The secret is to Keep Moving
Cardiorespiratory fitness (CRF) refers to the body’s maximal to process oxygen. Low CRF might be the best single predictor of risk of cardiovascular disease, premature death, and accelerated aging.
Lower mortality risk for older people
Levels of physical and cardiorespiratory fitness typically decline with age, while the tendency toward obesity increases. Nevertheless, the associations among fitness, obesity, and mortality are not well understood for older people. Data for 2,603 participants who completed a baseline health examination between 1979 and 2001 in the Aerobics Center Longitudinal Study were used to examine these associations. Follow-up averaged 12 years, and the average age of the participants was 64 years. After adjusting for confounding factors and compared to the lowest quintile of fitness, the mortality risks declined in a step-wise manner across increasing quintiles of fitness. For example, the mortality risk of participants in the top quintile was 70 percent lower than that in the bottom quintile. Similarly, after adjusting for confounding factors and compared to the lowest quintile of fitness, the mortality risks increased in a step-wise manner across increasing quartiles of body mass index. The mortality risk of participants in the top quintile of body-mass index was 129 percent higher than that in the bottom quintile. Thus, low cardiorespiratory fitness and obesity both predicted higher risk of mortality for older people, regardless of confounding factors. But here’s great news: Mortality risk did not increase for highly fit individuals as levels of obesity increased. How about that?
How much physical activity will boost cardiorespiratory fitness?
While low levels of cardiorespiratory fitness predict increased risk of death, increasing fitness can reduce this risk. Current recommendations call for at least 150 minutes of moderate-intensity physical activity per week. But how much would more or less physical activity boost fitness? Researchers used data from 464 sedentary patients with overweight or obesity and an average of 57 years at the Cooper Clinic in Dallas, TX, to find out. Patients were randomized into one of four physical activity groups that expended 0, or 4,000 or 8,000, or 12,000 calories per week for six weeks. The physical activity included thrice weekly supervised walking on a treadmill or riding a semi-recumbent cycle at a rate equal to 50 percent of maximum oxygen consumption (VO2max). At the end of the six-month program, participants increased their peak oxygen consumption in a graded manner as physical activity increased from 0 to 12,000 calories per week. Even exercising at the level of 4,000 calories per week (equivalent to 72 minutes of moderate intensity exercise per week or three brisk, 24-minute walks per week, which is less than half of the currently recommended minimum amount) increased cardiorespiratory fitness. Getting massive amounts of physical activity isn’t necessary to increase fitness for sedentary middle-aged women with overweight or obesity. This is great news!
Greater brain volume
Increased physical activity predicts reduced risk of Alzheimer’s disease. Physical activity data typically come from self-reports, which are subject to bias. On the other hand, cardiorespiratory fitness can be measured objectively and expressed as either VO2max, or VO2 anaerobic threshold, or peak muscle power. A recent study investigated links between total brain volume, gray matter volume and objectively measured cardiorespiratory fitness. Brain volumes were measured with non-invasive imaging. Higher levels of each measure of cardiorespiratory fitness predicted significantly greater total brain volume and greater gray matter volume. In particular, larger volumes occurred in gray matter areas associated with memory and executive function and not in areas associated with movement processing. Increased brain and gray matter volume might lead to improved brain health and better aging.
Reduced all-cause, cardiovascular and cancer-related mortality
Plenty of studies suggest that better cardiorespiratory fitness predicts lower risk of premature death in Western countries. But what about other countries? Researchers in China conducted a meta-analysis of 34 cohort studies to understand the dose-response of cardiovascular fitness with respect to mortality. The relative risk of all-cause mortality decreased by 12 percent with each one metabolic equivalent (3.5 ml O2 per minute per kg of body weight) increase in cardiorespiratory fitness. The comparable reductions for cardiovascular- and cancer-related mortality were 13 and 7 percent, respectively. When comparing lowest to the highest category of cardiorespiratory fitness, the risks of all-cause, cardiovascular-related, and cancer-related mortality were 53, 51, and 41 percent lower, respectively. If you want to reduce your risk of dying of cancer before your time and enjoy the myriad benefits of better fitness, find ways to elevate your heart rate every week.
Higher cardiorespiratory fitness predicts lower risk of cardiovascular disease, but factors that are linked with fitness in general population remain unclear. Researchers used data from 5,308 participants in their late fifties who had valid VO2 max data in the Swedish Cardiopulmonary Bioimage Study to see what factors predicted low CRF (defined as the lowest one-third of VO2max). Sociodemographic and lifestyle factors that predicted low CRF for both men and women included older age, less education, and high alcohol intake. Physical conditions and chronic illnesses that predicted higher risk of low CRF included somewhat bad/bad general health, obesity (nearly 17 times the risk), and high waist circumference (10 times the risk). Finally, self-reported and objectively measured physical activity patterns that predicted lower risk of low CRF included commuting to work bicycle—82 percent lower odds, 2) exercising more than three times per week—86 percent lower odds, and 3) regular exercise or training—94 percent lower odds. What does study mean for you? If you Keep Moving, you’ll increase the likelihood of having high CRF, living each day with more energy, and better aging.
Unfortunately, measuring CRF directly requires expensive specialized equipment operated by trained personnel, which limits its applicability for population-level research and clinical applications. Researchers at Cambridge University in the UK developed an algorithm that used data for heart-rate responses to differing levels of physical activity captured by wearable devices under real-life conditions to predict CRF. Plus, the algorithm predicted future CRF over a seven-year period. In the near future, you’ll be able to use data from your wearable device, such as an Apple watch, to monitor your aerobic physical activity and increase your CRF.