Muscular adaptations to computer-guided strength training with eccentric overload.
OBJECTIVE
In order to investigate the muscular adaptations to a novel form of strength training, 18 male untrained subjects performed 4 weeks of low resistance-high repetition knee extension exercise.


METHODS
Nine of them trained on a conventional weight resistance device (Leg curler, CON/ECC group), with loads equivalent to 30% of the concentric one-repetition maximum (1RM) for both the concentric and eccentric phase of movement. The other nine trained on a newly developed computer-driven device (CON/ECC-OVERLOAD group) with the concentric load equivalent to 30% of the concentric 1RM and the eccentric load equivalent to 30% of the eccentric 1RM.


RESULTS
Training resulted in significantly (P < or = 0.05) increased peak torque and a tendency (P=0.092) to increased muscle cross-sectional area for the CON/ECC-OVERLOAD but not the CON/ECC group, while strength endurance capacity was significantly (P < or = 0.05) increased in the CON/ECC group only. RT-PCR revealed significantly increased myosin heavy chain (MHC) IIa and lactate dehydrogenase (LDH) A mRNAs, a tendency for increased MHC IIx mRNA (P = 0.056) and high correlations between the changes in MHC IIx and LDH A mRNAs (r=0.97, P=0.001) in the CON/ECC-OVERLOAD group.


CONCLUSIONS
These results indicate a shift towards a more type II dominated gene expression pattern in the vasti laterales muscles of the CON/ECC-OVERLOAD group in response to training. We suggest that the increased eccentric load in the CON/ECC-OVERLOAD training leads to distinct adaptations towards a stronger, faster muscle.
Department of Sports Medicine, Medical Clinic and Policlinic, University of Heidelberg, Heidelberg, Germany.
B
B
Friedmann
R
R
Kinscherf
S
S
Vorwald
H
H
Müller
K
K
Kucera
S
S
Borisch
G
G
Richter
P
P
Bärtsch
R
R
Billeter
D000222:Adaptation, Physiological; D015444:Exercise / Q000502:physiology*; D006801:Humans; D007527:Isoenzymes / Q000032:analysis; D007770:L-Lactate Dehydrogenase / Q000032:analysis; D000080864:Lactate Dehydrogenase 5; D007866:Leg; D008297:Male; D008838:Microcomputers; D018485:Muscle Fibers, Skeletal / Q000502:physiology; D018482:Muscle, Skeletal / Q000033:anatomy & histology / Q000502:physiology*; D018995:Myosin Heavy Chains / Q000032:analysis; D024461:Myosin Type I / Q000032:analysis; D025221:Phosphofructokinases / Q000032:analysis; D010807:Physical Endurance / Q000502:physiology; D012333:RNA, Messenger / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D024744:Skeletal Muscle Myosins / Q000032:analysis
D007527:Isoenzymes; D012333:RNA, Messenger; D007770:L-Lactate Dehydrogenase; D000080864:Lactate Dehydrogenase 5; C409667:lactate dehydrogenase 1; D025221:Phosphofructokinases; D024461:Myosin Type I; D024744:Skeletal Muscle Myosins; D018995:Myosin Heavy Chains