In order to maintain effectiveness of your workouts over long term, you have to employ a concept known as cross training. Although there is no hard and fast definition of cross training, basic idea is that you continually change your exercise program to work both your muscular and your cardiovascular systems in a variety of ways, forcing your body to adapt to a new stimulus. Remember that whole idea behind exercise is to make your body do things that it is not used to doing. In response to that effort, your body naturally adapts in order to meet changing energy demands of activities that you engage in. This process happens with your muscles, as well as with your heart, lungs, and circulatory system - collectively known as cardiovascular system. To ensure you get most out of your cross training efforts, you should make changes to activities that challenge your muscles as well as your cardiovascular system.

Challenging Your Muscles

When you are putting together muscular training part of your exercise program, remember that primary mission of activities is to challenge your muscles and connective tissues - tendons and ligaments - beyond their normal boundaries. For example, if you were to pick up a suitcase that only weighed 5 pounds, it would probably not be very difficult for you. However, if that same suitcase had 50 pounds worth of items inside, it would be significantly more difficult to pick up and carry. In response to that increased demand, your body would recruit additional muscle fibers to assist with work, and in some cases would even recruit a different type of muscle fiber. Although we won't get into details about different types of muscle fibers in human body, you do want to take away fact that number and type of muscle fibers recruited for any given task is proportionate directly to difficulty of task.

Let's apply this concept to weight training - or resistance training, as it is often called. If you were going to do a basic bicep curl with 5 pounds, your body would engage a certain number and type of muscle fibers. Doing exactly same exercise with a more challenging weight would cause your body to need additional resources in order to handle increased demand. However, is that only true of picking up a heavier weight? What would happen if you used same weight, but did a higher number of repetitions? The same basic concept applies - your body will recruit additional resources in order to accomplish task. What can be determined from that fact is that in order to change stimulus on your body, two easy ways to do so are are to increase weight and/or increase number of repetitions.

However, there are other ways to challenge a particular muscle group in addition to simply adding weight or repetitions. What about changing position of your body when you do exercise? Using same example as above - bicep curl - most people do basic version of that exercise standing up, with their arms extended, elbows at side, and palms facing forward. What if you were to do same exact movement, only this time, you turn your palms to face center of your body throughout entire exercise? Do you see how that would change stimulus? You would still be engaging biceps of your upper arm, but you would also engage muscles of your forearms in a different way, just because of position of your palms.

Further, what if you were to change speed at which you did exercise? Most resistance exercises should be done as a basic count of 2 seconds during initial phase (also known as concentric phase), and then a count of 3 to 4 seconds during second phase of movement (known as eccentric phase). What if you were to reverse that process? Count to 4 during phase one, and only count to 2 during phase two. Do you think your body would need to react differently to handle different stress? Of course!