Have you ever asked yourself if it’s worth it to hit the gym despite a time crunch? You only have 30 minutes to squeeze in a workout before you need to pick the up kids, make dinner, or get to a client meeting. Will you really benefit from such a short workout? The short answer is, Yes! It is definitely worth it!

Here is why…

Science Behind the Calorie Burn

Long after the workout is done, your body continues to burn calories, prolonging the benefit of your efforts. This physiological phenomenon has a name – EPOC, or excess post-exercise oxygen consumption. Simply put, it’s the amount of oxygen required to return your body to its resting level of metabolic function. Metabolism is how the body converts nutrients into adenosine triphosphate (ATP), the fuel needed for muscular activity. ATP is produced in two ways: with oxygen using aerobic pathways or without oxygen, relying on anaerobic pathways.

During physical activity, once a steady state of oxygen consumption is achieved, aerobic energy pathways are able to provide enough ATP to sustain the workout, increasing the need for oxygen after the workout and enhancing your overall caloric burn. But when oxygen is required quicker than the body can produce it, as happens with bursts of energy, the body pulls from anaerobic pathways to get what it needs, requiring even more oxygen post-workout to recuperate and repair the muscles. The higher the EPOC effect, the more calories you will burn.

But how do you enhance the EPOC effect?

In short, the faster you burn through the aerobic ATP, the faster the body needs to pull from the anaerobic pathways which requires more recovery time to reach that proper resting metabolic state and thus a great EPOC effect.

So: how do you get your body to pull from the anaerobic pathways quicker?

1. Start with a warm up. A proper dynamic warm up of five to eight minutes allows the body to efficiently use the aerobic metabolism to produce most of the ATP necessary to sustain physical activity. When you move from warm up into the higher energy part of the workout that requires more oxygen quickly, your body starts to pull from the anaerobic pathway.

2. Increase the intensity of the workout, not the duration. Higher intensity workouts pull ATP from the anaerobic pathways because the body needs access to oxygen quicker than the aerobic pathways can produce it. My favorite “go to’s” for this as a coach are boxing style workouts, short hill sprints, and basic plyometrics (if appropriate for the client’s ability).

3. Increase the resistance instead of longer cardio sessions at a steady rate. Just like increased intensity, increased resistance for short time periods produces a greater EPOC effect because the body begins to pull from the anaerobic pathways quicker. Efficient and fun options include the updated aerodyne style bikes (such as the StairMaster HIIT Bike used in Cross Fit competitions), pushing or pulling a weighted sled, heavy battle ropes, full resistance on the HIIT Rower, the StairMaster stepmills (the one we all love to hate), and if you are injured or just want something really different try the StairMaster HIIT UBE.

4. Incorporate circuit training and high resistance strength training with shorter rest intervals. Strength training and alternating between upper and lower body workouts, particularly with short rest intervals keeps the body burning through ATP for an enhanced EPOC effect for greater caloric burn. Kettlebell movements are an excellent option for this.

Of course, as with any exercise regimen, you need to be prepared for the challenge. High intensity interval training (HIIT) is not for everyone. You also need to allow 48 hours of recovery time in between HIIT sessions and limit yourself to three high intensity sessions per week. Get to it!


Sonja is a world-class athlete who has trained people of all ages and abilities for nearly twenty years. She is also a skilled fitness programmer, holding Personal Training Certifications with ACSM, AFAA, and AFAA specialty certifications in Youth, Senior, and Pre-Natal Fitness. She is a certified Strength & Conditioning Specialist, a Schwinn Power Cycling Instructor, a BoxMaster Master Trainer and an ACE Health Coach, which enables her to work with those in the allied health field in regards to high risk or specialized clientele.

Sonja is also a successful club operator and businesswoman, having developed and coached fitness and personal training programs while serving as the Athletic Director for the esteemed Wellbridge full service health clubs in South Florida. She received the Wellbridge Athletic Director of the Year aware twice during her tenure there. She also founded FIT Studio, a personal training and Pilates studio in West Palm Beach, FL. Currently Sonja enjoys her position as a Wellness Director for Cool Springs MD in Nashville, TN and operating her own running coaching business (www.TheRunningWarrior.com) and fitness consulting group (www.FitwithSonja.com). Sonja can be reached at 800.228.6635 or [email protected].

Return to Blog