Today, a former student shared a video with me that exemplifies the distorted presentation of exercise science that often occurs in the effort to market exercise programs. To my student’s credit, she understands the science.
The video presents the question of which is better “cardio” or weight lifting—I presume to improve body composition (?). What the video clearly ignored was the principle of specificity. So, it prompted me to speak up.
One phrase that the creator of the video used was “Exercise Post Oxygen Consumption”. Now, this is a new one to me, as an exercise physiologist. So, this raises the red flag of credibility. The correct term in exercise physiology is “Excess Post-Exercise Oxygen Consumption” (or EPOC). What the maker of the video is probably intending to refer to is post-exercise energy expenditure (PEE—that probably won’t get far as an acronym!)
EPOC refers to the oxygen consumed after the cessation of exercise—also referred to as “oxygen debt”. Initially, oxygen is consumed—i.e., the exerciser continues to breath heavy post-exercise—to replace blood and muscle oxygen stores and to replenish stores of phosphocreatine in the muscle. Then, for a period—depending on the intensity of exercise and the condition level of the exerciser—the heart rate and breathing are elevated, levels of catecholamines (the hormones epinephrine and norepinephrine) are elevated, body temperature remains high, and lactate is being removed from the blood (oxidized). These keep metabolism elevated and oxygen continues to be consumed at a higher rate. This occurs in both aerobic activities (like running) and anaerobic activities (like lifting weights—think about how heavy you are breathing after a heavy set of squats). This occurs for a matter of minutes.
Post-exercise energy expenditure is related to the prolonged metabolism (hours) following a bout of exercise. Now, here, the video is correct that weight training will metabolize more energy in the hours post-exercise than will cardiorespiratory exercise (AKA, “cardio”). Rightly, the video points out that, during a bout of exercise, cardio will burn more calories per minute than weight training and that weight training will burn calories at a higher rate (and more prolonged period) post-exercise. So, the conclusion is made: weight training is better than cardio, right? Well, the answer isn’t as clear-cut as the video implies. First, what are the goals? Are we looking to only burn fat? Or are we looking to build muscle and/or improve cardiorespiratory function? We must remember the principle of specificity!!
If the goal is improved body composition, then, yes, lifting weights will burn more calories–if done right. I stress: “if done right.” We are talking heavy and hard lifting, not what is often done for general fitness. One must also remember that if you are small (i.e., a beginner lifter), and lifting lighter weights, the post-exercise energy expenditure will be smaller than that of a seasoned beef-cake.
But… cardiorespiratory fitness, muscle strength, and muscle endurance are distinct physiological adaptations. Specificity!! Certainly, the weightlifting post-exercise energy expenditure is increased by the caloric demand to actually repair and build muscle. It also (no matter how much the HIIT crowd will argue) does rather little to improve VO2max (calling it “Tabata” does not make it Tabata).
So the question when considering EPOC or PEE is not one of which exercise is better. The question, first and foremost, is what are the goals?
My student/friend is a powerlifter and isn’t planning to run any marathons or even 5Ks any time soon. So, for her, the whole discussion is moot—other than that she has to eat more food—especially carbohydrates—to fuel muscle growth and repair and that when it comes time to make weight for competition, she can benefit some from cardio, but will mostly just have to cut her food consumption.
So, my general recommendations—based on science are: if you want to lose fat, lift weights. If you want to get stronger, lift weights. But if you want to lose fat and improve VO2max, lift weights AND run (do some form of cardio). If you want to be badass strong, lift big weights (and eat!—i.e., getting lean isn’t a primary goal). If you want to be a badass marathoner, run and lift some weights. [You are probably not too concerned about burning fat, but the added muscle will improve performance. Don’t worry about putting on too much muscle, because the high amount of cardio exercise will minimize muscle hypertrophy.] If you want to post “six-pack abs” selfies, do HIIT. If you want to be an all-around badass (like Alex Viada who squats in excess of 700 lb and can run a sub-5-min mile) plan your training very carefully. [Check out Alex Viada’s book, Hybrid Athlete.]
Now, before I am accused of being anti-HIIT, let me explain. First, “HIIT” is a pretty broad category of exercise. High-intensity interval training (HIIT) has countless implementations. It can be a fantastic means of significantly improving cardiorespiratory fitness and performance, which is its original application. Or, as it has more recently become a trend in the fitness industry, it can become a method of training for general fitness. I say “general fitness” because this trendy application basically ignores the principle of specificity. HIIT exercise programs (often WODs or “workouts of the day” at trendy gyms) involve “high-intensity” body weight or weighted exercises performed in circuits (in the good ol’ days, we referred to this simply as “circuit training”). Circuit training has been shown to have minimal improvement in cardiorespiratory fitness (i.e., VO2max), so calling it “HIIT” or “Tabata” allows exercise program leaders to market these as “cardio”.
So, HIIT weight training sessions miss the bulls-eye for building strength and significantly improving cardiorespiratory fitness. They can, however, be outstanding for muscle endurance and improving body composition (at least for burning fat). They will not provide significant hypertrophy, if one is looking to improve the “athletic physique”. This requires heavy lifting. It will not build strength. This requires lifting even heavier weights (near the one-repetition maximum). There may be modest improvements in VO2max doing this kind of “HIIT”, but not near the level of improvement seen from the Tabata (IE1) protocol—requiring eight cycles of 20 second bursts of ultra-intense (~170% VO2max) followed by 10 seconds of rest (Tabata? You can’t handle Tabata!).
If you want a more well-rounded (e.g., hybrid athlete) level of fitness, you are best to segment your training into adaptation-specific sessions. Realize, however, that the idea of “opportunity cost” applies. If you are a strength athlete, every minute of training for cardio takes away from potential strength adaptations. If you are an endurance athlete, every minute in the weight room takes away from training to improve VO2max (though, given that performance requires more than just improved oxygen consumption, there is a strong argument in favor of some strength training—just realize that you build significant muscle mass while putting in high miles). If you just want to be lean and “fit”, by all means do “HIIT” workouts.
Specificity is king/queen! The question of what training program is better is not so straight forward without considering the goals. So, choose your exercise wisely. Know your goals!
Be your best today; be better tomorrow!