Physiology in motorsport

[Astraist]

Hi, I am a competetor and instructor of motorsport. I try to live up to the name motor-sport and teach my drivers not to underestimate the physical skill nessecary in terms of correct body positioning, utilization of vision, etcetra. As an instructor, I have two issues in need of solving:

 

1. Regarding our seating position: Some instructors teach their students to seat with the shoulders on the seat and the palms on the wheel in parallel heights. Others, such as me, teach a position where the palms are slightly lower than the shoulders, approximatly 5cm. I have heared it has to do with blood circulation, but without detail or proof. What to do and how?

 

2. Regarding the manner in which we steer our cars: Some prefer to use the hand in the direction of the turn in a pulling movement, some push with the opposite hand. As an advocate of the pulling method, I was taught the pulling movement involves a wider range of muscles including some very gentle muscles of finer motor skill, like forearm, palm and finger muscles, and that pushing encorprates stern upper body stregth resulting in less sensitivity and more physical effort.

 

The claim of the "Pushers", however, is that during pulling the wrist becomes quite bent, allowing for less smooth contorl. I have not been able to prove or disqualify this excuse, but it appears that the feeling in the fingers and palms remain identical when the wrist is twisted downwards (fingers aimed down). So, which hand movement is prefered?

[Double K]

What you're talking about is largely referred to as Ergonomics.

 

The first part to your question is something that would require some lab work, but wouldn't be hard to do. A pressure sensitive pad that covers an entire seat would give you the data you need to determine the best positions, however I suspect these would be determined individually as each person has an almost entirely unique body shape, length of limbs etc. Although you could manage a configuration and seating position that encourages a more desirable body position, I would be surprised if the top F1 drivers didn't have individually moulded seats.

 

Also, there would be certain body positions that force you to work harder through high-G turns, and high-G +ve and -ve acceleration. Assume a lower centre of gravity and the G-forces are likely to be reduced, if you go moving your head too far from centre you're going to work exponentially harder as the distance increases...

 

As for the last part of your question, the best hand position on the steering wheel for maximum control is (imagine a clock face) 2 and 10.

2 and 10 gives you optimal control, the wheel is shuffled as you make the turn, and gives you the perfect push/pull balance

Edited May 4, 2010 by Double K

[Astraist]

The problem with about everything in your post is that it does not consider the development in the world of motor cars. Modern cars, even road cars, have enough seat adjustment options available to reach a very suitable position. With the shoulders on a certain height, must the palms be placed in a parallel height or preferably slightly lower?

 

About steering, the 10 to-2 position is the grip of the wheel which relates more closely to the former subject of seating position. Additionally, it was a custom of older cars where the rim was very large and holding it across it's diameter would have the driver place his hands extremly apart. Modern rims are much better controlled when the hands are in 9 and 3.

 

About shuffling the wheel, I know for a fact that modern rims are also light enough to be rotated more smoothly in one hand movement rather than a succession of hand movements. My question is which hand gives you better control and less effort?

[Double K]

Unfortunately without a make or type of car and relevant information all I can say is generic information. Are you racing F1, F3, street vehicles, V8 supercars? Each of them have different seating positions.

 

If you look at a variety of race cars, you will see a variety of seating positions. In the open-wheel CART and Formula cars, it appears that the driver is almost laying down with arms fully oustretched (they are not). In a full-bodied NASCAR-type car, you see the driver more upright and almost cramped against the steering wheel. Neither position is the correct one for your street car in road racing.

 

The body of the open-wheel car is very shallow in height, and the cockpit is very narrow. This shape determines much of the driver's position. The driver's legs are relatively straight out with a slight bend in the knee, and the feet just barely below the hips. The pedals in many of these cars are almost touching each other. The pedals also require little more than a flexing of the ankle to go from 0-100% depression. The driver's arms have little room for movement, but the steering requires extremely little turning input by the driver. In the open-wheel car, function (driver's seating position and controls operation) follows form (the shallow and narrow cockpit).

