Low physical capacity increases death risk – 45-year study

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UnfitWEBA 45-year Swedish study in middle-aged men has shown that the impact of low physical capacity on risk of death is second only to smoking, and a greater risk than high blood pressure or high cholesterol.

“The benefits of being physically active over a lifetime are clear,” said lead author Dr Per Ladenvall, a researcher in the department of molecular and clinical medicine, Sahlgrenska Academy at University of Gothenburg, Sweden. “Low physical capacity is a greater risk for death than high blood pressure or high cholesterol.”

The study included 792 men from the “Study of Men Born in 1913”, a representative sample of 50 year old men in Gothenburg recruited in 1963. The study was designed to investigate risk factors for cardiovascular disease and mortality.

In 1967, at 54 years of age, the 792 men did an exercise test. Of those, 656 men also did a maximum exercise test in which they pushed themselves to the limit. The remaining men were excluded from the maximum exercise test because they had a health condition that could make it unsafe. Maximal oxygen uptake, called VO2 max, was measured in a sub-population of the 656 men using ergospirometry.

Ladenvall said: “VO2 max is a measure of aerobic capacity and the higher the figure, the more physically fit a person is. In 1967 it was difficult to do ergospirometry in large populations, so the researchers derived a formula using the measurements in the subpopulation, and then calculated predicted VO2 max for the remaining 656 men who had done the maximum exercise test.”

After the initial examination in 1967, the men were followed up until 2012, at the age of 100 years. Several physical examinations were performed, about one every 10 years. Data on all-cause death was obtained from the National Cause of Death Registry.

To analyse the association between predicted VO2 max and mortality the men were divided into three groups (tertiles) ranging from low to high: 2.00 l/min, 2.26 l/min, and 2.56 l/min.

The researchers found that each tertile increase in predicted VO2 max was associated with a 21% lower risk of death over 45 years of follow up, and after adjusting for other risk factors (smoking, blood pressure and serum cholesterol).
Ladenvall said: “We found that low aerobic capacity was associated with increased rates of death. The association between exercise capacity and all-cause death was graded, with the strongest risk in the tertile with the lowest maximum aerobic capacity. The effect of aerobic capacity on risk of death was second only to smoking.”

“The length of follow up in our study is unique,” continued Ladenvall. “When this study began, most data was derived from hospital cohorts and there was very limited data on exercise testing in a large general population. Our sample is representative of the male population in Gothenburg at that time. The risk associated with low aerobic capacity was evident throughout more than four decades and suggests that being physically active can have a big impact over a lifetime.”

He concluded: “We have come a long way in reducing smoking. The next major challenge is to keep us physically active and also to reduce physical inactivity, such as prolonged sitting.”

Abstract
Background: Low aerobic capacity has been associated with increased mortality in short-term studies. The aim of this study was to evaluate the predictive power of aerobic capacity for mortality in middle-aged men during 45-years of follow-up.
Design: The study design was a population-based prospective cohort study.
Methods: A representative sample from Gothenburg of men born in 1913 was followed from 50–99 years of age, with periodic medical examinations and data from the National Hospital Discharge and Cause of Death registers. At 54 years of age, 792 men performed an ergometer exercise test, with 656 (83%) performing the maximum exercise test.
Results: In Cox regression analysis, low predicted peak oxygen uptake ( ), smoking, high serum cholesterol and high mean arterial blood pressure at rest were significantly associated with mortality. In multivariable analysis, an association was found between predicted tertiles and mortality, independent of established risk factors. Hazard ratios were 0.79 (95% confidence interval (CI) 0.71–0.89; p < 0.0001) for predicted , 1.01 (1.002–1.02; p < 0.01) for mean arterial blood pressure, 1.13 (1.04–1.22; p < 0.005) for cholesterol, and 1.58 (1.34–1.85; p < 0.0001) for smoking. The variable impact (Wald’s χ2) of predicted tertiles (15.3) on mortality was secondary only to smoking (31.4). The risk associated with low predicted was evident throughout four decades of follow-up.
Conclusion: In this representative population sample of middle-aged men, low aerobic capacity was associated with increased mortality rates, independent of traditional risk factors, including smoking, blood pressure and serum cholesterol, during more than 40 years of follow-up.

Authors
Per Ladenvall, Carina U Persson, Zacharias Mandalenakis, Lars Wilhelmsen, Gunnar Grimby, Kurt Svärdsudd, Per-Olof Hansson

European Society of Cardiology material
European Journal of Preventative Cardiology abstract


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