Mixing Heavy & Light Weights for Exercises

Mixing the amount of weight you use to perform exercises will help you achieve three different results, specifically muscle-building, calorie-burning and improved muscular endurance. You can change weights, or loads, during the same workout, or alternate high-intensity and low-intensity routines on alternate days, depending on your specific fitness goals.

The amount of weight you use, or the resistance level you choose on a weight machine, is referred to as the load. The number of repetitions and sets you perform refers to the volume of work you do. Using higher loads and less volume, you’ll build muscle more effectively. Using lighter loads and higher volumes, you can create cardio workouts. Performing workouts in between those two extremes helps you create muscular endurance workouts.

For muscle-building exercises, consider using the maximum weight you can lift, or a load close to that, performing five repetitions of an exercise. Take a one-minute break, then perform two to four more sets. To create cardio routines, use light enough loads that you aren’t limited to a specific number of sets or reps. This will allow you to add resistance to an aerobic workout without having to stop because of muscle fatigue. To improve muscular endurance, use about half the weight you can lift and perform 10 to 12 reps of an exercise, or reps for 30 seconds, then change exercises.

The more weight you use, the more intensity you create with your weightlifting and more damage you do to your muscle fibers. The repair response to this damage is what builds your muscles. If your goal is more muscle building, calculate the maximum amount of weight you can use to perform each exercise, then try to increase that each week as you build strength. Knowing your max will allow you to create warm-up sets of exercise using a percentage of your max. For example, you might perform your first set of exercises using 60 percent of your maximum weight, your second set at 80 percent, then your final sets using your max.

Using less weight, such a 2- or 3-pound dumbbells, adds some resistance to your exercises but allows you to perform more repetitions. This helps you build muscle without bulking up, while you’re burning calories during a cardio routine. If you want to be able to use your muscles for long periods of time, such as during a racquetball game or tennis match or other activity, build muscular endurance. To create a muscular endurance circuit-training routine, try using 40 percent to 60 percent of your maximum weight, performing an exercise for 30 seconds. Take a quick break, then change to a different exercise. Keep performing 30-second circuits for the duration of your workout.

If you are not an athlete who wants to create specific bodybuilding or endurance workouts, but you want to build some muscle and improve your sports performance, you can mix your weights during a single workout. Start your workout without weights, or with very light weights, to get your heart rate into your target range. Toward the end of your workout, add a few sets of exercises using heavy weights to build more muscle, especially if you want to target a specific area of your body. Another option for a workout is to create a 10- to 15-minute endurance routine at the end or an aerobic workout by adding more weight to your exercises and performing 30-second sets. Be careful not to try heavy weightlifting after you’ve performed cardio and endurance exercises in one workout, which will have fatigued your muscles -- you might not have the strength to lift your maximum loads at the end of such a workout and might injure yourself trying.