Free weights are not versatile in the direction of force

Disclaimer : This information is not guaranteed to be accurate and I am not liable if you make any decisions or take any actions, in terms of medical treatment, health decisions, exercise, behavior or anything else based on the information presented.  I am not telling you any decisions to make even if I use terms like "you" but am using the word "you" as part of a writing style to simplify writing.  Any suggestions for what "you" should do are not for you personally to do but what someone might do as part of a exercise or nutrition program which might help some people's health and make other people's health worse.  You should not do any activity that will make your health worse even if "you" should do it according to the program described.  If the information is wrong and you believe it is true, act on it and it causes you problems, I am not responsible because I have warned you the information is not guaranteed to be accurate.

In order to achieve maximum force with the same size lever arm, you need to achieve maximum torque

In order to achieve maximum torque you need the lever arm to be perpendicular to the force

Free Weights only produce force in a downward direction which results in at least two problems 

The first problem is that free weights do not enable your muscle to work against maximum force for most of the range of motion in eccentric or concentric contractions in the sagital or coronal plane when individuals use them while sitting or standing upright.  

The second problem is that when sitting or standing upright and working on contractions in the transverse plane, free weights are often not contributing at all to the muscle group someone is trying to work for all practical purposes but instead are over exerting a different muscle someone is not targeting to such a degree of fatigue that they quit before they ever work the exercise enough to strengthen the muscle they are targeting significantly.

For example if someone tries to strengthen their shoulder or chest horizontal abduction and horizontal adduction or horizontal flexors and horizontal extensor muscles by holding free weights while standing and moving them left and right in the transverse plane they will primarily not strengthen the muscles that enable them to move weights left and right but only fatigue the muscles that keep the weight from moving down such as their sagital plane flexor muscles and their coronal plane abductor muscles.  After the wrong muscles get fatigued they will quit and since such a small portion of force is exerted by the muscle they intend to target relative to the muscle they do not intend to target they will not have used enough force for a long enough amount of time in the intended muscles to get good results.  

Maybe they will strengthen the muscles they want to target if the muscles they want to target work on diagonals and thus produce rotation in both the transverse plane and a second plane.  In such a case they are strengthened by exerting the force in the second plane even though they are not exerting much force in the transverse plane but then there is little point to the transverse plane motion.

This second problem can be overcome to some degree by lifting free weights while lying on your back or stomach on exercise benches or tables if you want to strength train transverse plane muscle groups but it still does not prevent the first problem of the unequal amount of force your muscle resists throughout the range of motion.

The first problem can not be fixed but can be dealt with by doing two different versions of the same exercise.  You would do the same exercise in two different perpendicular positions so that in the first position the torque is theorirically at 0 in one part of the motion and maximum in another and in the second position the torque is at it's maximum where it would theoritically be zero in the first position.

For example you could do a bicep curl while standing or sitting with the long axis of your humerus perpendicular to the ground and parallel to the direction of gravity and a second bicep curl with the long axis of your humerus alligned perpendicular to the direction of gravity.  Doing this requires more equipment like a soft but supportive object to rest your upper arm or the part of the flesh sorrounding your humerus on without resting your forearm or elbow on.  Without the extra equipment you will tire out other muscles keeping your shoulder in that position before you have significantly worked the muscles you are actually trying to exercise.  Alternatively you could lie on your back on the floor but at the very end of the range of motion the floor might reduce the amount of force required to lift the weight until it is off the floor.

Many people who want to make money selling you personal training will claim free weights are so much better than machines and some of them might possibly have the motive to get paid to teach you free weight exercises instead of you just doing the exercise listed in the picture or written description usually posted next to a machine without having to pay money to learn it.

Unlike free weights these machines usually are very nice because they produce force that changes directions based on the type of motion someone is trying to do.

A hamstring curl machine consistently produces force perpendicular to the long axis of the tibia and fibula or the leg below the knee.  This means you will experience approximately the same torque throughout the entire range of motion and resist the same force throughout the entire range of motion.

There are some problems with these machines in that they are usually only designed for one exercise or a small number of exercises but in my opinion if the machine changes the direction of force to keep torque constant throughout the range of motion then it is better to use a machine for the specific exercise it was built for instead of mimicking that specific exercise with free weights and losing out on force in parts of the range of motion where the torque becomes a minimum.

Sometimes free weights may provide benefits for learning postural control and developing core strength by trying to stabilize your body while doing exercises.  As long as free weights do not cause the muscles you are not targeting to get so fatigued you can not work out the muscles you are targeting sufficiently, then the working of additional muscle groups when you use free weights that you do not get with weight machines maybe beneficial.

