FRESH SCIENCE for Clinicians

News about basic science of interest and relevance for cancer clinicians

Tuesday, August 16, 2011

A Treadmill Desk Puts Science into Practice


©Julie Caine, 2011

Last month I ditched my desk chair for a pair of sneakers. Now, instead of coming to the office and sitting for numerous hours each day, I walk on a treadmill or stand while reading, interviewing researchers, and writing news stories.


I’m walking 1.2 mph as I type this blog post.


The extra movement isn’t going to win me any tournaments of fitness, but at least I don’t get really sleepy at noontime, my back doesn’t bother me, and I’m burning a few more calories during the day.


In fact, over the course of 17 work days, I’ve walked 51 miles and burned approximately 4700 calories. Like I said, my treadmill desk isn’t going to replace the need for vigorous exercise, but it definitely fits into the better-than-nothing category.


Exercise Reduces Cancer Risk

I’ve been writing about cancer for more than 10 years, so when I first heard about treadmill desks, I wondered whether this low-intensity, long-duration exercise might impact disease risk.


Numerous observational studies show a strong association between moderate-to-vigorous exercise and reduced risk of a variety of cancers and cancer recurrence. For example, I reported in 2009 on studies by Jeffrey Meyerhardt, MD, MPH, Assistant Professor of Medicine at Brigham and Women's Hospital and Dana-Farber Cancer Institute, in which people who walked just six hours per week at a moderate pace of 3 to 4 mph had a 50% lower risk of colon cancer recurrence than people who had a sedentary lifestyle.


However, my speed varies between 0.9 and 1.5 miles per hour – above that I can’t really concentrate on my work. So a key question is whether the slow pace of walking at a treadmill desk can mimic the effects of moderate paced walking or more vigorous exercise.


There is definitely a possibility,” said Kerry S. Courneya, PhD, Professor and Canada Research Chair in Physical Activity and Cancer in the Department of Physical Education and Recreation at the University of Alberta in Edmonton, who is leading the first randomized study on the effects of exercise and colorectal cancer recurrence. “There is a growing body of research on sedentary behavior and how avoiding sedentary behavior may also be associated with cancer risk, independent of the high intensity exercise we encourage people to do. So I think from that perspective it makes sense”


However, the randomized controlled trials (examples here and here) that have shown changes in cancer-associated biomarkers, including sex hormones, insulin, insulin-like growth factor, and immune markers, have all included high-intensity, structured exercise programs.


“That is not to say the light activity won’t have the same effect,” Dr. Courneya continued. “But we don’t have the same randomized controlled trials where people are randomized to this very light, long duration activity compared to sedentary behavior.”


Looking at the question from the obesity angle though, both Dr. Courneya and Kathryn H. Schmitz, PhD, MPH, Associate Professor at the University of Pennsylvania School of Medicine, agree that burning a few extra calories is a good thing in terms of cancer prevention and overall health.


“There has been a small amount of work – most of it by James Levine at the Mayo Clinic [examples here and here] – showing that if you set up a treadmill desk and walk while you are working, as opposed to just standing, it may actually be useful for preventing the onset of obesity, and perhaps for weight loss and weight control,” Dr. Schmitz said.


Some estimates suggest that even just standing might increase the number of calories one burns at work, though her own research didn’t bear that out. She measured the respiratory gasses, the gold standard for estimating caloric expenditure, of healthy volunteers who stood or sat at a desk and typed on a computer. “There was no difference in the energy expenditure. Not one bit,” she said.


As for the difference between standing and walking in an ergonomic sense, both researchers agreed that our bodies are designed to be moving. So with the right set-up, the low intensity walking should be safe and low risk.


Cost Can be a Barrier

Dr. Schmitz does caution that setting up a treadmill desk can be expensive. Ideally, she thinks people should have a desk that easily adjusts to both a standing and sitting height.


“There are going to be days when you don’t feel like walking or standing,” she said. “So you want something that will go up and down easily. And that desk costs about 10 times what other desks cost, but it goes up and down with a touch of a button.”


Personally, I opted for a cheaper, less flexible set-up because I wasn’t absolutely sure this was going to work. I bought a small end table and put it on top of my larger desk, which adjusts in height (though not easily). That seems to have worked out fine for now, and a quick Internet search shows that a lot of other people are rigging up less expensive systems as well.


Reading, Writing, but Not Weaving Stories

Before I started walking at work, I wondered how it might affect my productivity. So far, it’s been pretty good, though there are things I can’t do while walking. For example, my reading comprehension is seemingly normal when I’m walking, but I lack the coordination to hand-write notes on a journal paper while walking.


Typing is no problem, though I’m really glad I have a spell check. And if I know where a story is going, writing is no problem. Creating a story line, however, is more difficult. To put complex ideas in order, I seem to need to stand still or sit down. Once they are in place, then I can go back to walking as I write the remaining parts of the story.


My experience seems to be in line with the studies that have been done on testing productivity at treadmill desks. In one study, investigators found that 20 individuals were slower at mouse clicking and drag-and-drop tasks, slower at typing, and had lower math scores while walking compared with sitting. They showed no difference in attention and processing speed or reading comprehension, though.


Interestingly, the participants were not given any time to get used to walking and working before the test, so I wonder if they might have overcome some of the deficits.


The results were similar in a second study in which investigators compared typing and mouse performance in 30 participants while sitting, standing, walking, and pedaling on a stationary bike. They too found that typing speed and accuracy were less affected than mouse tasks.


For me, I’ve decided that a jumpy mouse cursor is worth the trade for getting a little bit of exercise at work.


As Dr. Courneya summed it up: “Anything is better than nothing. A primary focus of many of the exercise guidelines, including for cancer survivors, is to avoid inactivity. That means standing is better than sitting, moving is better than standing, and moving faster is better than moving slower.”


The fast moving, though, will have to wait until after work.


(Hat tip: Earlier this summer, I received a National Media Award from the American Society of Colon & Rectal Surgeons for my article, "A Step (or Leap, or Jump or Stretch) in the Right Direction," published in CR Magazine, which looked at exercise and colon cancer recurrence. I used the award money to purchase my treadmill. Thank you ASCRS!)