Just when you thought you had mastered the fine art of fitness, something new comes along. Every year a different dance-style-turned-cardio-class is born that you have to try, or maybe your tacky Timex has become obsolete because it can’t draw a map of your ocean swim. You buy into it all with full faith these updated auxiliaries will make you faster, stronger…better than your biggest workout rival (admit you have one). But what if all you need to knock out obstacles and conquer your goals is a few timeless formulas? It sounds almost too easy. Trust me, if you don’t know these four fitness stats, you’re focusing on all the wrong things.
1. AGE-PREDICTED MAXIMAL HEART RATE (APMHR)
What? APMHR is the maximum beats per minute your heart will pump under extreme exertion. When your heart rate no longer increases even when the workload or intensity does, you’ve reached the max.* It’s an easy calculation: 220 minus your age.
Why? Based on your APMHR, you’ll be able to exercise in the appropriate heart rate zone(s) for your fitness goals. Endurance athletes will spend most of their training in the 70-85% range. For a 30-year-old, this would mean working at a heart rate of 133-161. Do the math:
220 – 30 = 190
190 x 0.70 = 133
*APMHR is an estimation based on your age. To get a personalized MHR, consult a physician or personal trainer who can supervise a controlled exercise test.

2. BODY FAT PERCENTAGE
What? A body fat test determines how many pounds of fat makes up your total composition (versus lean muscle mass). Average, active ladies should shoot for 21-24% body fat and always be mindful of the 32% “obese” mark. Even though men seek the elusive single-digits, 14-17% is perfectly fit; 25% or above is their danger zone. (Don’t be too discouraged, guys. You naturally burn fat easier than us.)
Trainer tip: You may have gotten caught in the buzz around body mass index (BMI), but it’s nothing more than a ratio of your height to weight ““ which can be deceiving. Take a person weighing 150 lbs. at 5′ 5.” Their BMI would come to 25.0, which is considered “overweight.” But they show only 22% body fat, well within the fit range.
Calipers are generally a more accurate reading of body fat, though, they can be tricky to use and often require an extra set of hands. A digital, handheld monitor is easy and takes into account your age, height, weight, gender and level of activity. As you hold it, an electrical current passes through your body (don’t worry; you won’t feel a thing). This method is based on what’s called bioelectrical impedance analysis. Since fat doesn’t conduct electricity as well as water or muscle, the speed of the current determines your mass makeup. Trainer tip: test before your workout. Once you start drinking water, the current may slow down and offer false hope.
Why? A little meat on your bones will help maintain hormonal balance, support your immune system and make skin appear supple. Living with excess body fat, however, can lead to serious health conditions. Sadly, more than one-third of American adults suffer through the simplest of tasks, because they’re breathless walking up stairs or can’t sleep through the night without snoring. Don’t be another statistic. Track your body fat every month to help you reach that sweet spot, where you feel healthy and energized all day, every day!
What? Wrap a tape measure around the narrowest part of your torso, overlapping your belly button. For a true waist size, measure a bare belly. Do your numbers match Barbie’s? Let’s hope not. The ideal waist size for women is below 32 inches. Men are no Ken, either. They’re healthy at 35 inches, or less.
Why? Your mid-section is where hazardous-to-your-health visceral fat lurks. This is the fat that resides deep inside, between your abdominal organs. Though some fat is useful for protecting our precious parts, too much can out-weigh all the benefits. Waist sizes over 35 inches for women and 40+ inches for men have been associated with an increased risk of heart disease and diabetes. Enough said.
4. DAILY CALORIES (AND MACRONUTRIENTS)
What? The Harris & Benedict formula for resting metabolic rate (what your body burns at rest) is most commonly used to establish a healthy helping of calories for your body to survive. After calculating the minimum you need to function, add your exercise habits to the equation.
Formula for men: 66.47 + ( 13.75 x weight in kg ) + ( 5.003 x height in cm ) – ( 6.755 x age )
Formula for women: 655.1 + ( 9.563 x weight in kg ) + ( 1.850 x height in cm ) – ( 4.676 x age )
Add exertion:
Calorie breakdown (aka macronutrients):
15-20% calories from protein
20-35% calories from healthy fats (operative word: healthy!)
Why? This won’t be what you want to hear, but…in order to hold onto that svelte figure, you’ll have to control portions. However, if you don’t know how many total calories you need in a day, you won’t know how many portions (or what size servings) you can have without gaining weight. Even Olympians — who, by the way, burn an outrageous number of calories a day — know their limits, because they understand that food is fuel. Trainer tip: eat lighter on rest days than you do when you double-up workouts or go for a double-digit run.
Let’s say you aren’t happy with your weight and rather not maintain status quo. Take your daily caloric needs, subtract 500 and you have exactly the number you need to lose an average of one pound a week — by far the safest and most sustainable weight-loss rate. Whatever your goals, go after them! You now have the only tools that will far out-last any fitness fad…or exercise foe.