WEDNESDAY, March 6 (HealthDay News) -- Short bouts of moderately intense exercise appear to improve the self-control of youngsters and young adults, a broad review of existing research suggests.

The Dutch analysis of 24 prior studies highlights the potential mental health benefit for people 6 to 35 years old who engage in a half-hour cycle or run, for example, but it remains unclear how long the positive effects last.

And whether repetitive training programs spread out over weeks or months might have a similar impact on youthful inhibitions also remains an open question.

"There were too few studies looking into the effects of long-term regular exercise to really know what the impact is, but the effect of short-term exercise is clear," said study lead author Lot Verburgh, a doctoral candidate in the department of clinical neuropsychology at VU University in Amsterdam.

"Tests conducted immediately after short bouts of exercise showed a clear improvement among higher-order functions like self-control, a cognitive [brain] function that is really important for daily activities in terms of both social life and academic performance," said Verburgh.

The association, gleaned from 19 studies involving 586 participants, is discussed in the March 6 online issue of the British Journal of Sports Medicine.

The findings could have relevance for treating disorders associated with impaired inhibition, including attention-deficit/hyperactivity disorder (ADHD) and autism, according to the study.

The authors noted that past research has indicated that moderate exercise can positively affect mental function among older adults. Walking, for example, has been associated with improved memory and attention skills among otherwise sedentary seniors, they explained.

For this project, the team looked at studies conducted through 2012 that focused on three age groups: 6 to 12 years, 13 to 17 years, and 18 to 35 years.

Nineteen studies concerned the effects of acute-- or short -- bouts of moderate exercise. Such workouts might elevate heart rate to about 60 percent of maximum capacity and could include 10 to 40 minutes of cycling or running, for example. Twelve of these studies specifically assessed the impact of acute exercise on self-control.

Only five studies examined the impact of chronic-- or routine -- exercise, and the results were inconsistent.

The bottom-line: While unable to draw any conclusions regarding chronic activity, the team found that short bouts of exercise did seem to boost self-control across all three age categories, a lift that could give still-maturing younger brains a leg up in social, academic and sports-related settings.

What lies behind the apparent exercise-driven inhibition boost?

"A higher-order function like self-control, or inhibition as we say, is located mainly in the pre-frontal cortex of the brain. It may be that the effect we see is due to an enhancement of blood circulation in the brain," explained Verburgh.

"And that would lead me to think that if you want to have an effect that's long-lasting, you would probably have to exercise regularly and often," Verburgh added. "But if that's true or not remains unclear."

Ali Weinstein, an assistant professor and deputy director of the Center for Study of Chronic Illness and Disability at George Mason University in Fairfax, Va., suggested that the lack of clarity regarding the impact of long-term chronic exercise is a big sticking point in "a very interesting analysis."

"Exercise has traditionally been linked to many health benefits: cardiovascular, weight control, lower cholesterol (and) lower risk for some cancers," she said. "However, less research has investigated the more 'mental' health benefits of exercise."

It's already known that exercise can have mood benefits, Weinstein added. "If exercise can also be linked to long-term improvement in higher-order mental processes, exercise may soon be not only a treatment option for heart disease patients and individuals looking to control their weight, but also for ADHD and Alzheimer's patients," she said.

However, she cautioned, "if these effects are not sustained, then they are probably not that meaningful."

The review findings should be a wake-up call that investigations of chronic exercise are needed, Weinstein added. "If the acute exercise effects are replicated in chronic exercise investigations, then we have really found something that can enter recommendations for everyone," she said.

More information

For more on the benefits of exercise, visit the U.S. National Library of Medicine.