Higher training intensities (70–85% of one-repetition maximum) produce greater gains in maximal strength and power compared to lower intensities.

Study: Effect of High-Intensity vs. Moderate-Intensity Resistance Training on Strength, Power, and Muscle Soreness in Male Academy Soccer Players

Lifting heavier weights (around 80–90% of your max) helped soccer players get stronger and jump farther than lifting lighter weights, even though they did less total work. This means heavier lifts are more effective for building strength and power.

Study: Effects of 12 weeks of complex training on lower limbs strength and power in collegiate dancers

This study didn't directly compare light vs. heavy weights, but both groups lifted heavy enough to get stronger, and the group that also did jumping exercises got even stronger and more powerful. This suggests lifting heavy (like 70–85% of max) does help build strength.

Study: Effect of different velocity loss thresholds during a resistance training program on jump and sprint performances in trained female athletes

This study didn't use exact weight percentages, but when athletes lifted weights hard enough to slow down their movement, they got stronger. That supports the idea that lifting heavier weights (not light ones) helps you gain more strength.

Study: Optimizing Strength and Hypertrophy: The Combined Effect of Intensity and Velocity Loss Thresholds in Bench Press Training.

This study found that lifting heavier weights (70–85% of your max) makes you stronger and builds more muscle than lifting lighter weights, even when other factors like how tired you get are accounted for.