Table 2.

The characteristics of studies that did not involve an exercise performance or exercise capacity component included in this review

Author and Year	Participant characteristics	Study design	Hyperhydration osmolyte	Fluid amount co-ingested	Elapsed time between completion of hyperhydration and beginning of exercise	Comparator	Exercise protocol and environmental conditions
Beis et al. 2011 [65]	n = 14, M, 24 ± 5 years, 69.5 ± 5.0 kg, trained runners	Before and after	7 days of 10 g L−1 of creatine, 1.0 g kg−1 BM of glycerol and 75 g L−1 of glucose	1000 mL	Final dose 240 min pre-exercise	Pre-supplementation	Treadmill running for 2 × 30 min at 60% $\dot{V}$O2max in ~35 °C and ~69% RH, or 10 °C and ~69% RH
Cian et al. 2000 [66]	n = 8, M, 27.4 ± 3.7 years, 72.6 ± 5.9 kg, endurance trained	Crossover	1.1 g kg−1 BM glycerol consumed with	21.4 mL kg−1 BM	90 min	Fluid only (contained 1.2 g L−1 NaCl)	15–20 min arm-crank ergometer at 85% $\dot{V}$O2max in 25 °C and 40% RH
Freund et al. 1995 [19]	n = 11, M, 24 ± 2 years, 79.4 ± 2.4 kg, healthy and recreational athletes	Counterbalanced, crossover	1.5 g L−1 TBW of glycerol	5 mL L−1 TBW with initial bolus  +  32 mL L−1 TBW	N/A	Water No treatment	N/A
Fujii et al. 2021 [68]	n = 9 M, 23.4 ± 3.9 years, 65.9 ± 5.2 kg, healthy	Randomised, partially counterbalanced, crossover	0.7% NaCl 0.7% NaCl + 6% dextrin 0.9% NaCl 0.9% NaCl + 6% dextrin 6% dextrin (n = 3)	16–17 mL kg−1 BM	N/A	Water	N/A
Goulet et al. 2018 [15]	n = 15, M, 22 ± 4 years, 76 ± 7 years, recreationally active	Randomised, counterbalanced, crossover	7.5 g L−1 of NaCl 1.4 g kg−1 FFM of glycerol 7.5 g L−1 of NaCl + 1.4 g kg−1 FFM of glycerol	30 mL kg−1 FFM	N/A	Each treatment was compared with other hyperhydration treatments	N/A
Koehler et al. 2014 [27]	n = 14, 12 M, 2 F, 27 ± 5.4 years, 73.7 ± 8.1 kg, well trained	Crossover	1.0 g kg−1 BM glycerol	25 mL kg−1 BM	130 min	Sweetened beverage	90 min of cycling at 60% $\dot{V}$O2max in ~ 21.1 °C and ~ 45.2% RH
Latzka et al. 1997 [35]	n = 8, M, 23 ± 6 years, 76 ± 15 kg, trained	Crossover	1.2 g kg−1 LBM glycerol	29.1 mL kg−1 LBM	30 min	Euhydration	120 min of treadmill running at 45% $\dot{V}$O2max in 35 °C, 45% RH and air flow 1.0 m s−1
Lyons et al. 1990 [33]	n = 6, 4 M, 2 F, 26.2 ± 1.5 years, 71.1 ± 6.0 kg, recreationally trained	Randomised, crossover	1.0 g kg−1 BM glycerol + 0.1 g kg−1 BM of glycerol every hour after 2 h	21.4 mL kg−1 BM	150 min after initial dose	Sweetened beverage Limited fluid	90 min of treadmill exercise at 60% $\dot{V}$O2max in 42 °C, 25% RH and air flow 1.66 m s−1
Melin et al. 2002 [67]	n = 8, M, 27.4 ± 3.6 years, 72.6 ± 5.9 kg, healthy	Randomised, crossover	1.1 g kg−1 BM glycerol	21.4 mL kg−1 BM	N/A	Euhydration	N/A
Montner et al. 1999 [51]	n = 6, 4 M, 2 F, 27 ± 3 years, 68 ± 6 kg, well trained	Randomised, double-blind, crossover	1.2 g kg−1 BM glycerol	26 mL kg−1 BM	60 min	Sweetened beverage	110 min of cycling at ~44% $\dot{V}$O2max in 23.5–24.5 °C and 25–27% RH
O'Brien et al. 2005 [64]	n = 7, M, 22 ± 3 years, 78.9 ± 7.8 kg, trained	Crossover	1.5 g L−1 TBW glycerol 1	5 mL L−1  +  32 mL L−1 TBW	N/A	Water No treatment	N/A
Riedesel et al. 1987 [52]	n = 22, 13 M, 9 F, 65–67 kg, healthy	Randomised, crossover	0.5 g kg−1 BM or 1.0 g kg−1 BM or 1.5 g kg−1 BM of glycerol	21.4 mL kg−1 BM	N/A	Placebo	N/A
Savoie et al. 2015 [30]	n = 17, M, 21 ± 3 years, 79 ± 10 kg, recreationally trained	Randomised, double-blind, counterbalanced, crossover	1.4 g kg−1 of glycerol or 7.45 g L−1 of NaCl ingested	30 mL kg−1 FFM	N/A	Water	N/A
Savoie et al. 2016 [29]	n = 16, M, 21 ± 2 years, 77 ± 9 kg, trained	Randomised, counterbalanced, crossover	7.45 g L−1 of NaCl ingested in either solution or using dissolvable tablets or 1.4 g kg−1 FFM glycerol	30 mL kg−1 FFM	N/A	Each treatment was compared with other hyperhydration treatments	N/A
Siegler et al. 2021 [46]	n = 19, 13 M, 6 F, 28.3 ± 4.6 years, ~79.2 kg, healthy	Randomised, single-blind, partially counterbalanced, crossover	7.5 g L−1 of either sodium bicarbonate or sodium citrate	25 mL kg−1 BM	N/A	Sweetened beverage	N/A
Sugihara et al. 2014 [36]	n = 8, M, 22.6 ± 1.4 years, 65.6 ± 2.4 kg, healthy	Randomised, crossover	60, 120 or 180 mmol L−1 of sodium	16–17 mL kg−1 BM	N/A	Water	N/A

N number, M male, F female, kg kilograms, y years, g L⁻¹ grams per litre, VO_2max maximal oxygen consumption, RH relative humidity, g kg⁻¹ BM grams per kilogram of body mass, mL kg⁻¹ BM millilitres per kilogram of body mass, NaCl sodium chloride, TBW total body water, mL L⁻¹ millilitres per litre, FFM fat free mass, m s⁻¹ metres per second, LBM lean body mass, mmol L⁻¹ millimoles per litre