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Increased peak oxygen uptake may benefit in lowering CHD risk
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An increase in peak oxygen uptake, or VO2, may have substantial benefits in reducing the burden of CHD, according to findings published in the European Heart Journal.
Because most of the previous research on the association between cardiorespiratory fitness and CVD was based on indirect assessment of cardiorespiratory fitness in a clinically referred male population, the researchers sought to identify the connections between peak VO2 as measured by cardiopulmonary exercise testing and fatal or nonfatal CHD in a healthy and fit population.
“Cardiorespiratory fitness is strongly associated with all-cause and cardiovascular mortality and might be an important predictor of mortality beyond traditional risk factors such as hypertension, diabetes, cholesterol levels and smoking,” Jon Magne Letnes, a PhD candidate from the department of circulation and medical imaging at Norwegian University and the clinic of cardiology at St. Olavs University Hospital in Trondheim, Norway, and colleagues wrote. “A more limited number of studies also suggest that moderate to high [cardiorespiratory fitness] in apparently healthy people is associated with delayed CHD progression and reduced nonfatal events.”
The study cohort was made up of 4,527 adults from the HUNT3 Fitness Study (mean age, 48 years; 51% women) with no previous history of CVD or lung disease, cancer, and hypertension or antihypertensive medications. Information on smoking status, pack-years of cigarettes, snuffing status, alcohol consumption, family history of CVD and leisure-time physical activity were obtained from questionnaires.
Researchers identified the average peak VO2 as 36 mL/kg per minute for women and 44.4 mL/kg per minute for men, with the predefined maximum VO2 criteria reached in 80% of participants.
The 10-year risk for CVD was calculated and classified as low, medium or high based on the NORRISK2 risk production model, with researchers identifying 83.5% of the participants having low risk for CVD and CVD mortality.
The primary endpoint was diagnosis of or death from CHD, or coronary revascularization, with 3.3% of participants reaching the endpoint during the follow-up (mean, 8.8 years).
Risk lower
Researchers identified a 15% lower risk for the primary endpoint per 1 metabolic equivalent of task (MET) higher peak VO2 (HR = 0.85; 95% CI, 0.77-0.93), regardless of sex. The highest quartile of peak VO2 had 48% lower risk for an event compared with the lowest quartile (multi-adjusted HR = 0.52, 95% CI, 0.33-0.82).
According to the researchers, their results identified that peak VO2 is inversely related to the risk for CHD in healthy men and women and that ventilatory equivalents of oxygen and carbon dioxide also showed significant predictive value for the primary endpoint.
The findings support that peak VO2 has predictive value along the entire fitness continuum, and that future studies should further pursue integration of peak VO2 in risk-prediction algorithms, the researchers wrote.
“Exercise is associated with healthy living, increased cardiorespiratory fitness and reduced morbidity, and the potential for primary prevention is great, and not fully exploited,” Letnes and colleagues wrote.
Some better than none
In a related editorial, Sanjay Sharma, BSc, MBChB, MD, FESC, and Aneil Malhotra, PhD, MA, MSc, MBBChir, both from St George’s University in London, wrote: “In an era where primary prevention is playing an increasingly significant role in society, this study helps highlight that improving [cardiorespiratory fitness] is a pivotal factor in reducing CV risk and mortality. ... For those who are compromised due to comorbidities or functional status, there is overwhelming evidence that some physical activity is better than none.” – by Earl Holland
Disclosures: The authors and editorial writers report no relevant financial disclosures.
Perspective
Back to TopWilliam S. Weintraub, MD, MACC, FAHA, FESC
The takeaway is that people who are fit do better. They have a longer life expectancy and they remain healthier.
The researchers used peak O2 consumption as a proxy for overall CV fitness. That is pretty good, although one might argue it. This is consistent with a lot of other literature, that people have a better outlook if they are fit. One might say that exercise time is the best measure or a survey of how much people exercise per week is the best measure. You can come up with other measures.
The findings reinforce things we already know, that throughout the lifespan, it’s important to remain fit. That means to exercise regularly, vigorous exercise for younger adults and as people move through the life course, something a little less vigorous. What I tell elderly patients is that the best exercise is walking.
There are no randomized trials on fitness and life expectancy and there never will be. You cannot randomize people and keep them in an arm long term. The research that we are going to have is more observational studies. You have treadmill studies like this which measure O2 consumption and look at people over long periods of time. We need more epidemiologic studies, especially involving young people in which we look at exercise and fitness over long periods of time and look at outcomes. We also need more intervention studies in young people, in schools to get people to be active. A lot of schools, to save money, have done away with required gym classes and fitness. This is a huge mistake on a societal level. We need more young people fit and active.
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