Bohi question

[jeremy]

Hello

 

This is something that I've been wondering about for a few weeks. I've seen different blades with different kasane , thinner about 4mm and thicker 6mm kasane with bohi,  does the depth of bohi vary with the different kasane? On my shinsakuto I've measured  there is only approx 1.1mm of metal between valleys either side when I checked with my vernier in the middle of the blade. This seems to be very thin , the sakikasane is about 5mm. Can anyone else give me any other measurements of blades of the thickness of either side of the valleys on their blades just for comparison sake? Thanks!!

Jeremy 

[mas4t0]

I don't have any examples for you, but it makes less of a difference than you might expect.

 

From a mechanical perspective, a bo-hi effectively creates an I-beam with quite significant flange-thickness. Even when the web-thickness is quite thin, a significant proportion of the original strength and stiffness are maintained.

 

The losses in strength are only particularly relevant on an off-angle cut.

 

This calculator will let you compare the second moment of area for an I-beam Vs a solid rectangle and the diagram will give an indication of all the relevant measurements.

[jeremy]

Thanks for your feedback and reply.  The thing I am concerned about is actually off-angled cuts, which is why 1.1mm seems kind of thin , and maybe that the bohi was cut too deeply ? 

[mas4t0]

Too deeply in what sense?

 

Are there shinae (ripples or wrinkles in the skin steel) due to bending in the past?

 

If not it's likely not a problem.

 

Are you using the blade for tameshigiri and concerned about it bending in use?

 

If not, it doesn't really matter unless it interferes with your aesthetic appreciation of the blade.

 

A deep hi could have been cut to remove a flaw from the blade; there's likely a reason if it is unusually deep.

 

You can use the calculator above to see how significantly the bo-hi affects the capacity of the blade to resist bending, but you'll need some more measurements.

 

That'll give you a quantitative understanding of the extent to which it's been weakened.

 

Nihonto without a bo-hi will easily bend on an off-angle cut and a bo-hi will invariably weaken it further.

[jeremy]

19 hours ago, mas4t0 said:

Too deeply in what sense?

 

Are there shinae (ripples or wrinkles in the skin steel) due to bending in the past?

 

If not it's likely not a problem.

 

Are you using the blade for tameshigiri and concerned about it bending in use?

 

If not, it doesn't really matter unless it interferes with your aesthetic appreciation of the blade.

 

A deep hi could have been cut to remove a flaw from the blade; there's likely a reason if it is unusually deep.

 

You can use the calculator above to see how significantly the bo-hi affects the capacity of the blade to resist bending, but you'll need some more measurements.

 

That'll give you a quantitative understanding of the extent to which it's been weakened.

 

Nihonto without a bo-hi will easily bend on an off-angle cut and a bo-hi will invariably weaken it further.

Hello again and thank you for replying . 

The blade in question is a shinsakuto which I had a bohi cut into it to lighten it . It was getting too heavy for me after many years of use so I sent it to Japan through an agent to get the bohi carved. It did lighten the blade by 170 grams,  but on a slightly off cut it did kink the blade slightly. Something that never happened before I had the bohi carved into it. I did get it straightened and no visible shinae are seen,  but I measured between the valleys of the bohi and it seemed fairly thin at 1.1mm. Which is why I wanted to compare it to other people's blades with bohi and see if this is the general thickness or if my bohi has been carved too deeply? The cut was only very very slightly off angle and It still bent.  Anyway , thanks for your response .

[mas4t0]

Hi Jeremy,

 

Thank you for clarifying. I was unsure if you were enquiring about an art sword or a shinken.

 

I'm sorry to hear that, but with that in mind it seems that you've proven experimentally that the blade has been perhaps compromised too much.

 

I don't have all the measurements needed to calculate it, but I would guess that the bo-hi described would weaken the blade by less than 20% along the horizonal axis, but perhaps more than 60% along the vertical axis.

 

I use a thin, modern steel hira-zukuri for tameshigiri. I've never had any issues with bending and the blade is very light.

 

Maybe something along the same lines would be a suitable option and this blade could be reserved for kata?

[jeremy]

7 hours ago, mas4t0 said:

Hi Jeremy,

 

Thank you for clarifying. I was unsure if you were enquiring about an art sword or a shinken.

 

I'm sorry to hear that, but with that in mind it seems that you've proven experimentally that the blade has been perhaps compromised too much.

 

I don't have all the measurements needed to calculate it, but I would guess that the bo-hi described would weaken the blade by less than 20% along the horizonal axis, but perhaps more than 60% along the vertical axis.

 

I use a thin, modern steel hira-zukuri for tameshigiri. I've never had any issues with bending and the blade is very light.

 

Maybe something along the same lines would be a suitable option and this blade could be reserved for kata?

