The aim of the present study was to observe the effect of mild hypohydration on exercise performance with subjects blinded to their hydration status. Eleven male cyclists (weight 75.8 ± 6.4 kg, VO 2peak : 64.9 ± 5.6 mL/kg/min, body fat: 12.0 ± 5.8%, Power max : 409 ± 40 W) performed three sets of criterium-like cycling, consisting of 20-minute steady-state cycling (50% peak power output), each followed by a 5-km time trial at 3% grade. Following a familiarization trial, subjects completed the experimental trials, in counter-balanced fashion, on two separate occasions in dry heat (30°C, 30% rh) either hypohydrated (HYP) or euhydrated (EUH).In both trials, subjects ingested 25 mL of water every 5 minutes during the steadystate and every 1 km of the 5-km time trials. In the EUH trial, sweat losses were fully replaced via intravenous infusion of isotonic saline, while in the HYP trial, a sham IV was instrumented. Following the exercise protocol, the subjects' bodyweight was changed by −0.1 ± 0.1% and −1.8 ± 0.2% for the EUH and HYP trial, respectively (P < 0.05). During the second and third time trials, subjects averaged higher power output (309 ± 5 and 306 ± 5 W) and faster cycling speed (27.5 ± 3.0 and 27.2 ± 3.1 km/h) in the EUH trial compared to the HYP trial (Power: 287 ± 4 and 276 ± 5 W, Speed: 26.2 ± 2.9 and 25.5 ± 3.3 km/h, all P < 0.05). Core temperature (T re ) was higher in the HYP trial throughout the third steady-state and 5-km time trial (P < 0.05). These data suggest that mild hypohydration, even when subjects were unaware of their hydration state, impaired cycle ergometry performance in the heat probably due to greater thermoregulatory strain.
K E Y W O R D Scycling, heat stress, time trial, water intake
Summary
Taste thresholds for phenylthiourea were measured in 962 Israeli children and adolescents. The incidence of non‐toxic nodular goitre (endemic goitre) among these subjects was investigated. A large difference of nontasters frequency was found between goitrous and non‐goitrous subjects, i.e. 20·;8 and 4·7%, respectively. It has been concluded that non‐tasters may be somewhat more susceptible to the development of nodular goitre than tasters. The frequency of non‐tasters among the whole sample is 9·5%, which is as low as in Mongoloid groups, i.e. 10·6% for Chinese and 7·1% for Japanese.
SUMMARY
Taste threshold for phenylthiourea was measured in 115 paralytic poliomyelitis subjects and 120 healthy people of both sexes from 6 to 40 years of age originating from various countries (Israel, Europe, Asia and North Africa Jews).
A significant difference of non‐tasters frequency was found between paralytic poliomyelitis and healthy subjects, i.e. 31.3 and 16.7%, respectively.
It may be suggested that the non‐tasters of paralytic poliomyelitis patients are more susceptible to polio virus.
I wish to thank Prof. M. Makin, Director of the orthopedic hospital ‘Alyn’for crippled children in Jerusalem, Drs Mandel, Head of the Pediatric Department of the Government Hospital Sarafand, Goldman, Head of the Orthopedic Department of the Government Hospital Poriah for allowing me full access to their patients, and Dr A. Salamonovitsh, Head of the Health Centre Kiryath Shmonah for permission to examine school children.
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