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Health experts recommend at least 150 minutes per week of moderate intensity physical activity or 75 minutes of vigorous activity per week.Credit: mbbirdy via Getty Images ShareThere are good reasons to step away from the scale. It can be a place of supreme stress, in a society that prizes thinness and stigmatizes fat. Then theres the mounting scientific evidence that weightand, accordingly, body mass indexare unreliable indicators of health.Cardiorespiratory, or aerobic, fitness is a much better predictor of all-cause mortality and heart disease risk than BMI, according to a comprehensive review published November 12 in the British Journal of Sports Medicine. People classified as overweight and obese who had high cardiorespiratory fitness were not at higher risk of death or chronic diseases like hypertension than their thin counterparts. They also had 2-3-fold lower mortality risk than those of normal weight but with low fitness, per the recent research. Its just the latest entry into the litany of studies demonstrating that fitness and fatness are far from mutually exclusive.Once you factor in fitness, BMI really didnt have much statistical predictive ability at all, says Siddhartha Angadi, senior author on the November analysis and an associate professor of Kinesiology at the University of Virginia. The risks of being unfit are far greater than the risk of carrying a few extra pounds, he adds.Moreover, its not necessarily just because BMI is a flawed measure of body composition. Particularly muscular people might be wrongly categorized as overweight or obese by the BMI chart, but at the population level, the metric is pretty tightly correlated with body fat because the average person is not an NFL lineman, says Angadi. He points out that previous research specifically looking at body fat composition has found similar results: that fitness is a much better predictor of mortality than percent body fat. Once you have fitness, a lot of the value of knowing adiposity largely just goes out the window, he adds.Yet as January carries on and many work to maintain health-focused resolutions, you may be wondering how to keep tabs on your fitness without tracking weight. If not BMI (or even body fat composition), then what does indicate good cardiorespiratory fitness? It turns out there are multiple, alternative ways to get a sense of your health, and to determine if your exercise routine is working to your benefit.The best metricAerobic fitness is most directly characterized through VO max, which is a measure of your bodys peak rate of oxygen consumption, Angadi explains.BMI works fine at a population level, to assess risk, says Lee Stoner, a cardiometabolic physiologist, science consultant, and associate professor at the University of North Carolina. But when it comes to individual metrics, VO max is a much superior indicator of your overall health risk, he says. So much so, that Stoner notes, the American Heart Association has recommended it become a standard vital sign since 2016.Its your bodys max ability to breathe in oxygen, deliver it to working muscles, and utilize that oxygen to produce more energy, Stoner says. For your body to be able to do that, all of your internal systems must be able to work in tandem. Your lungs must work well, your cardiovascular system must work well. And your muscular system must work well. Its no wonder that high VO max is so highly correlated with reduced heart and metabolic disease risk and lower mortality.Getting a fully accurate read on your VO max requires a visit to a doctors office or clinic. VO max is measured via a specific test on a treadmill or stationary bike that relies on a respirometer and other specialized equipment. However, if you have a smartwatch or other fitness monitoring device, it may offer you an estimate of VO max as well. These estimates often arent so accurate, but what they can give you is a sense of changes over time. Even if a smartwatches internal algorithm isnt calibrated correctly for you, if your watch readout is increasing over time, with the introduction of more aerobic exercise, you can at least be assured youre improving.And if you dont want to shell out for a pricey fitness wristwatch, dont despairthere are other ways.Put it to the testNothing will be as accurate as an official VO max test. But there are a handful of fitness tests that are possible to complete on your own (at home or the gym), which offer a reasonable proxy for VO max, say Angadi and Stoner.In perhaps the simplest, called the Rockport walking test, you walk for one mile on a flat surface as fast as you can (without jogging or running), timing how long it takes. At the end, you count your own pulse rate for between 15 and 30 seconds, and either input your heart rate and speed into an online calculator, or do the math yourselfcomparing your score to a population norm table to get a sense of where you stand. The caveat here is the equations to go from walking time and heart rate to estimated VO max do require a weight, so technically a scale is necessary herebut weight is actually the least important variable in the algorithm.Similar tests include the Cooper 12-minute run test or 1.5-mile run test (which is used to gauge fitness in the military). However, if youre not accustomed to running or regularly exerting yourself, the walk test is a safer and more accessible place to start.If youre short on time, Stoner recommends the three-minute step test as another alternative that offers a score of aerobic fitness (this time without weight). For that, youll need a 12-inch tall step (perhaps a stool, crate, or actual step), a timer, and a metronome or handy Youtube video.Again, because all of these are estimates, a single score is less useful than tracking your score over time. Checking in with yourself once a month or so, with one of the above tests, offers a way to keep tabs on your cardiorespiratory gains without