Fitness buffs who can't make it to the gym but still want to exercise can turn to apps for a short, intense workout when they are pressed for time.

The US Centers for Disease Control recommend that adults do at least 150 minutes of moderate aerobic activity weekly. But recent studies suggest even short bouts of exercise can have positive health effects.

Sworkit, a new fitness app for iPhone and Android devices, takes users through workouts as short as five minutes that can be done anywhere.

"We realized that a lot of people don't have a lot of time, so we created an app for people to squeeze in bite-sized increments of exercise throughout their day where they don't need to be at a gym or use equipment," said Benjamin Young, CEO of Washington, D.C.-based company Nexercise, creator of the app.

The free app will put together a custom training circuit based on what users want to focus on - strength, cardio, or stretching, for how long, and the specific part of the body.

The routine is made up of 30-second exercises that are demonstrated with videos, or users can create their own workouts with the app.

The Johnson & Johnson Official 7 Minute Workout app for iPhone and Android devices also provides users with short fitness routines.

"We live in a fast-paced, addicted-to-speed society where everyone is looking for quicker and faster solutions in all aspects of their lives," said Chris Jordan, director of exercise physiology at Johnson & Johnson's Human Performance Institute.

The app employs videos to guide users through high-intensity circuit training routines that are customized based on fitness level and desired intensity.

"A lot of people are convinced they need to go to a fancy gym with fancy equipment, but something like a squat arguably is more beneficial and transferable to life than a leg press machine," Jordan explained.

Users can customize about 1,000 different workouts on the app, which is available in 30 countries.

Greg Wells, assistant professor of kinesiology at the University of Toronto, said even small bursts of physical activity have a positive effect.

"The physiology is such that you not only get a workout after the short seven minutes you do it, but you're also benefiting during the period after, when your body is recovering. So it could actually be 30 minutes of physical stress and that's why these workouts can be really effective," said Wells.

"But whether it's better than 40 minutes of interval training or an hour run, yoga class, or weights, I'm not 100 percent sure we can say that," he added.

Wells noted the surge in shorter workouts, including a 20-minute one at a Toronto gym called Medx Precision Fitness, where clients can exercise during a lunch break without changing clothes.

"It's getting people to do something. And that's what we have to accomplish right now," he said. – Reuters