Are you sitting down? Stand up! Move around! You train your whole body with dedication and persistence—don’t let any of that hard work go to waste by being immobile for long periods of time during the day. The consequences for your recovery from training are surprisingly large if you are sedentary for even a short period of time.
In just 20 minutes of sitting, your blood sugar and insulin can get out of whack. A little longer, and gene activity decreases, which directly influences protein synthesis and the clearance of waste from cells. This means recovery from training is slowed, and it leads to greater oxidative stress and inflammation.
Even though most trainers and coaches are far from sedentary, lack of movement when doing desk work, on days off, or while watching TV has drastic effects for health and body composition. In one study, for every hour Australians spent watching TV, they decreased their lifespan by 22 minutes! If the average man watched no TV in his adult life, he could increase his lifespan by almost 2 years.
What can you do about all this bad news about being sedentary? The obvious solution is to get rid of your TV and make a conscious effort to minimize leisure screen time as much as possible, and you need the specifics about what happens when you are immobile for lengthy periods. First, blood flow decreases as does the rate of tissue repair. Next, the body’s metabolism slows, production of enzymes needed for energy use drop, and the body shifts into fat storage. All this causes oxidative stress, leading to inflammation.
Naturally, this will directly affect your muscle cells, as seen by a recent study in the European Journal of Applied Physiology. Researchers had a group of young office workers perform a one-hour typing task, including work with a mouse, and found that that blood flow and oxygen saturation of the entire trapezius muscle decreased dramatically. In participants who had previous pain in the shoulders or neck, there was a much larger drop in blood flow and oxygen saturation than in participants who had not reported pain. The greatest decrease in blood flow occurred during the initial 30 minutes of the typing task at which point it continued to drop, but much more slowly.
The health implications of less blood flow and oxygen getting to the muscles are substantial, especially if you become immobile after hard training. For example, if you train before going to work at a desk job, you will probably have left over lactate and other waste products in your blood from training, and these will not be cleared efficiently. This leads to delayed recovery and oxidative stress. To combat this, do a cool down to help clear waste and lactate after your workout, especially if you are going to be sedentary after your workout. Other strategies for countering the ills of immobility include the following:
• Take a pause from desk work every 20 minutes and stand up. Do arm circles and move your legs—do knee grabs for instance. The pause doesn’t have to be long—a recent study showed that both an active and a passive pause from computer work improves muscle oxygenation but the active pause is most effective.
• Get up and walk as often as possible—certainly every hour. The longer the walk the better, but even getting water, coffee, or walking to speak to a colleague will improve blood flow. In addition, doing just a two-minute walk every hour has been shown to maintain stable blood sugar levels in office workers who normally sat for seven hours, whereas their blood sugar and insulin were all over the chart when they stayed seated for most of that time.
• Get an adjustable desk and stand during work—one study found that workers who stood all day burned hundreds more calories than when they sat for the same period of time.
• Longer walks and taking the stairs is even better for your muscles and metabolism.
• Consider training at lunch or at least doing a vigorous walk.
• For all the trainers and coaches out there who don’t have much desk time during the day, try not to be sedentary for long periods on your days off or at night. Obviously, rest is important, but opt for active rest when possible and minimize screen time.
• Get rid of your TV—your brain will work better, you’ll sleep better, and you’ll be more productive.
Cagnie, B., Dhooge, F., et al. Changes in Microcirculation of the Trapezius Muscle During a Prolonged Computer Task. European Journal of Applied Physiology. 2012. 112, 3305-3312.
Reich, K., Chen, Y., et al. Forty-Eight Hours of Unloading and 24 H of Reloading Lead to Changes in Global Gene Expression Patterns Related to Ubiquitination and Oxidative Stress in Humans. Journal of Applied Physiology. 2012. 109(5), 14041415.
Matthews, C., George, S., et al. Amount of Time Spent in Sedentary Behaviors and Cause-Specific Mortality in U.S. adults. American Journal of Clinical Nutrition. 2012. 95(2), 437-445.
Veerman, J., Healy, G., et al. Television Viewing Time and Reduced Life Expectancy. British Journal of Sports Medicine. 2011. Published Ahead of Print.