Think of your muscles like ropes. A thin rope can’t hold as much weight as a thick rope. Imagine these ropes were being used to tow heavy objects. Over time the thin rope would get damaged more so than the thick rope. Muscles are intelligent, alive ropes. They can sense when the tension is getting to be too much and they can alter themselves to suit ie; grow thicker. _ So when aiming to create this adaptation, we have to use enough tension to get the muscles to want to grow. But tension isn’t the only factor. Time also comes into play. The tension needs to be placed on the muscle for long enough for it to feel the need to change. The effort also needs to be intense enough. Muscle uses up a lot of energy, even when it's not doing much, so the brain doesn't want to create an energy demand unless it’s necessary. Meaning, you won’t grow muscle unless you have to. So frequency, consistency and intensity all need to be present. _ Just like with Strength, there is no “best” number of reps and sets. However, there are some guidelines. Most studies show that growth will occur with tension that is 60% or above 1RM (read the strength post) and more than 20 seconds (which is approximately 6 reps depending on the exercise). If it's any longer than ~60 seconds, the weight is probably too light to create enough tension. _ So your strategy is this: Choose a weight or resistance than makes it difficult to complete a set when using a rep scheme between 6 & 12, or a time frame between 20 & 45 seconds, rest and do another set. Anywhere from 1 to 10 sets has been shown to work. If your less trained go with lower sets, 3 should be fine. Stay consistent with that for 3-4 weeks, if you’re able to do more than 15 reps/60 seconds then you can increase the weight. This will work for months, even years before you’ll need to change strategies. But unless you're a seasoned bodybuilder, I doubt it will ever be a concern. _ Bench Press Example: Weeks 1-4: 150lbs - 8 reps x 3 sets. Weeks 5-8: 150lbs - 10 reps x 3 sets. Weeks 8-12: 150lbs - 12 reps x 3 sets Weeks 13-16: 160 lbs - 6 reps x 3 sets Weeks 17-20: 160lbs - 8 reps x 3 sets. _ Conclusion; There’s no magic numbers. Just stay consistent.