Often, I find myself walking onto a pool deck witnessing swimmers doing an endless number of core exercises, such as crunches and sit-ups. As a swimmer and coach, I realize the necessity of having a strong core. Many swimmers believe that more crunches will equal stronger abs. This may be true, but to a certain extent. 55% of abdominal muscles are made up of type 1 or “slow-oxidative” muscle fibers. 45% is made up of type 2 or “fast glycolytic” muscle fibers. This means that 45% of abdominal muscles will not be heavily recruited during high-rep, low weight exercises. Doing high amounts of crunches and sit-ups can also cause the body to learn bad posture through repeated spinal flexion and shoulder protraction (forward rounding of shoulders). I have seen many swimmers with mild kyphosis (forward rounding of the upper back) and they are notorious for bad posture. Poor exercise selection such as high repetition sit-ups, may exacerbate or cause these bad postural habits. What does this mean?

This means swimmers shouldn’t waste time doing hundreds of crunches. The abdominal muscles are already worked out during a typical swim practice. In order to strengthen the other 45% of abdominal muscles, swimmers should incorporate exercises that are weight bearing or produce high electromyography (EMG) activity. By increasing the load on the abdominal muscles, swimmers can increase their core strength in a more efficient manner. 

Some examples

SB Plank Reach
TRX Trunk Rotation
SB Super Pike
ISO Ab Wheel Rollout

Fun Fact about how your abs “look”

These 6 F’s can influence how your abs “look”. The amount of these 6 F’s that you have in your core can greatly contribute to how “chiseled” you are.

  • Food
  • Fluid
  • Feces
  • Flatus
  • Fat
  • Fetus

Never Forget

Your type 2 abdominal muscles are additionally recruited in the weight room when performing core lifts, such as, squats, pullups, deadlifts, overhead presses, and pressing on stability balls. Be aware on what abdominal fiber types you want to develop, and to not overdo it with spinal flexion, as it may increase the risk for lumbar injuries. Spinal flexion movements such as the cat-camel is a much healthier option for swimmers. This will ensure reduction of wear and tear on the lumbar discs. 


HÄGGMARK, T. and THORSTENSSON, A. (1979), Fibre types in human abdominal muscles. Acta Physiologica Scandinavica, 107: 319–325: 1748-1716.1979.

McGill S. (1979), Core training: evidence translating to better performance and injury prevention. National Strength & Conditioning Journal. 32: 33-46, 2010