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Physi-O-lympics – Morphological and Physiological Differences in Dolphins and Swimmers Shaun Borgula, Kurtis Esler, Angela Tsang, Fengqi Ye, BIOL321, (Ecosystem Sciences and Management Program), UNBC Introduction Materials and Methods Objectives and Goals Results Swimming takes place in a medium that presents different gravitational and resistive forces, respiratory conditions and thermal stress compared to air1. Dolphins are incredible swimmers compared to humans. Swimming is a learned ability in humans. Some humans are very good at it like Michael Phelps, a distinguished Olympic swimmer2. Out of the many different swimming techniques known as "strokes", butterfly is most similar to how dolphins swim. Dolphin kick is a technique used in butterfly that mimics the movement of a dolphin’s tail3. Humans and dolphins have different physical characteristics that they utilize while swimming: Humans Dolphins -arms -fins -legs -tail flukes -nose/mouth -blowhole Improved swimming technique and efficiency can be explained by local factors such as lactate levels (in the muscles), VO2 max (oxygen consumption), average velocity, total lung capacity, and heart rate (resting and swimming). This study hopes to compare a dolphin’s morphology to that of a swimmer’s. By studying a dolphin’s physiology, a swimmer could possibly mimic or adapt similar techniques for swimming. Other internal factors will also be compared like lactate level, O2 consumption, velocity and heart rate. Rational principles based on improved understanding of the biomechanics and physiology of swimming should be guidelines for swimmers in their efforts to explore the limits of human performance. Furthermore this study will look at Michael Phelps, an example of how some external and internal factors can influence a human’s ability to swim. Measurements were made as the dolphin floated under a metabolic hood while stationed infront of a padded force transducer to determine their VO2 max4. The Sonar Seabat 6012 (A video sonar device) recorded length of horizontal movements and speed of 14 bottlenose dolphins5. Human lung capacity was measured with a spirometer on swimmers3.12 swimmers were tested over an 8 month period. They swam 200m each time and their lactate levels were measured as soon as they completed their swim. The lactate levels were determined with a lactate velocity curve6. 6 swimmers resting and swimming heart rates were measured by radio telemetry7. Energy cost was measured by swimmers breathing through a respiratory snorkel and valve system connected to a telemetric portable gas analyzer (K4 b2, Cosmed, Rome, Italy)8. Oxygen consumption was measured during 200m trials during submaximal velocities until the swimmer could no longer swim at the predetermined pace8. VO2max in humans was measured by an incremental swimming test starting after a standardized warm up of 400 m of low intensity swimming8. The test comprised 56200 m repeats with 15 seconds rest after each repeat. Gas exchange during the incremental swimming test was measured breath by breath with a portable system (K4b2; Cosmed, Rome, Italy)8. Michael Phelps- Velocity was determined from Michael Phelps's 100m butterfly time in Beijing 2008 and was divided by his height (1.93m)2. Discussion Conclusions -The bottle-nosed dolphin (l=2.59m) achieved an average speed of 4.20m/s giving a ratio of 1.63s -1 to body length (Figure 1). Michael Phelps’ (l=1.93m) fastest time achieved was 50.58s in the 100m butterfly with a speed of 1.98m/s being a ratio of 1.02s -1 proportion to body length (Figure 1). -Lung capacity of one bottle-nose dolphin in a study (171kg) measured 32L and 0.18L/kg in ratio to body mass (Figure 2). Michael Phelps is believed to have twice the average human lung capacity (12L) giving a ratio of 0.13L/kg (Figure 2). -Lactate levels observed in a study of two dolphins (145kg each) averaged 2.77mmol/L of lactate in the blood in proportion to body mass (Figure 3). Phelps (88kg) averaged a lactate concentration of 5mmol/L (60% higher than the dolphins studied) in proportion to his body mass (Figure 3). Humans produce much more lactic acid in the muscles, tiring the body at a faster rate than the bottle-nose dolphin. -O 2 consumption measured in two dolphins (145kg each) averaged 7.5mL/kg/min in proportion to body mass (Figure 4). In a study of O 2 consumption in swimmers (averaged 70.1kg) measured 59mL/kg/min in proportion to body mass (Figure 4). The higher consumption of O 2 in humans shows more inefficiency the human respiration system is in comparison to dolphins. -In terms of proportion to body mass, the dolphin’s heart pumped less per kg of bodyweight (Figure 5). The human heart must work harder (~60% more) to provide oxygen to the muscles while surface swimming in comparison to dolphins. -Energy Cost measured in a bottlenose dolphin (91kg) was estimated to be 110W/kg while competitive swimmers had highest costs in backstroke (16.68W/kg) (Figure 6). The energy cost to body mass ratio shows that during strenuous swimming, dolphins can produce more energy per kilogram compared to that of a competitive swimmer. Humans in comparison to the bottle-nose dolphin are less efficient at allocating oxygen to the muscles. This may be due to the inferior lung capacity of humans compared to the dolphin in proportion to body mass. As a result, heart rate is more intense in humans in order to supply more oxygen. Dolphins also must have a superior system for buffering lactic acid build up in the muscles to reduce fatigue. Dolphins however expend more energy per kilo than humans while swimming. Acknowledgements: Dr. Gantner 0.54 0.96 0.91 1.60 0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 Resting heart rate (bpm/kg) Post-swimming heart rate (bpm/kg) Beats/min/kg Bottle-nose Dolphin Average Human 0.02 0.06 0.00 0.01 0.02 0.03 0.04 0.05 0.06 Bottle-nose Dolphin Michael Phelps Lactate Levels (mmol/L/kg) 0.18 0.13 0.00 0.05 0.10 0.15 0.20 Bottle-nose Dolphin Michael Phelps Lung Capacity (L/kg) 1.63 1.02 0.00 0.50 1.00 1.50 2.00 Dolphins Michael Phelps Velocity/Body Length ((m/s)/m) 7.50 59.0 0.00 20.00 40.00 60.00 80.00 Dolphins Average Human Maximal Oxygen Consumption (mL/kg/min) Figure 1. The average velocity per body length of a bottlenose dolphin compared to Michael Phelps. Figure 2. The average lung capacity per kilogram of dolphins and Michael Phelps. Figure 4. The oxygen consumption of dolphins and humans while swimming. Figure 5. Heart rate per kilogram of dolphins and humans at rest and swimming. Figure 6. Energy cost after strenuous exercise (Watts per kilogam) in Bottlenose dolphin and humans. 110 16.68 12.22 12.8 8.83 0 20 40 60 80 100 120 DolphinHuman BSHuman FLHuman BRHuman FS Energy Cost After Strenuous Swimming (W/Kg) Figure 3. Lactate levels measured after swimming in bottlenose dolphins and Michael Phelps.
