The heavy weights versus high repetition dilemma is a highly debated topic among female exercise enthusiasts and fitness professionals. The leg muscles are often the subject of this debate. The concern that big, bulky muscles will result from heavy lifting and destroy the legs' appearance is often based on misconceptions and misinformation.
Spot the Myth
The theory that high repetitions at a light weight is related to the spot reduction myth. Aerobic exercise and modified diet will reduce all over body fat, which will improve the legs' appearance. These tactics are the most effective at burning calories and putting you in a deficit, which leads to fat loss. Any tone in your leg muscles lies underneath fat -- until you lose it, all your efforts not going to be readily seen.
Exercising with light weights and high repetitions doesn't burn a lot of calories, nor does it reduce fat in the area worked -- you can't target one specific area for fat loss. Higher repetitions may increase muscular endurance, but this does not necessarily contribute to muscle tone.
When you're looking to be toned "toned," you're looking to be leaner and more sculpted. To get toned legs, your body must be relatively free of excess body fat. Since high, light-weight repetition exercise does not burn body fat, it will not increase leg muscle tone.
The Bulk Stops Here
Your genetic makeup affects a woman's ability to build muscle bulk. Testosterone, the male hormone, plays a significant role. A woman's fear that heavy weights build bulky muscles is unfounded. Women have testosterone levels that are only 5 to 10 percent of those of men, which limits their ability to build leg bulk by lifting heavier weights.
Lifting heavier weights will help expedite muscle development, however. Plus, you only need a few reps -- six to eight -- in each of three to four sets to get results. This gets you in and out of the gym faster.
The post exercise oxygen consumption theory suggests that weight training elevates the post exercise metabolic rate. A higher metabolic rate means less body fat, which ultimately contributes to leg muscles that appear toned. In a 2002 study published in Medicine and Science in Sports and Exercise, lead author M.K. Thornton compares two groups of women. One group performed eight repetitions of specific resistance exercises at 85 percent of their maximum ability. The other group performed 15 repetitions at 45 percent of their maximum ability.
The group that lifted the heavier weights had a higher level of post exercise oxygen consumption. This type of program may also reduce age-related fat gain, reports J.W. Bea, author of a 2010 paper published Medicine and Science in Sports and Exercise. Bea and team performed a six-year body composition study of 122 post-menopausal sedentary women. Those that performed three weekly resistance-training workouts, and did eight repetitions at 70 to 80 percent of their ability, showed significant weight and body fat reductions.