Friday, September 21, 2012

Man vs. Machine: Finding the Cure for Chronic Cardio

When you hear the word “cardio”, what comes to mind?  Do you see yourself going out for a long run on the beach?  How about tacking on an extra 15 minutes on the treadmill after lifting weights?  What about sweating buckets during a 90 minute spin class?  It seems like anything involving extended bouts of repetitive motion can be considered “cardio”.  It’s not hard to find a way to elevate your heart rate and keep it in “the zone” yet, oddly enough, there’s a lot of confusion over what the best methods are for improving cardiovascular health and maintaining a healthy body-weight.  The reason for this confusion is not because we’ve yet to develop the right machine, tool, or training method.  It’s because the whole rationale behind cardiovascular exercise has been misguided since treadmills became a marketing tool for fitness centers.   

If you’re like many of us who have consistently dedicated at least 2 to 3 hours a week to long periods of running, pedaling, stepping, or “ellipting”, then you might be just as hesitant to consider the possibility that most of that work was a waste of time.  If that's hard for you to swallow, then you can imagine how difficult it is to digest for  fitness professionals who accepted this prescription for cardiovascular health as training dogma.  People usually learn how to spread those hours out over the course of 5 to 7 days as 20 minute, 30 minute, or 45 minute sessions working within target heart-rate zones.  All a trainer has to do is help clients figure out which machine or method they could handle being stuck with for that long without getting bored and turning on the television.  Adding televisions to cardio equipment was no mistake, this was the public’s way of making time on human hamster wheels more bearable.  For a while now, fitness centers have been content with merely providing tools to their members with no instructions.  Unless they’re assisted by knowledgeable staff or trainers many of them are left to figure out things for themselves.  Some do eventually learn how to use machines effectively,  however the majority end up repeating the same patterns as they do at home and wonder why they don’t experience any changes.  Everyone will agree that any activity is better than none at all but the programs most commonly provided for cardiovascular training have limited results in reducing the general population’s waist line.  Why are obesity rates still on the rise when gym memberships are at all-time highs?  Aren’t we making changes when we go “workout”?  What’s the problem here?  Are people just not working themselves hard enough?  Are the programs, machines, or dare we say “trainers” not working them hard enough? 

One of the problems is that a lot of the cardio activities in gyms don't have any cross-over into daily function and activities.  They are just other ways to burn calories and let’s be frank…they’re boring, mind-numbing, and potentially detrimental to your health and performance.  We would think the more miles we cover or the more calories we burn in a session would indicate how up to par we are with our cardiovascular health.  In some ways they are but they are limited in how much they represent someone's overall physical conditioning. Why shouldn’t we train this way?  Why can’t we simply add time and energy to our runs and expect less fat, more energy, and happiness?  First of all, if that was the case, we wouldn’t be facing problems such as obesity because an overwhelming majority of gym members are already training this way on cardio decks nationwide. Secondly, it’s not the best way for us to cut through our fat stores and it’s definitely not the way we can best improve our overall strength and conditioning.

As living organisms we require energy in order to perform normal daily functions.  We acquire this energy from nutrients found in the foods we eat.  Foods are broken down into nutrients which are then further broken down into usable energy.  All of this occurs within the body via specialized metabolic systems which are activated at varying levels depending on what the body senses it is doing in the environment.   Running from a ravenous mountain lion, for example, will motivate the body to get its energy from a different system than one that runs while we sit and watch a 24 hour marathon of LOST.  Every energy system is active at any given time but the body will utilize one more so than the others depending on the demand.  The first system we have in place derives energy from the oxidation of fats.  The oxidative system runs to keep the body working during sleep, rest, and other things that don’t require much physical exertion.  Since a gram of fat yields more energy per gram than carbohydrates and proteins, the body uses fat more for prolonged physiological functions such as the ones just described.  If we prepare our bodies to sustain additional hours of low-intensity activity through chronic cardio training then it will prepare itself by storing more fat for use after it has depleted the carbohydrate stores.  So, working at 40% to 60% of the heart rate max for miles at a time may be more counterproductive to our goals because it teaches the body to store more fat in order to endure prolonged walks, runs, or bikes with limited rest and fuel (i.e. carbohydrates). 

