Abstract
PURPOSE: To estimate the maximum mass-specific oxygen uptake (VO(2max)) from the ratio of the heart rate at maximal exercise (HR(max)) to heart rate at rest (HR(rest)) in middle-aged men. VO(2max) is an essential measure of cardiorespiratory fitness, but it is difficult to utilize in clinical practice. The proportionality factor HR(max) to HR(rest) is known to approximate 15 in young well-trained adults. Presumably, the same value is inaccurate for middle-aged men. MATERIALS AND METHODS: Six-hundred thirty-four men belonging to the Kuopio Ischaemic Heart Disease Risk Factor Study. Their mean age, body mass index (BMI), the daily total physical activity (TPA), VO(2max), HR(max), and HR(rest) were: 49.4±6.4 years, 26.3±3.2 kg/m², 48.5±10.1 metabolic equivalent hours per day, 33.7±7.6 mL/min/kg, 170.1±15.4 beats/min, and 63.3±10.8 beats/min. They included never-smokers 38%, former smokers 29%, and current smokers 33%. RESULTS: The proportionality factor HR(max) to HR(rest) in around 50-year-old men approximated 12. One year in age, one step change in BMI (normal weight, overweight, obese), smoking status (never, former, current), and TPA (moderately active, active, highly active) reduced the proportionality factor by 0.1, 0.6, 0.4, and 0.1, respectively. The proportionality factor in obese or current smoking middle-aged men was one point lower compared to normal weight or never-smoking peers. This corresponds to approximately 10 years in chronological age. CONCLUSIONS: In around 50-year-old men with no cardiovascular diseases, bronchial asthma, or cancer, the HR(max) to HR(rest) ratio should be multiplied by approximately 12 to estimate VO(2max). BMI and smoking status can be considered in calculations to improve accuracy.