Table 1. Univariable associations between hydration indicators and study conditon (n = 107).

	Water	Control	p*
Mean (SD) morning urine specific gravity (Usg)	1.008 (0.01)	1.007 (0.01)	0.35
Mean (SD) morning Ucol (scale 1–7)	2.34 (1.54)	2.29 (1.24)	0.77
Dehydrated† in morning	4 (3.7%)	2 (1.9%)	0.69
Mean (SD) afternoon Usg	1.010 (0.01)	1.014 (0.01)	<0.01
Mean (SD) afternoon Ucol (scale 1–7)	3.10 (1.82)	3.44 (1.43)	0.11
Dehydrated† in afternoon	12 (11.2%)	17 (15.9%)	0.38
Mean (SD) afternoon self-reported thirst (scale 1–5)	3.2 (1.5)	3.1 (1.6)	0.21

*p-value based on McNemar’s test statistic for binary variables and paired sample t-tests for continuous variables

^†Pupils with a U_sg >1.019 classified as mildly dehydrated

Bold values indicate a significant association at α = 0.05