Another reason the effects chronic cardio training on improving cardiovascular health are minimal at best  is because training at consistently low-intensities doesn’t train your heart to work any harder than it normally does.  Let’s not forget that the heart is as much of a muscle as your pecs.  You wouldn’t do thirty minutes to an hour’s worth of bench presses for 5 to 7 days a week and expect a lean and strong chest, would you?  Why would you do the same to your heart and expect positive changes?   It needs to be challenged and this requires cranking up the intensity and varying up the activities. 

Since most societies don’t have to worry about foraging or hunting down their entrees anymore, most of the fats people ingest are stored for later use.  The same storage process occurs when we take in extra carbohydrates and proteins, each of which can be eaten in excess.  You could say it’s both fortunate and unfortunate that many of us nowadays do not have to rely as much on our fat stores for energy as we can on the grocery stores just around the block.  If all we’re missing is our need to wonder around a little longer for food then why can’t we simply recreate this wondering period in the form of aerobic activity?  If you have a regular job to go to, kids to take care of, classes to attend, or any other daily responsibilities then you know firsthand how impractical this is.  Even if you do find an extra hour or two to go for a run, this is not mimicking the caveman fitness program as many would think.  As hunter-gatherers, we didn’t run for hours at a time in pursuit of other animals.  The trick to catching these great sources of energy was…strategically planned intervals!  Just think about where you would be if you chased after a rabbit for an hour just for it to get away from you.  In this case you expended a great of energy for no return.  Good luck making it back home.  Keeping movement light throughout the day and saving the cardio energy for when it was needed most was more conducive to our survival.  Even though our situation is very different than that of hunter-gatherers this is no excuse to forgo the practice of saving our energy for smart and efficient movements.  
The moments of strike during the hunt are powered mainly by creatine-phosphate (CP), an organic compound providing us with a quick source of energy. The CP system is one of the energy pathways mentioned earlier that yields a small amount of energy molecules called ATP (adenosine triphosphate).  This ATP is made readily available for use by the CP system and so it is ideal power source for short and intense bursts of activity (i.e. about 10 to 20 seconds or maximal effort).  After the ATP-CP stores are depleted we then have to rely more on our other anaerobic systems (i.e. fast and slow glycolysis) that provide ATP synthesized from glycogen which helps power intense work lasting around 30 seconds to 3 minutes.  The extent to which these systems produce ATP depends on a variety of factors such as diet, genetics, and a person’s level of physical conditioning.  Every system is active to some extent and everyone will eventually have to rely on the oxidative system in order to produce more ATP if they continue the activity without stopping to rest.  

We don’t want to go into too much of a biology lecture so the basic message is that prolonged effort in the oxidative system is not the best way to train the body if the purpose behind exercise is to make us more efficient hunters, physiologically speaking.  If you want a hunter heart or just a hunter physique then you need to train like one with short burst of physically and mentally engaging activity.  Hours of mind-numbing cardio will burn calories just like any other activity does but too much will lead to oxidative stress.   When you incur too much oxidative stress you run your cells ragged.  Since this is occurring at such a microscopic scale it is that much harder to monitor and that much harder to remedy after you've made a habit of doing chronic cardio.  By the time you do start to feel it in your muscles and joints your cortisol levels already are through the roof because the body has constantly had to prepare itself for surviving repeated bouts of running around.  Keep in mind that cortisol is a hormone your body releases in response to stress.  If you had to go days without food cortisol would help your body store fat and slow your metabolism down in order to conserve energy.  We may need this when we’re shipwrecked but not when we’re trying to lose weight and increase our metabolism.

