Table 1.

Neuropsychological responses to hypoxia

	Baseline, raw scores	Creatine, raw scores	Placebo, raw scores	Effect of hypoxia^{^a}		Effect of supplementation^{^b}
	Baseline, raw scores	Creatine, raw scores	Placebo, raw scores	t	p	t	p
Alertness rating scale	4.1 ± 0.8	2.7 ± 0.9	2.6 ± 1.0	−4.1	< 0.001^*	0.1	0.464
Complex attention	93.7 ± 16.8	86.4 ± 22.7	70.7 ± 51.5	−2.0	0.031^*	1.8	0.049^*
ST, incongruent CE	1.9 ± 1.8	2.1 ± 1.8	2.0 ± 1.5	1.5	0.079^{^†}	0.9	0.195
SAT, errors	5.4 ± 3.8	6.4 ± 4.4	8.3 ± 6.9	2.4	0.017^*	−0.8	0.230
CPT, CE	0.7 ± 1.2	1.1 ± 1.7	3.0 ± 5.6	2.5	0.013^*	−2.2	0.020^*
CPT, omission errors	0.1 ± 0.3	0.9 ± 1.9	1.8 ± 4.6	1.4	0.087^{^†}	−1.1	0.140
Executive function	100.5 ± 17.9	100.9 ± 17.9	91.9 ± 28.9	−1.2	0.118	1.5	0.082^{^†}
SAT, correct	55.5 ± 9.0	56.6 ± 8.4	52.9 ± 12.4	−0.8	0.226	1.3	0.110
SAT, errors	5.4 ± 3.8	6.4 ± 4.4	8.3 ± 6.9	2.4	0.017^*	−0.8	0.230
Cognitive flexibility	98.8 ± 18.2	98.9 ± 19.3	88.9 ± 31.7	−1.4	0.092^{^†}	1.6	0.072^{^†}
SAT, correct	55.5 ± 9.0	56.6 ± 8.4	52.9 ± 12.4	−0.8	0.226	1.3	0.110
SAT, errors	5.4 ± 3.8	6.4 ± 4.4	8.3 ± 6.9	2.4	0.017^*	−0.8	0.230
ST, incongruent CE	1.9 ± 1.8	2.1 ± 1.8	2.0 ± 1.5	1.5	0.079^{^†}	0.9	0.195
Neurocognitive index	104.2 ± 10.6	99.7 ± 14.3	92.2 ± 23.0	−2.2	0.022^*	1.6	0.071^{^†}
Composite memory	106.0 ± 13.1	97.8 ± 21.2	96.1 ± 16.7	−2.1	0.029^*	0.3	0.400
Psychomotor speed	118.8 ± 18.5	114.5 ± 23.0	112.0 ± 22.9	−2.0	0.033^*	0.6	0.279
Reaction time	103.2 ± 10.6	100.7 ± 12.6	98.9 ± 13.8	−0.7	0.259	0.4	0.332
Complex attention	93.7 ± 16.8	86.4 ± 22.7	70.7 ± 51.5	−2.0	0.031^*	1.8	0.049^*
Cognitive flexibility	98.8 ± 18.2	98.9 ± 19.3	88.9 ± 31.7	−1.4	0.092^{^†}	1.6	0.072^{^†}

A range of composite domain (italic type) and standard neurophysiological scores were reduced by hypoxia during PLA (effect of hypoxia). CrM standard scores tended to be higher during hypoxia than PLA (effect of supplementation), suggesting that these processes were robust to the effects of hypoxia. Note that for standard neurophysiological scores, higher error scores indicate worse performance, and higher correct response scores indicate better performance. For composite domain scores, higher scores indicate better performance. The alertness rating was measured using a six-point rating scale and was reduced with hypoxia and not corrected by CrM. ST, Stroop test; SAT, shifting attention test; CPT, continuous performance test; CE, commission errors. Descriptive data are mean ± SD.
↵^aComparisons with baseline used one-sample t tests of normalized PLA scores compared to baseline (0) to assess the effects of hypoxia.
↵^bBetween-treatment comparisons used paired t tests of normalized scores for CrM compared to PLA to assess the effects of supplementation.
↵*p < 0.05;
↵^†p ≥ 0.05 and <0.1. Bold type highlights statistically significant comparisons.