Effect of swimmer’s head position on passive drag

The aim of this study was to investigate the effect of the head position on passive drag with a towing-line experiment in a swimming pool. The tests were performed on ten male swimmers with regional level swimming skills and at least 10 years of competitive swimming experience. They were towed underwater (at a depth of 60 cm) at three speeds (1.5, 1.7 and 1.9 m/s) and in two body positions (arms above the swimmer's head and arms alongside the body). These two body positions were repeated while the swimmer's head was positioned in three different ways: head-up, head-middle and head-down in relation to the body's horizontal alignment. The results showed a reduction of 4-5.2% in the average passive drag at all speeds when the head was down or aligned to the swimmer's arms alongside the body, in comparison to the head-up position. A major significant decrease of 10.4-10.9% (p < 0.05) was shown when the head was down or aligned at the swimmer's arms above the swimmer's head. The passive drag tended to decrease significantly by a mean of 17.6% (p < 0.001) for all speeds examined with the arms alongside the body position rather than with the arms above the head position. The swimmer's head location may play an important role in reducing hydrodynamic resistance during passive underwater gliding. © by Matteo Cortesi 2016.