Strength training with eccentric overload

In conventional strength training, the load or weight that is lifted (concentric contraction, where muscles shorten under load) is the same that is lowered (eccentric contraction, where muscles lengthen under load). However, it’s a well established fact that muscles are stronger when performing eccentric contractions (lowering) than when performing concentric contractions (lifting). This means that relative to maximum capability, if the same weight is being both lifted and lowered, the muscles are being worked at a relatively smaller % of maximum effort during the eccentric phase. However, it’s also known that the eccentric phase of resistance training is critical for strength gains, so a group of German researchers have been investigating the effects of applying an additional load during the eccentric phase of resistance training of the quadriceps muscles in order to increase relative eccentric loading.
The scientists carried out this study by comparing the effects of six weeks of classic concentric/eccentric quadriceps strength training to eccentric overload training (where extra loading was applied on the lowering phase) in 25 in athletes accustomed to regular strength training. Before and after the training, the researchers measured a number of parameters associated with muscle strength gains, including functional performance testing (squat jump), the quadriceps and muscle fibre cross-sectional area (CSA), the % of type IIX fibres (fast contracting fibres associated with power) in the quadriceps and also any changes in gene activity brought about by training.

The results showed that (as expected) both training forms produced increases in strength and muscle mass, with significant increases in quadriceps CSA, maximal strength, gene activity involved in general muscle growth and regeneration. However, only the eccentric overload training led to significantly increased height in a squat jump test. Eccentric overload training also produced significant increases in type IIX fibre CSA compared to the conventional training method and also stimulated gene activity for the development of these fibres.

The researchers concluded that ‘the enhanced eccentric load led to a subtly faster gene expression pattern and induced a shift towards a faster muscle phenotype, which together with associated adaptations, make a muscle better suited for fast, explosive movements’.

Eur J Appl Physiol. 2009 Nov 25. [Epub ahead of print]