The heavy weights vs. 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, but the concern that big, bulky muscles will destroy the legs' appearance is often based on misconceptions and misinformation. Because women tend to accumulate fat in their hips and thighs, the subject remains a hot topic.
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. Light weights and high repetitions do not accomplish this task. Higher repetitions may increase muscular endurance, but this does not necessarily contribute to muscle tone.
Bigger is Better
The term muscle tone refers to the minute muscular contraction, which is visible even when the muscles are in a relaxed state. Commonly called "lean muscle mass," muscle tone implies that the body is 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 your 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, explains Dr. C. Harmon Brown, chairman of the United States Track and Field Sports Medicine and Science Committee. Brown, in an article on the Coachr website, argues that women have testosterone levels that only 5 to 10 percent of those of men, which limits their ability to build leg bulk by lifting heavier weights.
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 toned leg muscles. In a 2002 study published in the "Journal of Medicine and Science in Sports and Exercise," lead author M.K. Thornton compares two groups of women. One group performed eight repetitions at 85 percent of their maximum ability. The other performed 15 repetitions at 45 percent. 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 article published in the "Journal of Medicine and Science." 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.
Find Your Balance
An unbalanced workout may make the legs appear to be bulkier, and may not be the result of lifting heavy weights. The quadriceps are significantly stronger than the hamstrings. If you continually use heavier weights on machines such as the leg extension, the arc in the front of your legs will be bigger than the arc in the back of your legs. The leg extension machine isolates the quadriceps, and exacerbates the problem. In contrast, the leg press machine, which works the quadriceps, hamstrings and gluteal muscles, may provide a suitable alternative.