If you been around the weight lifting scene for a decent amount of time there is no doubt you’ve probably heard of or even had someone tell you directly that you shouldn’t lift weights over one hour. As if there is this timer that goes off in your body after an hour that says “no more gains!” So where did this one hour window come from and how much truth is there to it?
In researching this topic I found multiple articles explaining why you need to keep training under an hour. There was plenty of this out there, so what was the most common reasoning? For the most part it all came down topics I’ve recently reviewed, how very convenient for me. They concluded since cortisol levels rise and testosterone levels fall after about an hour of training and since cortisol is catabolic and testosterone is anabolic training over an hour is bad. We don’t want catabolic hormones taking over and our anabolic ones depleted, obviously right?
If research out of McMaster University (1) tells us anything, that probably isn’t the case. In their research during a 12-week training program subjects who had the highest cortisol levels post-workout were more likely to gain muscle over the course of the study. In fact they found that workout-induced cortisol was more positively correlated with lean body mass and hypertrophy than testosterone, IGF-1 or growth hormone. This doesn’t make cortisol anabolic, it just shows that higher levels of cortisol due to training is more of an indicator of how effective your workout was (consider it controlled stress.) And I’ve already showed you here and here how short-term spikes in anabolic hormones mean nothing. Cortisol seems to work the same way.
If that wasn’t enough the studies everyone pointed to about cortisol levels going up after an hour were done on endurance athletes. Not exactly the same thing as strength athletes. I’d say the cortisol reason would be strike one for keeping exercise under an hour.
The next common reason to keep workouts under an hour was because if you workout for too long you will deplete all of your body’s glycogen stores and your body will start using muscle for fuel. This one makes little sense. If you have full glycogen stores in your muscles you have about 500 grams stored up. You are not going to burn through 500 grams of glycogen in an hour of working out no matter how hard you train. The utilization of carbs during exercise can be calculated from oxygen uptake and respiratory exchange ratio.
The rate of oxidation depends on the intensity of the exercise as well as how well-trained the individual is. A well-trained person has a much higher capacity to metabolize glucose and fat compared to an untrained person. Romijn et al. 1993 (2) and Loon et al. 2001 (3) showed the major carbohydrate source used in exercise above 70% is muscle glycogen. Hermansen et al. 1967 (4) showed well-trained subjects can more than oxidize 3 grams per minute which means after an hour of very intense exercise that would be roughly 180 grams from carbohydrates. Strike two for keeping exercise under an hour.
The last reason out there to keep exercise under an hour is the common fear of overtraining. Overtraining seems to be everywhere now days, and I believe it has really been blown out of proportion. It seems like everyone is so worried about overtraining that as soon as they do anything that gives them sore muscles they think they need to take some time off so they don’t overtrain. Okay I’m not saying overtraining doesn’t exist, but realize that overtraining is the point where things like fatigue and feeling burnt out becomes chronic. (AKA not because you are tired for 2 days…) Where the demands of training frequently outweigh the time for regeneration.
Most of the time this happens because someone isn’t fueling their body properly and/or they aren’t getting enough rest. Then there is overreaching which is basically the short-term version of overtraining. I think many people also confuse these two things. Many programs such as Sheiko, Smolov or many of the fast growing DUP crowd (Daily Undulated Periodization) are programmed to purposefully overreach and then go through a period of deloading where the gains are actualized. As long as you don’t overreach for too long (which in turn leads to overtraining) it can be used for our own good for strength and size. Not lifting for over an hour in fear of overtraining seems foolish at best, strike three you’re out!
This isn’t to say you have to go over an hour and there is nothing wrong with getting in and getting out, but if you were worried your body would go catabolic if you did workout over an hour, you can now lift worry free. As always genetics, goals and your own training protocols play a big role in how long and hard you should workout. As long as you are smart and listen to your body, and knock the weight down for a while when your body really needs it, you’ll be golden. What I am sure about, however, is that if you feel you need to workout longer than an hour to reach your goals you shouldn’t worry about it one bit.
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