Effects of dehydration and rehydration on the one-repetition maximum bench press of weight-trained males.

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.

An 11 year follow-up of individual radiation responses as assessed by micronuclei induction in peripheral blood lymphocytes.

In this short note we describe the results of a unique 11 year follow-up of the induction of micronuclei by radiation in three individuals. These individuals were all part of two larger studies carried out in 1987 and 1998 respectively, each having similar population characteristics. No significant differences in the average radiation response of these two populations were observed, nor were there any apparent differences in the 1987 and 1998 responses of two of the three individuals reassessed. Data from the third individual (and from a wider study reported elsewhere) do, however, provide some evidence for an age dependence. It is concluded that significant individual variations in the age-dependent responses to radiation may exist, and that while for some individuals there is no increase in radiosensitivity with age, for others there is. Such age dependences may be diluted by studying age-related responses in whole populations of limited size rather than by following individuals over a long period of time. The results reported here are from a limited data set and it is important that further studies are carried out to provide evidence for or against the existence of an age-dependent response to radiation in some individuals.