Why Elite Swimmers Train Underwater Kicking More Than Freestyle

In competitive swimming, the underwater dolphin kick has transformed from a niche skill into a decisive race-winning weapon. Elite swimmers now dedicate a significant portion of their training volume to underwater kicking — often exceeding the time spent on freestyle itself. This shift reflects a deep understanding of hydrodynamics, energy efficiency, and race strategy. In this guide, we explore the rationale behind this training emphasis, the biomechanical principles involved, and how to apply these insights to your own swimming development.

The Strategic Importance of Underwater Kicking

Underwater kicking is not merely a transition phase after starts and turns; it is a critical race segment where positions are won or lost. In elite competition, the underwater phase can account for 15–30% of the total race distance in short-course events, and even in long-course swimming, the cumulative effect of multiple turns makes underwater proficiency a major performance differentiator. Swimmers who generate powerful, streamlined underwater kicks gain a velocity advantage that is difficult to match with surface swimming alone.

Why Velocity Matters More Underwater

When a swimmer is submerged, the body experiences significantly less wave drag than at the surface. The absence of wave-making resistance allows a well-executed underwater kick to achieve speeds that cannot be sustained on the surface. Elite swimmers can maintain underwater speeds of 2.0–2.2 meters per second, compared to their surface freestyle pace of around 1.8–1.9 m/s. This speed differential means that every additional meter traveled underwater translates into a time gain. In a 50-meter freestyle event, a swimmer who can stay underwater for 15 meters after the start may gain 0.3–0.5 seconds over a competitor who surfaces earlier — a margin that often decides medals.

Energy System Efficiency

Underwater kicking relies primarily on the anaerobic energy system, with a smaller aerobic contribution than surface swimming. The kick itself is a high-intensity, short-duration effort that depletes phosphocreatine stores rapidly. However, because the underwater phase is brief (typically 5–15 seconds per turn), swimmers can recover during the subsequent surface swimming if their aerobic base is well-developed. Training the underwater kick specifically improves the body's ability to tolerate high lactate levels and maintain technique under fatigue. This is why elite programs incorporate underwater kicking sets that mimic race conditions — repeated maximal efforts with controlled rest intervals.

Biomechanics of the Effective Underwater Kick

The underwater dolphin kick is a whole-body movement that begins with the core and transfers energy through the hips, legs, and feet. Understanding its biomechanics is essential for designing effective training drills and correcting common faults.

Core Engagement and Body Position

A streamlined body position is the foundation of an effective underwater kick. The head should be tucked between the arms, with the biceps pressing against the ears. The core must remain engaged to prevent the hips from sinking, which would increase frontal drag. The kick itself originates from the chest and abdominal muscles, not from the knees. Many swimmers mistakenly bend their knees excessively, creating a 'pedaling' motion that increases drag and reduces propulsion. Instead, the legs should remain relatively straight, with the undulation coming from the torso. The feet should be relaxed and slightly pointed, allowing the water to flow over them smoothly.

Ankle Flexibility and Foot Position

Ankle flexibility is a critical differentiator between elite and sub-elite underwater kickers. Swimmers with greater ankle plantarflexion (pointing the toes) can create a larger surface area for propulsion during the downward phase of the kick. They also experience less drag during the upward phase because the feet remain streamlined. Regular ankle stretching and strengthening exercises — such as banded plantarflexion and resisted kicking drills — can improve range of motion over time. Some elite swimmers spend 10–15 minutes per day on ankle mobility work, treating it as seriously as any other training component.

Training Methods for Underwater Kicking

Developing a powerful underwater kick requires a systematic approach that combines technique work, strength training, and high-intensity conditioning. Below we outline a progression that many elite programs use.

Drill Progression

Begin with stationary drills to build body awareness. For example, practice the dolphin kick while holding onto the pool wall or using a kickboard held vertically. Focus on feeling the undulation from the chest. Once the motion is consistent, move to short-distance kicking sets: 10–15 meters of underwater kicking after a push-off from the wall, with emphasis on maintaining speed and streamline. Gradually increase distance to 25 meters, then incorporate into full turns. A typical session might include 8–12 repetitions of 15-meter underwater kicks with 30 seconds rest, building to 20–25 meters as fitness improves.

Strength and Power Work

Underwater kicking requires both muscular endurance and explosive power. Dry-land exercises that target the core, glutes, and hip flexors are beneficial. Exercises such as medicine ball throws, Russian twists, and resisted band kicks can translate into improved underwater performance. In the pool, using fins during kicking sets can overload the muscles and improve ankle flexibility, but caution is needed to avoid reinforcing poor technique. Many coaches prescribe fin work only after the athlete demonstrates proper body position and kick mechanics without fins.

Balancing Underwater and Surface Training

One of the most common questions in swim training is how to allocate training volume between underwater kicking and surface swimming. The answer depends on the swimmer's event specialty, current weaknesses, and competition calendar. However, some general principles apply.

