Better fitness in midlife appears to alter the onset and accumulation of multimorbidity over time.
Maintaining a high degree of cardiorespiratory fitness (CRF) appears to be one way to reach old age without developing multiple chronic diseases, including cardiovascular and metabolic conditions, according to data from a large observational study.
Among more than 38,000 adults followed for up to 15 years, those with high CRF had a lower risk of developing multimorbidity, delayed onset of disease development, and less overall accumulation of chronic diseases, Liyao Xu, BS (Tianjin Medical University, China), and colleagues report online in JACC: Advances.
“Higher CRF has a well-established relationship with lower all-cause mortality and reduced risk of specific chronic diseases, especially diabetes and cardiovascular disease,” senior researcher Abigail Dove, PhD (Karolinska Institute, Stockholm, Sweden), told TCTMD. “However, prior to our study, evidence was lacking on how CRF affects the overall accumulation of chronic diseases or the development of multimorbidity.”
Their data, Dove continued, “underscore the importance of maintaining high levels of CRF through exercise and physical activity to prevent the accumulation of chronic diseases and prolong health span as we age.”
Claudio Gil Araújo, MD, PhD (CLINIMEX, Rio de Janeiro, Brazil), who wasn’t involved in the study but who has investigated the clinical benefits of exercise and physical fitness, including balance, flexibility, and muscle power, said the new study “reinforces the possibility that improving aerobic fitness is likely the best and most impactful clinical intervention available to prevent chronic diseases.”
That higher aerobic fitness slows the trajectory of developing multiple chronic diseases over the next 10 to 15 years is an original finding, he said.
Given these and other data, Araújo told TCTMD, there is a need for cardiologists, as well as health professionals in general, to recognize that physical fitness—both aerobic and nonaerobic aspects—is important for longer and healthier lifespans. Exercise is akin to a polypill in terms of its effects on the brain, heart, lungs, bones, and musculature, and it’s not something that any pharmaceutical industry can ever develop, he added.
For Araújo, however, there needs to be a paradigm shift when it comes to thinking about and recommending physical activity and exercise for individual patients.
“Although everybody knows that exercise is important, the thinking is somewhat misleading,” he said. “The guidelines say you need 150 minutes of aerobic exercise per week, and so on, but that shouldn’t be the target. The target should be to be physically fit.”
UK Biobank Data
To TCTMD, Dove pointed out that the past decades have seen an increase in the average life expectancy, which is a win for public health. With this, though, come other challenges, such as a rise in the prevalence of multimorbidity, which is the co-occurrence of two or more chronic diseases in the same individual.
Besides negatively impacting quality of life, “multimorbidity poses significant challenges to the healthcare system,” she said. “Individuals with multiple chronic illnesses often require care from specialists to manage certain conditions.”
Such care then requires balancing potential interactions between conditions and their treatments, and “the evidence to support these complex clinical choices is limited,” said Dove. “From the patient perspective, people with multimorbidity shoulder a considerable burden with frequent medical appointments, complex treatment regimes, lifestyle adjustments, and other demands. This can be costly in terms of time, money, and mental resources.”
To look at the relationship between high CRF and multimorbidity, researchers analyzed data from 38,348 adults enrolled in the UK Biobank (mean age 55.2 years; 52% female) who were followed for a maximum of 15 years. CRF, which was measured by a 6-minute submaximal exercise test on a stationary bike while participants were hooked up to an ECG, was calculated as maximum oxygen consumption and then converted into metabolic equivalents (METs). To assess multimorbidity, investigators identified 59 common chronic diseases that were classified into three categories: metabolic, cardiovascular, and neuropsychiatric.
Participants with low CRF were older on average, tended to have lower education level and socioeconomic status, and were more likely to be nonwhite and to be physically inactive compared with those with moderate or high CRF.
Over a median follow-up period of 11.6 years, 15.7% of participants developed one chronic disease, 11.3% developed two, and 28.8% developed three or more.
Those with low CRF were more likely to develop three or more chronic diseases (33%) compared with those with moderate or high fitness levels (29% and 25%, respectively). In an adjusted model, each standard-deviation increase in CRF was associated with a lower risk of multimorbidity (HR 0.91; 95% CI 0.89-0.93). Similarly, the risk of developing two or more chronic diseases was 10% and 21% lower in those with moderate and high CRF, respectively, compared with those with the lowest fitness levels.
The accumulation of chronic diseases over the 15-year period was significantly slower in people with moderate and high CRF compared with low CRF. Specifically, those with the highest fitness had a slower accumulation of metabolic, cardiovascular, and neuropsychiatric diseases compared with the lowest CRF group. Moderate CRF also was associated with a slower progression of metabolic and cardiovascular diseases compared with low fitness levels.
For the general public, [cardiorespiratory fitness] can be thought of as a barometer for future health and disease risk. Abigail Dove
“I think the study provides compelling evidence that high CRF can be a buffer against the accumulation of chronic diseases as we age, which underscores the importance of maintaining good CRF in midlife and beyond,” said Dove. “For the general public, CRF can be thought of as a barometer for future health and disease risk.”
While fitness testing isn’t common outside sports medicine or cardiopulmonary care, it could be considered a useful clinical tool to assess a patient’s vulnerability to multiple chronic diseases, she said.
In an editorial, Carl J. Lavie, MD (John Ochsner Heart and Vascular Institute, New Orleans, LA), and colleagues say these data build on prior studies suggesting that high CRF at midlife appears to protect “against the cumulative burden of chronic disease, [or] what might be called the physiological trajectory toward multimorbidity.”
CRF, they add, might be a good addition to clinical risk-stratification tools as it gives a “system-wide snapshot of physiological reserve and disease vulnerability.” Fitness, they add, “deserves broader consideration in midlife health assessments.”
Personalizing Fitness Paths
The path to getting to higher levels of CRF is going to vary for everybody based on their baseline fitness, genetics, and more, and healthcare professionals should take this into account when prescribing exercise or developing programs for healthy and unhealthy individuals, said Araújo. To do this, aerobic fitness needs to be measured so that healthcare teams have a good idea of what needs to be done, just as they would when taking baseline assessments of blood pressure or lipids.
The current study, said Araújo, has numerous strengths and limitations. The UK Biobank provides an excellent sample size with good representations of men and women and of age groups. He also praised the researchers for investigating “multimorbidity,” which is a potentially useful clinical variable that measures healthy aging.
However, combining 59 common chronic diseases, some with unspecific criteria, such as migraine, and missing others makes the multimorbidity diagnosis a challenge to analyze and interpret clinically.
“Although I like the idea of something that could be called multimorbidity, as it was presented by the authors of this article, it has several weaknesses and omissions,” he said.
Also, Araújo questioned how accurate their estimation of CRF was based on their formulas and extrapolations. Nonetheless, it is now well known that higher physical fitness is better correlated with health outcomes than physical activity levels, he said. Additionally, there is now a large amount of data showing that individuals with high levels of VO2 max directly measured live longer.
“Remember Charles Darwin,” said Araújo. “Only the fittest will survive!”
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