Does an Optimal Load Exist for Power Training?

P ower training using different loads causes specific changes to the force–velocity relationship that creates variability in the degree to which power output is improved. Several investigations have indicated that training with the load that maximizes power output is more effective at improving maximal power production and athletic performance than either lighter or heavier loading conditions (5,7,8). Kaneko et al. (7) examined 4 loading conditions; 0% of maximum isometric strength (Po), 30% Po (the load that maximized power output), 60% Po, and 100% Po. After 12 weeks of elbow flexor training, maximal power production was improved in the 30% Po group significantly more so than both the 0% Po and 60% Po groups (26.1% versus 13.8% and 21.7%, respectively) and to a greater extent than the 100% Po group (22.4%). Thus, training with the load that maximized power output promoted all-round improvements to the force– velocity relationship (i.e., increased both maximum velocity and maximum force output), which translated into the most pronounced improvement maximal power output (7). Similarly, Häkkinen et al. (5) reported that explosive body weight jump training (load equivalent to approximately 30% of maximal dynamic strength—the load that maximizes power output in the jump squat [3]) resulted in a 21% increase in jump height after 6 months of training, whereas heavy resistance training (70–120% of 1RM in the squat) resulted in a significantly lower improvement of 7%. Although no doubt exists that increasing an athletes strength level through heavy resistance training directly impacts the ability to generate high power outputs, little evidence exists demonstrating that heavy resistance training is more effective at increasing maximum power than training with the load that maximizes power output.