For stronger and more powerful muscles, use higher resistance and lower reps with 2-3 minutes rest between sets is recommended. (Example: 4 sets of 5 reps)

For toning muscles and building stamina, use lower resistance and higher reps with 1-2 minutes of rest between sets is recommended. (Example: 3 sets of 15 reps)

Muscle confusion: an important concept to achieve the most from your fitness plan by constantly mixing up your exercise routine. Your muscles, like many things, become accustom to your routine. This can result in a plateau or a sudden decrease in your muscle gains. Constant changes or varied exercises challenge your muscles resulting in more muscular gains. Therefore, using one day/week/month to focus on lower reps with higher resistance and the other day/week/month to focus on higher reps with lower resistance helps you continue to see results.