G. Boggs, J. Berry, L. D’Acquisto.   Exercise Science Laboratory, Central Washington University, Ellensburg, WA.


As one ages, there are changes in functional capacity which lead to athletic performance decrements.  In swimming, declines in performance become exponential at approximately 40 years of age (Donato et al. JAP, 2003).  Surprisingly, little work has been conducted in examining those physiological changes that lead to performance decrements in an older swim trained population. PURPOSE: The purpose of this study was to compare the energetic response to freestyle swimming between younger and older trained male swimmers.   METHODS:  Seven trained collegiate (age, 20 + 1.9 yrs, 18-24) and six trained older (age, 48 +8.7 yrs, 40-64) male swimmers participated in this investigation.  Expired air was collected via a snorkel apparatus (indirect calorimetry) during a series of submax (steady velocity) and one max swim. Each of the swims was 274.3 m (300yds) with expiratory air collected over the final 45.7-68.5 m (50-75 yds). Blood lactate (Bla; YSI Analyzer) for each exercise effort was also determined.  RESULTS:  The younger swimmers were lighter (77.9+10.3 vs 83.7+12.4 kg, p=0.39), had a lower % adipose tissue (13.9+3.6 vs 22.9+6.3, p=0.008), and were equal in height (1.8 m) compared to the older swimmers. VO2 peak (lmin-1) tended to be greater for the younger (4.24 + 0.51, 3.33-4.84) versus the older swimmers (3.65 +0.65, 3.05-4.67) (p=0.09).   On average, the younger swimmers had a greater HR max (180 + 6 bpm, 171-187) compared to the older group (171+16 bpm, 153-195) (p=0.19).  No difference in peak lactate was found between the younger (9.38 +1.75 mM, 7.57-11.97) and older (9.99 + 2.96 mM, 6.73-13.77) swimmers.  Swimming velocity at a given metabolic power value of 800 Watts was similar between the younger and older swimmers, 0.94 + 0.09 ms-1 and 0.93 + 0.10 ms-1. CONCLUSIONS:  Nearly identical velocities at a metabolic power output of 800 Watts suggests that both the younger and older swimmers were able to apply the same amount of  mechanical power into overcoming drag (useful swimming power). This finding suggests that younger and older trained swimmers have a similar propelling efficiency during submaximal freestyle swimming.   The lower peak aerobic power in the older group with no apparent differences in submaximal propelling efficiency implies that at a given swimming velocity, the older group would work at a greater relative physiological load. This may compromise performance in a swimming event which requires a great rate of aerobic energy contribution. A limitation of this study is the low participant numbers. Irregardless, this investigation does provide some initial insight into the energetics of freestyle swimming between younger and older trained swimmers.