 

In a NASCAR type car, many things are completely opposite. The driver sits very upright, and is very close to the steering wheel. In fact, the driver can almost lay his whole forearm on the steering wheel. The cars themselves are larger, heavier, and have large front tires. Additionally, on even the large speedway tri-ovals, the percentage of time spent turning is much higher than on a road course. All this adds up, and means the driver's right arm and shoulder is going to get tired much sooner. Sitting upright and close to the steering wheel allows the driver to utilize more of the shoulder and back muscles.

 

There are three main aspects to setting the correct seating position. In a street car, it is possible that some balanced compromise of these three parameters is needed as the fixed position of the pedals and steering wheel may not be perfectly matched to your arm and leg lengths. In a race car, or a street car you spend the money on, the pedal arms can be modified, and a steering wheel with a specific dish dimension (the depth of the mounting plane to the face of the handling ring) can be selected to allow a perfect match to your needs.

 

This configuration is for road car racing

 

First, sitting in the seat itself, the driver's back should be flat against the back of the seat with the buttocks squarley tucked into the corner created at the intersection of the seat back and bottom. The underside of the legs should be in contact with the seat bottom. The purpose of this position is to provide as much surface contact between the driver's body and the seat. This has safety benefits as well as providing the driver with the most tactile feedback as possible.

 

Second is the arm position. When the driver is tightly strapped into the seat as described above, the arms when fully extended should allow the wrists to rest at the top of the steering wheel. This allows the arms to be slightly bent at the elbow when fully extended for a turn. The purpose of this position is to prevent the arms from being overextended during turns (the shoulders should not need to lift from the seat back even to do a full arm crossover). Overextending the arms will cause them to tire quickly, and will cause the driver to lose sensitivity to the vibrations in the steering wheel.

 

Third is the leg position. When any of the pedals are fully depressed with the ball of the foot on the pedal (not the toes), the leg should still be bent at the knee. This is to prevent overextension as described for the arms. Additionally, given that most hobbyists are driving their street cars, be sure that the knees are not against the underdash or steering column. In fact, there should be several inches room to prevent injury in event of a collision. The right leg in particular will need enough knee room to allow the ball of the foot to be on the brake pedal, and the heel to be on the acceleration pedal for heel-toe downshifting.

 

The proper grip of the steering wheel starts with the hands at the 9:00 and 3:00 positions. Contrary to the 10 and 2 o'clock positions you probably learned in driver's school, you have greater range of motion and control with your hands in the 9 and 3 o'clock positions. The palms should be cupping the outer diameter of the wheel, with the thumbs wrapped around the ring and resting on top of the cross brace. The heel of the palm should be positioned to apply a slight pressure on the front of the wheel for stabilizing your arm movements--don't make your thumbs do all the stabilizing. Most stock steering wheels in sports cars, and even sedans, today are properly designed for the 9 and 3 positions with padded thumb detents.

 

The grip itself should be relaxed--just tight enough to maintain control and good contact for sensory input. A tight grip on the wheel will tire your hands and arms quickly, and more importantly will significantly reduce the sensitivity to the vibrations needed to sense the control limits of the vehicle.

 

While it is a natural tendency to grip the wheel tightly while cornering, no amount of squeezing on that wheel will increase the traction of your tires! However, the more relaxed the grip (without losing contact with the wheel), the more of that traction you will be aware of. It is a learned response to relax your hands (in fact, your entire body) during high g-force cornering, but it is something that you must force yourself to learn as quickly as possible. It will increase your sensitivity to the car's traction limits, and improve your awareness of the car's handling.

 

Something to practice to ensure your hands, arms and shoulders are relaxed before entering a corner, is to take a deep breath during the straight beforehand. Breath deep, relax your muscles, and exhale. Another thing to do when you're in a long enough straight and clear of other cars, is to relax one hand at a time and wiggle the fingers (leaving the palm and thumb on the wheel). Doing this often will keep the muscles in the hand, wrist, and forearm from cramping.

