Muscle damage and its relationship with muscle fatigue during a half-iron triathlon.
BACKGROUND
To investigate the cause/s of muscle fatigue experienced during a half-iron distance triathlon.


RESULTS
We recruited 25 trained triathletes (36±7 yr; 75.1±9.8 kg) for the study. Before and just after the race, jump height and leg muscle power output were measured during a countermovement jump on a force platform to determine leg muscle fatigue. Body weight, handgrip maximal force and blood and urine samples were also obtained before and after the race. Blood myoglobin and creatine kinase concentrations were determined as markers of muscle damage.


RESULTS
Jump height (from 30.3±5.0 to 23.4±6.4 cm; P<0.05) and leg power output (from 25.6±2.9 to 20.7±4.6 W · kg(-1); P<0.05) were significantly reduced after the race. However, handgrip maximal force was unaffected by the race (430±59 to 430±62 N). Mean dehydration after the race was 2.3±1.2% with high inter-individual variability in the responses. Blood myoglobin and creatine kinase concentration increased to 516±248 µg · L(-1) and 442±204 U · L(-1), respectively (P<0.05) after the race. Pre- to post-race jump change did not correlate with dehydration (r = 0.16; P>0.05) but significantly correlated with myoglobin concentration (r = 0.65; P<0.001) and creatine kinase concentration (r = 0.54; P<0.001).


CONCLUSIONS
During a half-iron distance triathlon, the capacity of leg muscles to produce force was notably diminished while arm muscle force output remained unaffected. Leg muscle fatigue was correlated with blood markers of muscle damage suggesting that muscle breakdown is one of the most relevant sources of muscle fatigue during a triathlon.
Exercise Physiology Laboratory, Camilo José Cela University, Madrid, Spain. jdelcoso@ucjc.edu
Juan
J
Del Coso
Cristina
C
González-Millán
Juan José
JJ
Salinero
Javier
J
Abián-Vicén
Lidón
L
Soriano
Sergio
S
Garde
Benito
B
Pérez-González
D000328:Adult; D015415:Biomarkers / Q000097:blood / Q000652:urine; D003681:Dehydration / Q000378:metabolism; D015444:Exercise; D018737:Hand Strength; D006801:Humans; D008875:Middle Aged; D018763:Muscle Fatigue / Q000502:physiology*; D018482:Muscle, Skeletal / Q000293:injuries*; D010807:Physical Endurance
D015415:Biomarkers