[Laser]

I've been doing a linear progression focused on strength development - 3 sets of 5 reps with 5 min rest between sets

I recently decided to focus more on hypertrophy, increasing the volume to 3 sets of 8. I'm assuming I should decrease the rest time between sets as well. How long should I target for maximum hypertrophy gains?

[Blackwell]

For hypertrophy I would personally suggest a slightly higher rep range. 10-12. 8 is absolutely fine sure but I think 10-12 is the sweet spot, for me anyway. 8 is that spot where you are just edging out of the strength range into the hypertrophy range so if you want dual benefit I guess that would work.

However, in my experience 10-12 is where it's at. Also you wanna switch it up every now and again just to keep the body guessing, forcing it to adapt and to grow.

Also as you increase the reps you wanna increase the sets a little.

Think more 4/5 x 10/12 unless you are going to be doing 4/5 exercises per workout per muscle group.

Optimum rest in that range anywhere between 30-90 seconds depending on the exercise type, difficulty etc.

E.g you might take a 60-90 seconds on your bench press sets cause your moving a higher load but when your hitting rope pull down to finish you might shift to a 30-45 for more of a 'pump' effect and a burnout.

If this doesn't make sense to you, I don't know your level of training/expertise, just ask and I'll be happy to go into further detail.

[jSinSaTx]

Google Musclehack and download the free THT guide. It, and pieces on the site, covers your question and references studies where the answers came from. I have found it to be a good program.

[H1N1]

The answer is always 'as short as you can get away with whilst still hitting, or very nearly hitting, your target reps'. As Blackwell said, 8 reps is still having a fairly significant strength impact (so will 10-12 of course, but less so). Consequently, you may need more time to recover between sets of 8 than you do for sets of 12. Or you may not, that's an individual thing.

Equally, when trying to grow, I'm a big fan of picking 4/5 exercises for accessory work (DB rows, OHP, weighted chins, dips, for example) and working through a set of 8 on each, before starting back again with the first exercise. By the time you've had a swig of water and changed the weights, this might lead to longer rest periods, but I've never had any trouble growing from it when my intensity was high.

Essentially, there are many ways to skin the cat, pick one that fits your goals and that you enjoy, and work damn hard, eat well, and sleep properly. Do those right and you will grow.

[s3k]

I disagree with h1...i feel it depends on the excersize regime your doing. Me personally taking a 30-90 sec rest between sets would overtrain me. Than agian I do low volume high intensity work outs. RPT's the entire hour i'm at the gym, 2 sets per excersize and if it's dead or squats i'm looking at a minimal of 5+min rest. I time my rest periods.

[fortysix]

^hell yeah - this is my approach as well and I believe the one recommended by leangainz.

I take a long rest and then hit my fucking max x 6, take a long rest, then repeat.

On the flipside - although im ripped from this method, I recently tried to do a cardio workout and it wiped the floor with me. So I guess adjust for what your training goal is.

[Bushido]

It depends. What I read is to take shorter rest periods if your main goal is hypertrophy/conditioning and longer ones if you are prioritizing strength. Overall though, the shorter the better. Easy to get lazy with rest periods in my experience.