EFFECT OF HYPOHYDRATION ON DYNAMIC BALANCE IN TYPE II DIABETICS

Rebecca A. Mishler, J.D. Adams, Costas N. Bardis, Evan C. Johnson, LynnDee S. Summers, Weldon G. Murray & Stavros A. Kavouras, FACSM Human Performance Laboratory, Department of Health, Human Performance, and Recreation, University of Arkansas, Fayetteville, Arkansas Falls are a recognized as an important cause of morbidity and mortality. However, no data exist on the effect of hypohydration on dynamic balance in type II diabetics. Type II diabetics may have impaired balance due to complications of diabetic neuropathy. PURPOSE: Therefore, the purpose of this investigation was to examine the effects of hypohydration on postural balance in type II diabetics. METHODS: 10 type II diabetic males (52±8 y; 94.8±22.2 kg; 6.9±1.0 HbA1c) performed two trials on dynamic postural balance while either euhydrated (USGRESULTS: USG was lower in euhydrated trial (1.011±0.006) compared to the hypohydrated trial of (1.028±0.006; p0.05). Similarly, there were no differences in MD (4.2±2.8 vs. 4.9±3.6) or OSI (3.4±2.1 vs. 3.8±2.8; p\u3e0.05). CONCLUSION: The results indicated that hypohydration had no significant effect on dynamic postural indices in type II diabetes

BLOOD GLUCOSE KINETICS ARE RELATED TO HYDRATION STATUS IN MEN WITH TYPE II DIABETES MELLITUS

Evan, C. Johnson, Costas N. Bardis, J.D. Adams, LynnDee Summers, Wheldon Murray, Joseph Robillard & Stavros A. Kavouras, FACSM University of Arkansas, Fayetteville, Arkansas Daily total water intake (TWI) has been linked to a number of chronic diseases, such as urolithiasis and chronic kidney disease. Additionally, epidemiological and animal model data have tied low TWI to impaired blood glucose regulation. However, the effect of a fluid intake intervention on blood glucose regulation has not yet been observed in humans. PURPOSE: Thus, the purpose of the current investigation was to determine if the response to an oral glucose tolerance test (OGTT) was altered by manipulation of hydration status in people with diabetes. METHODS: Nine men (53±9 y, 94.9± 23.8 kg, 1.75± 0.11 m, 30.0± 4.3 mkg-2, 31.5± 6.5 %BF) who had previously been diagnosed with type II diabetes mellitus (T2DM) (hemoglobin A1C; 6.8±0.9 %) were recruited to take part. Participants completed two OGTTs in a euhydrated and hypohydrated state one week apart in a counterbalanced order. Euhydration was achieved by standard water prescription in line with the dietary reference intakes for water, and hypohydration was achieved through progressive water restriction over three days leading up to the OGTT. Blood samples were taken at time points 0, 15, 30, 45, 60, 90, and 120 min of the OGTT. RESULTS: The changes in TWI in the three days before each trial resulted in significantly lower body mass (-1.5±1.5 kg; p = 0.017) and increased urine specific gravity (0.017±0.009; p = 0.001), and plasma osmolality (10±8 mmolkg-1). Repeated measures analysis of variance identified a main effect of condition for blood glucose concentration F[1,48] = 10.772, p = 0.011, but not for insulin concentration F[1,48] = .657, p = 0.441. CONCLUSION: Hypohydration elicits an acute, negative effect on the blood glucose response to OGTT in men with T2DM. Although, blood insulin did not change, blood glucose was reduced during the euhydrated trial. This suggests that inadequate TWI hindered insulin sensitivity. Future research should aim to establish if longer periods of fluid restriction result in larger disturbances to blood glucose regulation

FLUID BALANCE OF ADOLESCENT SWIMMERS DURING TRAINING

Joseph I. Robillard, J.D. Adams, Evan C. Johnson, Costas N. Bardis, LynnDee G. Summers, Ainsley Huffman, Thomas Vidal, Mikell L. Hammer & Stavros A. Kavouras, FACSM Human Performance Laboratory, Department of Health, Human Performance, and Recreation, University of Arkansas, Fayetteville, Arkansas While there are a number of studies identifying a high percentage of athletes who start exercise in a hypohydrated state, there is limited data concerning hydration levels in swimming. PURPOSE: The purpose of this study was to identify the hydration status of adolescent swimmers during a typical day of training. METHODS: Forty-six adolescent swimmers (26 males; age: 12.8±2.3 y; weight: 50.6±13.4 kg) participated in the study. Hydration status was assessed in first morning urine samples as well as immediately before and after practice. Hypohydration was classified by urine osmolality (UOsm \u3e700 mmol/kg). Thirst perception was measured using a visual analog scale (VAS). RESULTS: 67% of the swimmers were hypohydrated based on their morning urine sample (USG: 1.021±0.007; UOsm: 788±252 mmol/kg). Pre-practice urine samples revealed that 78% of athletes were hypohydrated (USG: 1.021±0.008; UOsm: 828±304 mmol/kg). Swimmers consumed ad libitum fluid volume of 472±219 ml and acquired sweat losses of 394±268 ml over 120 minutes of practice resulting in a mild decrease in their body weight of -0.3±0.6%. Thirst perception did not change significantly from pre- (45.5±26.1 mm) to post-practice (55.4±32.5 mm). Post-practice hydration markers indicated that subjects improved their hydration state even while losing body water (USG: 1.018±0.011; UOsm: 630±390 mmol/kg). CONCLUSION: We conclude that the prevalence of hypohydration among adolescent swimmers is high, as indicated by elevated USG and urine osmolality values both in the morning and prior to practice. Post-swimming urinary markers could be misleading when trying to assess hydration state. Possibly water immersion increases diuresis, by attenuating vasopressin secretion via central volume receptors loading due to the hydrostatic pressure

Hydration in sport and exercise

Hypohydration, defined as a deficit in total body water that exceeds normal daily fluid fluctuations, is typically set as a fluid loss equivalent to >2% of body mass. The evaporation of sweat provides the principle means of heat dissipation during exercise in the heat; typical sweat rates of 300–2000 mL/h during sporting activities are generally not matched by fluid intake, leading to hypohydration. Although there are shortcomings in the literature related to hypohydration and sports performance, it is likely that some scenarios (hot conditions, larger fluid losses and prolonged aerobic exercise) are more at risk of incurring impaired performance. Guidelines for fluid intake during exercise and sporting activity are contentious since they need to span situations in which it is easy to overdrink compared with sweat losses and others in which significant levels of hypohydration occur. Nevertheless, athletes can be guided to develop fluid intake plans that are suited to their specific needs