If runners only do heavy-stress workouts, their bodies won't be able to recover from the heavy stress, and over time this can lead to injury. The Heavy/Light principle of running states that runners should follow workouts of heavy stress with workouts of light stress to give their bodies more time to recover from the heavy stress. A general rule-of-thumb for the amount of time needed for recovery is at least 48 hours, although the actual time is probably different for each person.

Runners ask what activity should they do for the periods of light stress. The answer is, "What ever they want to do as long as it doesn't put a lot of stress on their bodies."
For their light activities, some runners take days off and don't run or engage in other forms of physical activity other than their normal routines. Other runners run less distance, often at a slower pace. Still others engage in non-running activities such as cycling, swimming, walking, or lifting weights. Lifting weights is good for total body strength. We are all different, and we have different interests in choosing low-stress activities. The non-running activities are known as cross-training activities. Cross-training activities have one big advantage: they usually use our muscles in different ways than the muscles are used in running, thus giving the muscles a rest from the stress of running. Because of this broader use of our muscles, cross-training activities help us develop more well-rounded bodies.

The important consideration is that for runners who want to decrease their risk of injury, a day of light stress is a day of rest during which our bodies recover from the preceding day of heavy stress. This means that if we engage in cross-training on our light days, it should be at a lower rate of activity rather than our going "gung ho" with the cross-training. Athletes who are in intense competition, of course, will have higher intensity in their cross-training.

Here are articles from the web that further explain cross-training.
  • Eight Benefits of cross-training,7120,s6-238-263-266-7420-0,00.html
  • Cross-Training Has Benefits
  • Cross-Training Workouts
  • Mix It Up
Running/walking and cross-training are just parts of a program to provide exercise and physical fitness. The NIH Centers for Disease Control and Prevention says this about being fit.
There are 1,440 minutes in every day. Schedule 30 of them for physical activity!
Regular exercise is a critical part of staying healthy. People who are active live longer and feel better. Exercise can help you maintain a healthy weight. It can delay or prevent diabetes, some cancers and heart problems.
Most adults need at least 30 minutes of moderate physical activity at least five days per week. Examples include walking briskly, mowing the lawn, dancing, swimming for recreation or bicycling. Stretching and weight training can also strengthen your body and improve your fitness level.
The key is to find the right exercise for you. If it is fun, you are more likely to stay motivated. You may want to walk with a friend, join a class or plan a group bike ride. If you've been inactive for awhile, use a sensible approach and start out slowly.


Mark said...

This is really great stuff. I like that you've emphasized for people to perform their cross-training at a low-intensity. When training for shorter triathlons, I like to do bike/run bricks with swimming on my light days.

chiropractor sydney said...

Light activities target the cardiovascular system. You can train for endurance to improve your running.

Carol Appel said...

Glad you shared these articles to us. Cross-training is a bit hard but I think it's effective.

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