What is best for boosting power output - 'contrast' loading (alternating heavy and lighter weights) or constant loading, when the weights stay the same? That is the question addressed by a series of studies comparing the benefits of these two approaches to strength training in a group of six professional rugby league players.

Many PP readers will know contrast loading as 'complex training', which involves lifting at >85% of 1RM on a strength exercise followed by a power exercise or load of around 40% 1RM. This could involve, for example, heavy squats followed by squat jumps. When the power exercise is preceded by the strength exercise in this way the power output is increased, enhancing the training benefit.

In this study the research team wanted to discover if it was possible to achieve the increase in power on the lighter set if the preceding heavy set was within the power load range (30-60% of 1RM) and not the strength load range (>85% 1RM).

The athletes performed two different sets of squat jumps, as follows:

Condition 1 (contrast loading) involved two sets of six jumps with a 40kg barbell, interspersed by a set of six at 60kg;

Condition 2 (constant loading) involved 2 sets of 6 at 40kg.

The peak power output of each squat jump set was measured using the plyometric jump system. In condition 1, the power achieved during the two 40kg squat jumps (interspersed by the set at 60kg) was 1380 watts and 1482 watts respectively. In condition 2, without the inter-spersed heavy set, the respective power achieved was 1365 and 1406 watts. Thus it is clear that the addition of a heavier set of squat jumps between two lighter sets led to an increase in power in the second lighter set.

This mirrors the kind of effect that occurs during complex training. One example of specific contrast loading work that I use with my athletes is the resisted towing of sprint starts, in which they have to accelerate as hard as possible while I resist their progress by means of an elastic band attached to a belt. The athletes complete 4-5 x 10m resisted followed by 2-3 x 10m unresisted, with the effect that the unresisted body weight feels lighter after resistance and the power is enhanced.

This principle can also be applied to other disciplines, including throwing and jumping, giving coaches a very specific approach to enhancing power. Any training method which bridges the gap between the weights room and the sports field is highly valuable and should be included in training programmes, particularly in pre-competition and competition phases.

Journal of Strength and Conditioning Research, 2001, 15(2), 198-200

Raph Brandon