 

When turning a corner, lead into the turn by "pushing" the wheel with the hand opposite the turn (left hand for a right turn), and stabilizing the wheel with the other hand. Push the steering wheel through the 12:00 position rather than pulling it towards the 6:00 position when turning. For large steering inputs like a turn, the pushing arm has more control because the wrist stays in a firm position. The opposite wrist becomes quite bent and will not provide smooth control. "Pulling" the wheel is effective for small steering inputs such as moving across the track width where the action is really limited to a movement of the wrist, and not the whole arm. If you're a puller right now, it will take a little re-training to make this comfortable, but in the long run it will make you a smoother driver.

 

One of the critical keys to maximizing speed through corners is smooth car control which comes from smooth steering. If the car is to travel on a smooth consistent arc, then the steering input must also be a smooth consistent turn. The purpose of this smoothness is to maximize the traction of the tires. The traction of the tire is significantly influenced by your ability to provide smooth turning. The smoother driver will have more traction, and will have higher corner speeds.

 

It is common to think you are turning smoothly, when in fact you are turning on a smaller, tighter, and jerkier radius than you need to. In car video can be a great help to watching yourself, and recognizing where you need to be smoother. A typical tip off to a driver that needs to be smoother is when a car tends to understeer during the first half of a turn. More often than not this is caused by the driver's lack of steering smoothness than by car setup problems.

Edited May 5, 2010 by Double K
fixing typos

[Phi for All]

Unfortunately without a make or type of car and relevant information all I can say is generic information. Are you racing F1, F3, street vehicles, V8 supercars? Each of them have different seating positions.

 

If you look at a variety of race cars, you will see a variety of seating positions. In the open-wheel CART and Formula cars, it appears that the driver is almost laying down with arms fully oustretched (they are not). In a full-bodied NASCAR-type car, you see the driver more upright and almost cramped against the steering wheel. Neither position is the correct one for your street car in road racing.

 

The body of the open-wheel car is very shallow in height, and the cockpit is very narrow. This shape determines much of the driver's position. The driver's legs are relatively straight out with a slight bend in the knee, and the feet just barely below the hips. The pedals in many of these cars are almost touching each other. The pedals also require little more than a flexing of the ankle to go from 0-100% depression. The driver's arms have little room for movement, but the steering requires extremely little turning input by the driver. In the open-wheel car, function (driver's seating position and controls operation) follows form (the shallow and narrow cockpit).

 

In a NASCAR type car, many things are completely opposite. The driver sits very upright, and is very close to the steering wheel. In fact, the driver can almost lay his whole forearm on the steering wheel. The cars themselves are larger, heavier, and have large front tires. Additionally, on even the large speedway tri-ovals, the percentage of time spent turning is much higher than on a road course. All this adds up, and means the driver's right arm and shoulder is going to get tired much sooner. Sitting upright and close to the steering wheel allows the driver to utilize more of the shoulder and back muscles.

 

There are three main aspects to setting the correct seating position. In a street car, it is possible that some balanced compromise of these three parameters is needed as the fixed position of the pedals and steering wheel may not be perfectly matched to your arm and leg lengths. In a race car, or a street car you spend the money on, the pedal arms can be modified, and a steering wheel with a specific dish dimension (the depth of the mounting plane to the face of the handling ring) can be selected to allow a perfect match to your needs.

 

This configuration is for road car racing

 

First, sitting in the seat itself, the driver's back should be flat against the back of the seat with the buttocks squarley tucked into the corner created at the intersection of the seat back and bottom. The underside of the legs should be in contact with the seat bottom. The purpose of this position is to provide as much surface contact between the driver's body and the seat. This has safety benefits as well as providing the driver with the most tactile feedback as possible.

 

Second is the arm position. When the driver is tightly strapped into the seat as described above, the arms when fully extended should allow the wrists to rest at the top of the steering wheel. This allows the arms to be slightly bent at the elbow when fully extended for a turn. The purpose of this position is to prevent the arms from being overextended during turns (the shoulders should not need to lift from the seat back even to do a full arm crossover). Overextending the arms will cause them to tire quickly, and will cause the driver to lose sensitivity to the vibrations in the steering wheel.