Yeah, I think I'll be sticking to single mat rolls to cut , I didn't have any issues with those targets,  and kata of course.  The weight and balance is perfect for kata now

[Alex A]

On 1/21/2022 at 2:01 AM, jeremy said:

Hello

 

 does the depth of bohi vary with the different kasane? 

 

 

Look at old over polished blades where all that is left are very shallow traces of the original horimono.

 

When horimono is added a later date (atobori) there needs to be great care about the depth due to core steel. Openings in Bo-hi are common in old blades. Care has to be taken with even polishing Bo-hi etc, hence why you may even come across staining that has not been polished out, experienced polishers maybe thinking less is more.

[jeremy]

On 1/23/2022 at 9:30 PM, Alex A said:

 

 

Look at old over polished blades where all that is left are very shallow traces of the original horimono.

 

When horimono is added a later date (atobori) there needs to be great care about the depth due to core steel. Openings in Bo-hi are common in old blades. Care has to be taken with even polishing Bo-hi etc, hence why you may even come across staining that has not been polished out, experienced polishers maybe thinking less is more.

Thanks for your reply.  Sorry , what I meant by depth of bohi was on newly made and newly carved bohi, is there a standard depth or is it a case by case basis taking kasane into consideration? I'm guessing it would be the latter case but I'm not sure . It's just that when measured with a vernier  the metal between valleys either side of the bohi it's only 1.1mm thick on my blade, and wanted to compared to other people's newly made bohi and see how mine compares. 

[mas4t0]

The craftsman carving the bo-hi is (presumably) not an engineer, so there's no way he'd be accurately taking account of the engineering mechanics.

 

When you cut with the blade, you're exerting a bending moment on the blade. The stiffer the blade is, the less it'll flex, and the less it flexes, the more likely you are to remain in the elastic region and not plastically deform (permeantly bend) the blade.

 

Had you consulted an engineer ahead of time you could have optimised the depth and width to remove the necessary amount of weight or change the dynamics of the blade as required, with minimal y-axis loss of strength and stiffness.

 

A deeper bohi will make a louder sound during Iaido practice. The hi could have been wider but cut more shallow or otherwise cut differently to better optimise for your needs.

 

It may have been that through engineering analysis it would have been determined that the blade could not be lightened to your requirements without compromising it to too great of an extent.

 

This kind of analysis is not standard when carving a bo-hi and would be prone to inaccuracy due to the metal not being homogenous and the internal lamination structure of the blade along with the specifics of the heat treat and metallurgy being unknown.

 

With an iron core, the loss of overall strength and stiffness when removing the steel is greater than you would expect for a homogenous piece of metal, as the steel contributes disproportionally to the overall strength and stiffness of the blade.

 

If you cut a bo-hi on a blade with an iron core, you'll have lost much more strength than the loss of web-thickness would lead us to expect (on a homogenous blade). I assumed that the blade did not have an iron core, as you would presumably have reached it at this depth of carving.

 

All the same, analysing it geometrically would help understand the likely effects of altering the geometry (by carving a bohi).

 

I would guess that the craftsman carving the bohi carved it at a standard width and the depth was determined by the weight of metal to be removed.

 

It sounds like you now have an ideal Iaito and will be well served by a separate shinken.

 

It's not particularly uncommon for horimono to pierce all the way though the blade as part of the design. I certainly wouldn't recommend this on anything other than an art sword.

 

The person who carved it will be able to tell you more about the decisions made than we ever will.

 

How did the carving come about, what was the brief and which questions were asked at the time?

 

What purpose would it serve to know the depth of other bohi?

 

Even for a blade used in a cutting test, which had a bohi at the time (likely unverifiable), you'd need to know the complete geometry of the blade (at the time), the metallurgy and the internal lamination structure. Even this wouldn't be particularly helpful as you don't know if it was a fluke or a case of perfect tenouchi reducing the need for high y-axis strength.

[jeremy]

10 hours ago, mas4t0 said:

The craftsman carving the bo-hi is (presumably) not an engineer, so there's no way he'd be accurately taking account of the engineering mechanics.

 

When you cut with the blade, you're exerting a bending moment on the blade. The stiffer the blade is, the less it'll flex, and the less it flexes, the more likely you are to remain in the elastic region and not plastically deform (permeantly bend) the blade.

 

Had you consulted an engineer ahead of time you could have optimised the depth and width to remove the necessary amount of weight or change the dynamics of the blade as required, with minimal y-axis loss of strength and stiffness.

 

A deeper bohi will make a louder sound during Iaido practice. The hi could have been wider but cut more shallow or otherwise cut differently to better optimise for your needs.

 

It may have been that through engineering analysis it would have been determined that the blade could not be lightened to your requirements without compromising it to too great of an extent.

