Comparing High-Load and Low-Load Endurance Training for Strength and Hypertrophy: A Systematic Review and Meta-Analysis

If you lift heavy weights for fewer reps and lighter weights for more reps but do the same total work, you'll build about the same muscle size, but you'll get stronger faster with the heavy weights.

Lifting heavier weights makes you stronger faster in the first few months, but both heavy and lighter weights build similar muscle size over time if you do enough total work and push yourself hard.

When lifting lighter weights, you need to push until you can't do any more reps to build as much muscle as lifting heavy weights. But with heavy weights, you can build a lot of muscle without pushing to total exhaustion.

Lifting heavier weights is much better than lifting lighter weights for building muscle strength in healthy young adults, because it trains your muscles and nerves to work together more effectively for maximum power.

Lifting heavy weights and lifting lighter weights both build muscle about the same amount in healthy adults, as long as you do enough reps until you can't lift anymore.

Lifting heavy weights builds fast-moving muscle fibers for power, and lifting lighter weights builds slow-moving muscle fibers for endurance, letting you train muscles for different goals.