How to Warm Up Before Swimming: Deck Exercises and First Lengths

By the SwimmingClasses.sg coaching team · Last reviewed: October 2026

A swimming warm-up is not optional and it is not just a few arm circles on the pool deck. Done properly, a warm-up raises core temperature, increases blood flow to working muscles, prepares joints through their full range of motion, and reduces the risk of injury. Done poorly — or skipped — you start a training session or lesson at a fraction of your effective capacity and increase your chance of muscle strain.

This guide explains what a good warm-up looks like for swimming, what to do on deck before you get in, and how the first few minutes in the water should be structured.

Why Swimmers Need a Specific Warm-Up

Swimming is a full-body activity that puts particular demand on the shoulders, hips, and ankle joints. Cold muscles and joints are stiffer and less able to produce coordinated force — the kind of coordinated movement swimming requires. Cold muscles are also more prone to strain when they are asked to work suddenly through a large range of motion.

Water temperature makes this more acute. Even Singapore’s outdoor pools in warm weather are typically 28 to 32°C — cooler than your core body temperature. Entering cool water cold is a double stress: the water draws heat from your body at the same time as your cardiovascular system needs to respond to the effort of swimming.

A warm-up prevents this mismatch. By raising your heart rate and temperature before entering the water, your body is ready to work from the first stroke rather than spending the first few lengths catching up.

Deck Warm-Up: What to Do Before You Enter the Pool

Five to eight minutes of movement on the pool deck is the starting point. The focus is on dynamic movement — controlled movement through range of motion — rather than static stretching, which is better suited to the cool-down after a session.

Arm swings: Forward and backward in large circles, 15 to 20 repetitions per direction. This mobilises the shoulder joint through the same arc it will move through in freestyle and backstroke.

Cross-body arm swings: Swing each arm across the body at shoulder height, alternating sides. Targets the rear shoulder and upper back.

Hip circles: Hands on hips, feet shoulder-width apart, draw slow, large circles with the pelvis. 10 rotations each direction. Essential for breaststroke kick preparation.

Ankle rotations: Sit on the pool edge or balance on one foot and rotate each ankle through its full range. 10 rotations each direction per ankle. The ankle is the driving joint in the flutter kick and the breaststroke kick — cold, stiff ankles produce ineffective kicks.

Neck rolls: Slow, controlled half-circles from side to side. Prepares the neck for breathing rotation in freestyle and backstroke.

Torso rotations: Arms extended at shoulder height, rotate the torso left and right from the hips while keeping them forward. 20 repetitions. This activates the core rotation central to freestyle and backstroke.

In-Water Warm-Up: The First Four Lengths

The pool entry phase is as important as the deck work. Jump straight into training pace from cold water and you will feel it — breathlessness in the first 50 metres is a signal that the cardiovascular system has not yet caught up with demand.

Structure your first four lengths (100 metres in a 25m pool) as follows:

Length 1 — Easy freestyle or backstroke, focus on body position. No effort to go fast. Just feel the water, check that your body is horizontal, and exhale steadily underwater.

Length 2 — Easy breaststroke or choice stroke. Build rhythm. Take an extra beat in the glide if it is breaststroke. Let the stroke settle.

Length 3 — Drill work. Choose one drill for the stroke you are focusing on in today’s session — catch-up drill for freestyle, kick-on-side for backstroke, glide-and-pause for breaststroke. This reinforces technique while your body temperature continues to rise.

Length 4 — Build to 75% effort. This is the transition from warm-up to working pace. By the end of this length, you should feel ready to swim at full training intensity.

What Not to Do in a Warm-Up

Skip the deck work: Many swimmers walk straight from the changing room to the pool. Five minutes of arm swings and hip circles makes a measurable difference to how the first lap feels. It is worth the time.

Static stretch before swimming: Holding a hamstring stretch or a chest stretch for 30 to 60 seconds before swimming is counterproductive. Static stretching before exercise temporarily reduces muscular force production. Save static stretching for after the session.

Start hard: Jumping in and doing an all-out sprint to warm up faster does not work. It increases injury risk and increases the likelihood of breathlessness that disrupts the early part of your session.

Skip the in-water build: Even if you are pressed for time and your deck warm-up was thorough, the first two lengths in the water should always be easy. Cold water entry without a gradual build is a cardiovascular and musculoskeletal stress that is not worth the few seconds saved.

Warm-Up for Lessons and Coaching Sessions

If you are arriving for a swimming lesson, your coach should include warm-up time in the session structure. If they jump straight into stroke correction without any warm-up activity, it is reasonable to ask why.

For young children in swimming lessons, warm-up is usually built into the first water games and introductory activities rather than structured as a separate phase. Children warm up faster than adults and are often less affected by cold water entry, but the principle of starting easy remains.

Consistency Pays Off

Swimmers who warm up consistently tend to have better sessions, make faster technical progress, and experience fewer overuse injuries — particularly in the shoulder, which is the joint most commonly affected by swimming-related injury.

Five minutes on deck, four easy lengths in the water. It is not complicated, and it is the difference between a productive session and one spent managing early discomfort.