How Much Lifting is Enough? How Much is Too Much?

Jordan Feigenbaum (0:01)

In 1989, researchers at the University of Florida took 117 sedentary adults in their 20s and had them lift weights for 10 or 18 weeks. Some trained two days a week, some trained three, and some didn't train at all. The entire workout was one set of leg extensions for seven to 10 reps, taken to failure, and then you went home. At the end of the study, they didn't test a squat or a deadlift. They tested how hard the subjects could push against the leg extension machine when the pad was locked in a position and wouldn't move.

After 18 weeks, the three-day group had gotten 28% stronger. The two-day group got 21% stronger.

Would you believe me if I told you that this is the study the lift weights twice a week recommendation came from? Because it is.

It showed up for the first time the following year in the American College of Sports Medicine's position stand, the first one that ever included resistance training. The authors give their reasoning in two short sentences. The first quote, programs lasting more than 60 minutes per session are associated with higher dropout rates. And the second quote, although greater frequencies of training and additional sets or combinations of sets and repetitions elicit larger strength gains, the magnitude of difference is usually small.

They knew more was better and they recommended less anyway because they felt people would quit when the workout takes too long. That doesn't make much sense to me because if you look at the same amount of training and split it up into more sessions, each workout would be shorter. After all, exercise frequency, which is how many days per week you exercise, is mostly just a tool to distribute the training in a way that fits your schedule. And in this particular study, where they only did one set per workout, which the study says lasted 40 to 60 seconds, well, I don't know about you, but doing an extra minute or so of work to get 30% more strength seems like a good trade-off. So I went and looked at what that study cites for the recommendation. It says it's supporting. Reference 1 is a personal communication from ML. Pollock, Chairman of the ACSM Revision Committee, dated November 1988 Well, ML. Pollock is the third author of the very study we're talking about.

Did you catch that? I'll slow it down. 1998, a committee has a draft recommendation of two days a week sitting in it. 1989, a paper comes out with that committee's chairman as an author, and the thing it cites as support for two days a week is a letter from the chairman. 1990, the finished position stand cites the paper. The recommendation is its own evidence, and the study attached to it found that three days beat two days.

Later in the 1990 guidelines, it says that health and fitness are two different questions and that this document is answering the fitness one. The health one came out five years later, and it didn't discuss lifting at all. 18 years later, in 2008, the federal government took the two days per week number out of a fitness prescription and printed it as the health recommendation. But nobody ever did the health version of the work for lifting weights. When it comes to exercise's connection to health, there are really two questions here. One, how much training does it take to change you and your body? Two, how much do those changes improve your health? Those are two different questions that may produce two different answers, so we need to keep them separate.

Last week, we went through 150 years of people telling you not to lift. All of it built on vibes and most of it was proven wrong when it was actually studied. This is the same problem in reverse, where the study identified the correct answer, but the recommendation ignored it and was based on vibes anyway. And it's led to an interesting belief about the risk of lifting weights. The warning used to be that lifting weights is dangerous, period. Now, the warning is that lifting is dangerous if you do too much of it. Today, we'll find out where that one came from, whether there's anything behind it, and then try to answer the actual question, how much lifting should you do?

I'm Dr. Jordan Feigenbaum, and this is the Barbell Medicine Podcast.

I'll give you my full answer at the end with the obligatory snark, but here's the short version so you can see where I'm going. I think that most people should be doing roughly double what the guidelines say, because I think that many of the health benefits from exercise keep going, and I don't think anybody has found the top for all of them.