The unsung hero of swim performance: Core strength and stability

Often when people think of elite swimmers, and Elite Level performance, they might immediately picture their powerful strokes and streamlined bodies cutting through the water with picture perfect technique. But under the surface, there's a crucial, often overlooked factor that is a foundational element of elite level performance: core strength and stability.

In competitive swimming, your core plays a pivotal role in maintaining balance, generating power, and enhancing technical efficiency. While swimmers often focus on building strength in their arms and legs, neglecting the core is like trying to build a house without a proper foundation—no matter how strong or well-built the other components are, the house will be weak and break easily when stressed. Similarly, a swimmer’s performance and stroke mechanics are heavily influenced by the health and stability of their core.

But why exactly is core strength so crucial for competitive swimmers? Let’s dive into the science behind it and explore the connection between center of mass, force application on water, gravity, power output, and technical efficiency.

Understanding Core Strength in Swimming

The core, often described as the "center of power," refers to the muscles in the abdomen, lower back, and pelvis that provide stability and support to the body. In swimming, a strong core is necessary not just for maintaining an ideal body position in the water, but also for transferring the energy from your legs and arms to propel you forward. It is the link between the upper and lower body, enabling swimmers to move efficiently through the water.

1. Center of Mass and Balance in Water

In water, the body’s center of mass (COM) is not a fixed point like it is on land. Instead, it shifts as the swimmer moves through the water. Core strength helps maintain control over the body’s COM, ensuring that the swimmer remains balanced and streamlined. This balance is essential to avoid drag and maximize speed.

When a swimmer has poor core stability, they may begin to sink in certain areas—usually the hips or legs—because they can't maintain an efficient body position. This misalignment increases drag, forcing the swimmer to work harder for each stroke. On the other hand, a stable core helps maintain a horizontal, streamlined position that minimizes resistance and optimizes glide.

2. Gravity’s Impact on Swimmers

Gravity is constantly pulling the swimmer downward, and without adequate core strength, it becomes challenging to resist this force. A strong core allows the swimmer to counteract gravity by maintaining a stable, flat body position in the water. It also helps keep the body from sinking, especially in the lower back and hips, which can otherwise cause the swimmer to lose optimal body alignment and efficiency.

For example, while swimming freestyle, maintaining a neutral body position with a level head and spine is essential. A weak core often causes the swimmer's legs to drop, creating increased drag and wasting energy. By maintaining a stable core, swimmers can keep their body high in the water and conserve energy for the more powerful phases of each stroke.

3. Force Application and Transfer

Swimming is a sport of force application—each stroke is about applying force against the water in the most efficient way possible. However, force needs to be transferred effectively from one part of the body to another to produce maximum propulsion.

Think of the swimmer’s body as a chain: when you kick your legs, the force generated must flow through your core and into the upper body to drive the stroke. Your core connects and can initiate power to both legs and arms. A weak or unstable core interrupts this transfer of energy, meaning less power is translated into propulsion.

In butterfly, for example, the core is responsible for driving the "undulation" of the body. Without proper core engagement, the swimmer cannot generate the necessary body motion for an efficient stroke, and a strong connected pull and kick. Similarly, in breasstroke, the core stabilizes the body and helps to transfer the power from the legs into the arms, resulting in smoother and more powerful strokes.

4. Power Output and Efficiency

The link between core strength and power output is clear: the stronger the core, the more power a swimmer can produce with each movement. When the core is stable, the swimmer can generate force without wasting energy stabilizing the body, leading to more efficient movements and a better return on effort.

I often refer to the core at the “go muscles.” With your center of mass shifted, in relation to when you are on land, your core becomes your “platform” for force application and power output. Without a stable and strong core, we do not have the foundation to apply power to the water with either our arms or legs.

In the dolphin kick while swimming butterfly or the flutter kick in freestyle, the power comes from the core, particularly the lower abdomen. A stable core enables the swimmer to execute powerful, controlled kicks with minimal effort. The stronger and more efficient the core, the better the swimmer can control the motion of the legs and maintain speed with less fatigue.

Core strength is also tied to postural endurance, which is crucial for swimmers who need to maintain technical efficiency throughout the entire race. Without adequate core endurance, swimmers may start to break form toward the end of a race, causing a significant drop in performance.

