What I mean is, if I weight 215 lbs, with a somewhat muscular build, and I’m doing regular straight backed push-ups, how much of that weight am I lifting? I know it’s a lever problem, but I don’t know how to solve it with the differing weight distributions. Obviously the apparent weight is less if all the weight is in your feet, but most of my weight is in my upper body (chest, back, arms), and a decent amount in upper legs. So, are my pushups the equivalent of benching 115 lbs? 80lbs? 150 lbs? I can’t really go by feel, but I can do 60 pushups in good form in 2 minutes, and I know I can’t bench 135 lbs 60 times in 2 minutes, so it’s got to be less than that, but by how much?
Jman
(and yeah, I know they’re not identical exercises, since pushups use the abdominals a decent amount, but I’m concentrating on the chest/triceps lifting action here)
While there might be some complicated eqaution to figure this out, it would still not be acurate due to different weight distributions in different people.
Why not do it the easy way. Put your feet on a bathrom scale while in the push-up position and subtract whatever it reads from your body weight. I suspect it may change somewhat from the up and down positions.
A “simple” calculus look at the problem would say a little more than half your body weight. (This is assuming that each “slice” of your body, from foot to head, weighed about the same.) Your weight at your foot isn’t lifted at all, your weight at your shoulders is lifted fully, and your head’s weight is multiplied slightly because it’s on the far side of the lifting moment (shoulders) from the fulcrum (feet). Everything between shoulders and feet is lifted on a percentage basis from its distance from the feet. “Folding” these weight slices – shoulders (100%) to feet (0%), belly (60%) to knees (40%) – and averaging gives and overall 50%. Then add on the head’s weight (100-110%), and you get a little more than half.
Of course, this isn’t accurate: 1) the legs have much less weight in them by height as the torso; 2) men’s weight is centered higher, so they do more lifting than women; 3) the tiny amount of weight of your heels as you lift, being on the other side of the fulcrum, actually helps lift. :rolleyes:
So an educated WAG: 60-70% of your body weight is the equivalent bench weight.
Why not do it the easier way? Just put your hands on the scales and push-up away! This way you can even see how the force changes from the top to the bottom of the push-up cycle.
Thanks. Unfortunately, I don’t own a bathroom scale. I’d have done that already otherwise. I suppose I could go into a store and pull out a scale and do a push up on it, but that just seems way to wierd.
I did a simpler calculation than AWB’s and came up with about the same answer. I made the assumption that the arms and head are weightless and mass distribution in the rest of the body is constant (in the spirit of “assume the cow is a sphere”). I came up with an estimate of 71% of body weight. Then I dragged out the bathroom scales and actually did an experiment. It came out to 67% of body weight.
Why not put your feet on the scale in pushup position and have a friend read it? Of course, your hands would have to be level with the scale.
And pushing up from the scale would create a bit of an error. Think of it as if you were squatting on the scale. If you suddenly stand up, the scale’s going to register more weight because you’re pushing harder on it. Similarly, any read you get on the scale when you’re doing a pushup is going to have an error.
Assuming that your torso weighs more than your legs, I’d guess you’re lifting something like 110 lbs or so. However, I don’t know where weight is specifically distributed in your body.
How could this be? Your figure–67% of body weight–is about 125 pounds for me. While I can do 80-90 regulationpushups in one set,* doing 80-90 reps of just 128 pounds in the bench press would turn my arms into goo. Can someone explain this?
I try to sneak in 600-800 pushups every other day. It’s easy after awhile and not nearly as much as it sounds.
I have a bathroom scale and I just did a few push-ups with my hands on it. I am 6 ft tall and weigh 160 lbs, and I consider myself to have a standard male body build. When my arms are straight during a push-up, the scale reads a little over 100 lbs. When my chin is almost touching the scale, it reads a little over 110 lbs. I kept myself still in each of those positions for a couple seconds to make sure the reading was stable, and I also made sure my back was straight at all times.
If we assume that the distribution of your body’s weight is similar to mine, then your push-ups would be roughly equal to benching 135-150 lbs of weight. Since you’re more buffed up than I am however, those figures will be slightly higher as most of that extra weight you have will tend to be concentrate around your torso.
So how can push-ups be easier than benching when the same amount of weights are involved? First of all, I don’t think your abdominals are involved in this problem, since they only work to keep your back straight. The best reason I can come up with is that push-ups may involve more upper-body muscles than bench presses. By distributing the work between more muscles, you reduce the amount of strain on each muscle, and therefore allow them to function longer. You also have to remember that although you may be able to do 100 push-ups continuously, you probably can’t do 100 perfect keep your back straight at all times and touch the ground with your chin push-ups continuously. By just bending your back in either direction slightly during a push-up, you can significantly reduce the amount of strain your muscles must endure.