 

Third is the leg position. When any of the pedals are fully depressed with the ball of the foot on the pedal (not the toes), the leg should still be bent at the knee. This is to prevent overextension as described for the arms. Additionally, given that most hobbyists are driving their street cars, be sure that the knees are not against the underdash or steering column. In fact, there should be several inches room to prevent injury in event of a collision. The right leg in particular will need enough knee room to allow the ball of the foot to be on the brake pedal, and the heel to be on the acceleration pedal for heel-toe downshifting.

 

The proper grip of the steering wheel starts with the hands at the 9:00 and 3:00 positions. Contrary to the 10 and 2 o'clock positions you probably learned in driver's school, you have greater range of motion and control with your hands in the 9 and 3 o'clock positions. The palms should be cupping the outer diameter of the wheel, with the thumbs wrapped around the ring and resting on top of the cross brace. The heel of the palm should be positioned to apply a slight pressure on the front of the wheel for stabilizing your arm movements--don't make your thumbs do all the stabilizing. Most stock steering wheels in sports cars, and even sedans, today are properly designed for the 9 and 3 positions with padded thumb detents.

 

The grip itself should be relaxed--just tight enough to maintain control and good contact for sensory input. A tight grip on the wheel will tire your hands and arms quickly, and more importantly will significantly reduce the sensitivity to the vibrations needed to sense the control limits of the vehicle.

 

While it is a natural tendency to grip the wheel tightly while cornering, no amount of squeezing on that wheel will increase the traction of your tires! However, the more relaxed the grip (without losing contact with the wheel), the more of that traction you will be aware of. It is a learned response to relax your hands (in fact, your entire body) during high g-force cornering, but it is something that you must force yourself to learn as quickly as possible. It will increase your sensitivity to the car's traction limits, and improve your awareness of the car's handling.

 

Something to practice to ensure your hands, arms and shoulders are relaxed before entering a corner, is to take a deep breath during the straight beforehand. Breath deep, relax your muscles, and exhale. Another thing to do when you're in a long enough straight and clear of other cars, is to relax one hand at a time and wiggle the fingers (leaving the palm and thumb on the wheel). Doing this often will keep the muscles in the hand, wrist, and forearm from cramping.

 

When turning a corner, lead into the turn by "pushing" the wheel with the hand opposite the turn (left hand for a right turn), and stabilizing the wheel with the other hand. Push the steering wheel through the 12:00 position rather than pulling it towards the 6:00 position when turning. For large steering inputs like a turn, the pushing arm has more control because the wrist stays in a firm position. The opposite wrist becomes quite bent and will not provide smooth control. "Pulling" the wheel is effective for small steering inputs such as moving across the track width where the action is really limited to a movement of the wrist, and not the whole arm. If you're a puller right now, it will take a little re-training to make this comfortable, but in the long run it will make you a smoother driver.

 

One of the critical keys to maximizing speed through corners is smooth car control which comes from smooth steering. If the car is to travel on a smooth consistent arc, then the steering input must also be a smooth consistent turn. The purpose of this smoothness is to maximize the traction of the tires. The traction of the tire is significantly influenced by your ability to provide smooth turning. The smoother driver will have more traction, and will have higher corner speeds.

 

It is common to think you are turning smoothly, when in fact you are turning on a smaller, tighter, and jerkier radius than you need to. In car video can be a great help to watching yourself, and recognizing where you need to be smoother. A typical tip off to a driver that needs to be smoother is when a car tends to understeer during the first half of a turn. More often than not this is caused by the driver's lack of steering smoothness than by car setup problems.

Double K, if you don't cite sources when you copy/paste whole articles, it makes it look like you're stealing the works of others, and plagiarism is NOT allowed here. Please give credit where it's due.

[Double K]

Well that was not my intention - and as obviously you discovered a 10 second google cut/paste led you to the article didnt it?

Sorry but it's a forum, not a publication, I never stated it was my work or put my name to it, I will however add in the location for you - I see little point reinventing the wheel when someone has already done it...

