What is the rest time between sets?

In one line

The rest time between sets is the time you rest after finishing one set and before starting the next.

What is the rest time between sets?
The 'rest 1 minute, then the next set' time
Workout plans often list a rest time next to the weight and reps, such as 'rest 1 min' or 'rest 3 min'. This time you rest between one set and the next is one of the parts of planning a workout. This post explains what it is and what happens in your muscles while you rest.
In short
The rest after one set, before the next
The rest time between sets is the time you rest after finishing one set and before starting the next. A Korean dictionary defines rest as 'stopping what you were doing and resting for a moment'. It is set along with the weight, reps and number of sets when planning a workout.
First, reps and sets
A set is a group done in a row
Lifting a weight up and lowering it once is one 'rep'. A group of reps done in a row without resting is one 'set'. Usually you do several sets of the same exercise and rest between them. That rest time is the topic of this post.
In your muscles during rest
The fast energy store refills
Muscles store a substance that refills their energy fastest when they work short and hard. It is called 'creatine phosphate'. Right after exercising until exhausted, only about 1/6 of the normal amount is left, and it refills while you rest.
How fast it refills
Fast at first, several minutes or more to fill up
Once you start resting, creatine phosphate refills quickly over the first few tens of seconds. After that it slows down, and filling up completely takes more than several minutes. If you start the next set before it has refilled, the muscle produces less force.
With short rest
The next sets have fewer reps
When doing several sets with the same weight, the shorter the rest, the more the reps dropped in later sets. Resting 30 seconds cut the reps more than resting 2 minutes. Even with 2 minutes of rest, later sets did not match the first set.
How long to rest
It has been set by goal
According to a review of studies, when training for maximum strength, resting 3 to 5 minutes between sets let people do more reps over several sets and gain more strength. On the other hand, training for muscular endurance (the ability of a muscle to keep producing or holding the same force for a long time) has used short rests of 1 minute or less.
Different from resting inside a set
Rest between sets vs rest within a set
Some methods take a short rest of about 10 to 30 seconds in the middle of a set, then continue with the same weight. This rest placed inside a set is different from rest between sets and has its own names. 'Rest-pause' and 'cluster sets' work this way.
Common myth
Is short rest better because more hormones are released?
Some say short rest is better because more muscle-building hormones (substances that travel in the blood and carry signals) are released. In one study, the 1-minute rest group had a bigger rise in testosterone, but over the 4 hours after exercise, the rate of making new muscle protein rose about twice as much with 5 minutes of rest. A day later there was no difference.
Summary
The time you rest between sets
The rest time between sets is the time you rest after finishing one set and before starting the next. During it, creatine phosphate in the muscles refills. Resting briefly did not make the muscle-building response bigger. Related terms: creatine phosphate, muscular endurance, rest-pause.