Muscular adaptations to computer‐guided strength training with eccentric overload

Aims: 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 ≤ 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 ≤ 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.