Henrich, T. W., Pankey, R.B., & Soukup, G. J. (2010). The impact of tension in abdominal and lumbar musculature in swimmers on ventilatory and cardiovascular functions. A paper presented at the XIth International Symposium for Biomechanics and Medicine in Swimming, Oslo, June 16–19, 2010.

"Some theorists have proposed that contracting abdominal muscles and other lower trunk muscles will reduce resistance on the swimmer’s body and increase performance while swimming the crawl stroke." This study evaluated the effects of muscular tension in the abdominal area in swimmers. Ss (M = 8; F = 5) volunteered for evaluation of their ventilatory capacity, mean ventilatory volume, forced volume capacity, and resting oxygen volume and carbon dioxide volume under the two postural conditions. One was with muscles at rest (the control condition) and the other with the abdominal muscles and erector spinae statically contracted (the experimental condition). There was a three-minute rest between counter-balanced trials for all measurements. Ss' pulmonary functions and resting oxygen kinetics were expressed relative to age, body weight, and height.

There were significantly lower differences in ventilatory capacity, mean ventilatory volume, and forced volume capacity during the abdominal-contractions condition compared to rest. The contracted condition also resulted in significantly higher oxygen consumption values. There were no significant differences observed in carbon dioxide measures between the treatments.

Implication. Since there is no proof that abdominal muscle contractions actually decrease resistance of a swimmer's body and that ventilatory functions were significantly diminished while oxygen utilization requirements were significantly increased, it is suggested that similar alterations in body mechanics are not conducive to improving performances during crawl stroke swimming. It was demonstrated here that abdominal contractions will make the activity of swimming harder.

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