 

This kind of analysis is not standard when carving a bo-hi and would be prone to inaccuracy due to the metal not being homogenous and the internal lamination structure of the blade along with the specifics of the heat treat and metallurgy being unknown.

 

With an iron core, the loss of overall strength and stiffness when removing the steel is greater than you would expect for a homogenous piece of metal, as the steel contributes disproportionally to the overall strength and stiffness of the blade.

 

If you cut a bo-hi on a blade with an iron core, you'll have lost much more strength than the loss of web-thickness would lead us to expect (on a homogenous blade). I assumed that the blade did not have an iron core, as you would presumably have reached it at this depth of carving.

 

All the same, analysing it geometrically would help understand the likely effects of altering the geometry (by carving a bohi).

 

I would guess that the craftsman carving the bohi carved it at a standard width and the depth was determined by the weight of metal to be removed.

 

It sounds like you now have an ideal Iaito and will be well served by a separate shinken.

 

It's not particularly uncommon for horimono to pierce all the way though the blade as part of the design. I certainly wouldn't recommend this on anything other than an art sword.

 

The person who carved it will be able to tell you more about the decisions made than we ever will.

 

How did the carving come about, what was the brief and which questions were asked at the time?

 

What purpose would it serve to know the depth of other bohi?

 

Even for a blade used in a cutting test, which had a bohi at the time (likely unverifiable), you'd need to know the complete geometry of the blade (at the time), the metallurgy and the internal lamination structure. Even this wouldn't be particularly helpful as you don't know if it was a fluke or a case of perfect tenouchi reducing the need for high y-axis strength.

Thank you for that in depth response! So many things to consider , another factor would be the length of the blade,  the longer the blade (all things being equal) would be easier to bend than a shorter blade of the same geometry.  My blade is pretty long compared to many blades being at 31.5 inch nagasa, making it easier to bend I guess than shorter blades. Anyway it's been a fun discussion so thank you to you both 

[mas4t0]

On 1/26/2022 at 12:12 AM, jeremy said:

Thank you for that in depth response! So many things to consider , another factor would be the length of the blade,  the longer the blade (all things being equal) would be easier to bend than a shorter blade of the same geometry.  My blade is pretty long compared to many blades being at 31.5 inch nagasa, making it easier to bend I guess than shorter blades. Anyway it's been a fun discussion so thank you to you both 

 

Exactly Jeremy.

 

There's also the issue of the form, weight and strength of the user, and the nature of the cutting medium; which will determine the magnitude of the forces exerted and the proportion of those forces acting along the y-axis.

 

Lots of variables, and if we were doing this properly, we'd want quite a large safety factor to help account for the uncertainty.

 

I realise that in all these posts I never answered your initial question, but hopefully some clarity has been provided all the same.

[jeremy]

14 hours ago, mas4t0 said:

 

Exactly Jeremy.

 

There's also the issue of the form, weight and strength of the user, and the nature of the cutting medium; which will determine the magnitude of the forces exerted and the proportion of those forces acting along the y-axis.

 

Lots of variables, and if we were doing this properly, we'd want quite a large safety factor to help account for the uncertainty.

 

I realise that in all these posts I never answered your initial question, but hopefully some clarity has been provided all the same.

Yeah! It's been very informative and enlightening. Thanks again 

[Katsujinken]

This is a great thread, and an issue of ongoing concern and bewilderment for those of us who practice a sword art. I struggled with this decision myself awhile back and conducted similar research. Mark's responses above are fantastic.

 

As he said, adding a bohi will sacrifice some flexural rigidity in exchange for a proportionally outsized gain in agility via a reduction in weight and changes in balance. About 40% of nihonto katana have bohi, and I haven’t been able to detect much of a pattern. I’ve seen masterpiece blades with kirikomi from fighting with bohi and just as many without across all periods after Heian. I think the idea with bohi is to use it to make a heavier sword as light as an equivalent sword without bohi – so you essentially end up with the same mass but greater maneuverability. It improves the strength to weight ratio, basically. 

 

As Mark also said, a tamehagane sword will bend on any cut of sufficient power in which the hasuji is off. My shinsakuto, with very traditional geometry, cuts like a lightsaber when my hasuji is good and I cut with proper technique. If one or both of those elements are off it's a very different story, which is quite a different experience from the ultra-thin optimized "cutters" that are in vogue these days.

 

Re: depth of bohi, the bohi on my shinsakuto, a sword made by Ogawa Kanekuni in 1984, the bohi is quite shallow (and therefore tachikaze is generally low in volume, although an experienced practitioner can easily judge quality of tachikaze regardless of volume). My understanding is that shallow bohi on shinsakuto (relative to modern "shinken" not made with traditional materials or methods) are the norm. Basically, anecdotally speaking, bohi on real shinsakuto are shallower than on mass market swords intended for use in "iai".

