Citation

Krustrup P, Bradley PS, Christensen JF, Castagna C, Jackman S, Connolly L, Randers MB, Mohr M, Bangsbo J. Med. Sci. Sports Exerc. 2014; 47(1): 100-108.

Affiliation

1Department of Nutrition, Exercise and Sports, Copenhagen Centre for Team Sport and Health, University of Copenhagen, Copenhagen, DENMARK; 2Sport and Health Sciences, College of Life and Environmental Sciences, University of Exeter, Exeter, UNITED KINGDOM; 3Department of Sport & Exercise Sciences, University of Sunderland, UNITED KINGDOM, 4The University Hospitals Centre for Health Research, Copenhagen University Hospital, DENMARK, 5Italian Football Referees Association (AIA), Rome, ITALY; 6Football Training and Biomechanics Lab, Italian Football Federation (FIGC), Technical Department, Coverciano (Florence), ITALY; 7Department of Food and Nutrition, and Sport Science, University of Gothenburg, Gothenburg, SWEDEN.

Copyright

(Copyright © 2014, Lippincott Williams and Wilkins)

DOI

10.1249/MSS.0000000000000377

PMID

24824774

Abstract

PURPOSE: To examine the physical capacity and physiological response to the Yo-Yo Intermittent Endurance level 2 test (IE2) for untrained individuals and trained male soccer players, and to investigate the determinants of intense intermittent exercise performance.

METHODS: Thirty-four healthy untrained males (UTR) and fifteen age-matched trained soccer players (TR) performed a maximal incremental treadmill test (ITT) and a Yo-Yo IE2 test. Muscle biopsies and blood samples were obtained and HR were measured before, during and after tests.

RESULTS: UTR had a 67% lower (P<0.01) Yo-Yo IE2 performance (665±271 vs. 2027±298 m; ES:4.8), 34% lower (P<0.01) VO2max and 19% lower (P<0.05) resting muscle glycogen than TR. Blood lactate and heart rates during the first 560 m of the Yo-Yo IE2 test were higher (P<0.01) in UTR than TR (560 m: 7.4±2.8 vs. 2.4±0.8 mmol·L; ES:1.7-2.8; 188±11 vs. 173±8 bpm, ES:0.9-1.5) with no differences at exhaustion. Time >95%HRmax was lower (P<0.01) in UTR than TR (1.0±1.1 vs. 6.3±2.9 min, ES:3.1). Mean rate of muscle creatine phosphate utilization (16.5±9.5 vs. 4.3±2.7 mmol·kgd.w·min), muscle lactate accumulation (16.8±9.1 vs. 4.2±2.9 mmol·kgd.w·min), and glycogen breakdown (29.6±14.2 vs. 7.7±5.4 mmol·kgd.w·min) were 4-fold higher (P<0.01,ES:1.4-1.7) in UTR than TR. For UTR, correlations (P<0.01) were observed between Yo-Yo IE2 performance and VO2max (r=0.77), ITT performance (r=0.79) and muscle citrate synthase activity (r=0.57), but not for TR (r=-0.12-0.50; P>0.05).

CONCLUSION: The Yo-Yo IE2 test was shown to possess high construct validity by showing large differences in performance, heart rates and anaerobic metabolism between untrained individuals and trained soccer players. Additionally, VO2max appeared to be important for intermittent exercise performance in untrained individuals, but not for trained soccer players.

Language: en