Build Up Your Legs with Cardio?! Go Take a Hike! No, Really, Go Take a Hike!

I owe someone an apology.  Actually, I owe something an apology.

By and large, I’m an endurance athlete.  I’ve benefited greatly, physically and mentally, from running, specifically.  But for years I’ve been bad-mouthing running (and other aerobic, or “cardio”, activities).  Well, maybe bad-mouthing is too strong of a word, but I’ve certainly underappreciated it.  And for that, running, I’m sorry.

I’ve always (or as long as I’ve been in this industry) known cardio training to decrease . . .

  • Fatigue
  • Stress and anxiety
  • Depression
  • Heart disease
  • Diabetes
  • Cancer
  • Osteoporosis
  • Obesity

And increase . . .

  • Performance (work, recreational, and sports)
  • Sense of well-being
  • Blood [lipid] profile
  • Immunity

But when it came to increasing muscle mass, I shared the current paradigm that cardio had a negligible, if not negative, effect on muscle mass.

Everyone, and I mean everyone, knows the old (and true) adage, “use it or lose it”.  As [most] people age, they become weaker and fatter.  Many contribute this to age.  But to a pretty big degree, age is more correlative than causative.  Aging simply allows muscle mass more time to atrophy, or waste away.  When this happens, a person becomes weaker—because they’ve less muscle—and fatter—because less muscle means a slower metabolism.

You may be thinking, “Yes, but if I’m doing cardio, aren’t I using my muscles?!”  Yes, but like the current paradigm, I thought you were using (consuming) your muscles versus using (putting into action) your muscles.

But I was wrong.  At least according to an article I found that showed cardio training increases muscle mass.

Not only does cardio increase muscle mass, the authors propose that properly performed cardio is comparable to resistance (or strength or weight) training for doing so.  (For someone who places great emphasis on lifting weights, that’s kinda mind-blowing.)

I wanna hit on something, though.  The authors propose that properly performed cardio is comparable to resistance training.

“The effectiveness of aerobic exercise . . . to induce . . . muscle [growth] most likely depends on obtaining sufficient exercise intensity, duration, and frequency to achieve . . . muscle compared with traditional . . . resistance exercise programs.”

For this particular study, participants exercised 4-5 days per week, for 30-45 minutes, at an intensity of 70%-80% of their heart rate reserve, for 12 weeks.  (Also, this study was performed on a stationary bike.  So, if running’s outta the question, no worries.)

If you’re wondering, this study included both young and old men (ladies, other studies done with you have garnered similar results).  What’s interesting, although both groups increased their muscle mass similarly, the older men completed half the work the younger men did.  It’s not to say they worked half as intensely, they simply worked at a slower cadence.  What’s more, this study suggests older men “can reverse 15 to 20 [years] of age-related muscle loss in a 12-[week] duration.”  Wow.

Note: since 2005, eight of nine studies have reported similar findings.  I share this because I want us to be careful to not hang our hats on any one study.

Do I think everyone should still lift weights?  Absolutely.  But I now acknowledge that cardio is an effective way to not only counter muscle loss, but to build muscle.  So, do you forgive me, running?!

You know what?  I do owe someone an apology.  I owe an apology to anyone I’ve dismissed that said they use cardio to tone their legs.  Forgive me?!