@Article{Schuth2026,
journal="Biology of Sport",
issn="0860-021X",
year="2026",
title="Are three recovery days enough? Elevated match day creatine 
kinase levels under congested schedules in youth soccer",
abstract="We examined if creatine kinase (CK) activity differed between congested (CS) and non-congested schedules	(NCS)	in	elite	youth	national	team	soccer	players.	The	CK	activity	of	188 players	(16.53	±	1.78 years)	was	measured	in	national	team	training	camps	(2489 individual	data	points).	Training	load	one	day	before	the	match (MD-1) was monitored with global positioning system (GPS) devices. CS occurred, when the athlete played	at	least	60 minutes	in	the	previous	3 days	leading	into	the	match	(MD).	CK MD 	was	significantly	higher	in	CS	than	in	NCS	(median:	309 vs	220 U/L,	p < 0.05).	More	recovery	days	between	matches	were	associated	with lower values on the second CK MD . CK values one (CK MD+1 :	678 vs	487 U/L)	and	two	days	after	the	match	(CKMD+2:	395 vs	303 U/L)	were	higher	for	CS	(p < 0.05),	however	relative	CK	changes	from	MD	to	one	(CK MD→MD+1% :	181 vs	135%)	or	two	days	after	(CK MD→MD+2% :	74 vs	44%)	were	higher	for	NCS	(p < 0.05).	11 out	of	15 MD-1 training	load	parameters	were	significantly	higher	for	NCS	(p < 0.05).	CK MD  was sensitive to congested schedule and the number of recovery days between matches. Therefore three recovery days between matches might be inadequate for complete recovery. Higher CK MD , CK MD+1  and	CK MD+2  values,	but	lower CK MD→MD+1%  and CK MD→MD+2% 	changes	were	found	for	CS	than	for	NCS.	MD-1 training	load	was	lower	in CS than in NCS, making it an unlikely cause of the elevated CK MD  and CK MD+1  values. Instead, it might be the result of residual fatigue from the last match.",
author="Schuth, Gabor
and Szigeti, Gyorgy
and Dobreff, Gergely
and Revisnyei, Peter
and Gabbett, Tim
and Szilas, Adam
and Pavlik, Gabor",
pages="1051--1060",
doi="10.5114/biolsport.2026.157992",
url="http://dx.doi.org/10.5114/biolsport.2026.157992"
}