The use of resistance bands or cable machines may allow more versatility in the direction of force than free weights.  Although, they still primarily only pull force in one direction, you can choose that direction based on the direction between the origin where the band is attached or the pulley for the cable is located and where the object is grabbed by you.  Unlike freeweights the direction changes as you move and the direction between the origin and your grip changes but the force will stay in approximately only one direction during the exercise a lot of the time and thus will still be subject to locations of maximum and minimum often as low as zero theoritical torque.

"Barbells and dumbbells are the two main types of free weights."

http://web.archive.org/web/20210907114920/https://www.livestrong.com/article/388359-is-there-a-difference-between-dumbbells-barbells/

One benefit of a type of free weight called barbells over exercise machines maybe that there is no weight limit to what you can attach to a weight lifting bar except that is not entirely true because if you stack too much weight on a bar it will bend, but this problem primarily only occurs for people in the olympics or trying to set world records or at least lifting far above maybe what 99% of the population will lift.  I have seen videos of people lifting world records in non olympic settings and the bar they are using bends, and if what they are lifting is not a world record and they are illegitimate since internet videos simply having the word "record" in the title do not count then this makes the problem all the more common if it bends for people lifting less than world records unless they are using bad equipment and most barbells would not do that.

This benefit of being able to lift more weight with free weights may not be such a benefit after all for most people doing leg exercises.  But I will only explain so after explaining how much people can lift.

As long as they have not had an injury or disability are not obese and know how to do so safely and believe they can, I would guess that it is very reasonable for a 25 year old male with very little free lifting or weight machine experience to be able to lift four times their body weight through a limited range of motion with their legs in a inverted squat using a leg press machine after maybe only about 8 weeks of training if they increase by half their body weight per week.   I am not claiming people can increase muscle strength at a linear rate indefinitely but that neurological adaptation to exercise initially produces very large increases in strength without much increase in muscle mass for beginners then after that the rate of strength increase slows down when future gains become more based on muscle mass.  I am not claiming the rate is linear but simply claiming they could increase weight by a constant amount every week in the beginning which would result in a linear function if they followed that regiment.  They probably already have enough muscle mass to do it but need to believe they can and learn to have their neurons fire to recruit the muscles that are already strong enough to do so if a high enough percent of the muscle fibers are recruited at the same time.  Very old people who studied judo and who do not look very muscular can stand one one leg to lift someone their own weight to throw them.  If you can lift someone your body weight on one leg (as I already said that old people who studied judo can do) then you are lifting your own body weight by standing on one leg plus lifting your own weight a second time by holdimg someone your own body weight.  Twice your body weight with one leg means four times your body weight with two legs.  Although you might be able to lift four times your body weight with two legs when inverted using a machine because you do not have to support your weight by standing, when lifting weights while standing this would only be three times their body weight because although you can lift four times your weight you also have to lift the weight of your own body.  Maybe you should only be able to lift three and a half times your body weight with the machine while inverted if only the half of your body weight for your torso is subtracted but not the weight of the legs.

http://web.archive.org/web/20210829185351/https://www.t-nation.com/training/is-the-leg-press-worthless/

Peoples legs are extremely strong but there arms are not.  It is reasonable for a begginner with less than a year of training to lift three times their body weight in a squat in a very controlled manner and limited range of motion with their legs but for some of those same people it is not reasonable to lift one times their body weight with their arms and possibly also not reasonable to do so with their back.

But what if most people squat less than their body weight after eight weeks of squatting practice?  Is that because I am wrong?  No, although I might be wrong about the exact ratio, it is because of the arms.  You have to lift a weight with your arms and torso in order to do squats using free weights or barbells instead of machines unless you use a weight rack and that means that people who had muscular enough legs to squat three times their body weight if their neurons fire in the correct pattern can not do it because of their arms and possibly also the back and core muscles of their torso.  And, additionally because they have trouble balancing the weight to keep the barbell even so the added weights do not slip off and fall to the ground and the challenge to avoid hurting their neck if they use a squat rack to bipass use of the arms 

Beginner 141 lb

http://web.archive.org/web/20220513112714/https://strengthlevel.com/strength-standards/squat/lb

The average American man 20 years old and up weighs 197.9 pounds

http://web.archive.org/web/20220517002854/https://www.healthline.com/health/mens-health/average-weight-for-men

You can theoritically squat or deadlift more than squatting machines or leg press machines allow with barbells because the machines come with a maximum setting, but with barbells as long as the bar is long enough you can keep adding weights.  But, I do not see most people using squatting machines on maximum settings.  Maybe that is because people who use squat machines are weak and not strong like those using free weights who know how to get real results and could work those machines at maximum.  But, I doubt it, because most people I have seen using barbells to squat lift or deadlift, lift less than the maximum setting on the squat machine. 

Now I will agree with the criticism that squat machines do not allow enough weight, but that does not mean squat machines should be eliminated and people should just do squats with free weights.  Instead it means squat machines should be built with higher limits.

