Speed workouts are a staple in many training plans – and for a good reason. Whether you are training for a fast 5K or want to complete a marathon, speed work is essential for becoming a faster and stronger runner.
Speed work refers to a type of running workout in which you are running for certain intervals near, at, or even faster than your VO2max pace. Your VO2max is a measure of how much oxygen your body can use; most runners will hit their VO2max pace around their 5K to 3K (2-mile) pace, although you do get benefits doing it slightly slower.
During speed workouts, you maximally activate your slow-twitch muscles and intermediate muscle fibers, which increases your aerobic capacity.
Speed workouts also increase your production of myoglobin, which is a protein found in your muscles. Myoglobin transports oxygen to the mitochondria in your muscles, which in turn produce ATP to give your muscles energy. So, as you increase your myoglobin, you improve your body’s ability to quickly transport oxygen to the muscles for energy, making you able to run faster. Speed work is uniquely beneficial in this aspect, as research indicates that high-intensity running is the best way to develop myoglobin.
While you may not significantly increase your VO2max (genetics can limit it), you will see clear benefits of speedwork. Your body will become more efficient at recruiting your fast-twitch muscles. Your running economy will improve, so that you expend less energy and can run faster at the same effort level, whether you are running a 5K or 50K.
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