Effects of prolonged strenuous endurance exercise on plasma myosin heavy chain fragments and other muscular proteins. Cycling vs running.
BACKGROUND
This study evaluates creatine kinase, myosin heavy chain, and cardiac troponin blood levels following three types of exercise: 1) short-distance uphill or downhill running; 2) alpine ultramarathon; and 3) alpine long-distance cycling.


METHODS



METHODS
Comparative field study; follow-up up to 10 days.


METHODS
Department of Sports Medicine. All biochemical markers were analysed at the Department of Medical Chemistry and Biochemistry.


METHODS
Subjects included healthy, trained males (N = 53). All subjects were nonsmokers and free from medication prior to and during the study. Each volunteer was an experienced runner or cyclist, who had at least once successfully finished the Swiss Alpine Marathon of Davos or the Otztal-Radmarathon before.


METHODS
Running or cycling.


METHODS
Plasma concentrations of creatine kinase, myosin heavy chain fragments and cardiac troponins were measured to diagnose skeletal and cardiac muscle damage, respectively.


RESULTS
Skeletal muscle protein release is markedly different between uphill and downhill running, with very little evidence for muscle damage in the uphill runners. There is considerable muscle protein leakage in the ultramarathoners (67 km distance; 30 km downhill running). In contrast, only modest amounts of skeletal muscle damage are found after alpine long-distance cycling (230 km distance).


CONCLUSIONS
This study proves that there is slow-twitch skeletal muscle fiber damage after prolonged strenuous endurance exercise and short-distance downhill running. Exhaustive endurance exercise involving downhill running and short-distance downhill running lead to more pronounced injury than strenuous endurance exercise involving concentric actions. From our results there is no reason for suggesting that prolonged intense exercise may induce myocardial injury in symptom-less athletes without cardiac deseases.
Koller
A
A
Department of Sports Medicine, University of Innsbruck, Austria.
Mair
J
J
Schobersberger
W
W
Wohlfarter
T
T
Haid
C
C
Mayr
M
M
Villiger
B
B
Frey
W
W
Puschendorf
B
B
D000328:Adult; D001642:Bicycling / Q000502:physiology*; D003402:Creatine Kinase / Q000097:blood; D015444:Exercise / Q000502:physiology*; D006801:Humans; D008297:Male; D018657:Muscle Fibers, Slow-Twitch / Q000473:pathology; D009124:Muscle Proteins / Q000097:blood*; D018995:Myosin Heavy Chains / Q000097:blood*; D010807:Physical Endurance / Q000502:physiology*; D012420:Running / Q000502:physiology*
D009124:Muscle Proteins; D003402:Creatine Kinase; D018995:Myosin Heavy Chains