The Benefits of Varying your Workout Routine
Individuals should consider varying their exercise routines for two fundamental reasons: (1) to prevent boredom associated with doing the same things workout after workout and (2) to avoid or delay reaching a plateau in workout performance and, subsequently, training results. Research has shown that adding variety to an exercise program can improve adherence. Exercise scientists at the University of Florida observed that varying your exercise routine can help you stay physically challenged. Many of the body's physiological systems (e.g., the muscular system) adapt to an exercise program within approximately six to eight weeks. If you do not modify your exercise routine, you reach a plateau because your body has adapted to the repetitive training stimulus.
There are several ways you can spice up your current workout routine, including boosting the intensity of your workouts. For instance, if you jog or run, try incorporating some intervals of sprinting (e.g., sprint to a given landmark, then jog to the next one) or adding more hill work to your run. You can also cross train and perform different activities to provide your body with a new challenge. A nice alternative for resistance-training exercises involves changing the sequence in which you perform the training exercises. By fatiguing the muscles in a new order or pattern, you are requiring them to adapt to a new training stimulus. Another option for adding variety to strength-training workouts is to replace some or all of the exercises in your workout routine (e.g., substitute a dumbbell pectoral fly exercise on a stability ball for your typical barbell bench press exercise).
Keep in mind that doing the exact same workout, day after day is not necessarily a bad thing. Some people enjoy a predictable, consistent routine. They don't mind the possibility of experiencing a training plateau and are content to maintain their health and fitness levels with a comfortable exercise habit. However, many individuals need to push themselves to new levels and try different activities to stay enthusiastic and excited about their workouts. By varying their exercise routines, individuals can not only stay physically challenged, but mentally stimulated as well.
Reference: ACE FitnessMatters