"I would love to live like a river flows, carried by the surprise of its own unfolding.”
John O'Donohue
My first foray into group fitness was as an Indoor Cycling instructor. This was long before Peloton, and several years before bikes used devices that measured wattage, pedal speed, heart rate, or calories. These bikes were low tech—the intensity of the workout was dependent on a rider’s cadence and a knob on the handlebars that changed the position of a clamp suspended over the flywheel. Turn the knob to the right and the clamp squeezed the wheel, making it harder to pedal; turn it to the left and tension was released. Too little resistance and the participants bounced around on the saddle, too much and the rider would grind the gears and struggle to breathe. Those clamps wore out regularly and were rarely replaced, so instructors had to finesse how to cue intensity: a turn of the dial on one bike would take a person on a climb up Mt. Everest while on another bike the same turn of the dial would have a rider coasting downhill.
I got into group instruction reluctantly. As a personal trainer working in a gym, I was surprised by how little people understood cardiovascular training. Most people were not clear about the difference between physical activity and exercise; many thought that simply getting on the treadmill counted as exercise, regardless of how fast the belt was moving. This was at a time long before wearables such as FitBit and Apple watches, which offer more objectivity and specific measurements. I approached Indoor Cycling as an opportunity to educate, a way to coach people about intensity using a metric called the Borg Rating of Perceived Exertion. This scale was beautifully simple: intensity could be measured by noticing how much effort it took to breathe. If you could easily talk while working out, then intensity was low, whereas breathlessness was correlated with higher intensity levels. While this may seem archaic in our age of wearables, a large body of research has shown that it correlates with actual heart rates. Armed with my knowledge of the Borg scale and CD’s full of electronic music, I started out on my mission to educate everyone on the difference between movement, physical activity, and exercise.
It comes as no surprise that most people weren’t interested. Many participants thought the Borg scale had something to do with Star Trek. There were groups who were enthusiastic and thought the scale was helpful. One class was particularly disinterested. They despised the music, preferring classic rock, Village People, Michael Jackson, Pink—anything they could sing along with while twirling their towels. Week after week, I watched this group with dismay as they bounced in the saddle, laughing, singing, and talking to their friends. They were there for the party, and my messages of “if you can sing loudly or carry on a conversation, you aren’t working very hard” did not resonate. Still, I persisted with my cues of talking, breathing, and subjectively measuring intensity.
Everything changed for this group when we got new bikes, a higher tech model that measured power, cadence, and provided an estimation of calories. I clearly remember the first day I taught that party loving group on those bikes. I was excited, finally able to cue more precisely, using the bike’s measurements of wattage and cadence to guide effort. But that first class on the new bikes did not turn out as I anticipated. The screen’s information immediately dampened the party atmosphere. No one was singing and very few were talking as their eyes stayed riveted to the calories on the screen. Very few were singing or talking while they tracked caloric expenditures that barely broke 200 kcal at the end of class. They seemed crushed. On the way out, one of them complained that she thought indoor cycling burned 700 kcal, yet she didn’t even get to 300 kcal. Although deep inside I was shouting “I told you!”, a big part of me felt her disillusionment. It made me wonder what may have been lost. Those singing, cheering towel twirlers may not have been working very hard, but they clearly enjoyed the class, coming back week after week full of enthusiasm. Subsequent classes on the new bikes were a more solemn affair. I got my wish—those bikes gave information that provided clear evidence of effort, but at what cost? Did the measurements help or simply suck the joy and fun out of movement?
Before the dawn of devices, the use of perceived exertion was a simple, organic way of connecting with the body and noticing the changes that occur when we start moving. Due to its planned nature, exercise is an intentional way of stressing the body, a specific chunk of time during which we are aware of a number of intense sensations—uncomfortable breathing, sweating, muscle fatigue--and learn to stay with the moment and push through. Although devices can measure changes in our heart rate, perceived exertion brings us in close contact with our senses, requiring us to tune in to subtle cues that can’t be measured by a watch. Devices can tell us what is changing, but perceived exertion is a visceral experience that connects us with our physical being, offering a window into how we are responding. I recently heard a cardiologist suggest that we stop wearing devices while exercising, stating they were decreasing our fitness by distracting us with measurements of calories. There is much more to be gained from exercise than caloric expenditure—the self-knowledge that comes when we tune into the deep recesses of our body, noticing our breath, sensing fatigue and discomfort, tuning into our thoughts without reacting, consciously deciding to stay with it a bit longer. This is mindfulness of a different sort, one that builds our physical as well as emotional resilience.
The deeper shifts that exercise can create in self-awareness and resilience are buried beneath our obsession with its role in weight loss. Attempts at losing weight are framed within an oversimplified equation of “calories in, calories out”, with exercise, physical activity, and movement acting as the force that tips the scales in favor of energy depletion. The use of activity tracking devices has only strengthened this piggy bank approach to weight loss. Our devices measure calories expended from standing, steps, and exercise that we plug into the energy equation we use to calculate how much food to eat. Unfortunately, this approach is flawed in many ways, as numerous factors impact energy expenditure, not all of which can be accurately measured by devices. And a focus on “calories out” gives exercise more attention than it deserves in the total picture of our health, obscuring the role movement and physical activity also play in our lives.
