The dolphin kick is one of swimming’s most distinctive and dynamic movements. It underpins underwater speed, distance per breath, and the ability to transition from starts and turns into race momentum. In this guide, you will find a thorough explanation of the dolphin kick, the biomechanics behind it, the best drills to improve it, and practical advice for integrating this undulating kick into a training programme. Whether you are a budding sprinter or a seasoned club swimmer, understanding and refining the dolphin kick can unlock faster times and more efficient water travel.
What is the Dolphin Kick?
In essence, the dolphin kick is an undulating, wave-like motion that propagates along the length of the body, generated primarily by the hips and core, with the legs moving together in a dolphin-like flexion and extension. Unlike a vertical flutter kick or a straight-leg whip, the dolphin kick relies on a continuous, rhythmic wave that starts at the chest, travels through the hips, and finishes with the feet. The feet point and flex in a coordinated manner to maintain propulsion and minimise drag.
Commonly associated with butterfly technique, the dolphin kick is equally valuable in freestyle during underwater phases and after starts and turns. When executed well, it creates a sustained speed that reduces the time swimmers spend breaking the surface. In competition, the ability to stay underwater and maintain a strong dolphin kick can be the difference between a podium finish and a respectable time behind the leaders.
Biology and biomechanics of the undulating kick
Understanding the physical science of the Dolphin Kick helps swimmers train smarter. The undulating kick works as a chain reaction: a wave generated by the torso travels through the hips to the legs and feet, producing propulsion while maintaining a streamlined posture. The key components are:
Hips and torso drive the wave
The primary driver of the dolphin kick is the hips. A controlled, powerful hip extension (and subsequent flexion) creates the large amplitude of the wave. The upper body helps stabilise the movement, while the core transmits the energy down the spine into the pelvis and legs. A stiff, neutral spine reduces energy leakage, so focus on core engagement without locking the ribcage rigidly.
Ankles, feet, and propulsion
Though the legs move as a unit, the ankles act like a hinge that allows the ankles to extend and flex in a coordinated manner. The feet stay relaxed yet pointed, following the wave through plantar flexion and slight dorsiflexion as the wave travels. Proper ankle flexibility is essential; tight calves or stiff ankles can blunt the kick and reduce propulsion.
Breathing, head position, and drag reduction
Breathing during the underwater phase should be calm and controlled. A raised head disrupts the horizontal line and increases frontal drag. Practising with a streamlined head position—eyes looking slightly forward and down—helps preserve a long, narrow silhouette. This position supports the undulation by keeping the waterline stable and reducing resistance as the wave travels down the body.
Timing and frequency
Timing is critical. The aim is to maintain a steady cadence that suits the swimmer’s height, leg length, and core strength. Most swimmers find a cadence between 0.9 and 1.3 cycles per second workable in the underwater phase, depending on distance to surface and race discipline. Too slow a cadence wastes energy, while too fast a cadence can cause loss of streamlined position and reduced propulsion per cycle.
Benefits of a powerful Dolphin Kick
Mastering the Dolphin Kick offers several advantages that translate directly to speed and efficiency in the pool:
- Increased underwater speed: A strong undulating kick can push a swimmer ahead during starts and turns, enabling them to cover more distance underwater before breaking the surface.
- Improved efficiency: The wave-like propulsion uses the body’s natural biomechanics, often requiring less energy per metre than a pure leg-driven kick when executed correctly.
- Enhanced glide through streamline: A well-timed dolphin kick drives the body forward while maintaining a tight streamline, reducing drag at important transition points.
- Better stroke integration: When the kick is well coordinated with arm movements, it creates a seamless propulsion sequence that speeds up the entire stroke pattern.
- Versatility across strokes: Although particularly beneficial for butterfly, the same technique can be adapted for freestyle underwater work and is useful for backstroke starts as well.
Common mistakes and how to fix them
Even skilled swimmers can struggle with the dolphin kick. Here are frequent issues and practical fixes you can apply in practice sessions:
1. Over-ambitious knee bend
Too much knee flexion can turn the kick into a blunt, inefficient motion. Focus on a smooth knee bend that follows the natural undulation rather than a deep, forceful bend.
2. Tense hips and rigid spine
A stiff torso kills the wave. Teach yourself to relax the shoulders and neck, keep the core engaged, and allow the spine to flex subtly with the kick, creating a fluid wave rather than a stiff column.
3. Poor ankle mobility
Stiff ankles blunt the ripple effect. Incorporate ankle mobility exercises into warm-ups—circular rotations, calves stretches, and gentle plantar-flexion drills to improve flexibility.