stressing over your waistline or jiggly bits.Count it outYou may have noticed that all of the above tests involve measuring your heart rate. And thats because your pulse offers an informative snapshot of your fitness baseline. Your resting heart rate, in and of itself, is a good measure, says Stoner. Your heart is a muscle and the more you work it, the stronger and larger it grows. A bigger, brawnier heart means each pump circulates more blood and oxygen, and so fewer pumps are needed to maintain the body. When people start doing regular aerobic exercise, theyre resting heart rate starts to fall, Angadi says.A normal resting heart rate (taken after about five minutes of inactivity) is between 60 and 100 beats per second. The lower the number, the more fit youre likely to be. Athletes or those in particularly good shape often have resting pulses below that 60 threshold.To measure your pulse manually, use two fingers on your wrist, below your thumb or on the side of your neck below your jaw to feel your heartbeat. Set a timer for 15, 30, or 60 seconds and count how the beats in that time window.If youre just beginning a regular exercise routine, or otherwise seeking to boost your fitness, regularly checking your resting heart rate can offer a metric of cardiovascular improvement. For the best accuracy, take your pulse at the same time every day (things like eating, sleep, and stress can impact our heart rate throughout the day).More detailed assessments, like heart rate recovery time and heart rate variabilityagain, often estimated by smartwatchescan provide additional information. Though, if you have any questions or concerns about your heart rate and rhythm, your physician is the best resource.Doctor dataSpeaking of visiting your physician, if you show up for a yearly physical, then youre getting a good snapshot of your health in data already. Metrics like blood pressure, HDL cholesterol, and A1C (which tracks blood glucose fluctuations over time) are all related, in part to exercise and aerobic fitness. Studies have demonstrated that regular aerobic exercise can reduce resting blood pressure, increase good cholesterol levels, and help regulate blood sugar. Age is a factor, but If these values are increasing significantly over time, it may be a sign that your fitness is declining. An at home blood pressure cuff or glucose sticks can also be used to keep closer tabs, says Stoner.Time and effortPerhaps the simplest way to understand your cardiorespiratory fitness is to honestly assess how active you are. Your heart, lungs, and muscles all essentially operate on a use it or lose it paradigm. If youre not exerting yourself on a regular basis, youre almost certainly less aerobically fit than you could be and less than is ideal for minimizing health risks. The ability to complete an exercise or to move for a certain period of time ison its owna fitness indicator, and more movement each week is generally better.But you need not become a gym rat nor aspire to great athletic feats to improve your health. If your primary goal is to reduce your risk of cardiovascular disease and boost your longevity, then at least 150 minutes per week of moderate intensity physical activity or 75 minutes of vigorous activity is the goal, according to the American Heart Association and the American College of Sports Medicine. Thats just 30 minutes of moderate movement or 15 minutes of vigorous activity five times a week.Moderate activity is any physical movement that gets your heart rate up, but leaves you still able to talk comfortably (though makes it harder to sing). It can include everyday activities like cleaning, gardening, and brisk walking. At a vigorous activity level, talking beyond a few words at a time without running out of breath becomes more challenging.If you can do moderate physical activity for 150 minutes a week, thats great. If you want to do more, fantastic. But at least do that, says Angadi. Some combination of both moderate and vigorous activity, spread over multiple days, is ideal. Incorporating some strength training reduces risk even more, and is especially important for older adults seeking to maintain independence, he adds.If youre just starting out with exercise, 150 minutes a week may be initially hard to reach. However, as your fitness improves, the length of time you are able to move before exhaustion will rise. No matter how low your initial baseline, increasing the amount of movement and aerobic exercise you do carries health benefits. When it comes to boosting fitness and reducing risk, the biggest bang for your buck is when you go from doing absolutely nothing to just doing somethingthats when your risk falls the most, Angadi explains.A lot of people think of exercise as just a way of getting rid of calories. I really hope people get away from that. When you think of exercise, think of it instead as cardiac, pulmonary, vascular, muscular, metabolic medicine. Thats what its good for, he says. The one thing exercise is not great at is getting people to lose weight..Weight loss vs. fitnessMany New Years resolutions are centered on weight. But if youre concerned with your overall health, thats not the best approach. Weight is not a direct measure of health and disease risk, and it can even become a counterproductive focal point, which discourages people from sticking to a routine.When you use the scale to tell you if youre exercising enough or not, youre doing the one thing that is probably not likely to result in a fruitful outcome, Angadi says. A lot of times, people will get frustrated and say, ah, the numbers arent moving. I quit. But I would say exercise is for your heart. Its for all the other organs in your body. Where you land in terms of weight, thats a genetic problem.If you want your heart and your muscles to get better at moving youand its in your best interest to improve thatthere is no shortcut outside of exercise, Angadi adds. We dont have that in a pill, unfortunately.