There are many factors that influence how we balance our energy needs. Our basal metabolic rate (BMR) is the energy we expend just being alive, when we are completely at rest, accounting for about 60% of our total daily energy needs. This number varies widely between people, influenced by a number of factors including a person’s level of lean muscle, breathing rate, hormonal status, medications, and emotional state. Eating and digestion require energy, measured as the thermic effect of food (TEF). Before you decide to burn calories by eating chips and salsa, keep in mind TEF accounts only for 10 -15% of our daily energy expenditure. The rest of our energy needs come from our activities, namely our daily movements and general physical activity, from standing to steps to an episode of exercise.
Beyond resting, our daily activity level accounts for the variability in energy expenditures observed between individuals. For most of us the role exercise plays in our overall energy balance equation is very small, if not negligible. Even in avid exercisers, the bulk of the daily energy expenditure beyond our BMR comes from what is known as non-exercise activity thermogenesis, or NEAT. This is the energy we expend as part of being a vibrant, interactive human, all the activity we use to get through daily life. NEAT includes the energy needs of our occupation and what we do for leisure, as well as all the sitting, standing, walking, talking, fidgeting and toe-tapping that happens in a day. Given the enormous variety of movements each of us make, NEAT is challenging to accurately measure and its role in maintaining energy balance is incredibly difficult to study. Unlike a bout of exercise which is planned and can be measured, NEAT reflects the subtle energy we expend as we go through life. It is strongly influenced by our environment, culture, biology, and perhaps even gender, with small changes having a significant impact over time.
Although the exact mechanisms involved in how our body regulates the energy used for daily living is still unclear, understanding the role of NEAT helps put the role of exercise in perspective. There is evidence that the real benefits of exercise may not be in its role in weight loss. Research has shown that our bodies seem to have a certain set point of desired energy storage, with our metabolism acting as a type of biological safe that guards against our attempts to withdraw too much. Research shows that we tend to burn more calories when we start an exercise program but, at a certain point, our energy expenditure plateaus, even when our activity level continues to increase. There is also evidence that intense exercise can create a decrease in metabolism if a person is dieting, which may be a reflection of the body’s attempt to preserve energy stores.
Research into how our bodies regulate energy is challenging our long-held belief that more movement creates a greater calorie deficit. The Hadza of Tanzania are one of the last remaining communities in the world that still forage and hunt for food. They are extremely active, walking up to twice as far as most Westerners in one day and have a remarkably low incidence of chronic diseases. Scientists tracked the caloric expenditure of 30 Hadzas and found that they did not burn an extraordinary number of calories even though they were significantly more active than an average urbanized individual. Interestingly, their total daily caloric expenditure stayed remarkably stable, regardless of how much they walked in a given day. This phenomenon is also observed in the wild. For example, monkeys in their natural habitat do not burn any more calories than those living in zoos, where they move less. Longitudinal research shows that Westerners are getting heavier even though our rates of exercise have increased by more than 50% since 1988. It seems that the energy we spend moving does fit neatly into our “calories in, calories out” equation.
This is not to say that movement, physical activity, and exercise do not play a role in our health—they are essential, with each playing a significant role in our overall well-being. Most likely their impact can be measured in ways that go beyond calorie burning. We know that cardiovascular training is essential for heart health and moderate physical activity significantly improves insulin sensitivity. Strong muscles create strong bones, and regular movement keeps joints lubricated. There are numerous benefits to staying active; focusing only on physical activity as a way to lose weight is a gross oversimplification of its importance to our health.
What our devices cannot measure is how movement is an essential part of being human. Ours is a species that is built to move, climb, run, twist, dance, wiggle, and fidget. All our physiological systems are designed to respond positively to physical activity. We are built with bones, muscles, tendons, and ligaments--an elegant collection of levers and pulleys that allow us to move freely through space. Sweating, muscle endurance, and the ability to store fat are what allowed us to become successful hunters: most animals are much faster than humans, but we outlasted our prey, who overheated and ran out of energy. And the range of information we receive from our sensory, kinesthetic, and perceptual processes when we move opens us to all the wonders of our environment, encouraging us to explore the richness of life while we travel through it.
If future research shrinks the role physical activity and exercise plays in the energy equation, will we be able to let go of our obsession with calories? Can we stop evaluating every movement for its weight loss benefits and end our obsession with counting steps or the minutes we spend standing? Is it possible to stop tracking our every move and simply reclaim the joy of physical activity? I think of the towel twirling participants in my cycling classes and wonder if perhaps they understood something about exercise that can't be measured on a device or the Borg scale—that moving just feels good and being in our body is, by itself, a reason to celebrate.
Commentaires