Why Swimmers Need to Train the Core

Many athletes will identify a stronger or more stable core as something they want to improve to enhance their performance in sport. And swimmers are no different.

But while many swimmers may know the importance of training the core, few understand why.

The following is a recap from the book Developing the Core which talks about 6 reasons this matters in swimming.

1. Maintain a Streamline Position

In swimming movement occurs when one, or both, limb(s) are reached overhead in a streamline position. This occurs during the underwater portion at the start, at the turn, and at various points during each of the four strokes. 

I remember growing up and a swim coach stood in the water with a small hula hoop. When we pushed off the wall we had to squeeze our arms against our ears overhead, keep the head neutral, squeeze your butt and kick hard. The last part, or kicking hard, depended on the stroke and race you were in. But the concept was to teach us to be streamlined and to try and fit through as small a hula hoop opening as possible.

If we let our legs drag, by not kicking, or having a weak core, we would feel the feet and toes touch the hula hoop, indicating that we weren't as streamlined as possible, and thus were losing speed.

A strong core facilitates a better streamline position, less leg drag, and faster times.

2. It Allows for Optimal Mobility

When the body has optimal stability, we have more mobility available to us. Oftentimes when we lack range of motion, the knee jerk reaction is to stretch the tissue in question in order to increase our flexibility. Those that been down this path, and tried this, know it's often not this simple.

Sometimes a lack of strength can limit our ability to move. For the land based athlete with 'tight hamstrings', range can be unlocked by strengthening the lower abs and hip flexors. 

In a similar way, performing a couple of sets of weighted deadbugs can sometimes work to stabilize the core and allow for increased shoulder flexion, and a longer catch at the beginning of a freestyle stroke.

3. Over-reliance on the Extremities 

A number of years ago some friends introduced me to outrigger canoeing. And at first glance it appears to be an upper body pulling sport. And yes, you do hold an oar in the hands and move the arms, but the paddling action is heavily dependent on the legs, hips and rotary action of the trunk. A novice paddler will try and muscle their way through the water by using the extremities, only to find that they fatigue sooner and have trouble keeping up.

This is similar to swimming in that a swimmer with a weak core will rely on their extremities more and core less. Not only is this less efficient than swimming with a strong core, it can also cause the swimmer to deviate from an optimal stroke path. For example, in freestyle, the swimmer may sink the arm deeper or cross the midline, in order to find the stability not supplied by the core.

4. A More Effective Kick

One way to think about core stability is that is helps transfer energy produced by the body through the extremities. When the core is weak, energy can leak rather be applied as propulsion (in this case). 

Sometimes the analogy is to think of firing a canon from a canoe or a barge. A canoe would be similar to having a weak core and when the canon is fired, the canoe moves in the water. The consequence is that the canon ball doesn't travel as far. Contrast this to firing a canon from a barge and the barge won't move at all. No energy is lost and the canon ball travels much further.

When a swimmer has a strong core, each impulse from a kick helps propel the body forward with little wasted effort. If the core is weak we may see lots of effort on the part of the athlete i.e. hard and fast kicking, with very little speed produced as a result.

5. It Facilitates Body Roll

Do you know those little toys that you can wind up and then they shuffle across the desk or table? Well, we can think of swimming freestyle or backstroke in a similar way. 

Only this time the spring is our core, and we wind it up by dissociating our hips and thoracic spine. In other words, as one arm is surging forward the opposite hip led the way. And it's this rotary action that propels the body during backstroke and freestyle. 

When the core is weak, in the transverse plane, we may lack the strength to rotate the body to set up the catch, and propulsion, for each stroke.

6. Store and Recover Elastic Strain Energy

During sport, especially those that involve high speed, muscles will alternate between periods of high and low activity. We don't want our muscles to be maximally engaged all the time, as this would be fast fatiguing and slow moving. And we don't our muscles to only fire slowly as we would never win a race.

A stronger core helps us store energy between various phases of the strokes. We experience less physical stress compared to someone with a weaker core. And we are better able to maintain optimal technique during a race. 

Whether you are a competitive or recreational swimmer, it is essential you train the core. You will swim more efficiently i.e faster, and put less stress on key joints i.e. the shoulders. For more details on how to assess the core, and train for specific strokes in swimming, leave a comment below. 

Reference

Willardson, J. M. (2013). Developing the core. Part II Sport-Specific Core Development. Chapter 12: Swimming. Human Kinetics.