Regardless of the intensity and duration of training the body will always turn to carbohydrates and fats for fuel.  The notion that you’ll burn mostly fat at 40% to 60% of your heart-rate max is a bit mistaken.  Your body will always derive as much energy from  carbohydrates as it can since they are the easiest to convert into usable ATP, so throw the “fat-burning zone” out the window.  That’s just the way it works.  An easy way to understand this is to think your body as a car.    All cars are useless without fuel.  For us this fuel comes in the form of carbohydrates.  Aside from needing fuel we need oil to help keep all of our parts moving efficiently.  In other words we need fats.  The fuel and oils also need a strong body to power and that is primarily made up of proteins.  This analogy may help clarify why the U.S. Department of Agriculture and the U.S. Department of Health and Human Services recommends the dietary guidelines that it does for the macronutrients in our diet.  They recommend that carbs encompass the bulk of our calorie needs (45% to 65% of total calories consumed per day), followed by fats (20% to 35%), and then proteins (10% to 35%).  If you continue driving the body on little to no fuel it will start to burn oil.  Not only does this usually smell bad, it dries out the engine.  Trying to lose so much fat within one given session is like doing one too many laps around the track without stopping to refuel.  You’re going to blow something soon enough. 

We’re not trying to discourage people from doing things like going for long walks at the park or train for an upcoming marathon.  What we want to stress is that long walks in the park belong in the park, not on the treadmill.  If you simply enjoy to pedaling, stepping, or walking in front of a television for half an hour then we’re not going to stop you.  However, if you’re doing that because you want to improve your health and performance, then we want to help you use your time more effectively.  One of the best ways proven to do this is through intervals which require you to use more energy over a shorter period of time. By increasing intensity via intervals you do several things for your health apart from decreasing your body’s need to store more fat:

      You increase your anaerobic threshold, something that is good to develop for instances where you are required to sustain an intense level of energy (e.g. walking a couch up the stairs).  

         You increase your fat metabolism since you’re heart rate has longer to go before it returns to its resting state.  In other words you leave with a greater EPOC (excess post-exercise oxygen consumption).  This basically means you burn more calories long after you’ve finished the activity because your metabolism is taking longer to drop back to its resting rate.
        You prevent the negative effects of chronic cardio such as inflammation, weakening of joint cartilage, increased cortisol levels, and general fatigue. 
     You don’t get bored!  The continual change and complexity of the movements keeps you mentally involved in what you’re doing.  This helps develop better neuromuscular control and brain health. 
      You find new strengths and improve old weaknesses.  Wouldn’t you like to develop more skills than riding a bike? We’ve all done that since we were kids.  Let’s try something new. 

     You can start experimenting with intervals yourself by changing the pace.  For example, if you regularly do 3 hours a week of med-high intensity cardio, then try limiting yourself to just an hour of high intensity cardio this week.  That’s equivalent to three 20 minute sessions.  During these sessions you can work 30 second, 60 second, or 90 second intervals where you’d run at 85% to 100% of your maximum effort followed by a 40% to 60% of a resting pace.  If you want more variety then try a circuit workout where you perform a number of exercises for a special amount of time or reps.  Circuits are a great way to let one part of you rest while others continue to work thereby keeping the heart rate elevated as if it were functioning to power a long distance run.  Like your typical cardio session, these workouts can also last anywhere between 30 to 45 minutes but guess what?  They’re not boring!  They also don’t ask you to repeatedly pound on your knees and heels.  They instead ask you to move as you would in real-life where you have to lift furniture, walk up  flights of stairs, throw your kids around, knock out thugs, et cetera. 
     If you’re not convinced yet, then we invite you to take a break from the long run.  For some people this may be more of a dare but don’t worry, you can always go back.  If you’ve already spent 200 hours on the treadmill, what’s sacrificing a couple of those for a different workout going to do?  Try interval and circuit training for a week, try them for two weeks, or try them for a month and see how you feel.  We guarantee you’ll take many things away from this experience including knowledge and results that will last a lifetime.  

-  - Noel L. Poff, CSCS, CPT, LMT

1 comment:

  1. Tracie - great article! Several excellent points on the benefits (and challenges) of high intensity interval training. I have personally seen great gains in strength and energy through this style of training. Love it!