After about age 25, our Resting Metabolic Rate (RMR), which is the amount of energy our body uses in calories at rest in a 24-hour period for all metabolic functions, starts to decline at the rate of 2-4 percent per decade.
If you started out with an RMR of 1500 at 25, by 55 you’re down to about 1300 (and this doesn’t account for how much you may have sabotaged it with all the calorie-restricting diets you did over the years).
Even those of us who continued to exercise and maintain a healthy diet are noticing a little extra fat around the middle; it’s harder to gain muscle, and we are not quite as fast as we used to be. Those are all things that we see, feel and accept as part of the aging process.
As I write this I am two days from turning 50 and I understand that a 50-year-old body is not the same metabolically as a 25-year-old one. Although I have been on this earth for 50 years, this metabolic decline does not have to match my chronological age.
Just because I’m 50 doesn’t mean that “biologically” I’m fifty.
On a cellular level, which is what determines your health and “true age,” you can be functioning at a much younger or much older age. Your true age is primarily determined by your lifestyle choices, with the main influencers being fitness level, quality of nutrition, stress level and sleep.
The way I see it, how you exercise and how you eat are the actions that you can best control. Life stressors are not always predictable, therefore hard to control or strategize for. Not that we don’t choose how to respond to everything. Sometimes navigating unknown emotional territory is hard. As I am the contributing fitness writer, I’ll address the exercise factor.
No matter what else we do, as we age our fitness level is going to decrease. Some studies have shown that even those who exercise regularly will have a 10% per decade decline in VO2max, despite activity level, and we already know we are losing lean tissue. But research also shows that the more exercise we get, the less our cells age.
According to a study done by Larry Tucker, professor of exercise science at Brigham Young University, of close to 6,000 adults found that those who exercised had longer telomere length. Telomeres are the end caps on chromosomes and are markers of aging and overall health. When a cell replicates, a little bit of the telomere is lost, so they shorten with age as a sign of cell deterioration.
“We know that, in general, people with shorter telomeres die sooner and are more likely to develop many of our chronic diseases,” Tucker said. “It’s not perfect, but it’s a very good index of biological aging.”
His study found that people who did vigorous exercise had telomeres that signaled about seven fewer years of biological aging, compared to people who did moderate levels of activity.
Our bodies are meant to move. We even have three different energy pathways to “make energy” for different movement demands. Each pathway, or system, has different physiological and metabolic effects.
When it comes to cellular aging, preserving muscle and our metabolism, research has shown that specific types of exercise are more effective than others. High Intensity Interval Training (HIIT) proves to have the most significant effect on cellular function, mitochondrial (the power house of the cell) size, number and ability to generate energy, insulin sensitivity, maximum volume of oxygen consumed (VO2 Max), improved bone mineral density, reduced blood pressure (if elevated), reduction in body fat, cholesterol and triglyceride levels, increase glucose metabolism… I could go on, but I’m pretty sure I’ve hit enough things that are important to you.
Don’t worry, this doesn’t require sprints or coming to my Insanity Live class. You can do intervals on a stationary bike, a treadmill, or trudging up a hill. Basically anything that will get you huffing and puffing, is sucking up your oxygen, is working your whole body, and you even feel some burning in your muscles.
Although HIIT can quite literally give you back years of life and vigor, it seems that it needs to be complemented with resistance training in order to preserve muscle tissue. There is no way you can maintain your metabolism or keep the muscle tissue you have as you age without resistance training. Period. In my article, “Positive impact on lean muscle,” in the August 2015 issue of this magazine, I highlight several approaches to designing a training plan.
Start to look at your exercise and eating as simply providing information, or instructions, to your body. Are you telling your body to be strong, independent, alert and energetic; stable, able to handle and overcome challenges, and to be good at processing nutrients and use them for replenishment, healing, repair, growth, resynthesis, and proper storage?
Or will you be telling your body to be weak, fragile, unable to handle stress, lethargic and confused, unable to process and absorb nutrients properly and store them inefficiently? And who wants to live longer if you’re just living sick longer?
Your body is obedient and will learn by doing what it is told. But it is also forgetful, so CONSISTENCY IS THE KEY.