostaglandins and cytokines, including interleukins, tumour necrosis factor alpha and leptin. These inflammatory molecules secreted by fat tissue are associated with metabolic syndrome and are known to contribute to the predisposition and development of type 2 diabetes.

Given this direct association between systemic inflammation and abdominal obesity, it should not surprise anyone that a small reduction in fat results in metabolic function improvements and reduces the risk of cardiovascular events. Furthermore, with several studies showing a strong link between physical inactivity and obesity, using exercise to treat obese patients and potentially reverse metabolic syndrome is promising.

Currently no guidelines on how much exercise to prescribe to patients

However, there are no specific guidelines on how much exercise to prescribe a patient with systemic inflammation. There are programs available that have been specifically designed to help reduce body fat, but adherence to these programs remains an issue.

The average daily exercise requirement for optimal results varies. The American College of Sports Medicine (ACSM) recommends with 150-200 minutes of moderate-intensity exercise per week, while other studies suggest 30 – 60 minutes of exercise per day. Performing on average 3000 steps above normal activities is also believed to improve an individual’s health status, although this potentially does not fit in with the ACSM recommendations.

The UK researchers reported that another review conducted by Hayashino and colleagues suggested that the effects of exercise as medicine are dose-dependent, where an increase in the duration and frequency of exercise interventions was shown to be more effective in reducing systemic inflammation. These results have recently been challenged, with research suggesting that short-duration, high-intensity interval training (HIIT) has more beneficial effects for reducing the risks of metabolic syndrome.

Adherence to exercise programs is a challenging aspect when prescribing exercise

Adherence to exercise programs is one of the most challenging aspects when prescribing exercise as a treatment, especially for patients who are overweight or obese and have been inactive for possibly years. However, adherence to HITT programs has been shown to be higher, as this type of exercise is usually shorter in duration and therefore less disruptive to a patient’s lifestyle.

In one study, overweight or obese participants were required to complete two to three short interval training sessions per week that would last between 15 to 20 minutes. The results showed that the prevalence of metabolic syndrome was reduced by 32.5% after a follow-up at 9 months and adherence rates were incredibly high, at 97%. Another suggested method to improve adherence is increasing activity gradually, even by as little as five minutes per day, tailored to every individual in order to deliver optimal results.

A sedentary lifestyle is a main risk factor for metabolic disease

In conclusion, the review showed that in the developed world, the main factors contributing to the incidence of metabolic disease is a sedentary lifestyle and lack of exercise. Since metabolic syndrome can be reversed, significant evidence has supported that exercise is medicine and is an effective treatment that can be prescribed for the treatment of abdominal obesity and therefore metabolic syndrome.

As the main challenge for patients is motivation and adherence to exercise, research has shown the use of HITT programs combined with resistance training and a general increase in physical activity every day can promote high adherence. However, the optimal dose and type of exercise remains unknown and potentially needs to be prescribed on an individual basis.

Written by Lacey Hizartzidis, PhD

Reference: Paley CA, Johnson MI. Abdominal obesity and metabolic syndrome: exercise as medicine? BMC Sports Sci Med Rehabil. 2018 May 4;10:7. doi:10.1186/s13102-018-0097-1. eCollection 2018. Review. PubMed PMID: 29755739;PubMed Central PMCID: PMC5935926.

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