L.J. D’Acquisto, G. Boggs, J. Dickinson, M. Garver

Central Washington University, Ellensburg, WA

PURPOSE: This descriptive study examined metabolic responses and propelling efficiency (Ep) of freestyle swimming performed by older trained male swimmers. METHODS: Volunteers included a 59, 60, 64, 64 and 76 yr old. This select group of older swimmers had a history of participating in competitive swimming and engaging in swim training for the last 10 to 22 years, averaging ~9000 meters per week. A series of submaximal freestyle swims (4 to 6 efforts) and one maximal swim to exhaustion were performed. A snorkel apparatus worn by the swimmers allowed for the collection of expired air into meteorological balloons (indirect calorimetry). Heart rate (HR, telemetry), blood lactate (BLa, finger stick), and rating of perceived exertion (RPE, 6-20 Borg Scale) were measured. Rate of oxygen uptake and carbon dioxide production were used to compute metabolic power (MP, Joules/second (J/s); Garby et al., 1987). Ep, the quotient of mechanical power to overcome drag to total mechanical power, was estimated according to the work of Toussaint et al. 1988, 1994, 1998. RESULTS: Average peak MP, HR and BLa were 1137 J/s (3.2 lO2/min), 152 bpm, and 7.0 millimolar (mM), respectively. As a group, swimming velocities ranging from 0.73 to 0.94 m/s elicited a MP of 475 to 800 J/s (~ 42 to 70% of peak MP). For the same velocity range, HR, BLa, and RPE were 97 to 127 bpm, 2.3 to 5.0 mM, and 8 (~ “very light”) to 14 (“somewhat hard – hard”), respectively. Collectively, the correlation coefficient between MP versus submaximal swimming velocities was 0.69 with velocity explaining 44% of the variance in metabolic response (p=0.002). At a velocity of 0.92 m/s (~67% peak MP), estimated Ep was 39% (range: 32-47%). The 76 year old achieved a peak MP of 885 J/s (~2.5 l O2/min), and peak HR, BLa, RPE of 144 bpm, 4.2 mM, 18, respectively; and, an Ep of 32%. CONCLUSION: This study estimates that 39% of the total mechanical power generated during submaximal swimming was utilized to overcome drag forces (useful power to move the body forward) and 61% was lost in giving masses of water a kinetic energy change (wasted power). The range of Ep values (32 to 47%) suggests a varying mechanical skill (technique) set among our older swimmers. Lastly, findings on our 76 yr old are believed to be unique since we have not been able to find data describing physiological responses to swimming for this age level.

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