title: Effects of dehydration and rehydration on the one-repetition maximum bench press of weight-trained males.
abstract: Dehydration, a common practice among competitive athletes in sports including weight classes, has uncertain effects on strength. This study examined the effects of passive dehydration (D, approximately 2 hours in a sauna) followed by rehydration (R, approximately 2 hours of rest with water ad libitum) on bench press one-repetition maximum (1RM). Ten weight-trained males (x +/- SE; age = 25 +/- 1 years; mass = 85.5 +/- 5.2 kg; height = 173.5 +/- 1.7 cm; body fat = 17.8 +/- 2.2%; 1RM = 118 +/- 8 kg) completed 2 testing sessions (E1/E2 and D/R) consisting of, respectively, 2 euhydration 1RM measurements separated by 2 hours of rest; and D 1RM followed by R 1RM. Testing sessions were administered in counterbalanced order and separated by 1 week. D resulted in increases (p < 0.005) in body temperature, urine specific gravity, hematocrit, and hemoglobin (calculated 8% decrease in plasma volume) as well as decreased body mass (p < 0.005). 1RM was decreased following D (111.4 +/- 7.2 kg) compared to both E1 (118 +/- 7.6 kg, p = 0.0015) and R (117.3 +/- 7.8 kg, p = 0.0023), with no significant difference between E1 and R. A significant association (r = -0.67, p < 0.05) was observed between percent lean body mass (%LBM) and the change in 1RM following D. In conclusion, passive dehydration resulting in approximately 1.5% loss of body mass adversely affects bench press 1RM performance. The adverse affects of dehydration seem to be overcome by a 2-hour rest period and water consumption.
authors.affiliation: Department of Exercise Science, Physical Education, and Recreation, Old Dominion University, Norfolk, Virginia 23529, USA.
authors.forename: J E
authors.initials: JE
authors.lastname: Schoffstall
authors.forename: J D
authors.initials: JD
authors.lastname: Branch
authors.forename: B C
authors.initials: BC
authors.lastname: Leutholtz
authors.forename: D E
authors.initials: DE
authors.lastname: Swain
mesh_terms: D000328:Adult; D001132:Arm / Q000502:physiology; D001794:Blood Pressure; D001824:Body Constitution; D001831:Body Temperature; D003681:Dehydration / Q000503:physiopathology*; D005440:Fluid Therapy; D006339:Heart Rate; D006400:Hematocrit; D006454:Hemoglobins / Q000032:analysis; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000502:physiology*; D010806:Physical Education and Training; D010809:Physical Fitness / Q000502:physiology*; D010953:Plasma Volume; D013647:Task Performance and Analysis; D016482:Urinalysis; D014891:Weight Lifting / Q000502:physiology*
chemical_list: D006454:Hemoglobins