Other researchers are emerging with variations on that theme. The primary mood effect of moderate exercise was energy enhancement, he found, while a secondary effect was tension reduction. With the aerobic group, the main effect reported was tension reduction. Participants' energy in this group at first declined, and later rebounded. John Raglin, PhD, of Indiana University, has been comparing the effects of aerobic exercise and anaerobic exercise, a little-studied, more intensive form of exercise.
Anaerobic exercise involves short, intense bursts of activity, such as weightlifting.
The level of exercise kicks the body into an energy system that uses a different metabolic pathway than the oxygen-bound system of aerobic activity. Anaerobic activity produces lactic acid, a metabolic byproduct that can disrupt the body's pH balance. Raglin, an associate professor in the department of kinesiology at the university, conducted the study in part to examine a posited link between the production of lactic acid and the onset of panic attacks. But he also found that participants who did a less intense aerobic activity experienced a steady decline in anxiety that lasted for up to three hours. In the more intense anaerobic condition, however, the exercisers' anxiety levels initially rose, then fell to baseline.