Swim performance with and without snorkel and the underlying energetic differences

Swimming requires frequent lifting and rotating of the head to inhale. A snorkeler saves energy by avoiding this maneuver, but the snorkel adds breathing work due to air flow resistance. The needed power of these head movements has never been examined, although the extra power of breathing through a snorkel was studied recently. This study aimed: 1) to model the work of vertically lifting and rotating in comparison with the breathing work added by a snorkel; 2) to compare heart rate (HR) and velocity (v) while swimming under both conditions; 3) to evaluate the results for surface-swimming divers. Presumably the power when using a snorkel is less, and the difference in power predicts the difference in swimming velocity. Kinematics of head lifting and rotation, and the difference between the hydrodynamics were modeled. A swim test lasting 12 minutes at maximum speed (Cooper swim test) was performed in a pool by nine recreational divers in the front crawl style, with face mask but without fins. All subjects performed the test both with and without snorkel. The average velocity with a snorkel, 0.72±0.09 m∙s-1, was 4.4±3.9% higher than without (p=0.008), but HR (144±16 bpm) showed no difference (0.8±3.4%). The model based on our subjects’ performance showed that 7.5% of the total power is spent in the inhaling maneuver while crawling and 2.7% while snorkeling. Theoretically this would allow the snorkeler to swim 5.2% faster. It is concluded that snorkeling is energetically advantageous as well as for divers swimming on the surface.