Have you heard of ZuzkaLight? She has a youtube channel and a blog where she posts workouts. Most of her workouts are short and use either body weight only or relatively light weights. I haven't tried any of her workouts yet, but they look like they might be short enough to not aggravate acne.
You don't necessarily want light weights. You want brief but intense Exertion.Heavy weights achieve that.
A typical workout with heavy weights would be 30-45 minutes with about 5 exercises with 2 sets and 10 reps each. Doing this 3x a week really upset my skin. I was getting inflamed acne, which I don't usually have, and my skin also became much more oily. Ideally I'd like to still be using heavy weights, but I'm not sure how to modify this without breaking out. One set with heavier weights instead of 2? Less reps?
Heavy weights will actually stimulate the greatest production of hormones unfortunately (Can provide academic sources if you want). What you can try to do is lower the weight but increase the number of reps per set; focusing on perfect form and good tempo with the lighter weights. This will slightly adjust how your muscles fatigue, and turns the exercise more towards endurance rather than strength training.
So pick a weight than you can perform 12-15 reps to fatigue for, then do 2 or 3 sets. This rep range will still give you a great cardiovascular workout as well as make you strong and toned. It might be worth a shot for a week or two to see if you like it.
I work with heavy weights in the 8-12 rep range because I want the greatest Testosterone spike, while it will give the best results it will also mess with your skin the most.
Honestly though, the difference will be pretty small. Testosterone and it's derivative DHT are double edged sword; just try to find balance with a workout that you like AND that you skin likes lol
And length guidelines for a workout are very person specific. It depends on your recovery ability, fitness goals, and lifestyle. A good rule of thumb is not to exceed 4 hours of strength training in any given week unless you are training for something, being directed by a trainer, or are an athlete and know what you're doing. I know people that workout 6 times a week for 40 min each; and some that workout 3 times a week for 1.5 hours each. Find what you feel the best doing; the duration of your workout will have little to no affect on your acne other than from how long sweat is on your skin.
(Those time guidelines don't include cardio, you can do that as often as you have the energy for)
Edited by CBIOT13, 22 June 2013 - 08:41 PM.