How often should one take breaks when lifting weights for muscle size gain?

Question

All the literature seems to suggest I should do between 4 to 5 sets of bench presses, but after my third set or so, I start to feel very exhausted, often to the point where I couldn't even complete a single rep if I tried. (This actually holds for all compound lifts, not just bench.) I find myself taking 30 second breaks at first, then 90 second, then sitting for 5 minutes waiting to get my breath back, procrastinating the next set, and getting nothing done.

How often is it appropriate to take a break while lifting, and how long? If I could take 5 to 10 minute breaks between each set (even if I did so by lifting other muscle groups) I could definitely meet the 5 sets goal. But would that negate the effect of doing 5 sets? Does letting your muscles recuperate between sets defeat the purpose?

Answer 1

For bodybuilding and muscle growth, you want to keep your rest periods relatively short. This approach differs from strength training and power-oriented Olympic weightlifting, in which rest periods of three, five, or even ten minutes is called for between max effort sets.

Rippetoe and Kilgore recommend very short rest periods to optimize muscle size:

If muscle hypertrophy is the only concern, rests of 45 seconds or less are best. There seems to be a link (although not necessarily a causal relationship) between lactic acid production from resistance exercise, hormonal status, and increases in muscle mass. Between-set rests of about 45 seconds would be optimal in maintaining this relationship.

(Page 82, Practical Programming)

I am not a bodybuilder, but I imagine it would be reasonable to have longer rest periods for those exercises where you're focusing more on strength than hypertrophy. You might not have any exercises where that is true, but it's worth considering strength work even in a hypertrophy program. In those cases it would still be good to keep the rest periods short--say, three minutes.

If you can't complete your later sets, then I would lower the weight, reduce the number of sets, or accept a longer rest period until you're better adapted to your current program.