Just my thoughts based on personal experience from training as a “hobby” for years, and more recently getting on stage, I’ve gone in phases of shorter workouts (45-60 minutes) all the way to very long work outs (2-2.5 hours), so here’s what I’ve come to learn about myself based from these experiences, which may or may not be applicable to others.
Firstly, I’m not sure there is an “optimal” workout time, because anything you do for long enough, you’ll adapt to and it won’t be optimal anymore. I think anyone who says if you workout longer than 60 minutes you’re not gaining or have passed the point of diminishing returns need a lesson under some iron with a good few plates on each side, and has probably never done so. But, I also think that if you continuously workout for very long sessions, eventually you’ll need to change something.
My favorite program is a typical 4 or 5 day bodybuilding split, these workouts take 60-90 minutes depending on the muscle group, and this includes warm up sets with possibly a little foam rolling for legs before I start. I don’t think I’ve EVER finished a workout in 45 minutes or less, ever, and really don’t know how you could do a workout in that amount of time, unless you’re very specifically training one muscle group and are moving incredibly fast, and maybe skipping warm up sets. I’m not saying it’s not possible, I just can’t imagine doing it myself. During these workouts there is always some heavy compound movement time, some isolation time, some drop sets and such, and usually 1:15 to 1:30 later, I’m done. When I started in the gym, my first training program’s were CT’s Indigo Hypertrophy Programs, which certainly take more than an hour, so I just got used to longer workouts.
Out of necessity with my schedule, there have been other times I’ve run a 3x per week full body program, based on Leroy Colbert’s method from this article, “Full Body Workouts of the Legends”. This was 6 sets per muscle group, plus I’d add some calves or abs at the end, totaling about 45 working sets. Some compound movements, and an isolation exercise for each muscle group. I’d make an “A,B,C” workout and rotate exercises each day. These usually took no less than 2 hours to complete due to warm up sets for each muscle group, and overall high volume. I had some serious gains on this program, but also fueled up accordingly with a Finibar and 3 scoops of Plazma, totaling 160g carbs and about 900 calories just for the workout. I’d also say that anyone who told me I wasn’t training with enough intensity if my workouts took that long should try to hang with me during one of those sessions, so I can step over their limp, lifeless bodies after they pass out and I’m still working. Even still, after a while (about 5 months) I really needed a change. Which brings me to my next point, again based on my personal experience only and my body.
In my opinion, a “long” workout is longer than 75-90 minutes, a “short” workout would be anything less. I think both long and short workouts can be extremely beneficial, and of course it matters what you do in that time frame, and also how you fuel up for them. If you’re doing a long workout, you better have your pre, peri and post workout nutrition in line. If you don’t, there’s no doubt you’ll only dig yourself further into a hole with your metabolism, cortisol and limited gains. Even if you do fuel up accordingly, as with anything, eventually your body will adapt, so where as “long workouts” might give you some great gains at first, the more you do them, the more efficient you’ll become, until you’ll probably want to change up for shorter workouts with more compound movements and focus on strength or something similar.
I disagree, sounds like broscience to me. Feeling like you’re about to die is not necessarily indicative of a good workout. Again, sometimes it might be what you’re going for, but I think in terms of constant gains and longevity, I think you should concentrate more on muscle contraction and performance of the exercise, and less on feeling like you’re about to hit the floor. If I’m going in for an abs, biceps and triceps workout, I’m not exactly trying to kill myself with intensity. If I’m going for heavy squats, that’s a different story. We’ve all seen people in the gym that are certainly intense and not doing a damn thing right. Again there will be times when intensity is key, like a HIIT workout, but that shouldn’t be a measure of success.
Ultimately, looking up scientific references to anything bodybuilding or training related won’t provide a ton of info as research isn’t very extensive, AND, more importantly, what matters most is if it works for YOU. For example, I’ll again reference Leroy Colbert who no doubt was an incredible bodybuilder and trained in full body sessions with crazy high volume, then you’ve got a got like Dorian Yates, obviously one of the best ever, who trained with minimal working sets, sometimes working up to just 2 working sets for an exercise. If you really want to see how long workouts, or anything affects you, then try it for a while. Plan your nutrition smartly, be objective about your results, and ultimately be sure to never do the same exact thing for TOO long, because no matter what type of program or the length of your sessions, your body will adapt and it’ll be time for a change.