Muscles are made up of slow- and fast-twitch fibers, the ratio of which can determine a person's optimal speed.
When it comes to running, swimming or cycling, building up your leg muscle strength can help you become a quicker, more efficient athlete. The main leg muscle groups used in fitness activities include your quadriceps, hamstrings and gluteal muscles. Working on building up the strength in these muscle groups will help you become faster. There are several exercises that can help promote strength while improving your overall speed.
While they primarily work your quadriceps, hamstrings and glutes, squats are considered a total-body exercise. These exercises, when done properly, can help you build power and speed in your leg muscles. Squats strengthen the muscle groups that work together to propel your body forward. The stronger the muscles, the quicker your body can react, which results in a faster speed. In addition to the traditional air squat, you can add variations like the side-step squat, where you start with your feet together and step one foot to the side before completing the movement, to further build strength in your leg muscles.
The hamstrings and gluteus muscles are primary muscle groups in your legs that help you move faster. The hamstring pulls the leg back so you can quickly push off the ground, while the gluteus muscles help promote propulsion. A study by the American Council on Exercise found that the forward lunge is one of the best exercises to to promote activity in your hamstrings and gluteus maximus and medius. Because the lunge movement is similar to the natural human gait pattern, it challenges both your lower-body muscles and your body's ability to balance.
Known for their explosiveness, plyometrics are a type of exercise that focus on jump training. In doing so, it trains muscles to work together, helping develop quicker and more powerful legs. A study published in the October 2013 issue of the Journal of Strength & Conditioning Research found that when combined with sprint workouts, plyometrics helped improve acceleration. Plyometric exercises include box jumps and tuck jumps. These exercises can also include traditional exercises like squats and lunges that are modified to incorporate plyometric movements.
To increase intensity and keep your muscles engaged as you build up strength, add weight to your body-weight leg strengthening exercises. This helps your muscles gain strength by adapting to more resistance, helping you move quicker and more efficient when the load is removed. Exercise tools and equipment like sandbags, kettlebells and medicine balls allows you to easily incorporate this weight. Weights can also be used in plyometric exercises, but do require some balance and coordination so that you do not injure yourself.