Before answering, we have to accept two proven facts:
1. The body can only improve at a certain rate. 2. You can only exercise for a given amount of time without significantly increasing your risk for injury.
Let’s look at the first one. Your fitness level can improve about 50% per week sequentially, based on the training load or how much exertion you put on your body.
To further explain this, if you increase your training load (whether that load is adding five miles per week to your running or lifting an additional 20 pounds of weight per strength training session, etc.), your body will improve and adjust to the new load at the rate of:
• 50% the first week • 25% the second week (50% of 50%) • 12.5% the third week (50% of 25%) • 6.25% the fourth week (50% of 12.5%)
To show it another way, it would look like this:
• Week one – 50% • Week two – 75% • Week three – 87.5% • Week four – 94%
So after four weeks of training using your new routine, your body has improved 94%. To increase any more significantly, you would have to increase the load and start over again from your last stopping point.
Time for Fitness
Let’s look at the second one – you can only exercise for a given amount of time. Regardless of your fitness level, your body is conditioned at a certain level.
If you try to push your body harder than you should, you increase your risk of an injury. Plus add to the fact that your body only has so much energy it can burn at any one time.
Based on these two facts, don’t expect to go from being a couch potato to running 5 miles in one day- it’s just not going to happen.
However, if you begin by walking 30 minutes the first day and then start a progressive walk/run exercise routine where you strive to walk less and run more, you should, over the course of a month, reach your goal of running 5 miles.
The other fact worth noting is that different parts of the body develop at different rates.
Your heart and skeletal muscles responds more quickly to exercise than do your bones. So for example if you have been doing cardio training by biking, your heart and large lower muscle groups may be ready to run, but your leg bones may not and thus you have an increased risk of a stress fracture due to the pounding of running. So to take up running, you must start slow and build from there.
The bottom line is when trying to improve your fitness level, listen to your body. It will tell you if you are trying to progress too fast. Listen and adjust or be prepared to suffer the consequences.