 

I realize I haven't added much substance to Mark's already excellent contributions, but hope this is helpful in some small way.

[jeremy]

1 hour ago, Katsujinken said:

This is a great thread, and an issue of ongoing concern and bewilderment for those of us who practice a sword art. I struggled with this decision myself awhile back and conducted similar research. Mark's responses above are fantastic.

 

As he said, adding a bohi will sacrifice some flexural rigidity in exchange for a proportionally outsized gain in agility via a reduction in weight and changes in balance. About 40% of nihonto katana have bohi, and I haven’t been able to detect much of a pattern. I’ve seen masterpiece blades with kirikomi from fighting with bohi and just as many without across all periods after Heian. I think the idea with bohi is to use it to make a heavier sword as light as an equivalent sword without bohi – so you essentially end up with the same mass but greater maneuverability. It improves the strength to weight ratio, basically. 

 

As Mark also said, a tamehagane sword will bend on any cut of sufficient power in which the hasuji is off. My shinsakuto, with very traditional geometry, cuts like a lightsaber when my hasuji is good and I cut with proper technique. If one or both of those elements are off it's a very different story, which is quite a different experience from the ultra-thin optimized "cutters" that are in vogue these days.

 

Re: depth of bohi, the bohi on my shinsakuto, a sword made by Ogawa Kanekuni in 1984, the bohi is quite shallow (and therefore tachikaze is generally low in volume, although an experienced practitioner can easily judge quality of tachikaze regardless of volume). My understanding is that shallow bohi on shinsakuto (relative to modern "shinken" not made with traditional materials or methods) are the norm. Basically, anecdotally speaking, bohi on real shinsakuto are shallower than on mass market swords intended for use in "iai".

 

I realize I haven't added much substance to Mark's already excellent contributions, but hope this is helpful in some small way.

Thanks for the reply. I'm not sure if the bohi on mine would be considered shallow or deep ? If its got 1.1mm between the valleys of the bohi, would that be standard or deeply carved? How long is your shinsakuto and what's the sakikasane? 

[Katsujinken]

1mm blade thickness at the deepest point of the bohi seems like a deep bohi to me given a 5mm sakikasane. 
 

My sword has a 70cm nagasa and also has a 5mm sakikasane. If memory serves my bohi is only about .5-1mm deep (on each side, of course). 
 

But again these are all interrelated variables and craftsmen make choices for different reasons (theoretically balancing all the variables discussed above against the intended use for the sword). 

[Ken-Hawaii]

Jeremy, there's no way to make a general statement about the appropriate bo-hi, as Mark pointed out. I've never needed to have a bo-hi cut, but I'd refer to a similar statics/dynamics formula. And, as Michael stated, proper hasuji is the real key to cutting successfully.

 

Tachikaze is a good way to tell if your hasuji is right. If you can't hear it, even with a blade with no bo-hi, I suggest that you NOT try to cut anything, even single tatami omote!

[mas4t0]

As Ken alluded to, I should clarify that the information I've given above is oversimplified and is really only illustrative.

 

Every dimension of the blade will have an affect on it's structural properties.

 

This will give additional outline for anyone curious.

 

If I needed to cut a bo-hi, I'd model the blade in CAD/ CAE software and test it computationally.

 

As Michael expressed above, the ideal would be to carry out such modelling before the blade is made, and include the bohi as an integral part of the design. In that case, a bohi could be incorporated to better optimise the properties of the blade at a given weight.

 

Ken also mentioned dynamics, the importance of which can't be overstated. This might also be of interest, regarding the dynamics of a blade.

 

As an aside I'd also suggest that, if at all possible, a practitioner would generally be better served to incorporate a proper strength program into their training than to have a bo-hi carved.

 

For anyone who isn't strength trained, you'll likely be able to increase your overall strength by 50% in 6 months with a good training programme and age need not prevent you.

 

At that, your sword will feel the same in your hands as if you'd reduced its weight by 1/3, and you'll likely find that your form, hasuji and overall coordination are improved.

[Katsujinken]

The only thing I would add to Mark’s excellent post is that “strength” for the sword is not the same as strength in the traditional western sense. 
 

You need to be careful not to bulk up your shoulders and chest too much. The power to wield and support the sword should come from the legs and through the tanden once a base level of upper body conditioning has been achieved. 
 

Hida Harumichi said the power of the kissaki is in the base of the big toe. Musashi had a similar point of view on the role of the legs in swordsmanship. Ultimately internal practices are the way to longevity with the sword. 

[mas4t0]

  

2 hours ago, Katsujinken said:

The only thing I would add to Mark’s excellent post is that “strength” for the sword is not the same as strength in the traditional western sense. 
 

