Physics and Weight Training Questions

[dreiter]

Hi all! I have a few questions about physics and weight training. I searched around a bit but only found these two threads:
https://www.physicsforums.com/showthread.php?t=451027"
https://www.physicsforums.com/showthread.php?t=381643"
which don't totally cover my interests. I know that muscles are built due to exerting force against a weight, and that for one rep the force is always equal to the amount of weight lifted, but I am also wondering how other aspects of the rep affect the amount of muscle gained, according to physics. For example, how does the speed of the rep affect muscle gain? How about the number of reps versus the weight (as in high reps + low weight or low reps + high weight)? I have a solid understanding of physics but I guess my brain is locking up because I can't wrap my head around how these ideas relate to classical mechanics. Has anyone here studied how the concepts of physics can relate to weight training?

 

[Dr Lots-o'watts]

Well having done both, I have thought about the subject, but there are intermediary sciences called physiology and nutrition that are more closely related to weight training than physics. But even these won't necessarily answer why a certain number of reps cause more muscle gain than another. The best information I have found on the subject has come from the lab rats themselves (with all due respect), i.e. those who have spent hours in the gym and who have made careers out of it. Weight gain is dependent on many factors, including body type, which are far too complex to be made into a rigorous physics problem.

Briefly, lifting weights will actually cause micro-tears in your muscles, and growth happens when proper nutrition goes into repair and rebuild the muscles, preparing it for a future session. This happens while you are resting in between training sessions. (Immediate growth during a training session is of course a temporary increase of blood flow).

Now it's common knowledge that practice makes perfect, or that our bodies adapt to the specific conditions it is subjected to. So if you train with 3 sets of 10 reps, your muscles will optimize themselves to handle 3 sets of 10 reps. It is by the experience of the gym rats that similar numbers have revealed themselves to be about optimal for mass gain. Studies in physiology have shown that certain types of muscle cells are used for short bursts of energy, while other types are used for sustained effort. It so happens that to be able to handle 3x10 (roughly) type training, one type of muscle cell gets bigger, and according to some accounts, may multiply, adding overall mass. No such size increase is related to long term muscle or aerobic endurance, nor to single rep, very high weight effort (olympic lifting).

Training to gain mass really involves tearing the microfibers as much as possible during the exercise and depleting it of all available glycogen, so that it will overbuild itself when the next loads of building nutrients come along. 10x3 training happens to be what is most effective for this type of muscle "exhaustion". Rep speed, negative reps, supersets, and all these other specific methods are very subjective and lack true scientific backing.

Modeling all this with equations (i.e. mass variation as a function of reps and sets) would be very empirical, and calling it physics would not be right.

 

[dreiter]

Thanks for the reply Dr! I suppose I have always used physics to describe why things work the way they do, and coming across a subject that doesn't fit that is disconcerting to me. I have been doing a 5x8 routine (sets x reps) and that is working well, but I just wish I had a scientific reason (other than group studies) for preferring one method over another. :|

 

[christopherV]

best source of information on the subject I've ever found on the subject.

Hardcore Bodybuilding: A Scientific Approach by Frederick Hatfield.

 

[Dr Lots-o'watts]

If you look at the routines of professionals, they all have different numbers, and then different numbers for different muscles. It all depends on your specific lifestyle, diet, sleep, genes, habits etc. You just have to find something that works for you. But something everybody agrees on is that the numbers involving nutrients are just as important as the ones in the gym, if not more. How far one is willing to go to get these numbers right is a big, and very difficult, part of the sport.

There are certainly scientific physiology papers on the subject, but I haven't been there. There are so many different molecules, reactions, and studies involved that it's downright scary.

Physics rather, is about systems so simple they can be approximated by equations having relatively few variables.

 

[dreiter]

best source of information on the subject I've ever found on the subject.

Hardcore Bodybuilding: A Scientific Approach by Frederick Hatfield.

Thanks for the idea. I just looked through this page: http://drsquat.com/content/knowledge-base/fresh-look-strength" [Broken] and I'm not entirely sure how much I believe in his approach of time minimization. It was still a good read though!

If you look at the routines of professionals, they all have different numbers, and then different numbers for different muscles. It all depends on your specific lifestyle, diet, sleep, genes, habits etc. You just have to find something that works for you. But something everybody agrees on is that the numbers involving nutrients are just as important as the ones in the gym, if not more. How far one is willing to go to get these numbers right is a big, and very difficult, part of the sport.

There are certainly scientific physiology papers on the subject, but I haven't been there. There are so many different molecules, reactions, and studies involved that it's downright scary.

Physics rather, is about systems so simple they can be approximated by equations having relatively few variables.

Yes I know diet plays a major part of achieving results, but I feel like the diet portion is easy to understand scientifically, while the exercise mechanics are not! :D

 

[christopherV]

dreiter,

no problem glad i could help. his minimalistic method did work wonders for my bulk size and strength. you might also find this http://abcbodybuilding.com/articles.html [Broken] helpful.