A new study from Cleveland clinic
found that increased cardiorespiratory fitness (CRF) or aerobic fitness is
associated with lower long-term all-cause mortality with no upper limit
observed for the amount of exercise. Patients who demonstrated extreme CRF (≥2
SDs above the mean for age and sex) was at the lowest risk of adjusted
all-cause mortality as compared to other performance groups.
People with poor aerobic fitness face
the same likelihood of dying as that due to chronic diseases like diabetes,
hypertension and cardiovascular disease note the researchers of this
retrospective study published in the Journal of the American Medical Association Network Open.
This retrospective study recruited the
largest reported cohort of 122 007 patients between Jan. 1, 1991, and Dec. 31,
2014, who underwent Exercise treadmill testing (ETT) at a tertiary care center.
ETT eliminates the bias introduced due to self-reporting and is the most widely
used method to measure the CRF.
Demographics and other co-morbidities
were noted at the time of undergoing specified stress test under the
supervision of exercise physiologist. Patients were classified into performance
group by age- and sex-associated cutoffs as follows: elite (≥97.7th
percentile), high (75th-97.6th percentile), above average (50th-74th
percentile), below average (25th-49th percentile), and low (<25th
percentile).
The mean age was 53.4years, and about
60% were male. As the performance level increased, the associated
co-morbidities decreased except for hyperlipidemia (present in 30% of elite
performers).
After multivariate analysis, it was
seen that at any given point of time, patients in the elite group were 80% less
likely to die as compared to patients with low CRF (elite vs. low: adjusted HR,
0.20; 95% CI, 0.16-0.24; P < .001). The survival benefit was more evident in
older patients (70 and more) and those with hypertension. Long-term survival
was adjusted for a patient’s age, sex, height, weight, BMI, medications, and
comorbidities.
Hypertensive patients in the elite
group were 30% less likely to suffer mortality as compared to those in the
high-performance group (75th-97.6th percentile).
Patients with lowest aerobic fitness
(<25th percentile) faced risks that were comparable or more than patients with
chronic disease like CVD (24% more), diabetes (40% more) and smoking (40%
more).
These findings highlight the
importance of aerobic fitness concerning prolonging life and improving the
quality of life. This study reinforces the results of previous studies that
have demonstrated the benefits of achieving CRF.
“Aerobic fitness is something that
most patients can control. And we found in our study there is no limit to how
much exercise is too much,” said Wael Jaber, M.D., Cleveland Clinic
cardiologist and senior author of the study in a news release. “Everyone should be encouraged to achieve and
maintain high fitness levels.”
It also stresses the importance of
continued high-level physical activity in older adults and the benefits of
maintaining the highest aerobic fitness. Some recent studies have demonstrated
an association between extreme high level of exercise and an increased
incidence of atrial fibrillation, coronary artery calcification, myocardial
fibrosis, and aortic dilation. However, it is not clear whether these findings
are a simple physiological adaptation or because of cardiovascular pathology.
“We were particularly interested in
the relationship between extremely high fitness and mortality,” said Kyle
Mandsager, M.D., an electrophysiology fellow at Cleveland Clinic and the lead
author of the study. “This relationship
has never been looked at using objectively measured fitness, and on such a
large scale.”
The authors conclude,
“Cardiorespiratory fitness is a modifiable indicator of long-term mortality,
and health care professionals should encourage patients to achieve and maintain
high levels of fitness.”
