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Effect of Additional Speed Endurance Training on Performance and Muscle Adaptations


Medicine & Science in Sports & Exercise: October 2012 - Volume 44 - Issue 10 - p 1942–1948
doi: 10.1249/MSS.0b013e31825ca446
Applied Sciences

Purpose The present study examined the effect of additional speed endurance training (SET) during the season on muscle adaptations and performance of trained soccer players.

Methods Eighteen subelite soccer players performed one session with six to nine 30-s intervals at an intensity of 90%–95% of maximal intensity (SET) a week for 5 wk (SET intervention). Before and after the SET intervention, the players carried out the Yo-Yo intermittent recovery level 2 (Yo-Yo IR2) test, a sprint test (10 and 30 m), and an agility test. In addition, seven of the players had a resting muscle biopsy specimen taken and they carried out a running protocol on a motorized treadmill before and after the SET intervention.

Results After the SET intervention, the Yo-Yo IR2 test (n = 13) performance was 11% better (P < 0.05), whereas sprint (n = 15) and agility (n = 13) performances were unchanged. The expression of the monocarboxylate transporter 1 (n = 6) was 9% higher (P < 0.05). and the expression of the Na+/K+ pump subunit β1 (n = 6) was 13% lower (P < 0.05) after the SET intervention. The Na+/K+ pump subunits α1, α2, as well as the monocarboxylate transporter 4 and the Na+/H+ exchanger 1 (n = 6) were unchanged. After the SET intervention, the relative number of Type IIx fibers and oxygen consumption at 10 km·h−1 were lower (P < 0.05), whereas V˙O2max was unchanged.

Conclusions In conclusion, adding ∼30 min of SET once a week during the season for trained soccer players did lead to an improved ability to perform repeated high-intensity exercise, with a concomitant increase in the expression of monocarboxylate transporter 1 and an improved running economy.

Department of Exercise and Sport Sciences, Section of Human Physiology, University of Copenhagen, DENMARK

Address for correspondence: Professor Jens Bangsbo, August Krogh Building, Section of Human Physiology, Universitetsparken 13, DK-2100 Copenhagen Ø, Denmark; E-mail:

Submitted for publication December 2011.

Accepted for publication April 2012.

©2012The American College of Sports Medicine