The counterintuitive proposition that exercise gives you energy just got a big boost.
According to a new University of Georgia (UGA) study, sedentary people who normally feel fatigued can increase their energy levels by 20 percent and decrease their fatigue by 65 percent by engaging in regular, low-intensity exercise.
Previous studies—including one published in 2006 by the same team—have shown that exercise can significantly improve energy levels and decrease fatigue.
But those studies involved patients with medical conditions such as cancer, heart disease and mental health problems.
In this latest study, the UGA team studied volunteers who had fatigue that was persistent yet didn’t meet the criteria for a medical condition such as chronic fatigue syndrome (Puetz TW et al. 2008).
Patrick O’Connor, co-director of the UGA Exercise Physiology Laboratory, said about 25 percent of the general population experiences such fatigue.
As he said, “A lot of people are overworked and not sleeping enough. Exercise is a way for people to feel more energetic. There’s a scientific basis for it, and there are advantages to it compared to things like caffeine and energy drinks” (UGA 2008).
Mild exercise proves energizing
The researchers recruited 36 volunteers who did not exercise regularly and had reported persistent fatigue based on a commonly used health survey.
The volunteers used exercise bikes, which allowed the researchers to control their level of exertion.
The UGA scientists defined low-intensity exercise as 40 percent of participants’ peak oxygen consumption, while moderate-intensity exercise was defined as 75 percent of peak oxygen consumption.
To put this in perspective, the researchers considered an leisurely, easy walk to be low-intensity exercise, and deemed a fast-paced walk with hills to be moderate-intensity exercise.
The volunteers were divided into three groups:
- One group engaged in 20 minutes of moderate-intensity aerobic exercise three times a week for six weeks.
- Another group engaged in low-intensity aerobic exercise for the same time period.
- The control group did not exercise.
The low- and moderate-intensity groups had a 20 percent increase in energy levels over the control group.
Surprisingly, the low-intensity group had a greater reduction in fatigue levels than the moderate-intensity group: a 65 percent reduction compared to only 49 percent.
As Dr. O’Connor said, “It could be that moderate-intensity exercise is too much for people who are already fatigued, and that might contribute to them not getting as great an improvement as they would had they done the low-intensity exercise” (UGA 2008).
The team’s analysis also found that the improvements in energy and fatigue were not related to increases in aerobic fitness that the exercisers experienced: a finding that suggests exercise acts directly on the central nervous system to increase energy and reduce fatigue.
According to co-author Tim Puetz, Ph.D., “Exercise traditionally has been associated with physical health, but we are quickly learning that exercise has a more holistic effect on the human body and includes effects on psychological health. What this means is that in every workout a single step is not just a step closer to a healthier body, but also to a healthier mind” (UGA 2008).
- University of Georgia (GA). Low-intensity exercise reduces fatigue symptoms by 65 percent, study finds. Accessed online April 4, 2008 at http://www.uga.edu/news/artman/publish/080228_Fatigue.shtml
- Puetz TW, Flowers SS, O'Connor PJ.A Randomized Controlled Trial of the Effect of Aerobic Exercise Training on Feelings of Energy and Fatigue in Sedentary Young Adults with Persistent Fatigue.Psychother Psychosom. 2008 Feb 14;77(3):167-174 [Epub ahead of print]