And no increased mortality risk was observed from extreme fitness in a large observational study.

Better cardiorespiratory fitness is associated with lower all-cause mortality in several studies. However, some evidence suggests that excessive physical activity may be detrimental, especially in older adults. To better understand the association between cardiorespiratory fitness and mortality risk across the age spectrum, investigators examined deaths in about 750,000 US veterans aged 30 to 95 years (94% men), including about 111,000 in their 70s and 27,000 in their 80s, who had undergone a standardised exercise treadmill test. Cardiorespiratory fitness was assessed using peak metabolic equivalents (METs) achieved.

During a median follow up of 10.2 years, after multivariable adjustment, there was an inverse association between cardiorespiratory fitness and mortality across age, sex and race strata. The highest mortality risk was seen in the least fit individuals (20th percentile for peak MET [about 5]), who had a fourfold higher risk compared with the most fit individuals (98th percentile for peak MET [about 14]), who had the lowest mortality risk, regardless of gender. The investigators did not find any evidence of increased mortality risk with extremely high cardiorespiratory fitness, even in the oldest individuals.

Comment: These data support a large body of evidence showing an inverse association between cardiorespiratory fitness and mortality. This study also verifies the consistency of this association across the age spectrum, including the very elderly, and across gender and race groups. Also of note, no increased risk was observed with extreme fitness. These data support encouraging our patients to exercise regardless of age and should offer reassurance that extreme levels of exercise are safe.
KAROL E. WATSON, MD, PhD, FACC
Term Endowed Chair and Professor of Medicine/Cardiology, David Geffen School of Medicine at UCLA, Los Angeles, USA.

Kokkinos P, et al. Cardiorespiratory fitness and mortality risk across the spectra of age, race, and sex. J Am Coll Cardiol 2022; 80: 598-609.

This summary is taken from the following Journal Watch title: Cardiology.