medwireNews: Sedentary time, higher intensity physical activity (HPA), and cardiorespiratory fitness all independently affect the risk for type 2 diabetes and the metabolic syndrome, data from The Maastricht Study show.
Furthermore, low cardiorespiratory fitness in combination with either low HPA or high sedentary time is associated with “a particularly high risk of developing the metabolic syndrome and type 2 diabetes,” Jeroen van der Velde (Maastricht University, the Netherlands) and co-researchers report in Diabetologia.
They add: “To improve cardiovascular risk and to prevent type 2 diabetes, these data support the development of new strategies that target all three components—[sedentary time], HPA and [cardiorespiratory fitness].”
The study included 1993 adults aged 40–75 years (mean 59.7 years, 49% men) who had sedentary time and HPA – a surrogate for moderate to vigorous physical activity – measured using an accelerometer device, and cardiorespiratory fitness assessed by cycle–ergometer testing.
The team found that longer periods of sedentary time, less time participating in HPA, and lower CRF were each independently associated with an increased likelihood for having type 2 diabetes and the metabolic syndrome.
When the researchers then looked at high, medium, and low levels of sedentary time, HPA, and cardiorespiratory fitness in combination with each other they found that compared with individuals with high cardiorespiratory fitness and a high level of HPA, those with a low or medium cardiorespiratory fitness were more likely to have type 2 diabetes and the metabolic syndrome regardless of HPA.
For example, individuals with low cardiorespiratory fitness and low HPA were 6.4 times more likely to have type 2 diabetes and 5.7 times more likely to have the metabolic syndrome than those with high cardiorespiratory fitness and high HPA.
Similarly, individuals with a combination of medium or low cardiorespiratory fitness and medium or high sedentary time were significantly more likely to have type 2 diabetes or the metabolic syndrome than those with high cardiorespiratory fitness and low sedentary time.
Even participants with high cardiorespiratory fitness had a significant 2.2-fold increased likelihood for type 2 diabetes and a 2.9-fold increased likelihood for the metabolic syndrome when they also had high compared with low sedentary time.
This suggests that high cardiorespiratory fitness “may not be sufficient to ‘counteract’ the deleterious health outcomes associated with sedentary behaviour,” van der Velde et al remark.
The patients with the highest likelihood for type 2 diabetes and the metabolic syndrome were those with low cardiorespiratory fitness and high sedentary time where the odds ratios were 8.4 and 9.2, respectively, compared with patients with high cardiorespiratory fitness and low sedentary time.
In a statement to the press, the authors acknowledge that the study “is limited by its cross-sectional design, which makes it difficult to determine causality. Future work that incorporates health changes over time is needed to determine if the observed associations hold true.”
They added: “We also need to find out what amount of [sedentary time] is associated with a clinically relevant increase in risk and which levels of HPA and [cardiorespiratory fitness] are associated with clinically relevant lower risk for the metabolic syndrome and type 2 diabetes.”
By Laura Cowen
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