Blog | Thursday, November 29, 2018

The value of fitness


Long time readers know that I often write about exercise and fitness. Over the past three years I have written often about Orange Theory Fitness. OTF focuses on high intensity interval training (cardio) complemented by strength work. Working out regularly makes me feel better in many ways, and I would do it for a variety of reason, but this new study at JAMA Network Open adds even more fuel to my OTF fire: “Association of Cardiorespiratory Fitness with Long-term Mortality among Adults Undergoing Exercise Treadmill Testing.“ The study is free. (CNN has a great article explaining the study, “Not exercising worse for your health than smoking, diabetes and heart disease.”)

Here are some important quotes from the article:

Consecutive adult patients referred for symptom-limited exercise treadmill testing were stratified by age- and sex-matched cardiorespiratory fitness into performance groups: low (<25th percentile), below average (25th-49th percentile), above average (50th-74th percentile), high (75th-97.6th percentile), and elite (≥97.7th percentile).

We need this to understand how they defined fitness. This study differs from previous studies because they have data on fitness (the treadmill performance) rather than patient reports on exercise.

The study population included 122,007 patients (mean [SD] age, 53.4 [12.6] years; 72,173 [59.2%] male). Death occurred in 13,637 patients during 1.1 million person-years of observation. Risk-adjusted all-cause mortality was inversely proportional to cardiorespiratory fitness and was lowest in elite performers (elite vs low: adjusted hazard ratio [HR], 0.20; 95% CI, 0.16-0.24; P<.001; elite vs high: adjusted HR, 0.77; 95% CI, 0.63-0.95; P=0.002). The increase in all-cause mortality associated with reduced cardiorespiratory fitness(low vs elite: adjusted HR, 5.04; 95% CI, 4.10-6.20; P<0.001; below average vs above average: adjusted HR, 1.41; 95% CI, 1.34-1.49; P<0.001) was comparable to or greater than traditional clinical risk factors (coronary artery disease: adjusted HR, 1.29; 95% CI, 1.24-1.35; P<0.001; smoking: adjusted HR, 1.41; 95% CI, 1.36-1.46; P<0.001; diabetes: adjusted HR, 1.40; 95% CI, 1.34-1.46; P<0.001). In subgroup analysis, the benefit of elite over high performance was present in patients 70 years or older (adjusted HR, 0.71; 95% CI, 0.52-0.98; P=0.04) and patients with hypertension (adjusted HR, 0.70; 95% CI, 0.50-0.99; P=0.05). Extreme cardiorespiratory fitness (≥2 SDs above the mean for age and sex) was associated with the lowest risk-adjusted all-cause mortality compared with all other performance groups.

This study does give us another reason to approach fitness like younger athletes. Fitness really does matter. I think I'll go exercise this morning.

db is the nickname for Robert M. Centor, MD, MACP. db stands both for Dr. Bob and da boss. He is an academic general internist at the University of Alabama School of Medicine, and the former Regional Dean for the Huntsville Regional Medical Campus of UASOM. He still makes inpatient rounds regularly at the Birmingham VA and Huntsville Hospital. His current titles are Professor-Emeritus and Chair-Emeritus of the ACP Board of Regents. This post originally appeared at his blog, db's Medical Rants.