You need to be careful not to bulk up your shoulders and chest too much. The power to wield and support the sword should come from the legs and through the tanden once a base level of upper body conditioning has been achieved. 
 

Hida Harumichi said the power of the kissaki is in the base of the big toe. Musashi had a similar point of view on the role of the legs in swordsmanship. Ultimately internal practices are the way to longevity with the sword. 

 

 

I respectfully disagree, by which I mean that I don't really disagree, but feel the need to further clarify my position.

 

Bio-mechanically speaking, the key to proper technique, in most cases, is kinetic linking; facilitated by adequate flexibility, mobility, co-ordination and strength.

 

For clarity, the kinetic link principle is:

 

The principle that body segments generate high end-point velocity by accelerating and decelerating adjacent links, using internal and external muscle torques applied to the body segments in a sequential manner from proximal to distal, from massive to least massive, and from most fixed to most free. The kinetic link principle is applied when different body segments rotate during throwing and kicking. These actions have been likened to the motion of a bullwhip. If segmental rotations are free to occur at the distal end, the body's base-segments in contact with the ground act like the handle of a bull-whip. Just as the tip of the bullwhip can be made to travel at supersonic speed, the small distal segments of the hand and foot can be made to travel very fast by the sequential acceleration and deceleration of the body segments.

 

Poor kinetic linking (aka poor technique) can result from a lack of adequate:

• muscular flexibility
• joint mobility
• muscular strength
• co-ordination

 

Assuming that the technique has been learned and the athlete is adequately strong, flexible, mobile and coordinated to properly perform it; the reason why technique falters is generally that one (or more) of the muscles involved in the kinetic linking is too fatigued to play its part. In many cases (across countless sports), force is supposed to be generated primarily in the large muscles of the posterior chain (as you describe). Unfortunately the kinetic linking through the core, shoulders and arms is poor in the majority of people due to muscular weakness or a lack of mobility, flexibility or co-ordination; and a lot of the energy is wasted along the way (with an accompanying injury risk). Additionally, many people are relatively immobile and even the muscles of the posterior chain are weak to the point of generating very little force to begin with. Low strength also goes along with poor flexibility, as the muscles tighten and reduce ROM in order to prevent injury.

 

Muscles will fatigue more rapidly with a heavier blade. If the technique has been perfected using a light weight aluminium iaito, the added weight of a heavier shinken should not affect the technique beyond a short adjustment period. If the technique remains adversely affected or the blade is otherwise fatiguing or uncomfortable to use, there is a lack of adequate strength (to properly handle the shinken) and the iaito had reduced the strength requirement (due to its lighter weight).

 

When the problem is the weight of something, additional physical strength is almost invariably the lion's share of the solution, and strength gains carry over to almost all other areas of life. In this case the opposite choice was taken; lightening the blade. As the issue at hand was the weight of the blade, it didn't seem necessary to address the other factors contributing to technique, but they are of course all of great importance and we can't neglect any of them.

 

Assuming technique deteriorates during practice, this lack of endurance is really a symptom of a lack of strength. The muscle fibres being employed are fast-twitch, not slow-twitch, so it comes down to rep ranges at different percentages of your one rep max (the maximum amount you can lift for a single repetition). To illustrate this point; you can lift you 1RM for only a single repetition, but you would generally be able to lift 65% of that amount for 15 repetitions! With a greater 1RM, any given weight would represent a smaller proportion of it and you would be able to manoeuvre it with much less fatigue than if it represented a greater proportion.

 

Barbells and compound movements work best for strength training and can be progressively increased in weight for years with consistent strength gains. Many other forms of training will stop giving any meaningful strength gains after the first few months of transitioning from inactivity to some modicum of activity. Not only do heavy weights lifted for maximal ROM bring maximal strength gains, but they also work every muscle involved and self-correct any weakness in the kinetic chain. If any particular muscle is limiting you, you'll not be able to progress until that muscle group has become adequately strong to facilitate progression.

 

In addition to that, the neuromuscular junction also undergoes a training effect, thickening the insulation of the myelin sheath around your nerves, increasing nerve conductivity; thereby improving your muscular control (coordination). This training effect is not seen to anywhere near the same extent in any type of training not involving heavy lifting.

 

As I understand it, your concern was with the lack of mobility and flexibility that can come along with significant muscle gain. Stretching and mobility work will prevent this, as will sticking to compound movements and focusing on strength instead of size as the training goal. Compound barbell movements also train the stabilisation muscles (vital for Iaido) which can be entirely neglected when using machines or isolation exercises (as are popular among bodybuilders).

[Katsujinken]

Yes I do think we agree overall! 

 

I would only add/clarify that upper body strength alone, without proper development of the legs and tanden, is insufficient and will 1) fail as the body ages, and 2) lead to poor technique overall. 
 

