You will not become more fit by doing the same training regimen every day. Athletes train by taking hard workouts on one day, feeling sore on the next, and not taking another hard workout until the muscles stop feeling sore. You cannot make a muscle larger or stronger unless you put enough resistance against it to damage it. An intense workout damages your muscles to cause burning during your workout and the muscle soreness you feel on the next day. Then you should go very easy or you may cause so much additional muscle damage that you can injure yourself and not be able to recover for weeks or months. If you wait until the soreness disappears, your muscles will be stronger than they were before your workout. As you continue to take stressful workouts only after the soreness disappears, you will become progressively stronger and faster and have greater endurance. For a detailed explanation see Recovery: The Key to Improvement in Your Sport
Interval Training to Build Endurance, Speed and Strength
Interval training means that you alternate fast and slow paces in your sport (running, cycling or other continuous motion activity). The increased intensity of interval training makes it the most effective way to strengthen your heart and lungs to increase your ability to take in and use oxygen (VO2max). I do short intervals that take less than 30 seconds each. You do not need to go at your maximum speed; I recommend that non-competing athletes should not do 100-percent-effort intervals.
Both continuous and interval training can increase endurance, but adding interval training to an endurance training program specifically makes muscles stronger than continuous endurance training (Med & Sci in Sprts & Exe, June 2017;49(6):1126–1136).
Before you start a program of interval training to improve your endurance, you should have exercised regularly for many months, be in good shape and not have any health conditions that can harm you. Caution:Intense exercise can cause a heart attack in a person who has blocked arteries or heart damage. Check with your doctor before you start a new exercise program or make a sudden increase in the intensity of your existing program.
Your Interval Workout Day: Warm up your muscles for 5 to 10 minutes. Pick up the pace until you feel short of breath and a tightness in your muscles, then slow down until you recover. If you are just starting to do interval training, you can do intervals that take only 10 seconds. If your muscles feel fresh, you can try to keep your fast pace for about 30 seconds. Alternate a 10-to-30-second intense pace that will start you breathing hard and then slow down for as long as it takes for you to regain your breath and for your muscles to feel fresh again. You do not need to time your recoveries because starting your next interval before you have recovered from your previous interval just shortens how fast you can run the next interval. The faster you run your intervals, the greater the improvement in your ability to run fast and long.
Stop the workout as soon as your leg muscles do not recover in a few seconds after you slow down after each interval. Continuing to do intervals when your leg muscles take longer to recover after each interval can cause enough damage to prevent you from being able to do intervals again for several days. After you have finished your interval workout, cool down for several minutes by moving at a slow pace. Note: When you are training properly, your muscles will probably feel sore every morning when you get up. However, after you exercise for 5 to 10 minutes, the soreness usually goes away and you will feel better. If the soreness remains, you should not take an intense workout that day. Either take the day off or exercise at a very slow pace.
The Day After an Interval Workout Day: If you have done a proper interval workout, your leg muscles will feel sore on the next day. You should never do interval training when your leg muscles are sore. Go at a slow pace as long and far as you like, or take the day off. When your muscles feel fresh again, you can take your next interval workout day.
You can do upper body and core strength training in two ways:
• You can try to lift heavy weights in two or three sets of 10, feel very sore on the next day and then do not lift weights with that same muscle group until those muscles feel fresh again, or
• You can lift lighter comfortable weights until your muscles start to fatigue and then stop immediately for that day. You can do up to 100 repetitions in a single set for each muscle group in your workout. This type of training can be done almost every day. For older people who have the time, I recommend a program of single set repetitions until your muscles just start to fatigue.
Strength Training Guidelines
Good and Bad Pain
There is a difference between the good burning of training and the bad pain of an injury. The good burning usually affects both sides of your body equally and disappears almost immediately after you stop exercising. The bad pain of an injury usually is worse on one side of your body, becomes more severe if you try to continue exercising and does not go away after you stop exercising. If you feel this kind of pain, stop your workout immediately.