Effects of strength training with eccentric overload on muscle adaptation in male athletes

Abstract

In classic concentric/eccentric exercise, the same absolute load is applied in concentric and eccentric actions, which infers a smaller relative eccentric load. We compared the effects of 6 weeks of classic concentric/eccentric quadriceps strength training (CON/ECC, 11 subjects) to eccentric overload training (CON/ECC+, 14 subjects) in athletes accustomed to regular strength training. The parameters determined included functional tests, quadriceps and fibre cross-sectional area (CSA), fibre type distribution by ATPase staining, localisation of myosin heavy chain (MHC) isoform mRNAs by situ hybridization and the steady-state levels of 48 marker mRNAs (RT-PCR) in vastus lateralis biopsies taken before and after training. Both training forms had anabolic effects with significant increases in quadriceps CSA, maximal strength, ribosomal RNA content and the levels of mRNAs involved in growth and regeneration. Only the CON/ECC+ training led to significantly increased height in a squat jump test. This was accompanied by significant increases in IIX fibre CSA, in the percentage of type IIA fibres expressing MHC IIx mRNA, in the level of mRNAs preferentially expressed in fast, glycolytic fibres, and in post-exercise capillary lactate. The enhanced eccentric load apparently led to a subtly faster gene expression pattern and induced a shift towards a faster muscle phenotype plus associated adaptations that make a muscle better suited for fast, explosive movements.

Stretching skeletal muscle in vitro: does it replicate in vivo physiology?

“…Typically increases in muscle cross sectional area are observed in humans following resistance training programmes of 6-16 weeks duration, with the extent of hypertrophy from 7.5 to 25% depending on the study participants, muscle type studied and exercise regime (McCall et al 1996;Kosek et al 2006;Holm et al 2008;Friedmann-Bette et al 2010). In vivo animal studies have also demonstrated robust hypertrophic responses to muscle loading (Goldberg 1967;Goldspink et al 1995).…”

Prevention of Hamstring Muscle Injuries in Sports

“…The optimal intensity of eccentric training programs is not yet clear. Some authors recommend that intensity should be high to provide the stimulus necessary to produce further adaptations (Hortobagyi et al 1996;Brughelli and Cronin 2007;Friedmann-Bette et al 2010), while others have found that the protective effect of eccentric training may be observed even using low resistance (Lavender and Nosaka 2008;Chen et al 2010). If strength gain is required to address a strength deficit, eccentric actions should be overloaded between 20 % and 80 % beyond the maximal isometric strength.…”

Acute neuromuscular response during eccentric overload protocol by using a mechanical device to increase the load

“…Training where ECC actions were overload (ECC overload [EO] training), performed with more load than during CON action it was verified after training an increase on the size of type IIX fibres 7 , a higher increase at isokinetic and isometric force production 8 and higher neuromuscular activation [8][9][10] . Owing to the importance of ECC actions in neuromuscular activation 11 and the benefits of EO training, machines have been developed to increased load during the ECC action [12][13][14][15] .…”