Western athletic science is an important/accretive component of holistic kenjutsu training, but one must also focus on specifically developing the role of the tanden in sword work, specifically connecting the spine and arms to power from the legs. The role

of the upper body is the transmission of power that is generated below. 
 

This isn’t highfalutin martial arts fantasy, it just hasn’t been merchandised well and frankly is offered by very few qualified instructors/dojos. 

 

Simply “swinging” the sword is not correct, nor is it enough. 

[mas4t0]

59 minutes ago, Katsujinken said:

Yes I do think we agree overall! 

 

I would only add/clarify that upper body strength alone, without proper development of the legs and tanden, is insufficient and will 1) fail as the body ages, and 2) lead to poor technique overall. 
 

Western athletic science is an important/accretive component of holistic kenjutsu training, but one must also focus on specifically developing the role of the tanden in sword work, specifically connecting the spine and arms to power from the legs. The role

of the upper body is the transmission of power that is generated below. 
 

This isn’t highfalutin martial arts fantasy, it just hasn’t been merchandised well and frankly is offered by very few qualified instructors/dojos. 

 

Simply “swinging” the sword is not correct, nor is it enough. 

 

As far as I'm concerned, you perfectly described kinetic linking, so we're on the same page exactly.

 

I hadn't thought to clarify that point, so thank you for doing so! Only an idiot would train only the upper body, and all the key strength sports (Powerlifting, Olympic Lifting and Strongman) are relatively lower body dominant. Someone with an underdeveloped lower body will perform very poorly in almost any athletic pursuit and especially in strength sports, they'll also place very poorly in any bodybuilding competition.

 

A guy who goes to the gym only to bench press and bicep curl is most definitely not a strength athlete!

 

The program I'd recommend for a newcomer to strength training would be quite lower body dominant, something along the lines of:

 

Workout A

3 x 5 Squats

3 x 5 Overhead Presses

1 x 5 Deadlifts

 

Workout B

3 x 5 Squats

3 x 5 Bench Presses

1 x 5 Deadlifts

 

Alternating these workouts three days a week, for example on Monday, Wednesday, and Friday, with the listed sets being only work sets after a thorough warm-up.

 

I would also argue that Olympic Lifting would be a perfect accompaniment to JSA (at least in my experience they go very well together), as the kinetic linking requirements are very similar and Olympic Lifting will train the nervous system much more efficiently.

 

 

I'm sure you can see how this would carry over to JSA (heavier weights at the end of the video).

 

I would also add that training with an extra heavy sword or bokken is not a good way to develop strength. Strength is strength (in a given muscle) and you want to train in the safest, most effective and most efficient way. There's a strong desire to train in a way that resembles the sport you play, but this is the wrong way to approach strength training and often loads and stresses the joints and ligaments in damaging ways.

[Gakusee]

So, Mark, you don’t think weight lifting, deadlifts etc also stress the joints and the body? I would train with a heavy sword any day rather than compress my body with these weights. 
Also, you talk about kinetic energy and linking. Surely, you are aware that a large body mass such as the one of a bodybuilder, weightlifter, heavy wrestler also slows you down to an significant extent. In the martial arts I trained (not JSA but in my system of martial arts we also trained with blades - thin swords, large swords, butterfly sword etc), superior speed and velocity were much more important than relative strength. In fact, smaller guys were faster and more dangerous than these big blokes above. Surely, overall body training was important and done but squatting, presses and dips were sufficient. 

Apologies for digressing from the bohi topic. 

[mas4t0]

4 hours ago, Gakusee said:

So, Mark, you don’t think weight lifting, deadlifts etc also stress the joints and the body? I would train with a heavy sword any day rather than compress my body with these weights. 
Also, you talk about kinetic energy and linking. Surely, you are aware that a large body mass such as the one of a bodybuilder, weightlifter, heavy wrestler also slows you down to an significant extent. In the martial arts I trained (not JSA but in my system of martial arts we also trained with blades - thin swords, large swords, butterfly sword etc), superior speed and velocity were much more important than relative strength. In fact, smaller guys were faster and more dangerous than these big blokes above. Surely, overall body training was important and done but squatting, presses and dips were sufficient. 

Apologies for digressing from the bohi topic. 

 

This is difficult to approach succinctly, but I'll give it a go. I'll try to keep it brief, but I can reference everything I'm saying, so let me know anything you're dubious of.

 

The nature of the loading and the form of the stress is what matters.

 

Structurally, the human body is similar to a suspension bridge. The bones are like concrete, strong under compression but weak under tension and torsion. The ligaments and tendons are akin to cables, strong under tension, but offering no resistance to compression. The muscles can be considered as motors attached to the cables (tendons) via winches.