4. Head bobbing and rising too early
Lifting the head breaks the streamline. Maintain a long, neutral head position and practise breathing only after a consistent portion of the wave has carried the body forward.
5. Inconsistent cadence
Cadence should be controlled and repeatable. Use metronome cues or tempo drills to stabilise your rhythm until the wave becomes a natural part of your swim pattern.
6. Inadequate core engagement
The core should act as a stabilising bridge between the upper and lower body. Include plank variations, hollow body holds, and anti-extension exercises in training to keep the core active during the kick.
Training drills and exercises for the Dolphin Kick
Drills are a swimmer’s greatest ally for refining the Dolphin Kick. The following sequence builds strength, timing, and body control while emphasising a smooth underwater wave.
Drill 1: Streamline dolphin kick with fin separation
From a streamlined position, perform small, controlled dolphin kicks focusing on hips driving the wave. Keep the legs together and the feet pointed in line with the body. Use a kickboard or fins to fine-tune ankle flexibility and avoid arm movement that disrupts the streamline.
Drill 2: Single-leg undulation drill
Hold a relaxed streamline, but kick with one leg while the other remains stationary. This drill teaches you how energy is transferred along the body and highlights any asymmetries in movement. Alternate legs to maintain balance and even development.
Drill 3: Dolphin kick on back
Perform the kick while floating on the back to focus on ankle and hip drive without the interference of a forward-facing role. This drill helps you feel the wave without worrying about surface position and breathing.
Drill 4: Dolphin kick with board
Hold a kickboard to isolate the legs while you practice the undulation. This drill improves leg strength, timing, and the ability to sustain propulsion over longer distances.
Drill 5: Vertical dolphin kick
In a vertical position, perform small, rapid dolphin kicks from the hips. This drill builds power generation and teaches you to maintain balance and control when weight is not supported by water drag across the chest.
Drill 6: Underwater sexagesimal (timed) kicks
From the starting position, push off the wall and maintain underwater kicks for 10–15 seconds, counting cycles. Then surface and assess speed and distance. Build up intensity gradually while preserving form.
Drill 7: Cadence control with metronome
Use a tempo device or metronome to establish a consistent cadence. Start at a comfortable tempo, then increase gradually as your body adapts. This drill helps the wave become a rhythmic, repeatable motion rather than a sporadic burst.
Drill 8: Core and hip stability routine
A strong core supports the entire kick. Combine planks, side planks, bridges, and leg raises into a short circuit after every practice session to fortify the engine that drives the Dolphin Kick.
Underwater phase and race strategy
Strategic use of the underwater phase can provide a critical advantage in races. While the exact rules may vary by competition and federation, the general guidance is clear: minimise surface time during starts and turns while maintaining a powerful underwater kick.
In butterfly, the underwater dolphin kick remains a primary weapon: swimmers propel themselves with the undulating motion right after the start and after each turn, before surfacing to complete the race. In freestyle, the underwater phase is equally important for sprint events and mid-distance races where conserving energy and maintaining speed matters. Practising starts, turns, and underwater transitions will unlock the most benefit from the Dolphin Kick when it matters most in competition.
Incorporating the Dolphin Kick into different strokes
The rider of the wave, the Dolphin Kick adapts to different strokes with subtle changes in timing and posture. Here are some practical notes for the major strokes:
Butterfly
Butterfly naturally integrates the undulating kick into both the arm pull and the body’s rhythm. The kick and arm pull must be coordinated so that the kick’s wave carries the swimmer through the undulating rhythm, while the arms complete their pull. Keep the kick consistent through the entire stroke cycle, especially during the underwater phase after the dive and at the end of the lane turn.
Freestyle
In freestyle, the Dolphin Kick is most effective during the underwater portion after starts and turns. When surfacing, the transition to a conventional flutter kick should be smooth and timed to avoid losing speed. The dolphin kicker should be mindful of a streamlined body position to maximise distance per stroke.
Backstroke
Backstroke can benefit from an underwater kick during dives and entries, though the body’s orientation differs from the forward-facing strokes. Focus on maintaining symmetry between the upper body and the lower limbs, and ensure the kick remains controlled and efficient in the dorsal position.
Equipment and safety considerations
Most swimmers will train the Dolphin Kick with minimal equipment. A few tools can help, but they should be used judiciously to avoid dependency or technique compromises.
- Fins: Provide resistance and help learners feel the wave. Use lightly and gradually to avoid over-reliance or altered body position.
- Kickboard: Useful for isolating leg work and practising undulations without arm involvement.
- Swim paddles: Generally not advised for kick-focused work, as they encourage arm-dominant propulsion. Consider using paddles only in overall stroke development sessions, not during kinetic kick drills.
