Recovery kinetics throughout successive bouts of various exercises in elite cyclists.
OBJECTIVE
In the present study we investigated whether a high volume of cycling training would influence the metabolic changes associated with a succession of three exhaustive cycling exercises.


METHODS
Seven professional road cyclists (VO2max: 74.3 +/- 3.7 mL.min.kg; maximal power tolerated: 475 +/- 18 W; training: 22 +/- 3 h.wk) and seven sport sciences students (VO2max: 54.2 +/- 5.3 mL.min.kg; maximal power tolerated: 341 +/- 26 W; training: 6 +/- 2 h.wk) performed three different exhaustive cycling exercise bouts (progressive, constant load, and sprint) on an electrically braked cycloergometer positioned near the magnetic resonance scanner. Less than 45 s after the completion of each exercise bout, recovery kinetics of high-energy phosphorylated compounds and pH were measured using P-MR spectroscopy.


RESULTS
Resting values for phosphomonoesters (PME) and phosphodiesters (PDE) were significantly elevated in the cyclist group (PME/ATP: 0.82 +/- 0.11 vs 0.58 +/- 0.19; PDE/ATP: 0.27 +/- 0.03 vs 0.21 +/- 0.05). Phosphocreatine (PCr) consumption and inorganic phosphate (Pi) accumulation measured at end of exercise bouts 1 (PCr: 6.5 +/- 3.2 vs 10.4 +/- 1.6 mM; Pi: 1.6 +/- 0.7 vs 6.8 +/- 3.4 mM) and 3 (PCr: 5.6 +/- 2.4 vs 9.3 +/- 3.9 mM; Pi: 1.5 +/- 0.5 vs 7.7 +/- 3.3 mM) were reduced in cyclists compared with controls. During the recovery period after each exercise bout, the pH-recovery rate was larger in professional road cyclists, whereas the PCr-recovery kinetics were significantly faster for cyclists only for bout 3.


CONCLUSIONS
Whereas the PDE and PME elevation at rest in professional cyclists may indicate fiber-type changes and an imbalance between glycogenolytic and glycolytic activity, the lower PCr consumption during exercise and the faster pH-recovery kinetic clearly suggest an improved mitochondrial function.
Hug
François
F
University of Nantes, Nantes Atlantic Universities, Laboratory of Motricity, Interactions, and Performance, Nantes, France. francois_hug@hotmail.com
Grélot
Laurent
L
Le Fur
Yann
Y
Cozzone
Patrick J
PJ
Bendahan
David
D
D000328:Adult; D001642:Bicycling / Q000502:physiology*; D016022:Case-Control Studies; D016552:Ergometry; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism*; D010710:Phosphates / Q000378:metabolism*; D010725:Phosphocreatine / Q000378:metabolism*; D010807:Physical Endurance / Q000502:physiology; D010809:Physical Fitness / Q000502:physiology; D020127:Recovery of Function / Q000502:physiology*
D010710:Phosphates; D010725:Phosphocreatine