Art De Vany has some great insights on power law variation. Hunter-gatherer lifestyle is full of power law variation. In physical activity it means that they move a lot at low intensity and less at high intensity (so far nothing new), but that the distribution is not linear. This means that sometimes they'll have high intensity activities a few days in a row, and sometimes maybe not for a week.

So I think that working out (strength or power training) more than every 48h can be ok, even beneficial, but you will have to take care with the long term consequences. The rule of 3 workouts a week (linear) could maybe mean 12 times a month, but with a power law variation to it.

You probably should look up Art De Vany's say on this, he could explain this much better. Another incredible resource is Keith Norris' Theory to Practice blog.

• Listen to your body. It will tell you if it wants more than 24 hours rest between muscle groups.

• Recovery is more a function of intensity/volume than it is specific muscle groups. If you can do 50 push-ups in a row, it probably won't harm you to bench press 3x5 today and 5x10 push-ups tomorrow (as part of a conditioning workout). Not saying it's optimal, but it's fine.

• Most people don't work out at all, and when they do, they don't work out hard. For these people, I'd rather err on the side of doing push-ups (or whatever) every day, or often. They will get stronger and increase endurance, and the volume/intensity will not be too much. If they start to feel worn down, back off.

• In short, I think the 48-hour "rule" has pretty good value for intermediate trainees who take their training seriously, but it's laughable for people who "work out" recreationally.

• The more advanced you get, the more time you need to recover [edit: when working with near-maximal loads]. If your max deadlift is 505, you will need more time to recover than someone whose max deadlift is 185. True recovery may take more than a week, possibly more than a month, if you are an advanced or elite athlete.

48 hour rest periods are indeed conventional wisdom that has glaring holes. I would highly recommend browsing "The Science and Practice of Strength Training" by Zatsiorsky for an in depth view on this issue. Part of it is available on the google books thing.

Optimal recovery time seems to be quite complex and variable, depending on time-under-tension, muscle fiber type per muscle group, etc. There was a chart in some paper a while back, that showed recovery times per bodypart for experienced vs novice lifters. The takeaway is that there is quite a bit of variability between individuals.

The kicker is that paleo type workouts use most if not all major muscle groups. That means that there might be a bottleneck somewhere for recovery. In olympic lifting and powerlifting, the legs are often the bottleneck for recovery, whereas the back is fine to go another round. In pilates, the abs are a bottleneck. The caveman might not have any bottlenecks, if he spends his time doing low-intensity things compared to crossfit etc, such as squatting to hunt prey, throwing some spears, scratching himself, etc.

Great question, I completely agree. It's only going to be hypothesising, but I imagine that our ancestors may have taken it easy for a day or two if circumstances permitted when they had undertaken really strenuous work the day before. They were also probably in significantly better shape than we are, and so their bodies would probably be more resistant to a beating.

I think we also forget that many hunter-gatherer societies, and also other primates, spend a large portion of the day sitting around doing nothing other than social activity. When they do something (hunt, fight, etc) it can be intense, but other parts of the day are often sedentary.

I've recently started strength training every day, and am getting better results than I did under the CW regime of two or three times a week. My workouts are brief, lasting under ten minutes.

It depends whether you are training to failure or max effort or not. There is a reason the majority of good, old-school 5x5 and 3x5 strength training programs are typically three days a week, M - W - F for example. When you are pushing max weights every time, with lots of volume, you need time (and a lot of food!) to recover and adapt to the stress on your muscles, CNS etc.

However, you can train the same lifts every day if you train well below failure, take a look at Pavel's Power to the People and Dan John's 40-day program for example ...short, simple workouts, two easy sets of five on a the same couple of lifts, five, six, or seven days a week. Basically spreading the volume out over a week-long period, instead of one big workout, rest, another big workout.

You could try training all-out every day, but I doubt you'd last very long.

Your muscles will still grow without the rest, but it isn't optimal for hypertrophy.

I think it depends on how much your muscles are hurting. If they are not hurting you are probably fine. If hurting a bit, you can probably get away with it. If they really hurt, let em rest! Overworking muscles can result in slower progress overall and also increases risk of injury. If you don't really know what you are doing, I'd say don't push it too fast. Also, recovery time depends a LOT on things like age, health, experience, genetics, type of exercise, intensity of exercise, muscle group worked, etc. Forty eight hours is just a guideline. If you are a 50 year old female with high blood sugar, you may need twice as long!

It also depends on your goal. If your goal is to be a caveman, then do whatever you think a caveman did. If your goal is to increase strength efficiently, then you might want to be a bit more scientific about it. Cavemen sometimes fell to exhaustion and died. That does not mean the same is good for us!

My advice is don't do the same EXERCISE on back to back days but I generally will work the same muscle groups from time to time. My exercise plan is one lower body, one upper body pull and one upper body push. I may do the bench press one day and an overhead press the next. Because I don't stick to a "Mondays is arms, Tuesdays is back..." segmented rigid schedule, I let life come up and sometimes I can go to the gym 3 days in a row, sometimes I don't go for 5 days. Because I do this alternating pattern and give my body rest when I know I need it, I make strength gains and some anabolic gains with minimal soreness and loss of function. An important point I have to make is that I follow Pavel's Grease the Groove protocol and I DO NOT push to failure. If you are pushing yourself to failure, that's a whole nother ballgame. That is getting involved with far too many muscle fibers being torn to bounce back in 18 hours. If you follow his 5x5 plan and leave a little left in the gas tank, your muscles are getting stronger and you are tearing enough muscle fibers to add some mass but you won't walk with a limp the next day and you will be able to use those muscles, for the gym or otherwise, going forward without issue.