Event-Specific Considerations

Sprinters (50–100 meters) benefit most from underwater kicking because the race is short enough that anaerobic capacity dominates. These swimmers might spend 30–40% of their total training volume on underwater work, including starts, turns, and dedicated kicking sets. Middle-distance swimmers (200–400 meters) require a more balanced approach, with perhaps 20–25% of volume underwater, as they must also maintain a high aerobic base. Distance swimmers (800 meters and above) typically spend less time underwater — around 10–15% — because the cumulative fatigue from repeated maximal kicks can compromise their pacing strategy. However, even distance swimmers cannot afford to neglect underwater work, as poor turns can cost several seconds over a long race.

Periodization and Recovery

Underwater kicking is physically demanding, particularly on the lower back and shoulders. Overtraining can lead to injuries such as shoulder impingement or lower back strain. A well-structured training plan includes periods of reduced underwater volume to allow for recovery and technique refinement. During the base phase of training, focus on building aerobic capacity and technique. As competition approaches, increase the intensity and specificity of underwater work, simulating race conditions with maximal efforts and short rest.

Common Mistakes and How to Avoid Them

Even experienced swimmers fall into patterns that reduce the effectiveness of their underwater kick. Here are three frequent errors and their solutions.

Excessive Knee Bend

As mentioned earlier, bending the knees too much creates a 'bicycle kick' that increases drag and reduces propulsion. The fix is to focus on core-driven undulation. Drills such as kicking on your side or using a snorkel to maintain head position can help. Video analysis is also valuable — recording underwater footage allows swimmers to see their knee angle and make adjustments.

Rushing the Kick

Many swimmers try to kick as fast as possible, but a rapid, shallow kick is less effective than a slower, deeper kick. The optimal kick frequency depends on the swimmer's size and flexibility, but a common guideline is to aim for 1.5–2.0 kicks per second. Using a tempo trainer or counting kicks per 15 meters can help establish a sustainable rhythm. In training, practice kicking at different tempos to find the most efficient rate for each individual.

Poor Timing with Turns

The transition from the turn to the underwater kick is often where time is lost. Swimmers who delay their first kick or kick too early disrupt the streamlined position. The ideal sequence is: push off the wall, hold a tight streamline for 1–2 seconds, then initiate the first kick. The kick should begin from the core, not the legs. Practicing turn-specific drills — such as 'push and glide' sets where the swimmer holds the streamline for increasing distances — can improve this timing.

Frequently Asked Questions About Underwater Kicking

Below we address common queries from swimmers and coaches, based on our experience working with development programs.

How long should I stay underwater after each turn?

The optimal underwater distance varies by event and swimmer. In sprint events (50–100 meters), elite swimmers often stay underwater for 10–15 meters after the start and 5–10 meters after each turn. For longer events, the distance may be shorter to conserve energy. A good rule of thumb is to surface when your underwater speed drops below your surface swimming speed. Practitioners often use a 'breakout' drill where the swimmer kicks underwater until they feel a significant deceleration, then surfaces — this helps develop an intuitive sense of the optimal distance.

Can I improve my underwater kick without fins?

Yes, and it is advisable to spend a significant portion of training without fins to develop proper technique. Fins can mask poor body position and encourage over-reliance on leg strength. However, fins are useful for building ankle flexibility and power when used judiciously. A balanced approach is to use fins for 20–30% of underwater kicking volume, focusing on high-intensity sets where the added resistance helps develop strength.

How often should I train underwater kicking?

Most elite programs include some form of underwater kicking in every training session, even if only for 10–15 minutes. The key is consistency rather than volume. Two to three dedicated underwater kicking sessions per week, combined with turn practice in every main set, is a sustainable approach for most competitive swimmers. During peak training periods, this can increase to four to five sessions per week, but always with attention to recovery.

Putting It All Together: A Sample Training Week

To illustrate how underwater kicking can be integrated into a weekly training plan, we provide a sample schedule for a competitive swimmer preparing for a sprint event. This is a composite scenario based on common practices observed in development programs.

Weekly Structure

Monday: Technique focus — 30 minutes of underwater kicking drills without fins, emphasizing body position and core engagement. Followed by a main set of 8×50 meters freestyle with turns, focusing on breakout speed. Tuesday: Strength session — dry-land core and leg work (30 minutes), then pool work including 20×15 meters underwater kicks with fins at maximal effort, 45 seconds rest. Wednesday: Endurance day — 3000 meters of aerobic swimming with moderate underwater work (10–15 meters per turn). Thursday: Speed work — 12×25 meters underwater kicks without fins, building from 10 to 20 meters, with full recovery. Then 6×50 meters race-pace freestyle. Friday: Active recovery — light swimming and stretching, including ankle mobility exercises. Saturday: Competition simulation — starts and turns practice, including 4×50 meters from a dive with full underwater phase. Sunday: Rest.

This schedule balances underwater development with overall swim fitness. Adjustments should be made based on individual response and competition timing. The key is to progress gradually, monitor fatigue, and prioritize technique over volume.