Younger Next Year
Crowley, Chris; Lodge, Henry S.
Citation (APA): Crowley, C., & Lodge, H. S. (2019). Younger Next Year: Live Strong, Fit, Sexy, and Smart—Until You're 80 and Beyond [Kindle iOS version]. Retrieved from Amazon.com
The Biology of Strength Training
Strength training is primarily about your muscles’ ability to deliver power, which, surprisingly, has as much to do with a special form of neural coordination as actual strength.
Strength training causes muscle growth, and that’s important, but it’s the hidden increase in coordination that changes your physical life. This is not eye-hand coordination; it’s the coordination of fine muscle detail through the elaborate networks of nerves that link your brain and body.
Generally, we aren’t aware of nerve decay as we get older, but it’s the main reason our joints wear out, our muscles get sloppy, and our ability to be physically alert and powerful begins to fade.
And it is reversible with strength training.
You have millions of potential neural networks in your body, and you shift between them with each step. Your body grows and your brain learns the tiniest amount from each one. They have to, because C-6 is in the background, helping them to forget all this, just a little bit, every day.
The trouble comes when your muscles, brain connections, and the controlling spinal reflex arcs get sloppy and weak from years of a relatively sedentary existence. The casual motion of daily life is not enough to turn on the C-10 of growth. Pushing your chair back from the desk is an insultingly trivial task for your physical brain, and over the decades large parts of it have deliberately gone to sleep in protest.
Remember the threshold for C-10? It takes a critical amount of effort to cross that threshold and secrete enough C-6 to trigger the production of C-10. Below that threshold, all you have is the C-6 of chronic decay. You need to do strength training to cross that threshold for power and coordination, to get C-10 into your neural networks, into the meat of your muscles, into your joints, and into your tendons.
Aerobic exercise takes you across the threshold for endurance, circulation, and longevity, but you need strength training for power and neural coordination.
A single step on level ground doesn’t turn on C-10. Nor does climbing a few stairs. But climbing stairs until you feel your legs burn will turn on C-10. Lifting weights until you can’t lift them anymore . . . that really turns on C-10.
Strength training creates an intimate connection between your body and your brain. It’s easiest to look at this from the top down, starting with your brain and nervous system. Your physical brain—the remarkably complex, physical brain—integrates the millions of messages coming up from your body and coordinates them with all the impulses it’s sending down to move your muscles against resistance. The neural impulses to create coordination and power blaze a trail through your neural circuits. Each time you use them, you directly strengthen the balance, power, and muscular coordination centers of the physical brain. And the trail gets broader, smoother, and faster.
Consistent strength training can change all that by bringing your neural connections out of hibernation.
They will fatigue, and the fatigue will damage them. Taking them to fatigue is what turns on the surge of C-6—the good stress of exercise that turns on C-10.
By the way, this is why you have to sweat when you do aerobic exercise; at low levels of demand, your endurance cells alternate too much to get fatigued. This is also why you have to push to the point of muscle fatigue with weights—to that burning feeling in your muscles that most of us hate and would skip if it were up to us.
Unlike endurance units, which recover from aerobic exercise overnight, your strength units need to enter a forty-eight-hour repair cycle. Two days a week of strength training is enough. Three days is the maximum.
You do not build new muscle cells with strength training; in fact, you continue to slowly lose them as you age, regardless. What you do instead is build new muscle mass inside each remaining cell: the protein, the substance—in short, the red meat. And the potential growth in those remaining cells is extraordinary: certainly enough to keep you strong and fit for the rest of your long life. Put another way, you can lose half your muscle cells over the course of your life, lose half your peak fitness, and still end up stronger at eighty than you were at twenty. Besides, when were you ever at your peak fitness? No one but Olympic athletes and Navy SEALS ever get there.
So the signals to your brain from strength training are loud and important: priority news. And they create growth—first in the signaling pathways themselves, blazing that direct trail through the forest of neural networks, and second in the muscles, tendons, ligaments, and joints directly. With this growth comes a new integration between your brain and body. They have always been fused; we just forgot it. This is how you reconnect them. It’s a literal, physical reconnection: nerve fibers you can see under the microscope, brain chemistry you can see on MRI scans, reaction time you can measure in the lab. It’s skiing better, feeling stronger, feeling better. It’s also not falling down. As Chris mentioned, you’re much more likely to fall as you get older unless you stay in great shape. This is a major public health issue, because you also fall harder and do more harm to yourself. C-6—hiss and, literally, bump in the night. Falls have been carefully studied, and it turns out you do not stumble any more often as you age; in other words, you catch your toe just as often as you did at twenty. But instead of easily recovering your balance, you’re more likely to hit the pavement.
Strength training gives you the power to fight gravity and stay on your feet. Even if you do take a fall, having strong reflexes and powerful muscles changes it from a head-on collision to a softer impact. Like the crumple zones in your car, your coordinated muscle action softens the blow. You will fall less if you are strong, and you will fall better, dramatically lowering your odds of serious injury.
Falls aside, strength training lowers your chance of injury with all forms of exercise—in large part by speeding up your proprioceptive reflexes, but also by strengthening your tendons, ligaments, and joints. Tendons and ligaments are living tissue, but they grow more slowly as you get older. Pulling hard on a tendon strengthens the nerve connections and makes the tendon grow a bit farther into the bone, strengthening the attachment and rendering it more resistant to injury.
Whatever you decide to do, do it. Strength training is critical to the rest of your life, and you can start at any age. Sedentary, seventy-year-old men double their leg strength with three months of weight training. Sadly, men do strength training even less than aerobic exercise. Only 10 percent of Americans over sixty-five even claim to be doing any form of regular strength training. That’s appalling. It should be clear by now that everyone—certainly everyone over fifty—should be doing real strength training two days a week. You can do a quick routine in half an hour, or spend an hour or more if you get into it, but don’t skip it. Aerobic exercise saves your life; strength training makes it worth living.
The Biology of Growth and Decay: Things That Go Bump in the Night
Cytokine-6, or C-6 for short, is the master chemical for inflammation (decay), and cytokine-10, or C-10, is the master chemical for repair and growth. C-6 is produced in both the muscle cells and the bloodstream in response to exercise, and C-10 is produced in response to C-6. This is your body’s brilliant mechanism for coupling decay and growth. C-6 actually triggers the production of C-10. Decay triggers growth.
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