CrossFit and Caloric Expenditure

Aerobic and resistance training workouts increase your body’s need for oxygen in the post-exercise period. This factor—called EPOC or excess post-exercise oxygen consumption– elevates metabolism and plays a major role in exercise-related weight loss. Type of exercise, duration and workout intensity influence EPOC.

Whilst many research studies explore this subject matter, the results of a number of studies indicate that a high-intensity, CrossFit style workout yields the best results.

Resistance Training

EPOC increases with weight-lifting intensity, reports KL Osterberh, lead author of a March 2000 article in the “International Journal of Sport Nutrition and Exercise Metabolism.” Seven women were told to perform five sets of 10 different exercises. The research team paired the exercises according to opposing muscle groups, and told the subjects to perform 10 to 15 repetitions per set, and to perform the last two sets of each exercise to failure.

Exercise pairs consisted of the leg extension and hamstring curl machines; the chest press and bent-over row; the military press and sit-ups; the biceps curl and triceps extension; and lunges and lateral raises. The team measured the subject’s resting metabolic rate every 30 minutes, and reported a 13 percent increase in their before-exercise. Sixteen hours after the workout, their resting metabolic rate was still 4.2 percent higher than their before-exercise rate.

Aerobic Exercise

The results of a February 2008 study published in the “International Journal of Sport Nutrition and Exercise Metabolism” indicate that subjects who perform aerobic exercise for 30 to 45 minutes on three to five days a week at moderate intensities potentially elevate their resting metabolic rate. After 16 months, the women in the study increased their resting metabolic rate by 129 calories a day, and then the men increased theirs by 174 calories a day.

An Argument For High Intensity

Increasing your metabolic rate by 129 calories a day might sound good, but high intensity training yields even better results. Len Kravitz, exercise physiologist at the University of New Mexico, details the results of numerous research studies:

“The evidence suggests that a high-intensity, intermittent-type of training (interval training) has a more pronounced effect on EPOC (Haltom et al. 1999). Also, it appears that resistance training produces greater EPOC responses than aerobic exercise (Burleson et al. 1998). The research suggests that high-intensity resistance exercise disturbs the body’s homeostasis to a greater degree than aerobic exercise. The result is a larger energy requirement after exercise to restore the body’s systems to normal (Burleson et al. 1998), and thus an explanation for the higher EPOC. Studies have also shown EPOC can increase your metabolic rate 13% up to 3 hours post exercise and 4% up to 16 hours post workout.”

Most Effective Exercises

The more of your major muscle groups engaged in your exercise program, the higher your caloric expenditure.  Aerobic exercise such as running, jumping rope, cross-country skiing and martial arts burn the most calories, for example. Likewise, exercises that target more than one muscle group simultaneously, called compound weight-training exercises, also increase caloric expenditure. Examples include squats, lunges, the bench press and the lat pull-down machine. Much of this sounds like a typical CrossFit WOD.

Which Comes First

Researchers have not yet determined the ideal sequencing of aerobic and resistance training exercise, says Mayo Clinic physical medicine specialist Edward Laskowski M.D. Intense weightlifting might deplete the glycogen stores and reduce your aerobic endurance, but a vigorous aerobic workout might make you too tired to perform your weight training workout in proper form. A CrossFit WOD alternates strength and aerobic exercises, thereby mitigating these issues.

Combined with a proper diet, CrossFit training might be just what you need for weight control.

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