Supervisors info:
Κοσκολού Μ., Επίκουρη Καθηγήτρια, ΤΕΦΑΑ, ΕΚΠΑ
Γελαδάς Ν., Καθηγητής, ΤΕΦΑΑ, ΕΚΠΑ
Ψυχουντάκη Μ., Αναπληρώτρια Καθηγήτρια, ΤΕΦΑΑ, ΕΚΠΑ
Summary:
The functional ability to preserve the recommended water balance in the human body deteriorates with aging. It has been found that in elderly people mild dehydration, corresponding to fluid loss 1-2% of total body weight, can significantly reduce physical performance and cause mental dysfunction. In this study, the effect of mild dehydration on the physical and mental performance of 20 elderly men and women (60-75 years) was evaluated by using the Senior Fitness Test, as well as a test for the assessment of mental concentration.
All participants (10 males and 10 females, 65.5±4.7 years old) performed the physical fitness and mental concentration tests under two different hydration states, following a counter-balanced order. In order to participate in the dehydration condition (DEH), all subjects had to abstain from fluid intake for a 24-hr period before performing the tests, while in the hydration condition (HYD) they were encouraged to consume liquids ad libitum for the same amount of time (a minimum amount of 2.5L/day was suggested). In both conditions, morning urine specimens were collected to assess hydration level, using three methods: a) via estimation of the specific gravity (USG), b) via urine reagent strips (USGD), as well as c) via using urine color chart (UCC). As DEH limit was defined at a USG value ≥ 1020, while as HYD, USG <1020. In addition to the scores achieved in the physical fitness and mental concentration tests, heart rate, arterial pressure, body weight and perception of thirst were registered.
For the statistical analysis, t-test for dependent samples, two-way ANOVA (gender x hydration status) with repeated measures and Pearson correlation were used. The significance level was set at p<0.05.Results show moderate to very high correlation among the three methods of hydration level assessment for both conditions (r=0.565-0.864; p< 0.01). In DEH condition, a 1,4% loss of total body weight was achieved (p<0.001) and the perception of thirst was greater (p<0.001). Moreover, lower scores compared with the HYD condition were observed in the tests: "30sec chair stand/ sit to stand" (DEH: 17.9 ± 5.1 rpts vs. HYD: 19.5 ± 4.1; p<0.05), "6 minute walking test" (DEH: 521,3 ± 79.4 m vs. HYD: 565,8 ± 94, 8m; p<0.001) as well as in the mental performance concentration test (DEH: 17.7 ± 2.2 score vs. HYD: 21.0 ± 3.9 score ; p< 0.001).
On the contrary, no statistically significant difference (p>0,005) was found between DEH and HYD in the performance of the following tests: "arm curl" (DEH: 24.9 ± 3.9 rpts vs. HYD: 26.5 ± 5.8 rpts; p=0.101), "back scratch" (DEH:-9.2 ± 9,3cm vs. HYD: -8.0 ± 9.4 cm; p=0.119), "chair sit and reach" (DEH: 0.0 ± 9.1 cm vs. HYD: 1± 10.2 cm; p= 0.118), "8 feet trial up and go" (DEH: 5.0 ± 1.1 sec vs. HYD: 4.9 ± 1.1 sec; p=0.119). The performance of females in all tests was similar to that of males (p>0.05) and no significant interaction was detected between gender and hydration status in the performance of any test.
In conclusion, the results of the present study confirmed the hypothesis that mild dehydration negatively affects physical and mental performance in elderly people, especially cardiorespiratory endurance and mental alertness. According to this study, the importance of adequate hydration on a daily basis is essential in order to preserve good physical and mental performance, particularly in elderly people.