But why are squat machines so easy?  One reason is the torque, the same reason as what is wrong with free weights.  Like free weights squat machines only send force in one direction.  I find the hamstring curl machine much more difficult than the squat machines because the direction of force is always perpendicular to the lever arm of the leg below the knee.  Squatting with free weights is not more difficult than squat machines because it is a better leg workout but because of the arm, core and back strength required for free weights as well as the challenge of not hurting your neck or tilting the bar uneven dropping it and injuring people.  If the challenge of not accidentally injuring people makes an exercise better than free weights are more challenging and therefore better than squat machines.  People using barbells can have the weight in front of them in which case it is really more of a arm, core, torso and back exercise but not much of a leg workout because most people can lift less than their body weight comfortably in front of them with their arms but carry around their full body weight on one leg like it is nothing every time they walk.  People using barbells can instead put the weight behind their neck and avoid the arm exercise by using a squat rack in which case they avoid limiting how much you can lift on account of arm strength but have to be careful not to hurt their neck.

As I already mentioned one of the problems using free weights to do leg exercises is that if you hold them in your arms and they weigh your body weight that is extremely difficult to do for the arms but is like walking a stroll in the park for the legs.  Unless you have much stronger arms than most people than your arms will get fatigued and tired and you will quit before you lifted enough force for enough time to get a good leg workout or get injured if you lift the weight for long enough to really effectively workout the legs by using more than body weight.  Sometimes people do lots of squats and lunges holding weights with their arms and get really strong legs but that does not mean using free weights gave them strong legs.  If someone did lots of squats and lunges without holding free weights they would also get really strong legs.

But what about holding free weights with your legs.  First there is a requirement of shoes in the gym so you can not grab them with your toes.  Second most people could not grab them with their toes if they were barefoot.  Third if you put weights on your feet and lifted them up and down they would not be versatile because you would have to avoid positions where they fall off.   Fourth if you rested heavy weights on your feet and lifted them up and down you are likely to get a foot fracture if they do not roll off if you accidentally put your foot on the ground in the wrong manner.  Fifth you could try to stick your feet in kettlebells and lift them but the holes are not big enough unless you are barefoot which will scrap away at the skin of the top of your feet, cause bleeding and likely cause foot pain and injury to the muscles that dorsiflex your feet and a sensation that feels like pain in the bones of your feet, although maybe weights with loops with a wider radius might work for going around the leg but not the feet.  Sixth, you could use leg weights that strap on but those tend to be too light weight for effective exercise and fall off.  Seventh you could use resistance bands or a cable machine but then you would not be using free weights with your feet because those items are not free weights.  Eighth using free weights with legs still has the two problems of the freeweights only providing force in one direction I mentioned at the beginning of the article.

What is wrong with using free weights for back and core exercises.  In the case of the deadlift one can not use a rack to bipass using the arms in the same manner one can for a squat.  If the back and core are much stronger than the arms one can not effectively use free weights held in the arms at a sufficiently high weight for optimal back and core exercise because holding the weights for prolonged periods of time will fatigue the arms to the point of quitting before sufficient back and core exercise has been achieved or result in injury to the arms if held long enough and with enough force to make a significant difference in long term strength improvement for those of average arm strength compared with doing the other or maybe even the same back and core exercises without the added free weights and without exercise machines.

But people of average strength who start to deadlift can improve the amount of deadlift weight they can lift and therefore get a stronger back?  Wrong! They get stronger arms and therefore can lift closer to the capacity of what their back could already lift.  The arms were the weakest link not the back, their back gained negligible strength but their arms gained a lot of strength because if the arms were not involved they could already lift that much with their back.

Someone can lift 500 pounds with their back and 500 pounds with their legs but only 100 pounds with their arms.  They start deadlifting and squatting lifting weights off the ground in either a squatted or forward bended position using a barbell without a rack and can lift 100 pounds in both squat and deadlift.  After training for a while they can now lift 120 pounds in those types of squats and deadlifts and think their legs and back can now lift 20 more pounds but actually it is their arms that can lift 20 more pounds because their arms were the limiting factor not their legs.  If before training in the squat and deadlift using free weights they used exercise machines to test the strength of their legs in a similar motion to the squat and their back in a similar motion to the deadlift but did not engage the arms they would know they already could lift 500 pounds with their legs and 500 pounds with their back, so lifting 120 pounds does not actually prove their legs or back got any stronger but it would prove their arms got stronger.  They would have to squat or deadlift over 500 before they knew their legs or back could generate more force.  As such they went from lifting 20% of their maximum to 24% of their maximum with their back and also with their legs but they were lifting 100% of their maximum with their arms the whole time.

Copyright Carl Janssen 2022 June 7