There are two ways to warm up for a lifting session. A general warm-up raises your temperature: five to fifteen minutes on a bike or a rower. A specific one rehearses the lift: lighter sets of the exercise you are about to do, climbing toward the working weight. For strength training the evidence favors the second, and it takes less time.

The short answer

Warm up with the exercise itself: two or three lighter sets that climb to your working weight, with fewer reps at each step. The heavier the working sets, the more they need it; sets of 12 reps or more barely do, because their first reps do the job. A general warm-up is optional, and long static stretches before lifting cost some strength, so keep them short or save them for later.

What the studies found

  • Warming up helps, in general. A 2010 meta-analysis of 32 studies found that a warm-up improved performance in 79 percent of the measures, with little evidence that it harms.
  • It does not add reps to hard sets. In a 2014 trial, 15 men did four sets to failure at 80 percent of their one-rep maximum on the bench press, the squat and the arm curl: the reps were the same with no warm-up, a specific one, an aerobic one or both. In a 2024 trial of the back squat, neither a heavy warm-up set nor a fast light one beat the usual eight light reps.
  • It prepares a heavy first set. In a 2020 study of 40 trained men before three sets of six at 80 percent of their maximum, the squat moved faster after a warm-up set at 80 percent of the working weight than after one at 40, and the bench press did best after one at 40 and one at 80. A few light reps, the authors concluded, are not enough.
  • Heavy work needs it most. A review of time-efficient training found little support for a general warm-up and advises exercise-specific warm-ups, above all before loads over 80 percent of your maximum; in sets of higher reps, the first reps are a warm-up. A review of 31 upper-body studies found strong evidence that dynamic warm-ups with heavy loads improve strength and power.

So warm-up sets are not a bonus set of gains. They make the first working set go as planned: the lift rehearsed, the weight known before it matters.

Stretching before lifting

A meta-analysis of 104 studies found that static stretching before exercise lowered strength by 5.4 percent on average, least with stretches of 45 seconds or shorter. The time-efficiency review adds that dynamic stretching does not appear to reduce strength, and advises stretching only when flexibility is itself the goal. If a joint feels stiff, move it: leg swings, arm circles, the empty bar through the full range.

How many warm-up sets

The research compares warm-ups; it does not set percentages. What follows is common gym practice, and close to the pattern of our programs, with each weight a part of your working weight:

Exercise Warm-up sets
The first heavy lift of the day 2: about half the weight for 5 to 8 reps, then about three quarters for 3
A second heavy lift 1: about half the weight for 5 to 8 reps
A heavy deadlift, or sets of 5 or fewer near your limit 3: about 40% for 8, about 60% for 5, about 80% for 2 or 3
Isolation exercises and sets of 12 or more None, or a lighter first set

Let the reps fall as the weight climbs, so the warm-up prepares you without tiring you, and rest only as long as it takes to load the next weight. A Barbell Back Squat for sets of five at 100 kg (about 220 lb), the first lift of the day, could run: 50 kg for 6 reps, 75 kg for 3, then the working sets. In pounds, about 110 and 165.

What it means for your week

Of the 397 exercise rows in our 25 programs, 67 carry warm-up sets: 21 rows one, 42 rows two and 4 rows three, all four of them the Deadlift. Each is a squat, a hinge, a press or a row with a barbell, dumbbells or a machine: the Barbell Back Squat, the Barbell Bench Press, the Deadlift, the Standing Barbell Overhead Press, the Bent-Over Barbell Row, the Leg Press and a few more. No isolation exercise has any, and neither do the bodyweight, kettlebell, suspension-strap and circuit programs; start those at an easy pace instead.

Strength Workout B of Beginner Strength Barbell, 3 days shows the pattern: two warm-up sets for the squat, two for the overhead press and three before the day’s one heavy set of five deadlifts. No row says how many reps a warm-up set takes or at what weight; the table fills that in. Warm-ups add minutes, which How Long Should a Workout Be? counts in, but not working sets, which is what How Many Sets per Muscle per Week counts.

How to apply it

  1. Warm up the first lift of the day with two sets, a second heavy lift with one, a heavy deadlift with three.
  2. Climb in steps: light and easy first, then closer to the working weight for only a few reps.
  3. Read the last warm-up set. If it moves slower than usual, start the working sets a little lighter; How Much Weight Should You Lift? has the rule.
  4. Go easier on what follows. An exercise for muscles that are already warm needs one light set at most.
  5. Log them as warm-ups, so your records stay honest.

In Trenno a set becomes a warm-up with a tap on its number: Select set type, then Warm-up, and the number turns into a W. A program saved from Explore arrives with its warm-up rows already marked W ahead of the working sets, the weight and the reps left for you. Warm-up sets stay out of the tonnage, the records, the charts, the sets per muscle group and the recovery estimate, unless you switch on Count warm-ups in totals in the workout settings.

Mistakes and myths

  • “Twenty minutes of cardio warms me up for lifting.” It warms you, but it does not rehearse the lift. The lighter sets are what prepare the working ones.
  • A warm-up that tires you. Ten reps at 90 percent before a heavy set is a working set. Keep the heavy steps short.
  • No warm-up before heavy sets. The first working set then becomes the warm-up, and the week’s heaviest set is spent on it.

FAQ

Do I need to warm up before every exercise?

No. Warm up the first exercise for each muscle. Later exercises for muscles that are already working need one light set at most.

How long should a warm-up take?

About five minutes for two or three sets with short breaks. A general warm-up on top of that is up to you.

Should I stretch before lifting?

Moving the joints through their range, yes. Long static stretches are better after the session, or on another day.

Do warm-ups prevent injuries?

The research barely says. The upper-body review above found no study of warm-ups and injury prevention at all. Warm up for the reason the studies support: a first working set that goes as planned.

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