What is a Rep or Repetition in Exercise?

Reps

Exercise has a lot of nuance. On the surface it is just picking up weight and putting it back down, but it is way more than that. Exercise is about setting a plan that is based on the goal you set. 

Many different factors lead to a goal: diet (macro calories), weights, sets, rest, and repetitions. If any one of these parts of the whole are incomplete, then you won't be able to reach your goal.

Repetitions are one of the most crucial parts of lifting. There are three main factors that affect reps: tempo, form, and breathing.

Tempo is important based on what you want to develop strength or endurance. Typical tempos are 2 seconds up, no hold at the top, and 2 seconds down; written as 2-0-2.  This tempo is helpful for building strength. Another common tempo is 4-1-3. This is 4 seconds up, 1 second hold at the top, and 3 seconds down, which is a slow tempo that focuses on endurance and helps build size.  Focusing on tempo helps optimize muscle work.

Form is another key factor in repetitions. You may have seen people at the gym who lift weights really fast, especially on fixed machines. They are letting momentum take over their lift and not working their muscles through their full range of motion. It is also really annoying because they bang the weights.

Finally, breathing helps control the work that the muscles are doing. A common mistake in lifting is holding your breath when exercising.  This is called the Valsalva Maneuver. It can increase internal pressure which can cause heart attacks in people with high blood pressure who are at risk. Controlled breathing helps lifting optimally. You want to breathe in as you lower weights and breathe out as you are lifting weights.