John P. Troup

Relationship between power and sprint freestyle swimming.

In an effort to determine the role played by power in sprint swimming, 40 competitive swimmers (22 females and 18 males) were tested for arm power at velocities ranging from 1.60-3.28 m . s-1 using an apparatus that was specifically designed to mimic the arm action during swimming. Measurements were also made to determine the contribution of fatigability to spring swimming performance. In addition, each swimmer performed a series of 25-yd (22.86 m) freestyle sprints. A close relationship was found between power output and sprint swimming performance (r = 0.90). The highest power recordings were obtained at test velocities of 2.05 and 2.66 m . s-1, with the average velocity required for peak power being 2.40 m . s-1. This point is referred to as the optimal velocity. Four detrained swimmers were tested before and after 4 wk of isokinetic strength training only. On the average, performance improved 3.76%, while arm power increased by 18.66%. The fatigability of the competitive swimmers was not related to their sprint ability (r = 0.01). It is concluded that power, as measured in this study, offers an objective assessment of a component essential for success in sprint swimming.

Energy expenditure of swimmers during high volume training

The purpose of this study was to examine the total energy expenditure (TEE) of swimmers during high volume training (17.5 +/- 1.0 km.d-1) using the doubly labeled water method. Five female swimmers (age, 19 +/- 1 yr; height, 178.3 +/- 2.2 cm; weight 65.4 +/- 1.6 kg) were administered a dose of 2H2(18)O and monitored for 5 days. Training consisted of two sessions per day, lasting a total of 5-6 h. Energy intake (EI) was calculated from dietary records. Resting energy expenditure (REE) was measured on a non-training day and averaged 7.7 +/- 0.5 MJ.d-1 (1840 +/- 130 kcal.d-1). There were no changes in body weight (day 1, 65.4 +/- 1.6; day 5, 65.2 +/ 1.5 kg) over the measurement period. TEE of the swimmers during the training period averaged 23.4 +/- 2.1 MJ.d-1 (5593 +/- 495 kcal.d-1). EI averaged 13.1 +/- 1.0 MJ.d-1 (3136 +/- 227 kcal.d-1), implying a negative energy balance of 43 +/- 2%. TEE expressed as a multiple of REE was 3.0 +/- 0.2. The results of this investigation describe the total energy demands of high volume swimming training, which may be used to address the dietary concerns of the competitive swimming athlete.

396 ISOTOPIC DETERMINATION OF GLYCOLYTIC FLUX DURING INTENSE EXERCISE IN HUMANS

We used a new stable isotope tracer approach incorporating muscle intracellular lactate enrichment to determine the flux of glucose/glucosyl toward lactate [i.e., nonoxidized pyruvate (Pyr) production (Pyrno)] in moderately trained cyclists exercising at approximately 80% (259 +/- 16 W; n = 6) and approximately 100% (341 +/- 9 W; n = 8) maximal O2 uptake (VO2max). Primed constant infusions of [6,6-2H2]glucose and [13C]lactate or [13C]Pyr tracers were given, and rapid achievement of plateau was obtained during exercise by increasing the infusion rates at exercise onset to correspond with expected increases in production. The accumulated O2 deficit was simultaneously determined over the 1st 3 min of exercise as an indirect means of quantifying glycolytic flux for comparison with our tracer-determined values and was significantly greater at the higher intensity (38 +/- 3 vs. 30 +/- 3 ml O2.kg-1.3 min-1; P < 0.02). Pyrno was also significantly higher (6.38 +/- 0.91 vs. 4.38 +/- 0.65 mmol.kg-1.min-1 over 3 min at 100 and 80% VO2max, respectively). The blood lactate rate of appearance at approximately 100% VO2max (828 +/- 69 mumol.kg-1.min-1) represented a higher percentage of Pyr rate of appearance (RaPyr; 31 +/- 3%) than that at approximately 80% VO2max (416 +/- 36 mumol.kg-1.min-1; 22 +/- 2%; P < 0.02). Although only approximately 27 +/- 2% of RaPyr was oxidized, this provided 78 +/- 2% of the total energy demand during the 1st 3 min of exercise at either intensity. Our new method provided values for Pyrno that were in the expected range and were highly correlated with respective accumulated O2 deficit values (r = 0.87, P < 0.0001). In conclusion, our new tracer method appears to be valid for the measurement of RaPyr and Pyrno during high-intensity exercise lasting even < 10 min.