 

http://www.turnfast.com/tech_driving

[Cap'n Refsmmat]

Sure, it's okay to provide links or quotes, but please do provide the source when you do. The source might have other useful information, and copyright law generally frowns upon unsourced copying, even if you have good intent.

 

I don't think you'll be sued, of course, but sourcing is a good idea.

[Phi for All]

Well that was not my intention - and as obviously you discovered a 10 second google cut/paste led you to the article didnt it?

Sorry but it's a forum, not a publication, I never stated it was my work or put my name to it, I will however add in the location for you - I see little point reinventing the wheel when someone has already done it...

 

http://www.turnfast.com/tech_driving

It's a discussion forum, we want *your* input, and your Double K name is on every one of your posts. It's assumed to be your writing unless you quote someone else and give citation. You don't have to reinvent the wheel, but you do need to give credit to the guy who invented it in the first place.

 

Are we cool with this?

[Double K]

It's a discussion forum, we want *your* input, and your Double K name is on every one of your posts. It's assumed to be your writing unless you quote someone else and give citation. You don't have to reinvent the wheel, but you do need to give credit to the guy who invented it in the first place.

 

Are we cool with this?

 

Where do you draw the line at this Phi? (Phi being the golden ratio, a name I'm willing to bet you didnt invent or cite the origins of?)

I mean "Are we cool?" should possibly have been cited from "Dude, Where's My Car (2000)" (which is appropriate when you consider the OP)

 

Secondly I sat there earlier thinking, should I post the link? And after about 1 second of thinking on it thought - "well if anyone wants to find it all they do is paste a phrase into google and it will take them there." Double K (May 5th 2010)

 

You've already made your point, you got an apology and a citation, how much more cool with it do we need to be?

 

Knowing the temperament of moderators in general I'm sure you'll throw a ban at me now for speaking up. My point really is, you already berated me once, was it really necessary to take a second shot at me mate?

[Astraist]

The information citated from Turnfast.com is percisely the reason why I am asking: They state that Pushing is better because the wrist stays firmly positioned. I was always taught to use the other hand because the muscles generating the movement are more sensitive in nature.

 

Can any of you confirm or deny any of these claims, from an Ergonomic source, and not a racing-related source.

[Cap'n Refsmmat]

Knowing the temperament of moderators in general I'm sure you'll throw a ban at me now for speaking up. My point really is, you already berated me once, was it really necessary to take a second shot at me mate?

I don't think anyone intends to "berate" anybody. Or ban anyone.

[Phi for All]

My point really is, you already berated me once, was it really necessary to take a second shot at me mate?

You didn't seem to get my point the first time, so I clarified it. I don't mind you speaking up about it, if you truly think you were in the right.

 

Neither post was about berating you, just pointing out policy. I was careful to say that a lack of citations made it *look* like you were stealing, not that you *were* stealing. I'm sorry it doesn't seem to make sense to you.

 

This post is not about berating you either. It's not taking a shot at you, not an admonishment, not a slap on the wrist. You're new, you're not the first new member to do this, and you've got a dozen other posts that make you too interesting to ban.

---

Merged post follows:

Consecutive posts merged

The information citated from Turnfast.com is percisely the reason why I am asking: They state that Pushing is better because the wrist stays firmly positioned. I was always taught to use the other hand because the muscles generating the movement are more sensitive in nature.

 

Can any of you confirm or deny any of these claims, from an Ergonomic source, and not a racing-related source.

Most of the ergonomic sources are for much more heavy work than turning the wheel of a car. Those seem to favor pushing, but I can understand where you're coming from. Pulling would seem to allow for more of a "feel" for what's going on since it's restricted to fewer muscle groups.

[Astraist]

Thank you.

 

Can you rule pulling more sensitive than pushing in spite of wrist movement during a pulling movement? Can you citate a source? This is simply a long debate and I want proof in order to end it.

[Phi for All]

It would make sense that pulling on the back side of the steering wheel would give you more sensitivity than pushing on the front, since pulling is done with the more sensitive tip of the fingers as opposed to the less sensitive base of the finger and palm of the hand you'd use to push.

