Living in Boston means April is the time of year that thousands of people hit the streets, treadmills, and trails to prepare for the Boston Marathon. I have countless friends, family, and coworkers who raced this year and I always hear a similar story, some variation of "The race will be so rewarding to finish, and I will lose so much weight and get in great shape while training!"
And most of the time the get-in-shape/weight loss benefit is never realized. This has less to do with how much you train, but rather it is an issue of Metabolic Efficiency.
What is Metabolic Efficiency?
In simplest terms, it is how efficiently our body burns calories, or fuel. Think of your body as a car for a moment. How much gas does your car burn to go 10 miles? The answer is entirely dependent upon the type of car, and the type of driving. If you are running your body like an Electric Hybrid on the highway, you aren't going to burn much fuel (calories) per minute of exercise. To put it into context, roughly 1 pound of fat can fuel a 130 pound female for 15 hours at an aerobic state of activity (basically jogging comfortably). Humans evolved to be moving around all the time looking for food, shelter and safety. We would never have been able to sustain ourselves if we were burning significant calories at that level of steady exercise. We actually would have died of starvation if we were metabolically inefficient enough for jogging to be an effective calorie burn and weight loss routine.
Muscle Helps Too!
You can actually burn even more calories from just the presence of muscle mass alone. It takes 10 calories a day to keep 1 pound of muscle alive. So extra muscle actually helps you burn more calories each day regardless of your activity type. Looking at basic aerobic calorie burn for the average adult male, 45 minutes of activity will burn 300 calories, and that's what the calorie counter on the treadmill will tell you. But that is total burn, which includes roughly 100 calories that are burned just to run your bodily functions, even if you sat on the couch to watch TV. So you only have about 200 calories of "excess reward" for your efforts. And as you run more and more (like in marathon training), your body gets more efficient and that number drops to the 150 calorie range of excess reward burn. Factor in the muscle loss, 5 pounds for example, from a predominantly aerobic cardio workout plan, and you've tacked on 50 excess calories that you aren't burning. All that jogging has left you with net 100 calories burnt, which is probably offset by the hydration drink you have during/after your workout. So it's no wonder you don't lose any weight!
Why is High Intensity more effective?
By going deeper into what happens in your body during the two types of activity, you see the difference. During aerobic activity, fat oxidation (burning) stops upon completion of the workout. But during high intensity interval training, your body has to oxidize carbs during the workout for energy, not fat. The fat oxidation actually occurs afterwards to restore your short term systems to normal (restore carb depletion, lower your body temperature, re-oxygenate blood, lower your heart rate). In addition, there are long term system repairs going on (strengthen tendons/ligaments, increase bone density, repair muscle tissue, form new capillaries, etc.). You also build more muscle from this type of workout as your fast twitch muscles are firing more frequently, which will burn more calories. Your metabolism is boosted for hours after you work out, so the effects continue when you are just going about your day, and to top it off your appetite is also suppressed far more than with aerobic activity.
I am certainly not advocating abandoning running, I enjoy hours out on trails as much as anyone. And not everyone is trying to burn fat or lose weight, in fact if you are training for ultra runs you want to build up your metabolic efficiency. The point is that not all cars burn gas the same way, and neither does your body in different workouts, so just make sure you aren’t taking the V8 truck cross country or the Hybrid off-roading!
Getting into Interval Training
If you are brand new to interval training, one of the best workouts to do that literally can be done anywhere is a "Deck of Cards" workout. Just assign each suit an exercise, shuffle the deck, and start flipping cards. Each number is how many of that workout you must complete, so the 8 of Hearts could mean 8 burpees for example. Mix up the exercise to work your core, upper body, and lower body, and do this exercise for time to see your improvement. By using all bodyweight exercise (burpees, squats, sit-ups, and elbow taps as an example) you won't even need a gym to do this work out!
This is a guest post by Brian Lynch. Brian works in Wealth Management at UBS in Boston MA and has been involved in OCR since 2011. Recreation quickly turned to passion and then to obsession, and Brian now focuses his training on Ultra Distance OCR. Brian is a 2 time Worlds Toughest Mudder participant (finishing and completing 50 miles in 2012), a 2 time Spartan Ultra Beast finisher, and one of the 40 inaugural Fuego Y Agua Survival Run competitors. Brian's training focuses on body weight exercises for functional strength, high intensity circuit training for cardio and agility, and long distance trail running for endurance.