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Myth #3: Heavy Weights Bulk You Up, Light Weights Make You Look ‘Toned’
When I first suggest to runners that they will be better served by lifting heavy weights, their initial reaction is, “I want to look like Mo Farah, not Arnold Schwarzenegger.” This fear comes from a misunderstanding of how “bulking up” actually occurs.
Muscle bulk is not determined by lifting heavy weights alone. In fact, lifting heavy weights is the least important part of the equation. Nutrition, specifically excess calories, is what contributes to bulking up when lifting heavy weights. (As a side note, it’s the same for using running as a means to lose weight. The mileage itself is not the most important factor, but rather the negative calorie balance.)
Moreover, because the amount of time you will spend running will vastly outnumber the amount of time you spend lifting heavy weights, it will be virtually impossible for you to gain unwanted or detrimental mass (unless of course you’re seriously overeating, which is not a training problem).
Don’t be afraid of looking like a body builder if you’re including heavy lifting in your running routine. It just won’t happen.
Likewise, lifting lighter weights with more repetitions won’t make your muscles look more “toned.” The common belief is that high reps magically get rid of fat. While lifting light weight at high reps to fatigue can create a muscular response, it does not necessarily remove fat better than low reps with heavy weight. The mythical “toned” look is a result of not losing muscle mass in conjunction with losing weight.
As an example, one study from the University of Alabama in Birmingham showed that dieters who lifted heavy weights lost the same amount of weight as dieters who did just cardio, but all the weight lost by the weight lifters was fat while the cardio subjects lost a lot of muscle along with some fat.
Consider how these three common myths play into your current perception and approach to strength training. Hopefully you’ve been reading enough of the current literature to have already made positive changes to your strength training routine. If not, use the information we’ve presented to dispel these myths to make the most of your time spent in the gym.