Warm-up before training: what to do and how long to spend on it

You open the gym app, you have 50 minutes and you want to start lifting right away. The warm-up seems like wasted time. It’s a common mistake, and also the reason many shoulder or knee complaints show up in set 3, not set 1.

This guide is for you if you train between 2 and 5 days a week without being a competitor. Beginner and intermediate level, although the guidelines also serve advanced lifters who tend to skip this part. You’ll leave with specific times per modality, a base routine and criteria to adapt it.

Why warming up is not optional

Warming up raises muscle temperature, improves nerve conduction and prepares the joints. A review by Fradkin and colleagues (2010, Journal of Strength and Conditioning Research) concluded that warming up improved performance in 79% of the studies analyzed. It’s not magic, it’s basic physiology.

It also reduces the risk of musculoskeletal injury, although the effect is modest and depends heavily on the type of sport. In strength and explosive work, the current consensus is that a specific warm-up of 8-15 minutes is enough for almost any session.

How long the warm-up should last

It depends on the session, not on a fixed rule. Approximate ranges:

• Strength (hypertrophy or maximal strength): 10-15 minutes.
• Continuous cardio (running, cycling, rowing): 5-10 minutes.
• HIIT or intense intervals: 12-20 minutes.
• Team or racket sports: 15-20 minutes.

If you are over 40, coming from the sofa, or training first thing in the morning, add 3-5 minutes. Morning stiffness is real and is not resolved in 90 seconds.

Dynamic warm-up vs static stretching

Here there is a reasonable consensus. Prolonged static stretching (holding a position for more than 45 seconds) before training reduces strength and power output by between 3% and 5%, according to the meta-analysis by Simic et al. (2013, Scandinavian Journal of Medicine & Science in Sports).

A dynamic warm-up —controlled movements that take the joint through its range— improves performance and does not penalize strength. Practical translation: static stretching is best at the end of the session or on a separate mobility day. Before training, movement.

The three phases of a well-done warm-up

Phase 1: general cardiovascular activation (3-5 min)

Progressively raise your heart rate. Goal: reach 60-70% of your maximum heart rate, or an RPE of 4-5 out of 10. You should be able to talk in short sentences.

Options: treadmill, bike, elliptical, rowing, skipping rope, or going up and down a step at home. Anything that activates legs and arms works.

Phase 2: dynamic joint mobility (3-5 min)

Full-range movements, without bouncing. A base circuit:

• Shoulder circles: 10 forward + 10 backward.
• Standing hip rotations: 8 per side.
• Deep squat with pause: 5 repetitions.
• Lunge with torso rotation: 6 per side.
• Leg swings (front-back and lateral): 10 per side.

Phase 3: specific activation (3-8 min)

Here you rehearse the pattern you are going to train, with low load. If the session includes barbell squats, do 2 sets with an empty bar and then 1-2 ramp-up sets at 40-60% of the working weight. If the session includes sprint intervals, include 3-4 progressions of 60-80 meters.

This is the phase most people skip and the one that most improves performance.

Base routine according to what you are going to train

Upper body strength day (12 min): 5 min bike + shoulder and thoracic rotations + incline push-ups x8 + band row x12 + 2 ramp-up sets of the main exercise.

Lower body strength day (12 min): 5 min walking on an incline treadmill + deep squat x5 + glute bridge x10 + lunges x6 per side + 2 ramp-up sets.

Running 40-60 min at an easy pace (8 min): 5 min brisk walk, then easy jogging, ankle and hip mobility, 3 short progressions.

HIIT or intense class (15 min): all three phases complete, without cutting corners. This is where most injuries from entering cold occur.

At home without equipment: jumping in place, bodyweight squats, knee push-ups, slow mountain climbers. It works.

Common warm-up mistakes

1. Long static stretching before strength or speed work. We’ve already seen it: it hurts performance.
2. Warming up only with generic cardio. 10 minutes on the bike don’t prepare your shoulder for military press.
3. Going too hard. If you finish the warm-up out of breath, you’ve trained, not warmed up. RPE 5, maximum 6.
4. Skipping it when you’re short on time. It’s better to cut sets from the main workout than the warm-up.
5. Copying someone else’s warm-up at a different level. An advanced lifter with clean mobility needs less than you do.

Warnings: if you are pregnant, have a recent injury or a cardiovascular condition, consult your doctor or physiotherapist before setting a routine. Intensity progression should be even more gradual.

What to do tomorrow

1. Calculate your approximate maximum heart rate (220 minus your age) and aim for 65% on your watch or phone. That is the ceiling for phase 1.
2. Choose 4 mobility movements from the list above and always do them, in the same order. A fixed routine is easier to stick to.
3. Add 2 ramp-up sets before the first heavy exercise of the day. Just that.

Frequently asked questions

Can I warm up just with the light first set of the exercise?

It’s not enough if you are going to move heavy loads or do intervals. It may be enough for a very light maintenance session. As a rule, dedicate at least 8 minutes.

Does the warm-up count as cardio?

Not for accumulating the weekly activity minutes recommended by the WHO (150 min moderate). The intensity is too low and the duration short.

Should I warm up before stretching?

Yes. Stretching cold increases the sensation of pulling and does not provide more flexibility. Five minutes of gentle movement before any flexibility work.

And if I train early in the morning?

Extend phase 1 to 6-8 minutes and lower the starting intensity. Morning joint stiffness is resolved with time, not with more load.

Does a sauna or a hot shower work as a warm-up?

It raises body temperature but does not activate the neuromuscular system or prepare movement patterns. It can complement, but not replace, a warm-up.