When cardiorespiratory fitness levels are low in people, it could signal future health concerns even in the healthy and fit. So even when you are healthy and fit without any symptoms of disease, low cardiorespiratory fitness levels could imply future problems, so says a study published in the “European Heart Journal.”
Cardiorespiratory fitness implies the potential of the body to circulate blood throughout the system for providing sufficient amounts of oxygen to the muscles during physical activity. The chief measure is VO2max- maximum consumption of oxygen while exercising that increases with intensity.
In a study conducted in Norway, around 4500 healthy and fit men and women without any history of lung cancer or cardiovascular disease or hypertension were assessed for cardiorespiratory fitness in 2005-2008 [1]. They wore a heart monitor and face mask and ran on treadmill for ten minutes before running faster and faster. Measurement of the oxygen intake was done to evaluate VO2max. Information was also collected on alcohol consumption, tobacco use, physical activity, height, weight, blood pressure, family history of cardiovascular disease, cholesterol levels.
After following them up for nine years, it was found by the researchers that greater levels of cardiorespiratory fitness were associated with lesser risk of cardiovascular disease like heart attack. During this period hardly 3% of the participants suffered from heart disease or died due to it or needed intervention to unblock the arteries.
Dr Bjarne Nes, researcher at Norwegian University of Science and Technology said that there was a strong correlation between higher levels of fitness and reduced incidence of coronary event during the nine years in healthy adult samples. Recruits who were among the 25% of those with the highest cardiorespiratory fitness levels had half the risk as against those who were in the 25% of those with the lowest cardiorespiratory fitness levels.
Further, it was found by the researchers that in both women and men the incidence of cardiovascular issues reduced by 15% for each extra unit of metabolic equivalents (METs). These metabolic equivalents measure the amount of oxygen required for expending energy on physical activity. One MET is the amount required when a person is sitting quietly, not doing anything while strenuous activities like extensive running would involve up to 8 METs
Dr. Nes said that this shows that more cardiorespiratory fitness provides protection against acute and chronic blood vessel and heart problems. Even a very small increase in fitness can have a big effect on health.
Study’s main author, Dr Jon Magne Letnes said that the results should endorse the use of exercise as a measure for prevention. Barely some months of exercise could be a great way of reducing cardiovascular risk.
Study’s major strength is that cardiorespiratory fitness was measured with a maximal exercise test of VO2peak- the first in healthy sample of general population. Previous studies in which an association between fitness to disease risk have been established are based on estimates which are not very accurate.
Study’s limitation is that engaging in voluntary exercise testing brings about the possibility that more active people may join the study which reduces its application to general population.
In another editorial, Sanjay Sharma, medical director of the London Marathon and Dr Aneil Malhotra say that this study is an addition to the current literature by exhibiting same benefit in an apparently healthy population with progressive benefit that extends beyond 12 METS and says that there is no obvious verge for the exercises’ cardioprotective effects [2]. Although the number of subjects is praiseworthy but there are many points to be noted.
The high point is that there is an intrinsic selection bias towards recruits who had the motiation to participate and were more aware of lifestyle modifications for avoiding cardiovascular disease and recruits were young and healthy which justifies the less incidence of cardiovascular related events in the follow up period.
For concluding they say in a time and age where primary prevention plays a critical role in society, the study highlights that improving cardiorespiratory fitness is essential for reducing the risk of cardiovascular diseases and death. So regular exercise and measures of cardiorespiratory fitness should be be there in CV risk models and clinical practice. Everyone should be motivated to engage in physical activity at least to the minimum recommended levels for prevention of disease. Although studies suggest that higher levels of physical activity provide prognostic benefits. There is evidence that some exercise is better than nothing.