Twenty-two participants (8 female and 14 male, age 29.0 ± 3.0 years, weight 71.6 ± 10.7 kg, height 175.6 ± 8.7 cm) were included in the study and no dropouts occurred during the trial. After randomisation we could observe in each group three left-handed participants, and three participants with a PSQI score > 5 (range 6-11) indicating mild sleeping disorders. There were no differences between groups regarding the intake of alcohol, coffee, caffeine products, energy drinks and cigarettes. Time spent with exercise was similar in both groups. Handiness revealed. There was no significant difference of any outcome between groups at baseline (Table 1).
We could not detect significant differences between intervention and control regarding the occurrence of the false memory rate (0.80 ± 0.12 vs. 0.76 ±0.16, unpaired t-test p = 0.456), false alarm rate (0.40 &plusamn;0.12 vs. 0.43 ±0.08, p = 0.40), or true recognition rate (0.70 ± 0.13 vs. 0.67 ± 0.15, p = 0.56, see Table 2). Effect sizes do not suggest only small effects between groups, i.e. false memories (Cohen’s d= 0.32, effect size correlation r = 0.16), false alarms (d = 0.36, r = 0.18), and recognition (d = 0.25, r = 0.12).
Time x group analysis of the d2 test showed a trend (p < 0.1) towards an improved cognition. Posthoc t-tests for inner-subject effects sustained this trend for all d2 items in the exercise group, i.e. attention (p < 0.001), as well as concentration performance (p < 0.001), and performance speed (p < 0.001). The attention score improved within the exercise group by 17.22 ± 15.21% versus 3.53 ± 20.57% in the control group (Table 2, Figure 2). The magnitude indicates a strong effect (d = 0.76, r = 0.35). This effect was consistent for performance (d = 0.78, r = 0.36) and speed (d = 0.71, r = 0.34).
Time x group analysis of sleepiness, the dimensions of mood, balance, grip strength, and pressure pain revealed no significant effects (see Table 2).
There were inner-subject effects on sleepiness (p = 0.019), with an increase of 0.59 ± 4.30 cm VAS in the intervention and 2.97 ± 3.54 cm VAS in the control group, with no significance between groups (posthoc unpaired t-test p = 0.171). The magnitude corresponds to a strong effect (d = 0.60, r = 0.29).
Subgroup analysis dependent on a PSQI > 5 (cut-off for sleeping disorders) did not alter the observed trends. However, improvements in attention in the exercise group were significantly more pronounced in participants with a PSQI ≥ 5 (∆-32.43 ± 18.29%) versus PSQI < 5 (∆‑11.51 ± 32.43%; p = 0.033). The PSQI did not affect other outcomes.
Covariate analysis including gender did not reveal differences in the time x group analysis. Female gender led to decreased errors in the balance test (∆‑8.25 ± 5.44 versus ∆+2.71 ± 7.27, p = 0.029) in the intervention group. Pressure pain threshold was significantly reduced in female participants in the exercise group (p = 0.038), and grip strength in both female groups, exercise (p = 0.004) and control (p = 0.011). Gender had no effects on attention and false memories.
No harms have been observed within this study.