When you lift weights, your muscles work together, and concentric and eccentric muscle contractions happen at the same time. As you lift the weight up toward your shoulder during an arm curl, your bicep muscle shortens (concentric muscle contraction) and your triceps lengthen (eccentric muscle contraction).

How long does it take to see results from weight lifting?

How long it takes to build muscle and see results. Gaining muscle is a slow process. It can take about three to four weeks to see a visible change. You'll see some real results after 12 weeks, but it "all depends on your goals, and what type of strength training you are doing," says Haroldsdottir.

Can you build muscle just by lifting weights?

In fact, despite the widespread belief that muscles only grow after lifting heavy, you can and will build muscle just as effectively using lighter weights and higher reps.