 

I wish Mokele, another of our Mods, were currently available, he does a lot of work with muscle groups. Mostly in reptiles, but his knowledge is much more technical, just what you're asking for.

 

I'll keep looking though.

[Double K]

Muscles are much stronger in eccentric contractions (which is where the muscle is lengthening under load - this always confused me as its called a "contraction" I never understood why but was always a good way to trick people up in the exams!) A good example of this is an exercise on the leg press where you load alot of weight, two people assist and actually force the weight downwards as you resist, and the aim is to lower slowly and control the lowering of the weights (not to actually lift it - the two assistants actually do most of the work pushing the weights back up). This forces the muscle into an eccentric contraction which is the muscle actively lengthening. Also a good example of this is a basketball player, they hop before dunking the ball which 'pre-loads' the muscle into an eccentric contraction and allows greater height in the jump.

 

For a more technical explanation of this see here

http://www-neuromus.ucsd.edu/musintro/contractions.shtml

 

This means that your push arm is in eccentric contraction and the pull arm is concentric. Meaning your push arm is actually stronger in regards to force generation. If it's stronger in this position it would mean less fatigue, less fatigue means more endurance and as most moto sports are endurance events less fatigue is better...

 

Oh I might add (but its a little unrelated to the OP - anyone doing weight training - if you wish to bulk up quickly, especially your legs, the method I described above (referred to as a forced eccentric by trainers) is THE fastest way to bulk up very quickly. I would recommend though that you don't plan on doing much walking for the next few days after your forced eccentric session tho! it leaves you feeling pretty sore!)

---

Merged post follows:

Consecutive posts merged

Pulling would seem to allow for more of a "feel" for what's going on since it's restricted to fewer muscle groups.

 

Also I'm not really in agreement here, because basically you're using larger muscle groups to perform the push action - another cause of less fatigue as larger groups will work less and fatigue slower.

 

If I'm pulling thru the corner I can perform the action almost solely without engaging the shoulder, but the push action requires engaging the rotator-cuff and powerful deltoids and lats.

Edited May 5, 2010 by Double K

[Phi for All]

Also I'm not really in agreement here, because basically you're using larger muscle groups to perform the push action - another cause of less fatigue as larger groups will work less and fatigue slower.

 

If I'm pulling thru the corner I can perform the action almost solely without engaging the shoulder, but the push action requires engaging the rotator-cuff and powerful deltoids and lats.

I'm not sure I understand the correlation of larger muscle size with sensitivity to the driving/steering environment. While it's certainly not required to be intuitive, it doesn't make sense that larger muscles are better at sensing the small vibrations than the smaller muscles.

 

I think fingers and fingertips (used in pulling the wheel) are much better at feeling subtle movements than are the palms of the hands (used in pushing the wheel). Fatigue may come into play after a while but I'm not sure that physical strength is being questioned here so much as which muscles allow for more sensitivity and control while turning.

[Double K]

While it's certainly not required to be intuitive, it doesn't make sense that larger muscles are better at sensing the small vibrations than the smaller muscles.

 

I think fingers and fingertips (used in pulling the wheel) are much better at feeling subtle movements than are the palms of the hands (used in pushing the wheel). Fatigue may come into play after a while but I'm not sure that physical strength is being questioned here so much as which muscles allow for more sensitivity and control while turning.

 

Ok let me attempt address these points if I can.

 

I think firstly it's important to note that whilst the palm is used for pushing the rest of the hand still remains on the wheel. Also the technique described from the drive_tech website also suggests the thumbs are wrapped around the wheel. In essence, not just the palm is used in the push motion - granted it is the main point of contact but the tactile senses of the rest of the hand are undiminished.

 

The somatosensory system is a pretty complex organ, and actually athletes with something as simple as wearing lycra pants can improve performance through greater feedback to this system, it also can help to reduce injury. Also a larger muscle group covers larger surface area, and has more nerve endings, resulting in a greater area recieving bio-feedback for propriocetion...

