Why more cardio may not be the answer.

If someone is thinking about losing weight and changing their physical appearance the immediate thought is usually cardio.  Running is cheap or free, depending on your shoe situation.  It can be done anywhere at any time.  Plus, conventional wisdom tells us running produces weight loss.  While I think running and cardio in general can be a great addition to a training/weight loss program, here are a few considerations as to why it should not be the core of your program.  (If your goal is to be a triathlete or marathon runner, you need to put miles down.  But incorporating some of the following tips can be helpful.)

  • Cardio just doesn’t use a lot of energy. I’m sorry but it is true.  If you run 3 miles you haven’t done much more than if you did not.  You will feel like you have, and you should be proud.  From a calorie consumption stand point however, you haven’t earned any extra food.  When we work with clients in our nutrition program they are often shocked to learn we treat cardio days as “non-training” days.  Resistance training causes the use of energy, depletion of muscle glycogen and requires tissue repair, all of which require more energy.  Short to medium duration cardio just doesn’t.  This can be extra problematic with the idea of excess carbohydrate feeding to “fuel” runs.
  • Extra carbohydrates are needed to replenish muscle glycogen (sugar stored as energy in muscle tissue) and for protein synthesis (muscle building and repair). As noted above, running causes these requirements to be very low if not non-existent.  Perceived exertion is not a great measurement of actual energy expenditure.  You can run yourself into the ground in short order but not expend much energy in the process.
  • Running can break down lean tissue. Runners are very lean but have very little lean tissue.  For overall health and fitness, lean tissue is very important.  It helps support our joints, creates that defined or tone look, and it has an overall higher energy requirement than fat.  We all have skinny friends who always run.  If they stop running they have no buffer against weight gain or anything invested in long term health (except a good VO2 max).  We also have a friend who lifts weights and doesn’t seem to eat great but stays lean.  The extra lean tissue has given a buffer from excess energy consumption and fat gain.
  • Millions of reps of anything is not great for you. The repetitiveness of cardio is bad for joints if there is no resistance training support.  Doing a million reps of anything can lead to overuse injuries.  Running is no different.  Aches and pains will continue and possibly get worse, especially if there is a pre-existing issue with joints or gait.

Increased cardiovascular capacity is a good thing.  It can increase capacity in other domains, it allows us to not run out of breath doing simple tasks, it can reduce blood pressure, and keep our hearts and lungs working well.  To much of any good thing can be bad, and for years this has been touted as a great weight loss tool.  It is a tool, but you should have others in your health and fitness tool box.