Effects of hydration status on aerobic performance for a group of male university rugby players

The object of this study was to examine the effects of hydration status on exercise performance in a group of amateur athletes under conditions of hypohydration (HYPO) and euhydration (EUH) at 'neutrally stable' temperatures. Eight healthy, physically active, amateur University rugby players (age 21.0±1.4 yrs, BMI 28.3±6.1 kg/m²) underwent two 12 hr programs of hydration (fluid abstinence and consumption at ∼20 °C) in order to induce states of EUH and HYPO. The participants completed two 30 min cycle ergometer tests under each hydration state in a random order. Changes in performance were measured using heart rate (HR), rate of perceived exertion (RPE) and relative rate of oxygen uptake (VO2). Urine osmolality values (UOsm) were also measured to quantify hydration status. UOsm values were EUH 385±184 mOsm/kg and HYPO 815±110 mOsm/kg. In the EUH condition, from rest to 30 min, HR values ranged from 78±12 to 116±12 beats/min, RPE 6±0 to 11±2 units and VO2 5.7±2.1 to 16.8±3.4 mL/kg/min. In the HYPO condition, HR 85±9 to 124±13 beats/min, RPE 6±0 to 13±2 units and VO2 6.2±2.8 to 20.1±3.5 ml/kg/min (mean±SD, p≤0.05). In conclusion, HR, RPE and VO2 variables increased significantly under HYPO conditions when compared to EUH conditions at ∼20°C and therefore having a detrimental effect on performance.