 

"In the periphery, the somatosensory system detects various stimuli by sensory receptors, e.g. by mechanoreceptors for tactile sensation. The sensory information (touch, pain, temperature etc.,) is then conveyed to the central nervous system by afferent neurones. "

http://en.wikipedia.org/wiki/Tactition

 

If you take a look at the attached diagram, you can see the nerve receptors in the hand are equally spread throughout the palm, thumb, index and middle fingers and some of the ring finger.

 

I'm hoping this addresses the querry above relating to sensitivity.

 

As for the question of control, again I believe that the stronger and larger muscle group will retain control to a higher degree.

Also you could argue (although the differences would be nano-seconds) that the palm is closer to the brain therefore the stimuli has less distance to travel to be recieved and less distance to travel to return the response to the palm rather than the fingers.

Edited May 6, 2010 by Double K

[Double K]

Also, just trying to further clarify the question regarding larger muscle groups (especially when in eccentric contraction)

 

When it comes to proprioception larger muscle groups typically require more motor units to be recruited for activation - which means a greater level of feedback is being recieved than with a smaller muscle group. There have been many studies done to measure the different levels of motor neuron recruitment during different contractions and to be honest it's a pretty complex topic, but this may help to clarify for you.

 

"Motor unit activation patterns were studied during four different force levels of concentric and eccentric actions. Eight male subjects performed concentric and eccentric forearm flexions with the movement range from 100° to 60° in concentric and from 100° to 140° elbow angle in eccentric actions. The movements were started either from zero preactivation or with isometric preactivation of the force levels of 20, 40, 60 and 80% MVC. The subjects were then instructed to maintain the corresponding relative force levels during the dynamic actions. Intramuscular and surface EMG was recorded from biceps brachii muscle. Altogether 28 motoneuron pools were analyzed using the intramuscular spike-amplitude frequency (ISAF) analysis technique of Moritani et al. [1]. The mean spike amplitude was lower and the mean spike frequency higher in the isometric preactivation phase than in the consequent concentric and eccentric actions. When the movements started with isometric preactivation the mean spike amplitude increased significantly (P<0.001) up to 80% in isometric and concentric actions but in eccentric actions the increase continued only up to 60% (P<0.01). The mean spike frequency in isometric preactivation and in concentric action with preactivation was lower only at the 20% force level (P<0.01) as compared to the other force levels while in eccentric action with preactivation the increase between the force levels was significant (P<0.01) up to 60%. When the movement was started without preactivation the mean spike amplitude at 20% and at 40% force level was higher (P<0.01) in eccentric action than in concentric actions. It was concluded that the recruitment threshold may be lower in dynamic as compared to isometric actions. The recruitment of fast motor units may continue to higher force levels in isometric and in concentric as in eccentric actions which, on the other hand, seems to achieve the higher forces by increasing the firing rate of the active units. At the lower force levels mean spike amplitude was higher in eccentric than in concentric actions which might indicate selective activation of fast motor units. This was, however, the case only when the movements were started without isometric preactivation."

http://linkinghub.elsevier.com/retrieve/pii/S1050641102000639

[Astraist]

My knowledge in ergonomics is slim, but I do know that we prefer fingers over palms. The fact mentioned in Turnfast.com, which suggests gripping the wheel from the palm is wrong. Therefore, it would seem that pulling is indeed more sensitive.

 

With modern cars we are talking about light racks and power steering, I doubt how much power from stronger muscles we actually need. As racers, we do our best to grip the wheel is lightly as possible to recieve the most feedback, and whenever a pushing or shuffling motion is applied and the upper body is brought into use, I feel it causing me to apply a greater effort.

[Double K]

As racers, we do our best to grip the wheel is lightly as possible to recieve the most feedback.

 

If you're pushing with the palm you are still gripping with your hand and fingers and actually need to put no pressure on fingers at all therefore enabling you to grip the wheel less, the other hand is (pull hand) is used for stabilisation, but the push hand does the work. Both hands are still on the wheel and sensitivity is undiminished. If you use the pull hand to turn and generate the force the fingers and thumb must grip the wheel tighter as they are 'grasping' to make the turn, this grasp is not required in the push motion.