Resistance exercises, not just aerobic exercises, are beneficial in metabolic syndrome treatment, Polish researchers show

Training causes a very rapid reduction in the concentration of important pro-inflammatory factors, improves atherosclerosis indicators and alleviates insulin resistance.

Metabolic syndrome is an increasingly common condition. It is estimated (according to the NATPOL PLUS study) that it affects over 20% of the population in Poland; it affects men slightly more often than women. According to the definition, it is not a separate disease entity, but the coexistence of key risk factors for the development of cardiovascular diseases (stroke, heart attack, coronary heart disease). It includes: diabetes or pre-diabetes, hypertension, lipid metabolism disorders and the most important factor, abdominal obesity.

EXCESS FAT TISSUE DISRUPTS THE ACTION OF HORMONES

Not everyone realizes that adipose tissue is hormonally active. It produces and secretes substances called adipokines, which are involved in the metabolism of glucose and lipids. One of them is leptin, called satiety hormone, which plays a role in regulating food intake and the body's energy management. Various signalling proteins are also produced in adipose tissue, e.g. pro-inflammatory IL-6.

In people suffering from abdominal obesity, the concentration of both these substances changes, and with the development of the metabolic syndrome, their imbalance increases. Importantly, there is an excessive release of pro-inflammatory factors and, at the same time, a reduction in the 'protective' ones. The result is inflammation in the body and the associated development of insulin resistance.

Researchers from the University of Physical Education in Krakow - project leader Dr. Agnieszka Suder and Dr. Karol Makiel from the Department of Anatomy, and their colleagues - decided to assess the impact of two types of physical training on body composition, insulin resistance markers, lipid profile and selected adipokine concentrations in men with metabolic syndrome. The experiment lasted 12 weeks, 62 men took part in it.

'They all had abdominal obesity, which is one of the components of the metabolic syndrome. In our case, their BMI was about 34 on average, and their waist circumference was about 115 cm' the scientists tell PAP. Blood tests confirmed that they all had metabolic syndrome.

'We started training with them three times a week, each time for 60 minutes. We divided them into three groups: typical aerobic training, i.e. fast walking or running, at which the heart rate remains at 70 percent of the maximum heart rate, combined resistance and aerobic training, i.e. typical strength exercises followed by exercises at a faster heart rate, and no training, which we used in the control group. After 12 weeks, they stopped training with us, but we continued to monitor them,’ the researchers say. 

TRAINING EFFECTS ARE QUICK AND SPECIFIC

It turned out that in both exercising groups, carbohydrate metabolism improved and the level of body fat decreased. But beyond that, researchers found some important differences.

'After the first six weeks, people doing aerobic exercises lost an average of 1.5-1.8 kg of fat tissue, and this effect persisted in the following weeks,’ says Dr. Makiel. 

He adds: ‘However, in people who did resistance exercises throughout the study period, the body weight did not change, but body composition measurements showed that the loss of fat tissue was even greater - about 2 kg, while their muscle mass increased on average by over 4 kg. Therefore, they underwent recomposition, which could have had the greatest impact on improving and stabilizing the level of adipokines. In addition to fat from the waist area, participants in this group also lost fat from other areas of their bodies.’

The level of pro-inflammatory substances (leptin and IL-6), which may contribute to the development of insulin resistance, decreased in both exercise groups, but in the 'resistance' group the difference was more significant and observed from the beginning of the training programme.

'It is clear that resistance training combined with aerobic training gave the best results in terms of reducing inflammation in the body, which is crucial in the case of metabolic syndrome, the researchers continue. 

‘This type of exercise also best regulated the levels of hormones and proteins that we monitored, including leptin and IL-6. We also noticed declines in the aerobic group, but significantly smaller ones, and in the control, non-exercising group, there were none at all. On the contrary, these parameters have deteriorated in the control group.’

As for insulin resistance, at the end of the experiment it also dropped the most in the resistance and aerobic exercise group. 'It can therefore be concluded that such training translates into a significantly lower risk of type 2 diabetes, the scientists say. 

Among people who exercised, unlike those who did not, scientists also noted improvement in other important parameters related to cardiovascular risk: waist circumference and atherosclerosis risk indicators (Castelli's Risk Index) decreased.

The researchers emphasise, however, that for these results to last, one needs to exercise regularly. Otherwise, the positive effects will quickly disappear.

Importantly, they add, the study participants did not follow any recommended diet. The described changes occurred only as a result of exercise. Currently, in another experiment, not yet published, Suder's team checks whether training combined with a menu prepared by a dietitian gives even better results. The scientists found that it does, and that the results are even more pronounced. 'We obtained very promising results: it turned out that after just six weeks, the participants' cholesterol levels dropped by several percent, which is a result comparable to the effect of statins, drugs used to treat hypercholesterolemia.’

LACK OF MOVEMENT SLOWLY KILLS

The researchers point out that an equally important implication of their study is what happened to people from the control group - those who did not exercise - after 12 weeks. 'In many cases, the tested parameters clearly deteriorated,’ says Dr. Makiel. 'Remember that obesity is a progressive disease. If no lifestyle changes are made, health continues to gradually deteriorate. And it happens very quickly; in this case, it was visible after twelve weeks'.

'Our study shows how to prepare effective recommendations for people with metabolic syndrome,’ the researchers conclude. They emphasise that the focus should be on introducing a healthy diet and regular physical activity, remembering that resistance training, although not always leading to weight loss, increases lean mass, which is crucial for insulin sensitivity, inflammation and lipid profile.

'Through the development of muscle mass and loss of fat tissue, combined aerobic and resistance training brings more beneficial changes than aerobic training alone,’ they say.

Three papers summarizing the discussed study were published in the Journal of Clinical Medicine - here, here and here. (PAP)

PAP - Science in Poland, Katarzyna Czechowicz

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