If you want to become stronger and faster and have greater endurance, you need to exercise on one day intensely enough to damage your muscle fibers and feel short of breath and sore on the next day. And then train at reduced intensity for as many days as it takes for your muscles to heal and the soreness to lessen. Then you take your next intense workout. Knowledgeable athletes in most sports train by stressing and recovering because:
• You can’t make a muscle stronger unless you damage muscle fibers. You can tell you are exercising intensely enough to damage them by a feeling of burning in your muscles when you exercise.
• You can’t improve your maximal ability to take in and use oxygen unless you train intensely enough to become short of breath
The faster your muscles recover from an intense workout, the greater your improvement. The key to athletic training is to speed up your recovery so you can take your next intense workout. The banned performance-enhancing drugs called anabolic steroids improve athletic performance by helping athletes’ muscles recover much faster from hard workouts.
How Muscles Become Stronger
Muscles are made up of thousands of fibers just as a rope is made of threads. Each fiber is made up of blocks called sarcomeres joined end to end at the Z-lines like a line of bricks. Muscles contract only at each Z-line, not along the entire length of a fiber.
Intense workouts cause muscle damage, which can be seen as bleeding into the muscles themselves and disruption of the Z bands that hold the muscle sarcomeres together. Significant increases in muscle strength and size come only with workouts intense enough to break down muscle Z-lines. When muscles heal they become stronger and larger.
The faster you move on your hard days, the faster you can move in competition. However, continuing intense exercise when muscles feel sore can cause injuries and an over-training syndrome that can take weeks or months for recovery.
Avoiding Injuries During Intense Workouts
Both continuous and interval training can increase endurance, but adding interval training to an endurance training program specifically makes muscles stronger. First you warm up for 10 or more minutes by going at a slow pace. Then you pick up the pace until you start to feel a burning in your muscles or start breathing hard, usually after about 5 to 30 seconds. Then slow down. When you have completely recovered your breath and your muscles feel fresh again, start your next interval. Alternate picking up the pace and slowing down for full recoveries until your legs start to feel stiff and then cool down by exercising at a slow pace for at least 10 to 15 minutes. You can avoid injuries as long as you listen to your body when it tells you to reduce the intensity of your workout. Non-competitive athletes avoid injuries best when they use intervals lasting less than 30 seconds and back off each interval when they feel their muscles just starting to burn.
Most athletes in endurance and strength sports exercise on their recovery days and do not plan to take many days off. However, on recovery days, they work at a markedly reduced intensity to put minimal pressure on their muscles. If you develop pain anywhere that gets worse as you continue exercising, you are supposed to stop for that day. Active recoveries on easy days at low intensity make muscles tougher and more fibrous so the athlete’s muscles can withstand harder intense workouts on intense days.
Almost all top runners, cyclists and weight lifters do huge volumes of work, and most of it is on their less-intense recovery days. The stresses of intense workouts are extreme; the recoveries take a long time and are done at low pressure on the muscles.