5. Technical Efficiency

Core strength directly impacts technical efficiency in all four strokes. Good technique is about minimizing wasted energy, and the body’s ability to stay aligned, minimize resistance, and transfer power efficiently is a function of core stability.

For example:

• In freestyle, the swimmer's ability to rotate through the torso with minimal movement in the lower body is facilitated by a strong core.

• In backstroke, core stability helps control the rotational movements, ensuring that the swimmer's body stays as straight as possible while executing a powerful stroke.

• In butterfly, the undulation of the body originates from the core, with minimal excessive movement from the head and legs.

• In breaststroke, the power to pull the body forward and the ability to kick effectively come from the torso, powered by a strong core.

A well-developed core allows for more precise body control and finer adjustments in technique. As the swimmer's body moves through the water, they can fine-tune their stroke mechanics and maximize every inch of their movement.

How to Improve Core Strength for Swimming

Core strength in swimming is not just about doing a few sit-ups or planks—it requires targeted training that mimics the demands of swimming. Here are some exercises that can help build core strength for swimmers:

• Planks and Side Planks: These exercises target both the deep and superficial muscles of the core, which are crucial for maintaining a stable body position in the water.

• Medicine Ball Rotations: Great for developing rotational strength, which is essential for stroke mechanics in freestyle, backstroke, and butterfly.

• Superman Holds: Helps build endurance in the lower back muscles, which are vital for maintaining proper body alignment and preventing lower back fatigue.

• Leg Raises and Flutter Kicks: These exercises mimic the kicking motions in swimming and engage the lower core, which is important for maintaining a streamlined position and generating propulsion.

• Stability Ball Rollouts: A challenging exercise that strengthens the entire core, helping swimmers maintain posture and control during strokes.

Final Thoughts: The Core as a Pillar of Swimming Performance

Core strength and stability are foundational to efficient movement, speed, and power in swimming. By improving core strength, swimmers can maintain better body alignment, transfer power more efficiently, and reduce energy waste. Whether you’re racing in the 50m freestyle or enduring the 1500m swim, your core is the central hub for every stroke and kick.

Ultimately, the swimmer who focuses on developing a strong, stable core will see significant improvements in their technical execution, race performance, and overall efficiency in the water. By strengthening the center of your body, you enhance the efficiency of every other part—leading to smoother, faster, and more powerful swimming.

So, next time you're in the pool, remember: your core is the foundation of your speed. Strengthen it, and you'll unlock new levels of performance that you never thought possible

References/want to learn more: 👇🏽

1. Core Strength and Swimming Biomechanics

• McGill, S. M. (2010). Core Training: Evidence Translating to Better Performance and Injury Prevention. Strength and Conditioning Journal, 32(3), 33–46.

  
  

  This paper discusses how core strength relates to injury prevention and athletic performance, with applications for swimmers.

2. The Importance of Core Stability in Swimming

• Gomez, A. M., et al. (2011). The Role of Core Strength in Swimming Performance. International Journal of Sports Science & Coaching, 6(2), 187-193.

  
  

  This paper emphasizes the role of the core in maintaining swimming posture, reducing drag, and improving efficiency during all strokes.

3. Power Generation and Force Transmission

• Sanders, R., & Keogh, J. W. L. (2017). The Effect of Core Stability Training on the Performance of Competitive Swimmers. Journal of Strength and Conditioning Research, 31(5), 1312–1321.

  
  

  This study investigates how improving core stability impacts force production and the transfer of power during swimming, specifically focusing on stroke mechanics.

4. Gravity and Hydrodynamics in Swimming

• Pendergast, D. R., et al. (2008). Swimming and its Biomechanical, Physiological, and Hydrodynamic Characteristics. Journal of Sports Science & Medicine, 7(3), 115-122.

  
  

  This paper covers the impact of gravity on swimming posture and how maintaining a stable body position in water helps to reduce drag and improve performance.

5. Rotational Mechanics and Core Strength

• Lehman, G. J., & McGill, S. M. (2010). The Role of the Core in Propulsion During Swimming.Journal of Sports Sciences, 28(9), 963-973.

  
  

  This article looks into how core strength helps to manage body rotation and streamline positioning, especially in strokes like freestyle and backstroke.

6. Core Training and Power Output

• Behm, D. G., & Sale, D. G. (1993). Resistive Training Effect on Sprint Performance and Power Output. Canadian Journal of Applied Physiology, 18(2), 243–256.