The Yo-Yo IE2 test: physiological response for untrained men versus trained soccer players.
OBJECTIVE
This study aimed to examine the physical capacity and physiological response to the Yo-Yo Intermittent Endurance level 2 test (IE2) for untrained individuals (UTR) and trained male soccer players (TR) and to investigate the determinants of intense intermittent exercise performance.


METHODS
Thirty-four healthy UTR males and 15 age-matched TR performed a maximal incremental treadmill test and a Yo-Yo IE2 test. Muscle biopsies and blood samples were obtained, and heart rate (HR) was 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; effect size (ES), 4.8), 34% lower V˙O2max (P < 0.01), and 19% lower resting muscle glycogen (P < 0.05) than those of TR. Blood lactate concentration and HR during the first 560 m of the Yo-Yo IE2 test were higher (P < 0.01) in UTR than those in TR (560 m, 7.4 ± 2.8 vs 2.4 ± 0.8 mM; 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 that in TR (1.0 ± 1.1 vs 6.3 ± 2.9 min; ES, 3.1). Mean rates of muscle creatine phosphate utilization (16.5 ± 9.5 vs 4.3 ± 2.7 mmol·kg d.w·min), muscle lactate accumulation (16.8 ± 9.1 vs 4.2 ± 2.9 mmol·kg d.w.·min), and glycogen breakdown (29.6 ± 14.2 vs 7.7 ± 5.4 mmol·kg d.w.·min) were fourfold higher (P < 0.01; ES, 1.4-1.7) in UTR than those in TR. For UTR, correlations (P < 0.01) were observed between Yo-Yo IE2 performance and V˙O2max (r = 0.77), incremental treadmill test performance (r = 0.79), and muscle citrate synthase activity (r = 0.57) but not for TR (r = -0.12 to 0.50; P > 0.05).


CONCLUSIONS
The Yo-Yo IE2 test was shown to possess high construct validity by showing large differences in performance, HR, and anaerobic metabolism between UTR and TR. In addition, V˙O2max seemed to be important for intermittent exercise performance in UTR but not for TR.
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 and Exercise Sciences, University of Sunderland, Sunderland, UNITED KINGDOM; 4Carnegie School of Sport, Leeds Metropolitan University, Leeds, UNITED KINGDOM; 5University Hospitals Centre for Health Research, Copenhagen University Hospital, DENMARK; 6Italian Football Referees Association, Rome, ITALY; 7Football Training and Biomechanics Laboratory, Italian Football Federation, Technical Department, Coverciano, Florence, ITALY; 8Faculty of Natural and Health Sciences, University of the Faroe Islands, FAROE ISLANDS; and 9Department of Food and Nutrition, and Sport Science, University of Gothenburg, Gothenburg, SWEDEN.
Peter
P
Krustrup
Paul S
PS
Bradley
Jesper F
JF
Christensen
Carlo
C
Castagna
Sarah
S
Jackman
Luke
L
Connolly
Morten B
MB
Randers
Magni
M
Mohr
Jens
J
Bangsbo
D000293:Adolescent; D000328:Adult; D002950:Citrate (si)-Synthase / Q000378:metabolism; D005080:Exercise Test; D006003:Glycogen / Q000378:metabolism; D006339:Heart Rate; D006801:Humans; D019344:Lactic Acid / Q000097:blood; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism*; D010101:Oxygen Consumption; D010725:Phosphocreatine / Q000378:metabolism; D010807:Physical Endurance / Q000502:physiology; D005082:Physical Exertion / Q000502:physiology*; D010809:Physical Fitness / Q000502:physiology*; D012916:Soccer / Q000502:physiology*; D055815:Young Adult
D010725:Phosphocreatine; D019344:Lactic Acid; D006003:Glycogen; D002950:Citrate (si)-Synthase