As a researcher and science nerd, I always stay on top of the latest research. Early this year, a study showed DHEA combined with burst training could boost testosterone levels in middle-aged men. I use that kind of information to help my clients become stronger, leaner, and more powerful.

Recently another trainer at my gym showed me a fascinating book entitled Biomarkers: 10 Determinants of Aging You Can Control. “Why have I not heard about this book?” I asked. Oh, it was published in 1991. That’s why.

Now, 1991 wasn’t that long ago. Maybe it feels like yesterday to you: to jog your memory, Lollapalooza made its debut and Silence of the Lambs ruled the box office that year. I think acid-washed jeans had finally gone out of style, but those horrid MC Hammer baggy pants were all the rage.

In science speak, however, this book was a dinosaur in 2013.

(Note to the authors William Evans and Irwin Rosenberg of Tufts University: all due credit to you in this blog. If you are reading this, please consider an updated version of Biomarkers. This book would be a huge hit among my nutrition and fitness colleagues and I would promote the heck out of it.)

"Regardless of its sometimes-outdated ideas, I remained fascinated as I devoured Biomarkers. The book contends with the right diet and exercise, you can become your leanest, healthiest, strongest self no matter what your age. You can’t turn back the clock, but these 10 determinants are among your best defenses against aging."

How could I not love that message?

One caveat before I discuss these determinants. Many of them have a genetic component that doesn’t always make them entirely “controllable.” I’m genetically predisposed to osteoporosis, for instance: I’ve lifted heavy for decades, yet I’m still osteopenic.

Likewise, maybe you’ve got a familial history of blood pressure. You do everything correctly yet your doctor always claims you’re borderline hypertensive. Frustrating, right?

But wait. We have an old saying in my profession: Genetics load the gun, but environment pulls the trigger. You can’t control your genes, but you sure as hell can make the best decisions on a day-to-day basis to become strong, lean, and in excellent health at any age.

I’ve seen this time and again at my gym: men and women in their 60s and 70s lifting heavier than their 30-something counterparts. They still enjoy sex, they wake up feeling exuberant and ready to tackle the day, and they exude a contagious optimism.

In other words: quit using age as a pretext to limit yourself.

On to the determinants: exercise plays a huge role in the first five. The ultimate message here is that no matter what your age or present condition, put these determinants in action and you have the capacity to become leaner, stronger, and healthier.

Muscle mass. Those fancy Tanita scales at your doctor or gym can measure muscle mass: the amount of your body’s lean mass (as opposed to fat mass) composed of muscle, bone tissue, and water. According to Biomarkers, two things determine muscle mass: how much you use your muscles and the amount of anabolic hormones your body makes to increase protein synthesis. Here’s the bad news: muscle mass declines with age, and Biomarkers argues the “rate of loss accelerates after age 45.” Yet the authors contend no matter what your current state or age, you can regain muscle mass with hard work and focus. Benefits of increased muscle mass include glucose control and reducing your risk for diabetes, since rather than convert glucose to fat, muscle mass can store more glucose as your back-up fuel glycogen. It’s a win-win: you also look way hotter and feel more confident with more muscle mass.

Strength. My friend Dr. Jade Teta often talks about weight lifting as the fountain of youth, and I couldn’t agree more. Stronger bones and muscles help you look and feel better, reduce your risk for illness, increase your metabolism so you burn more fat, and can even turn back the clock. According to Skyler Tanner, the youngest Superslow™ certified instructor in history, “strength training in the elderly reversed oxidative stress and returned gene expression in 179 genes to a youthful level. It moved them back to about 10 years. Let me repeat that. The genes got 10 years younger. That’s impressive.” No kidding.

Basal metabolic rate (BMR). BMR refers to your energy expenditure when you’re sitting on the couch noshing on Greek yogurt and watching Sex and the City reruns. In other words, this is your resting metabolic rate. Bad news first: your BMR drops about two percent every decade starting at age 20, and like everything else, it continues to decline as you age. Listen up, fad dieters: low-calorie diets can bring BMR to a grinding halt as your body adjusts to the decreased caloric load. Biomarkers also blames decreased muscle as the culprit that crashes BMR as you age. “We feel that older people’s reduced muscle mass is almost wholly responsible for the gradual reduce of their basal metabolic rate,” write Evans and Rosenberg. That also explains why a bodybuilder burns more fat sitting on the couch than sedentary people burn taking a vigorous stroll: more muscle cranks up your BMR. Talk about a two-for-one deal: increase your muscle mass and you also increase your BMR.

Percent body fat. Body fat is that other number on the fancy scales besides lean mass. Simply put: you want your muscle-mass number to be high and body fat to be low. “My doc told me more body fat is normal as I get older,” a 50-something client recently told me. Absolutely correct: body fat percentage increases as you age. Yet people use that excuse to “let themselves go” and go face down in the glazed donuts. Let’s stop accepting normal and buck the conventional wisdom. “If you’re the average middle aged person, your problem is not excess weight so much as it is excess body fat coupled with too little muscle,” [emphasis theirs] write Evans and Rosenberg. Weight resistance coupled with a lower-sugar, high-protein and good fat diet is a tried-and-true formula to reduce body fat no matter what your age.

Aerobic capacity. The word aerobic means “living in air,” which makes sense considering aerobic capacity refers to the maximum amount of oxygen your lungs, heart, and blood vessels can use during a workout. A higher aerobic capacity means increased lung capacity, stamina, and metabolism. Genetics partially determine those levels, but exercise can improve aerobic capacity. One study, in fact, showed high responders could double their aerobic capacity with exercise. I’m a huge fan of high-intensity interval training, or burst training, which improves aerobic capacity and BMR and burns more calories than low-intensity exercise.

Stay tuned next week when I’ll share five more determinants fully within your control to stay lean, muscular, and healthy no matter your age. In the meantime, I want your input: which of the five determinants I discussed this week are you strongest at employing, and which could you improve upon? Share your answers in the comments below or on my Facebook fan page.

Author's Bio: 

Fitness expert and strength coach Jini Cicero, CSCS, teaches intermediate exercisers how to blast through plateaus to create incredible transformations. Are you ready to take your fitness to a whole new level? Find out now! Take Jini's "Are you Ready?" Quiz at www.Jinifit.com. © 2011 Jinifit, Inc.