The Goldilocks Zone

From risk to reward—how much exercise is just right?

Everything in Moderation. It’s one of the hardest pieces of advice to follow. When I enjoy something, I go all in. When that something is wine, or cake, or pasta, I have to work hard to say enough is enough. But when it comes to exercise, what’s the harm?

My husband likes to say I don’t have a half-way point: the turn-around point on a hike when you should start heading back. He’s right—I often end up with a longer return trip than I bargained for. Mostly because I want to see what’s coming next, get to the next trail marker, or just keep enjoying myself. Plus, it’s exercise—it’s good for me.

But longer-than-planned hikes leave me hangry, dehydrated and exhausted by the time I get back. Overdoing it is not good for my body.

Of course, “under-doing” it is just as bad. We know about the dangers of sitting too much and sedentary lifestyles. As we age, doctors prescribe physical activity to prevent bone loss and muscle atrophy—two conditions that make us vulnerable to falls and fractures. We’ve got to use it, or we’ll lose it.

So how do we find the exercise Goldilocks Zone? Let’s look at three ways exercise stresses our body, and how we can find the just right dosage of stress to improve our health.

Neurological stress

The mental work of learning new things and coordinating movement challenges the nervous system. It makes new neurons and new connections between existing neurons. If the nervous system is a highway for information, learning adds more lanes and new roads to the system. It lets more signals run through our bodies via more routes.

Physically, this gives us better control and movement literacy—our ability to move efficiently in many different ways.

Too little: We can lose our movement literacy, forgetting how to move with ease and efficiency. You know how it feels when your foot falls asleep? Your brain isn’t getting any information from your foot (and vice versa), affecting balance and control.

It can also lead to cognitive decline. We all know that crossword puzzles help keep our brains sharp, but physical movement is also important for good brain health, because it uses so many of our neural connections.

Too much: We can overdo it by trying something too complicated: No one learned the Thriller dance in one try (we all spent at least two weeks working on it in the basement, right?). Exercises like the snatch are just as complex as Thriller, but the heavy barbell increases our risk of injury.

We also need to be careful when we’re under mental or emotional stress. Anxiety, relationship stress, performance stress cause our body to tighten up, preventing normal movement. This can put us at higher risk of injury, especially if we’re attempting a heavy or complex exercise.

Just right: To get the right dose of neurological stress try these things.

• New exercises and programs that get more complicated over time.
• Breaking up complicated movement into chunks. Just like we learned Michael Jackson’s choreography one move at a time, work on building mobility, strength and neurological control before attempting big lifts.
• Techniques like slow breathing restore normal movement when we’re under pressure. Think of a basketball player before a free-throw—the first step is always a big deep breath.

Mechanical exercise stress

This is the wear and tear on muscles, connective tissue, and bones. Mechanical stress tears muscle fibers, stimulates muscle growth, makes changes in our connective tissue and triggers bone cells to release calcium and collagen to strengthen bones.

Too little: A lack of mechanical stress can leave us too weak and tight for many daily tasks—opening jars, lugging bags through the airport, or yard work. The weaker and less mobile we feel, the fewer resistance tasks we’ll want to do, so we’ll get even weaker.

Mechanical stress also pumps fluids around our body. Connective tissue in particular needs exercise to squeeze water into it. Without this pumping, connective tissue dehydrates, and can tear more easily.

Too much: More mechanical stress, more problems. We often call this overtraining and it can include:

• elevated stress hormones
• connective tissue injury
• repetitive stress injuries
• adrenal fatigue
• amenorrhea in women
• rhabdomyolysis

Just right: It’s a myth that exercise only “works” if we’re in agony the next day. To get the dose just right, choose a program that builds up resistance gradually. Trying different kinds of exercise (also called variability training) challenges the body in many ways—lowering risk of overuse injury.

Metabolic exercise stress

We often think of our metabolism as a furnace burning energy, but it’s more like a wood stove, gas furnace and electric heater put together. It uses different fuels at different times. Metabolic training helps our body become more efficient at using the different fuels, enabling us to work harder and faster for longer.

Too little: Without enough metabolic stress, we become inefficient at burning energy and transporting oxygen around the body. This contributes to

• difficulty losing weight
• increased risk of cardiovascular disease
• low energy, easily tired
• low immune function

Too much: Whether you love spin class or water aerobics, too much of one type of metabolic stress wears on the body. This can result in adrenal fatigue, sore knees and the other symptoms of overtraining listed above.

Just right: Mixing up the intensity of training is one of the best ways to keep the dose manageable. Try alternating low-intensity with high-intensity days to get it just right for your metabolic health!

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