 

Strength training is how we increase the strength of these components, along with the torque and power of the motor. Not only does the power of the motor (muscles) increase through strength training, but also the tensile strength of the cables (ligaments and tendons) and the compressive strength of the concrete (bones).

 

Clearly if this training is done incorrectly, we can cause damage.

 

If you're genuinely curious about any of this, we can take it to PM. What I'll be saying (other than personal anecdotes) are supported by well established facts and are not my personal opinions.

 

Injuries generally happen in competitive strength athletes when they're working right on the edge of their capabilities (often the edge of what's humanly possible), so it's hit and miss as to whether they have enough muscular strength to achieve the lift. Under those conditions, technique can break down leading to loading the joints in a damaging way.

 

In practice, consider the knee, it's a complex hinge joint. It's imperative for health and longevity that the knee not be significantly stressed laterally or twisted. The joint doesn't work that way and you're reliant on the ligaments to provide support. There's no muscular support to ligaments, and they can be stretched or torn and the cartilage damaged; the bone can also be broken due to the torsion applied.

 

The stronger the person, the higher the strength of their bones, ligaments, tendons, etc. As detailed in the explanation above regarding a sword; with greater strength (for a given material) comes a greater ability to absorb energy and resist stress (with minimal strain). If a structure is twice as strong as average, it can absorb twice as much energy without being plastically deformed (bent) and twice as much without being fractured.

 

This strength increase is with regard to all forms of stress, so while a bone is weak in torsion, if you're trained and I'm not, your bones will also be stronger in torsion than mine.

 

Clearly a heavier person will exert larger forces on their bones and soft tissues, performing the same task, but strength is not about adding body-weight. Strength training is about maximising strength at a given body-weight (hence weight classes). I'm not suggesting that people should aim to become super heavyweights.

 

There's a major difference between adding strength and adding size, and there's a major difference between training and competing.

 

I took up strength training seriously about a decade ago. At the time I was regularly getting injured. I haven't been seriously injured since other than an unfortunate incident involving something sharp. I firmly believe that I would have died at that time if not for being in such good shape, and the doctors seemed to share that view.

 

In addition to combat sports, I've long competed in triathlon. Like any endurance sport, triathlon is catabolic; so some anabolic element is needed just to counteract the muscle wasting effects.

 

When I started strength training I was around 70kg and my major lifts were:

 

Bench Press: 45kg

Squat: 60kg

Deadlift: 70kg

Overhead Press 30kg

 

Around a year ago I was at basically the same bodyweight, but my 1RMs were up to:

 

Bench Press: 130kg

Squat: 170kg

Deadlift: 190kg

Overhead Press 80kg

 

Muscularly, increased strength is increased force production. Lifting weights is the best way to train that.

 

Force = Mass * Acceleration, so for a given mass (body-weight) you'll be faster and more agile with greater force production (greater muscular strength).

 

The idea that being smaller is an advantage (in anything other than endurance sports) is not widely held.

 

Proper technique with natural movement patterns are vital. With large forces, incorrect loading can cause a lot of damage.

[mas4t0]

I realised I missed a significant portion.

 

Why would you think a Weightlifter would have poor kinetic linking?

 

As shown in the video, you need perfect kinetic linking to pick up >2x your body-weight and throw it over your head.

 

Every fibre in the body needs to be perfectly choreographed, from the toes through to the fingers.

 

A heavy sword will not increase strength in an ongoing way, and it'll load your joints and strain your tendons in undesirable ways.

[Gakusee]

Mark

Good points. Agree with most of them. But greater mass will lead to lower acceleration and hence lower speed (from the two formulae below). I was trying to make the simple point that often in combat you might not need great force or great strength (unless wrestling or weightlifting) but greater speed. A swifter strike might overcome a much stronger but slower opponent.

 

Logically and also mathematically from the equations below solving for speed or acceleration given a fixed force or fixed kinetic energy, speed (or acceleration) is lower if mass is higher:

 

1) kinetic energy = 0.5 × mass × speed ²

2) Force = Mass * Acceleration

 

Regardless, I agree that if you keep the mass fixed (ie do not become too big or heavy) and improve strength, while also working on flexibility, then you improve performance. 

 

The other thing I used to work on was endurance or stamina. So, not absolute strength (heavier weights and increasing weights progressively) while of course any training improves strength to some degree, but being able to deploy consistently the same performance over longer time (more repetitions but perhaps with lighter weight). Now, of course, due to family and work commitments this has gone out of the window and I barely keep fit…. 

[mas4t0]

11 hours ago, Gakusee said:

Mark

Good points. Agree with most of them. But greater mass will lead to lower acceleration and hence lower speed (from the two formulae below). I was trying to make the simple point that often in combat you might not need great force or great strength (unless wrestling or weightlifting) but greater speed. A swifter strike might overcome a much stronger but slower opponent.

