How heavy should your weights be? The science of sustainable lifting

Experts say “heavy” is relative—roughly 80% of your max for six to eight reps with good form—yet the real health payoff comes from consistency and reps over chasing maximal loads. For beginners or older adults, heavier loading can yield larger gains in strength and bone density, while also improving insulin sensitivity; endurance athletes may gain power without gaining weight. But heavy lifting also increases recovery demands, joint strain, and potentially cardiovascular risk for those with heart disease. The take-home: use manageable, challenging loads, prioritize technique and full range of motion, and stay consistent rather than chasing heroic lifts.