Table 2. Within-group time effects.

	Estimate (B)	95%CI	P-value
Heading group
0h post-intervention	-0.27	[-17.06, 16.52]	0.98
2h post-intervention	0.99	[-15.94, 17.92]	0.91
24h post-intervention	19.57	[3.13, 36.02]	0.02*
Kicking-control group
0h post-intervention	10.78	[-6.83, 28.39]	0.23
2h post-intervention	-1.22	[-18.82, 16.38]	0.89
24h post-intervention	3.47	[-14.56, 21.49]	0.71

Note: Within group changes are in reference to S100B concentrations at pre-intervention baseline.

* p < 0.05,

** p < 0.01, *** p < 0.001.