| Young
Investigator Section, Research article |
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ADAPTIVE CHANGES OF MYOSIN ISOFORMS IN RESPONSE TO LONG-TERM STRENGTH
AND POWER TRAINING IN MIDDLE-AGED MEN
|
Raivo
Puhke1, Sirkka Aunola2 ,
Pirjo Ailanto3, Karin Alev1, Mika Venojärvi2,4,
Heikki Rusko5,6 and Teet Seene1 |
1Institute of Exercise Biology and Physiotherapy, University of Tartu,
Tartu, Estonia
2Laboratory for Population Research, Department of Health and Functional
Capacity, National Public Health Institute, Turku, Finland
3Department of Physiology, University of Kuopio, Kuopio, Finland
4Medical Laboratory Technology, Turku University of Applied Sciences, Turku,
Finland
5KIHU - Research Institute for Olympic Sports, Jyväskylä, Finland
6Department of Biology of Physical Activity, University of Jyväskylä,
Jyväskylä, Finland
| Received |
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08 November 2005 |
| Accepted |
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10
April 2006 |
| Published |
|
01
June 2006 |
©
Journal of Sports Science and Medicine (2006) 5, 349
- 358
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| ABSTRACT |
| The purpose of the study was to examine the adaptive changes in
myosin heavy chain (MHC) and light chain (MLC) isoforms in human vastus
lateralis muscle caused by long-term strength and power training (54
weeks, approximately 3 times a week) in untrained middle- aged men
(16 in the training and 6 in the control group). Muscular MHC and
MLC isoforms were determined by means of SDS-PAGE gel electrophoresis.
During the training period, maximal anaerobic cycling power increased
by 64 W (p < 0.001) and the maximal jumping height by 1.5 cm (p
< 0. 05) in the training group, but no significant changes were
found in the control group. However, the group by time effect was
not significant. In the training group, the increase of the maximal
jumping height correlated with the number of strength and power training
sessions (r = 0.56; p < 0.05). The change of the proportion of
MHC IIa isoform from 52.6 ± 12.2% to 59.4 ± 11.6% did
not reach statistical significance (p = 0.070 for group by time; within
training group p = 0.061) and neither did the change of the proportion
of MHC IIx isoform from 18.1 ± 11.4% to 11.1 ± 9.1%
(p = 0.104 for group by time; within training group p=0.032). The
degree of change of MHC IIx isoform correlated with the amount of
earlier recreational sports activity (r = 0.61; p < 0.05). In the
training group, the changes of MLC1s isoform correlated negatively
with the changes of MLC1f isoform (r = -0. 79; p < 0.05) as well
as with the changes in maximal anaerobic cycling power (r = -0.81;
p < 0.05), and positively with those of MHC I isoform (r = 0.81;
p < 0.05). In conclusion, the long- term strength and power training
~3 times a week seemed to have only slight effects on fast MHC isoforms
in the vastus lateralis muscle of untrained middle-aged men; the proportion
of MHC IIa tended to increase and that of MHC IIx tended to decrease.
No changes in MLC isoform profile could be shown.
KEY
WORDS: Anaerobic muscular power, contractile proteins, myosin
heavy chain isoforms, myosin light chain isoforms, training, transformation.
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