@Article{Brito2026,
journal="Biology of Sport",
issn="0860-021X",
year="2026",
title="Physiological and performance effects of a simulated prolonged 
service game in competitive male tennis players",
abstract="This	study	investigated	the	acute	physiological	and	performance	responses	to	a simulated	prolonged service game designed to replicate the most demanding phases of competitive tennis. Fourteen nationally	ranked	male	players	(17.8	±	0.9 y)	performed	12 consecutive	maximal	intensity	serves,	each	immediately	followed by eight alternating forehands and backhands. Internal load was monitored before, during and after the	protocol	using	heart	rate,	oxygen	uptake	and	venous	blood	samples	(ammonia,	creatine	kinase,	albumin,	sodium,	calcium,	lactate	and	glucose).	External	load	was	quantified	with	a Doppler	radar	gun	to	measure	ball	speed	and	high-frame-rate	video	to	assess	serve	precision.	Statistical	significance	was	set	at	p ≤ 0.05.	Plasma	concentrations	of	ammonia	and	creatine	kinase	(both	p < 0.01),	albumin,	sodium,	calcium	(all	p < 0.05),	lactate	(p < 0.01)	and	glucose	(p < 0.05)	increased	from	baseline	to	post-protocol.	Heart	rate	and	oxygen	uptake	rose	rapidly	in	the	initial	phase	and	stabilized	at	~85 and	62%	of	maximal	values,	respectively.	Serve	speed	and	precision	began	to	decline	from	the	sixth	point	onward,	with	reductions	of	5.4 and	29%,	coinciding	with	peak	lactate	and	ammonia	values.	A prolonged	service	game	imposes	considerable	anaerobic-metabolic,	cardiovascular, and neuromuscular stress on competitive tennis players, producing measurable impairments in technical performance well before task completion. Systematic monitoring of blood metabolites and electrolytes can help coaches individualize recovery intervals and design conditioning programs that enhance players’ tolerance to repeated high-intensity serving, thereby preserving technical consistency under competitive fatigue conditions.",
author="Brito, André
and Cardoso, Filipa
and Ogonowska-Slodownik, Anna
and Javaloyes, Alejandro
and Fernandez-Fernandez, Jaime
and Fernandes, Ricardo",
pages="1427--1435",
doi="10.5114/biolsport.2026.160854",
url="http://dx.doi.org/10.5114/biolsport.2026.160854"
}