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Thematic Poster Session Format: First 30 minutes of session – View posters: Remaining 90 minutes of session – Chair leads discussion: D-58 Thematic Poster – Hypohydration and Performance: THURSDAY, JUNE 1, 2006 3: 15 PM – 5: 15 PM ROOM: 101

The Influence of Mild Hypohydration on a Resistance Training Workout

1338

Board #2

Yamamoto, Linda M.; Kraemer, William J. FACSM; McCormick, Timothy J.; Nindl, Bradley C. FACSM; Volek, Jeff S.; Spiering, Barry A.; Hatfield, Disa L.; Fragala, Maren S.; Vingren, Jakob L.; Ho, Jen-Yu; Scheett, Timothy P.; Judelson, Daniel A.; Armstrong, Lawrence E. FACSM; Koziris, L Perry FACSM; Gordon, Scott E. FACSM; Triplett, N Travis; Maresh, Carl M. FACSM

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Medicine & Science in Sports & Exercise: May 2006 - Volume 38 - Issue 5 - p S176
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PURPOSE: The purpose of this study was to determine the effects of hydration status on hormonal and performance responses to a resistance training workout.

METHODS: Seven men (age (yrs)23.1 ± 2.4; height (cm)70.1 ± 4.0; body mass (kg)74.4 ± 10.3 and body fat (%)10.3 ±2.5) who were recreationally trained with at least 4.2±2.1 years of resistance training experience volunteered as subjects. Three conditions were examined using a multi-set, resistance training workout with 1 RMs determined for each lift. A control rest day (C), euhydrated day (E) and a hypohydrated day (H) experimental conditions were balanced and randomly assigned with the only difference between the two workout days was the subjects' hydration status. Hypohydration was achieve by a 3% reduction in body weight mediated by fluid and food restriction, and exercise the night before the day of testing.

RESULTS: The results of the strength tests showed a significant difference in the 1 RM shoulder press between the hypohydration (H) (69±5 kg) workout and the euhydrated workout (E) (73±6 kg). All other 1 RM tests were not significantly different between the H workout and the control (C) workout. There were no significant differences in the total work between the workouts. Lactate significantly (P <0.05) increased with the resistance exercise workout with no significant difference found between the workout conditions. The plasma osmolality was significantly higher in the H condition before and after exercise. No differences were observed between the workouts for serum testosterone or LH while expected increases in testosterone occurred immediately post-exercise. Cortisol increased post-exercise at 0, 15 and 30 minutes with no differences observed between the treatment conditions. However area under the curve analysis demonstrated a significantly higher total cortisol exposure under the H condition.

CONCLUSION: These data show that mild hypohydration impacts the osmolality concentrations and total cortisol exposure over the recovery period along with an impairment of strength in small muscle groups.

© 2006 American College of Sports Medicine