- Combination of good cardiorespiratory fitness (CRF), high-intensity physical activity (HPA) and low sedentary time (ST) can lower risk of type 2 diabetes and metabolic syndrome
- Type 2 diabetes and metabolic syndrome (comprising obesity, high blood pressure, high cholesterol levels) significantly increase risk of heart attack and stroke and pose a major global health threat
Being physically fit or having good cardiorespiratory health and less sedentary can reduce the risk of type 2 diabetes and metabolic syndrome, according to a recent study by Jeroen van der Velde and Annemarie Koster, Maastricht University, Netherlands, and colleagues. The findings of the study appear in the Diabetologia
(the journal of the European Association for the Study of Diabetes [EASD]).
Cardiorespiratory fitness (CRF)
measures the ability of the body to transport oxygen to muscles during prolonged physical activity, and ability of the body to use the oxygen efficiently. During exercise, the heart, lungs and blood vessels work together to sustain the increased activity and become more efficient and healthy in the process. Thus, physical activity is one of the factors that helps improve CRF although other factors may also be involved.
How Is This Study Different From Earlier Research Assessing Diabetes Risk?
Previous studies have separately looked at the effects of CRF, sedentary time (ST) and high-intensity of physical activity (HPA)
in influencing the risk of developing type 2 diabetes and metabolic syndrome. Many studies including HPA and ST did not analyze the effect of CRF; this study is the first to analyze the combination of ST and CRF
‘Newer strategies that address all three components namely cardiorespiratory fitness, sedentary time and high-intensity physical activity need to be developed to reduce the risk of type 2 diabetes and metabolic syndrome.’
It is known that CRF varies between individuals at least partly due to differences in frequency and intensity of exercise. Several recent studies have found that high levels of ST to be linked to lower CRF. However, about 10 to 50 percent of CRF is thought to be due to factors other than physical activity, such as genetic, environmental and behavioral elements.
- This simply means that a person could do regular HPA and still not have high CRF, or have a good CRF without frequent HPA
According to the authors, although HPA, ST and CRF may be partially interconnected, they should be considered as distinct traits
and may independently influence development of type 2 diabetes
and metabolic syndrome.
Studying Combined Effects of CRF and ST on Type 2 Diabetes
In this study, information was gathered from 1993 people between 40-75 years from the Maastricht Study, living in the southern part of the Netherlands.
ST and HPA were estimated by an accelerometer device
. CRF was measured by a cycle-ergometer testing
, and the power output and oxygen consumption were then calculated.
- The team found that greater sedentary time (ST), reduced high-intensity physical activity (HPA) and cardiorespiratory fitness (CRF) were independently linked to higher risk of type 2 diabetes and also metabolic syndrome
- The team then studied the effects of low, medium and high levels of ST, HPA and CRF together. Persons with both high CRF and high HPA had a 5.7 times lesser risk of metabolic syndrome and 6.4 times lesser risk of type 2 diabetes compared to the group with low CRF and low HPA.
- All subgroups with low or medium CRF had a higher risk of developing metabolic syndrome, prediabetes and type 2 diabetes, despite the amounts of their sedentary time (ST)
- Although some persons had high CRF, a high ST was still associated with thrice the risk of metabolic syndrome and twice the risk of type 2 diabetes, suggesting that a good CRF alone may not be sufficient to overcome the ill effects associated with high sedentary time
Thus, decreasing the sedentary time and spending more time being active is important
to reduce the risk of type 2 diabetes and metabolic syndrome.
- The highest risk of metabolic syndrome and type 2 diabetes was noted in the group with low CRF and high ST; this group demonstrated a nine-times more risk of metabolic syndrome, and three times higher risk of prediabetes and an eight times higher risk of type 2 diabetes in comparison to the group with high CRF and low ST.
The authors say, "High ST, low HPA, and low CRF were each associated with several markers of cardiometabolic health
and higher risk for the metabolic syndrome and type 2 diabetes independent of each other. A combination of low CRF and low HPA, and a combination of low CRF and high ST, were associated with a particularly high risk of having the metabolic syndrome and type 2 diabetes."
- Interestingly, the scientists found that changing from low to medium cardiorespiratory fitness seemed to be more helpful than changing from medium to high CRF to reduce the risk of type 2 diabetes and metabolic syndrome
Possible limitations of the study include its cross-sectional design which makes it difficult to establish a causal relationship. Future studies including health changes over time should be carried out.
In conclusion, the authors say, "We also need to find out what amount of ST is associated with a clinically relevant increase in risk and which levels of HPA and CRF are associated with clinically relevant lower risk for the metabolic syndrome and type 2 diabetes." References :
- M. Duclos,b J.-M. Oppert, B. Verges, V. Coliche, J.-F. Gautier, Y. Guezennec, G. Reach, G. Strauch., "Physical activity and type 2 diabetes. Recommandations of the SFD (Francophone Diabetes Society) diabetes and physical activity working group" Volume 39, Issue 3, May (2013), Pages 205-216 Diabetes & Metabolism http://dx.doi.org/10.1016/j.diabet.2013.03.005