- Breathing aids: Use only if necessary for technique attention; otherwise, practise maintaining a natural breathing pattern, especially when surfacing from an extended underwater phase.
Safety should always come first. Ensure warm-ups are thorough, joints are prepared, and you progress gradually in distance and intensity. If you experience any pain or discomfort in the lower back, hips, or ankles, consult a coach or physiotherapist to check form and flexibility before continuing with intensive kick work.
Programming a training plan: an 8-week plan to improve your Dolphin Kick
The following programme offers a balanced approach to developing the Dolphin Kick while maintaining overall swimming fitness. Adapt the weekly sessions to your schedule and gradually increase the intensity as technique becomes more automatic.
Weeks 1–2: Foundation and flexibility
- 2 x 60-minute swims per week focused on technique work and light aerobic conditioning.
- 4 x 15-minute kick-specific drills in a pool with a board or fins as needed.
- Core stability sessions 2–3 times per week (planks, side planks, bridges).
Weeks 3–4: Cadence and control
- 2–3 pool sessions per week with structured kick sets (e.g., 8 x 25m underwater dolphin kicks off the start with 20 seconds rest).
- Introduce short underwater distances (10–15 metres) with emphasis on control and streamline.
- Continue core work and begin light flexibility routines for ankles and hips.
Weeks 5–6: Power and distance
- 3 pool sessions per week, including longer underwater sets (4 x 25m underwater dolphin kicks followed by a short surface swim).
- Power sets: a few 50m butterfly or freestyle sprints with a focus on maintaining the dolphin kick during the underwater phase.
- Dynamic core work with rotational components to reinforce the undulation’s power transfer.
Weeks 7–8: Integration and peak performance
- 3–4 pool sessions per week, with an emphasis on race-specific starts and turns that exploit the dolphin kick.
- Practice with competition-like distances and realistic underwater segments to build confidence in the water.
- Tapering approach: reduce volume but maintain technique and cadence quality to preserve efficiency and speed.
Throughout the programme, maintain a training log to track sets, felt level, and any changes in cadence or power. A coach or experienced training partner can provide feedback on body position and wave progression to keep you progressing safely and efficiently.
Tips for coaches and swimmers: lessons from elite practice
Across competitive swimming, elite coaches emphasise a few practical principles for the Dolphin Kick. These include prioritising a strong core, ensuring a streamlined start and through the underwater phase, and reinforcing a smooth transition from underwater propulsion to surface swimming. The best performers train consistently, monitor their underwater distances with a focus on maintaining speed, and continually refine technique through video feedback and hands-on coaching.
Dolphin Kick: myths vs reality
There are several common myths surrounding the Dolphin Kick. Some swimmers believe the kick is solely about leg power. In reality, the kick is a full-body pattern where hips, core, and ankles all contribute. Others assume that more kick frequency always equals more speed. While cadence is important, efficiency and timing often trump raw frequency. The reality is that the best results come from a well-coordinated wave that travels efficiently from the chest to the feet, with the body maintaining a tight streamline across the entire underwater phase.
FAQs about the Dolphin Kick
What is the Dolphin Kick used for in competition?
The Dolphin Kick is primarily used during underwater phases after starts and turns, and, in butterfly, as a core component of the stroke. It helps swimmers accelerate into their surface swimming and increases the distance covered underwater before needing to surface.
Is the Dolphin Kick allowed in all events?
Under current rules, underwater kicking is permitted after starts and turns, with the length of underwater swimming and the speed of the kick depending on the event and federation rules. It is essential to check the latest competition rules for the exact limits in each event you are entering.
Do fins help or hinder the Dolphin Kick?
Fins can be useful for learning and providing resistance to strengthen the kick. However, relying on fins too often can alter an athlete’s natural feel for water and masking progression in technique. Use them judiciously and as part of a balanced programme.
How long should the underwater phase be for a typical race?
For most events, the underwater phase is typically kept as long as it remains efficient and legal under the rules. It should be long enough to gain the initial speed and distance but short enough to allow a smooth transition into the surface stroke.
Conclusion: harnessing the Dolphin Kick for faster swimming
The Dolphin Kick represents a powerful combination of biomechanics, timing, and technique that can transform a swimmer’s performance. By understanding the wave-like propulsion generated by the hips and core, focusing on ankle flexibility, maintaining a streamlined body position, and applying a disciplined training plan, you can unlock more speed, efficiency, and confidence in the water. Whether you are refining your underwater phase for butterfly or optimizing your start and turn speed for freestyle, the undulating kick is a fundamental tool in modern competitive swimming. Embrace the rhythm, practice with intention, and let the dolphin kick propel you toward your best times.
