David Harper is an ACE and AFAA-certified group exercise instructor, and a fitness trainer at SPAC and other fitness facilities across Chicago. He’s worked in the health and fitness industry for the past 15 years.

Spring in Chicago, my favorite time of the year! Flowers, bright sun, warmer days, and soon it’ll be time for the beach… which means taking off a shirt and baring more skin than probably should be allowed.

If that thought’s crossed your mind, you’re not alone. Countless students and Chicagoans spent this past winter with the best intentions of staying or getting fit. Whether you were one of the dedicated gym-rats with an iron will or the occasional jump-on-a-bike-for-30-minutes exerciser, there’s still time to work on that beach body.

But, these days, hardly anyone with a pulse has the time for extended workoutss. In my years of fitness training and teaching, I’ve found the best, most efficient fat-burning exercise is the interval workout, which involves alternating sets of hard work and lighter work. The “up and down” work intervals cause spikes in heart rate that efficiently burn stored body fat. The key is focusing on the large muscle groups and keep moving (no five-minute water breaks allowed). A good rule of thumb is to allow three to five minutes for each interval, with little time in between.

Generally, you should exercise three days each week, with a day of rest between each workout. If you’re an exercise veteran looking to shift your routine into a higher gear, five days a week can be just the ticket. Just remember to listen to your body. Muscle soreness is a good indicator: If you’re really sore, then give your body time to rest and exercise later. If you stick to a sensible workout regimen and pay attention to your diet (that’s another article all together), you should see visible results in three to six weeks, depending on the intensity of your routine.

I’ve included a sample workout below. Good luck, and see you at the beach!

30-minute interval workout

• 2 minutes of quick warm-up: Limber up your joints and muscles for the harder work to come. You can bike, walk briskly, run or use the elliptical trainer, etc.
• 4 minutes of moderate-intensity cardio: Continue your warm-up activity but up the intensity with added speed, incline and resistance.
• 3 minutes of weight training: Squats (or leg extensions) for 10-12 repetitions, then overhead presses for 10-12 repetitions. Repeat. For each set, the weight should be heavy enough to make your muscles burn by lift number eight or nine.
• 4 minutes of high-intensity cardio: You could do the same cardio activity as the warm-up or do something completely different. Varied activity is good because it keeps the body guessing with different types of movement and exercise.
• 4 minutes of weight training: Lunges (or leg curls) for 10-12 repetitions, then lateral (side) arm lifts for 10-12 repetitions. Repeat.
• 4 minutes of high-intensity cardio
• 3 minutes of weight training: Push-ups (or chest press) for 10-15 repetitions, then bent-over or seated row for 10-15 repetitions. Repeat.
• 4 minutes of high- or moderate-intensity cardio.
• 3 minutes of weight training: Bicep curls for 10-12 repetitions, then triceps extensions for 10-12 repetitions.
• As many abdominal curls as you can handle.
• Quick stretch: Stretch all of the muscles you worked to increase flexibility and reduce soreness.