Building muscle mass and toning are both increases in muscle size, and training is similar for both. The difference comes in the volume of training. Much more work is needed to significantly increase muscle mass. Walking offers many health benefits, but it will not cause significant changes in either muscle mass or tone.
Building Muscle Mass and Toning
According to Dr. Joseph Chromiak of the National Strength and Conditioning Association, "Strength training is an essential component of exercise programs for increasing muscular strength and size." Increases in muscle size occur when muscle fibers are overloaded and broken down, which only comes from consistent weight training. After muscle fibers are broken down, they adapt and heal back at a bigger size.
Walking is a cardiovascular activity that people of all fitness level can participate in. Walking effectively elevates your heart rate and burns calories, thus promoting cardiovascular health and an appropriate body composition percentage. But it does not provide enough of a stimulus to either build or tone muscle because it doesn't ever overload your muscle fibers.
How to Build and Tone Muscle
To build muscle mass or tone muscles in your legs, you must participate in consistent strength training. Weight-training exercises such as squats, lunges, step-ups, deadlifts and calf raises will target the muscles in your lower body. To build muscle mass, complete four to six sets of six to 12 repetitions three days per week. To tone your muscles, complete two to three sets of six to 12 repetitions two days per week. Make sure you allow at least 48 hours in between each strength-training session.
Incorporating steps or hills into your walking routine may provide a temporary overloading stimulus that can cause some minor muscle development. But the muscle size increases are likely to plateau rather quickly, because your muscles will adapt to stress after a short time and thus the walks will no longer provide enough of an overload.