CCPT Performance Variables

Reaction Time

A one-way within subjects (or repeated measures) ANOVA was conducted to compare the effect of exercise intensity on reaction time. Reaction times were 309.15 ± 39.42ms, 323.24 ± 34.11ms and 324.07 ± 34.44ms for resting, low and moderate intensity, respectively. Mauchly´s test indicated that the assumption of sphericity had not been violated (χ²(2) = 3.27, p > 0.05); therefore degrees of freedom were not corrected. The overall results from the one-way repeated measures (within subjects) ANOVA showed that reaction time was significantly affected by Exercise Intensity F(2, 58) = 7.48, p

< 0.005, ηp2 = 0.21. Observed power was .93. Polynomial trend analyses showed a significantly linear fashion of increase in reaction time with exercise intensity F(1,29) = 9.10, p < 0.05, ηp2 = 0.24 with a power of .83. Bonferroni adjusted post-hoc analyses indicated that reaction time during moderate intensity was significantly different from baseline (p < 0.05) but not from low intensity (p > 0.05).

Moreover, reaction time during low intensity was significantly different from baseline (p < 0.05).

These results suggest that exercise intensity really does have an effect on reaction time. Specifically, the results suggest that reaction time increases with exercise intensity. However, there is no real difference in reaction time when comparing low and moderate exercise intensity.

Figure 18: Reaction Time during running

Note. The x-axis represents the 3 conditions, baseline, low intensity and moderate intensity. On the y-axis reaction time is measured in milliseconds. The overall repeated-measures ANOVA was significant and Bonferroni adjusted post-hoc measures indicated that reaction time at baseline was different from reaction time at low and moderate intensity.

Commission Errors

A one-way within subjects (or repeated measures) ANOVA was conducted to compare the effect of exercise intensity on commission errors. Commission errors were 17.47 ± 7.38, 18.03 ± 8.89 and 19.93 ± 8.82 for resting, low and moderate intensity, respectively. Mauchly´s test indicated that the assumption of sphericity had not been violated (χ²(2) = 2.63, p > 0.05); therefore degrees of freedom were not corrected. The polynomial trend analyses showed a significantly linear fashion of increase in commission errors with exercise intensity F(1,29) = 4.23, p < 0.05, ηp2 = 0.13 with a power of .51.

However, the overall results from the one-way repeated measures (within subjects) ANOVA showed that commission errors were not significantly different during different exercise intensities F(2, 58) = 3.02, p = 0.057, ηp2 = 0.09. Observed power was .56. Bonferroni adjusted post-hoc analyses confirmed this by indicating that there was no significant difference between the commission errors made at baseline and during low intensity (p > 0.05), as well as during moderate intensity (p > 0.05).

These results suggest that there is a strong tendency that exercise intensity has an effect on inhibitory/executive control. Specifically, the results suggest that commission errors increase with

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exercise intensity in a linear, intensity dependent fashion. However, the fact that the overall result of the used statistical model is only close to significance is likely due to low observed power.

Figure 19: Commission Errors during running

Note. The x-axis represents the 3 conditions, baseline, low intensity and moderate intensity. On the y-axis the amount of commission errors is presented. The overall repeated-measures ANOVA was close to significance.

Reaction Time Standard Error

A one-way within subjects (or repeated measures) ANOVA was conducted to compare the effect of exercise intensity on reaction time standard error. Reaction time standard errors were 4.19 ± 1.21, 3.64 ± 0.97 and 3.74 ± 1.05 for resting, low and moderate intensity, respectively. Mauchly´s test indicated that the assumption of sphericity had not been violated (χ²(2) = 2.71, p > 0.05); therefore degrees of freedom were not corrected. The overall results from the one-way repeated measures (within subjects) ANOVA showed that there was a significant effect of exercise intensity on reaction time standard error F(2, 58) = 3.96, p < 0.05, ηp2 = 0.12. Observed power was .69. Polynomial trend analyses showed a significantly quadratic fashion of change in reaction time standard error with exercise intensity F(1,29) = 4.54, p < 0.05, ηp2 = 0.14 with a power of .54. Bonferroni adjusted post-hoc analyses indicated that reaction time standard error during moderate intensity was not significantly different from reaction time standard error at baseline (p > 0.05) and from the low intensity condition (p > 0.05). Instead, reaction time standard error during low intensity was significantly different from baseline (p < 0.05). These results suggest that exercise intensity really does have an effect on the consistency of reaction times throughout the test. Specifically, the results suggest that reaction time

standard error was lowest during low intensity running. However, there is no difference in reaction time standard error when comparing low and moderate exercise intensity.

Figure 20: Reaction Time Standard Error during running

Note. The x-axis represents the 3 conditions, baseline, low intensity and moderate intensity. On the y-axis reaction time standard error is depicted. The overall repeated-measures ANOVA was significant and Bonferroni adjusted post-hoc measures indicated that reaction time standard error at baseline was different from reaction time standard error at low intensity.

Reaction Time ISI change

A one-way within subjects (or repeated measures) ANOVA was conducted to compare the effect of exercise intensity on reaction time ISI change. Reaction time ISI change was 0.035 ± 0.023, 0.043 ± 0.023 and 0.044 ± 0.020 for resting, low and moderate intensity, respectively. Mauchly´s test indicated that the assumption of sphericity had not been violated (χ²(2) = 3.07, p > 0.05); therefore degrees of freedom were not corrected. The overall results from the repeated measures ANOVA showed that reaction time interstimulus interval change was significantly affected by Exercise Intensity F(2, 58) = 3.21, p < 0.05, ηp2 = 0.10. Observed power was .59. Polynomial trend analyses showed a significantly linear increase in reaction time ISI change with exercise intensity F(1,29) = 4.87, p < 0.05, ηp2 = 0.14 with a power of .57. Bonferroni adjusted post-hoc analyses indicated no significant change in reaction time ISI change in any of the exercise intensity conditions (p > 0.05).

These results suggest that exercise intensity really does have an effect on the change of reaction time at different ISIs. Specifically, the results suggest that adjustment to the different ISIs got worse with

Chapter 3 – Results 47

intensity (longer reaction times with increasing ISIs). However, there is no difference in reaction time ISI change when comparing low and moderate exercise intensity.

Figure 21: Reaction Time ISI change during running

Note. The x-axis represents the 3 conditions, baseline, low intensity and moderate intensity. On the y-axis reaction time interstimuli interval change is shown. The overall repeated-measures ANOVA was significant but Bonferroni adjusted post-hoc measures indicated no particular differences.