Choi, J. Y., Takahashi, H., Itai, Y., & Takamatsu, K. (1997). Comparison of training effects between power-up type and bulk-up type in strength training. Medicine and Science in Sports and Exercise, 29(5), Supplement abstract 54.

Power-up strength training is employed to mainly improve strength and power while bulk-up training is for muscular hypertrophy. This investigation compared the structural and functional adaptations that result from both forms of training.

Power-up training (the repetition method) was characterized by longer inter-set intervals while performing 5 sets of 90% of 1 RM. Bulk-up training (the interval method) consisted of shorter inter-set intervals while performing 9 sets of 40-80% (multi-poundage) of 1 RM. Two groups of six males trained twice per week for 8 weeks.

Power-up training showed a greater rate of improvement in all dynamic (1 RM), isometric, and isokinetic knee extension forces under maximal effort but less change in the cross-sectional area of the quadraceps femoris and average knee-extension force. The rate of decrease in 50 consecutive knee extension trials was less in the bulk-up trained group. The two types of training produced different effects.

Implication. These two forms of training produced very different types of adaptation. Power-up training, which focused on producing high levels of force per trial, produced the greatest increases in force production. Bulk-up training, which focused on executing the greatest number of repetitions with variable resistances, produced the greatest ability to repeat high-levels of force production.

The type of strength training that is undertaken should be that which is appropriate for meeting the objectives of training.

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