A new study has found links between cardiorespiratory fitness and lower death rates in women.

The study, published in the Medicine & Science in Sports & Exercise journal from the American College of Sports Medicine (ACSM), states that cardiovascular fitness level, not just a woman's size, may be the key predictor of health level and overall risk for death.

Entitled Cardiorespiratory Fitness, Adiposity, and All-Cause Mortality in Women, the study measured body mass index (BMI), body fat percentage, waist-to-hip ratio, waist circumference, waist-to-height ratio and cardiorespiratory fitness in 11,335 women from 1970 to 2005.

Participants were divided into groups based on their cardiorespiratory fitness levels - low fit equals the lowest 20 per cent; moderate fit equals the middle 40 per cent; high fit equals the highest 40 per cent. Researchers tracked death rates among all participants, and 292 deaths from all causes occurred during the study period.

Researchers found that death rates were significantly lower for fit women than for unfit women. Additionally, fit women with high values (based on standard clinical measures) for BMI, body fat percentage, waist circumference and waist-to-height ratio had no greater risk of death than their fit counterparts with normal adiposity values. These results suggest that fitness is a stronger predictor than thinness for predicting a long and healthy life.

Dr Stephen Farrell, lead author of the study, ACSM member ad science officer in the education division at The Cooper Institute, said: "In other studies, failure to measure cardiorespiratory fitness levels may be due in part to an underlying assumption that all overweight individuals are unfit and at high risk for mortality.

"This study makes clear that this assumption is not always valid."