We all know that exercise is supposed to be good for us, but only about 20 percent of people move regularly. Those of us who exercise may be drawn into popular workout trends, like CrossFit or hopping on the elliptical for 60 minutes, but in my research, I’ve learned that overly aggressive high-intensity interval training (HIIT) or chronic cardio may not be the smartest way to look and feel our best.
Overexercising releases two key hormones: CRH and cortisol, both related to the stress response. CRH increases the permeability (or leakiness) of the intestinal wall as well as the permeability of the lungs, skin, and blood-brain barrier. Cortisol levels rise with rigorous exercise, such as running, which may cause too much wear and tear and accelerate aging. High cortisol also alters tight junctions between cells such that small harmful substances may pass through the barrier. Additionally, high cortisol reduces gut motility, blocks digestion, blunts blood flow to the gut, and lessens mucus production, an important immune function. For people with dysregulation of the control system for CRH and cortisol, the hypothalamic-pituitary-adrenal axis, you may need to back off your workouts in order to fully heal, as part of a comprehensive functional medicine protocol. Even elite athletes get help from several workarounds, such as by supplementing with probiotics, omega-3s, and vitamin C; however, moderation may be your best bet.
Sometimes weight loss is counterintuitive.
Personally, I love to run. But at age 35, I discovered that my serum cortisol was three times what it should be in the morning. Intense exercise raises cortisol even further, which was causing several downstream problems for me: weight gain, short telomeres, blood sugar problems, knee pain, leaky gut, fatigue, and I was stuck in a pattern of revving my body too much with my workouts. When I backed down on running mileage each week and added more adaptive exercise like yoga, Pilates, gyrotonics, and barre class, my HPA healed and I got a better response to exercise. I lost weight. My joints were happier. My telomeres were better.
How much exercise is too much?
On the flip side, inactivity and sitting too much are not good for you either. In particular, sitting too much increases your risk of diabetes and heart disease, plus it makes your hip flexors tight, which can contribute to low back pain and stiffness. Just like Icarus’s mandate not to fly too high or too low, there’s a middle ground that provides the greatest longevity benefits. When you don’t exercise enough, it can harm your immune system, reduce your stress resilience, and dysregulate your circadian rhythm. When you exercise too much—too long, too intensely, too frequently, and without sufficient recovery—you may cause problems to your stress-response system, leading to immune problems, injury, and a leaky gut.
In summary, like many things when it comes to health, exercise has a U-shaped association, meaning that moderate amounts are optimal but low or high levels can be harmful. The general recommendation I subscribe to is to exercise 20 to 30 minutes per day four times per week.
What kind of exercise is ideal? I call it targeted exercise—burst training and adaptive workouts, like Pilates, barre, or yoga. These will stabilize cortisol levels, help with weight loss, and keep your muscles toned.
Here are my basic tenets for optimal exercise:
1. Move less but more often.
Aim for bursts of movement that fold into your natural rhythm. Do a one-minute burst of enthusiastic dancing after you wake up. Invest in a stand-up or treadmill desk, and use it daily (I’ve walked more than 2,000 miles on mine while writing my newest book, Younger). Practice heel lifts while you chat on the phone or stand in line at the grocery store. Perform 12 push-ups after going to the bathroom. The point is to incorporate moments of movement rather than only forced discipline that’s devoid of pleasure. Start small by adding one to five minutes of new movement to your routine each day during this week.
In the morning or before 1 p.m. two to three times per week, do an exercise where you focus on fast-twitch muscle bursts. Cave men and women tended to exercise in bursts: a quick run to the river to fetch water and carry a bucket back to the tribe, a jog with a sick infant to a neighbor’s dwelling for help. Our bodies perform well with burst training and then recover at a moderate intensity for one to three minutes. Protocols vary; use one that makes the most sense for you. Burst training can be applied to cardio exercise (e.g., intermittently sprinting on a trail alternating with a jog) or weight lifting (lifting a weight, such as with a biceps curl, as many times as you can with good form for one minute, followed bya one minute of rest). Other examples:
Walking three minutes fast (approximately 6 or 7 on an exertion scale from 1 to 10, or the green zone of 70 to 80 percent of your maximal exertion), then alternating with three minutes at a normal pace.
Chi running with sprint intervals or regular running with 30-second sprints.
High-intensity interval training (HIIT) with weights or cardio (stationary bike, elliptical, treadmill), alternating two to three minutes at a moderate pace with one to two minutes at your maximal pace.
3. After burst training, get a recovery drink.
It increases muscle mass and keeps the mTOR gene turned off. This is only for people who perform burst training (at least four to five bursts per session) or vigorous training of at least 30 minutes’ duration. What’s proven to work is a combination of macronutrients high in protein and carbohydrates, even in older folks. But drink it within 45 minutes of your workout; immediately after your workout is ideal. Avoid sugar. The best formula is somewhere between 10 to 40 grams protein (I suggest 20 grams for the average woman), 7 grams or more of carbohydrate (I suggest 10 to 20 grams for women), and up to 3 grams of fat.
4. Get enough sleep!
For optimal weight loss and energy levels, I recommend getting to sleep by 10 p.m. and sleeping seven to eight and a half hours. If you’re not getting enough sleep, try to aim for a nap if you’re feeling tired. This is so important for your body to produce enough growth hormone and repair itself after a workout. Sleep cleanses toxins and rejuvenates our cells in profound ways.
5. Schedule and take sufficient time for recovery.
Exercise affects your hormones, and adequate recovery keeps your hormone profile in balance so that your adrenals don’t get fried and take your sex hormones and thyroid down with them. It’s about galvanizing the full arsenal of repair mechanisms in your body: stitching together microtears in your muscles, ironing out the fascia when it gets jangled, reinvigorating mitochondria so you’re brimming with energy rather than feeling worn down or burned out. The official definition of recovery is your ability to repair tissues damaged during exercise, rebuild muscles, provide functional restoration of the body such that you prevent injury, rejuvenate emotionally and psychologically, and feel prepared to meet or exceed performance the next time.
Previously, I’d chronically limit my recovery, and I wonder if the same is true for you. If you exercise five days per week, then at its simplest, recovery means 24 hours between bouts of exercise and two rest days. If you exercise four days per week, you take three rest days. For me, my weekends are my harder exercise days, and Mondays and Fridays are my rest days.
Recovery allows you to heal from oxidative stress, which you may or may not feel as fatigue and muscle soreness. But recovery runs deeper; in a larger sense, it’s about paying attention to the messages of your cells, your inner voice, and not letting ego run the show. My ego tells me to overexercise and under-recover, which is a recipe for injury, spasm, and weak mitochondria. Don’t let that happen to you. Recovery is also about tuning into the messages your body is sending you—the ache in your left sacroiliac joint or the twinge in your right knee. Ironically, I taught myself to ignore those signals during medical residency when self-care came last, but I’ve been learning to hear and feel those sacred messages from my body in my recovery.
Even if you haven’t been exercising consistently, you still have the chance to get on track. Choose an exercise that you enjoy and break a sweat four times this week. As we know, exercise combats stress, helps us sleep better, and raises endorphins. It’s good for your sleep, weight, stress, genes, and mind. Even walking counts! Ideally, start to notice your heart rate at rest and while exercising, and after paying close attention to your body, weight, and mood, you’ll sort out the perfect route toward feeling and looking your best.