Muscle variables of importance for physiological performance in competitive football

Purpose To examine how match performance parameters
in trained footballers relate to skeletal muscle parameters,
sprint ability and intermittent exercise performance.
Methods 19 male elite football players completed an
experimental game with physical performance determined
by video analysis and exercise capacity assessed by intermittent Yo-Yo IR1 and IR2 tests, and a repeated sprint test
(RST). Muscle tissue was obtained for analysis of metabolic
enzyme maximal activity and key muscle protein expression.
Results Total game distance, distance deficit from first to
second half and high-intensity running in the final 15 min
of the game were all correlated to the players’ Yo-Yo IR1
performance (r = 0.55–0.87) and beta-hydroxyacyl-CoAdehydrogenase (HAD) maximal activity (r = 0.55–0.65).
Furthermore, platelet/endothelial cell adhesion molecule-1 (PECAM1) protein expression was weakly (r = 0.46) correlated to total game distance. Peak 5-min game distance
faster than 21 km h−1
was related to the Na+–K+ ATPase
subunit (α1, α2, β1 and FXYD1) protein levels (r = 0.54–
0.70), while Yo-Yo IR2 performance explained 40 % of the
variance in high-intensity game distance. Total and 1-min
peak sprint distance correlated to myosin heavy chain II/I
ratio (MHCII/I ratio) and sarcoendoplasmic reticulum Ca2+
ATPase isoform-1 (SERCA1) protein (r = 0.56–0.86),
while phosphofructokinase (PFK) maximal activity also
correlated to total sprint distance (r = 0.46).
Conclusion The findings emphasize the complexity of
parameters predicting physical football performance with
Yo-Yo IR1 and HAD as the best predictors of total distance,
while high expression of Na+–K+ ATPase proteins and the
Yo-Yo IR2 test are better predictors of high-intensity performance. Finally, sprint performance relates to skeletal
muscle fiber-type composition.