 

Logically and also mathematically from the equations below solving for speed or acceleration given a fixed force or fixed kinetic energy, speed (or acceleration) is lower if mass is higher:

 

1) kinetic energy = 0.5 × mass × speed ²

2) Force = Mass * Acceleration

 

Regardless, I agree that if you keep the mass fixed (ie do not become too big or heavy) and improve strength, while also working on flexibility, then you improve performance. 

 

The other thing I used to work on was endurance or stamina. So, not absolute strength (heavier weights and increasing weights progressively) while of course any training improves strength to some degree, but being able to deploy consistently the same performance over longer time (more repetitions but perhaps with lighter weight). Now, of course, due to family and work commitments this has gone out of the window and I barely keep fit…. 

 

Michael,

 

That is absolutely correct for anyone who gains weight without any corresponding strength gains. It's not the case though if we're doing any kind of strength training.

 

Here's a link to strength standards for the major lifts.

 

https://strengthlevel.com/strength-standards/male/kg

 

None of the variables remain constant if you increase body weight and do so while engaged in proper strength training. The argument is only sound in the absence of strength training, so its really an argument for the necessity of strength training and not an argument against it.

 

A heavier athlete (same training but different weight class) will generate more kinetic energy and more force.

 

The speed difference isn't all that great, and it's important to remember that the stronger person is structurally stronger (more durable, less easily hurt or injured) in addition to greater kinetic energy output and force generation.

 

I felt the same way too and enjoyed watching videos of Kaoklai and other small men (mostly Thais) who fought successfully against men far heavier than themselves.

 

But when I started seriously training, I spent time sparring with natural heavyweights and came to realise that the fights Kaoklai won showed an immense skill disparity. He was fighting journeyman level opponents and performed very poorly when he fought a true contender (Yoshihiro Sato) at his proper weight class.

 

 

 

Other than in a highly ritualised form of combat, such as Taekwondo, Kendo or Olympic fencing, I don't think speed is anywhere near as important as we sometimes think.

 

There are many other vitally important factors.

 

This is well illustrated in both; Julio César Chávez vs. Meldrick Taylor and Roberto Durán vs. Sugar Ray Leonard I.

 

Even fighting with knives, the smaller guy might get the first hit, but then the bigger, stronger guy grabs him and mutilates him.

 

If you're close enough to hit, you're basically close enough to grab, and if he's big enough to gladly take a shot from you in order to get hold of you...

 

I think the best way to think about it is that a strength and size advantage grants a large error margin.

 

Mike Tyson was very fast, but he was a natural heavyweight. Roy Jones Jr was faster, but in order to compete at heavyweight needed to add a huge amount of mass. He knew he couldn't hold his own in the heavyweight division when giving up too much weight.

 

 

 

Roy Jones Jr was an exceptional fighter, but could only take the heavyweight belt due to a major lack of talent in the division at the time. In order to do so he had to gain a lot of weight.

 

Similarly, several years ago, Alistair Overeem entered the K1 tournament, as a wildcard. An MMA fighter with very little kickboxing experience. Unexpectedly, he was significantly stronger than the other men, and manhandled the best kickboxers in the world with ease. It wasn't until others gained significant size and strength that they were able to hold their own.

 

 

I'm not suggesting that Strongmen make the best fighters (they don't) just that strength and size are a huge advantage, all else being equal.

 

In any combat sport its very rare for someone who fought (as a fully grown adult) in a weight class below light-heavy to take the heavyweight title.

 

I've sparred with heavyweights twice my weight. It's nerve wracking. There's an ever present awareness that one strike landed with intent could easily leave you in the hospital, in addition to being unable to do anything at all in the clinch.

 

You know you're outmatched when you perfectly defend an upwards angled hook (thrown with no ill intent during sparring), and are lifted into the air by it like something out of a comic book. Which has happened to me on several occasions.

 

There's also the lovely experience of throwing a teep at full force on a big heavyweight's chest and instead of him being pushed back, he pushes out his chest and you lose your balance and fall backwards. Someone of a similar weight would be pushed over, but a big enough weight disparity will reverse the outcome and he'll barely even feel the kick.

 

A middleweight fighting a natural heavyweight is like an average adult man fighting his 12 year old son.

 

At a certain point, you might as well be fighting a dehorned rhino.

 

A stronger man can more deftly weild a larger, heavier blade and manoeuvre it more easily and with less fatigue. He doesn't need to incorporate his whole body into everything he's doing.

 

What you're doing through kinetic linking is using the joints of the body as a series of simple machines. A hook thrown to the jaw should have relatively little mass behind it, but travel at a very high velocity, in order to whip the head around. A hook thrown to the body on the other hand needs more mass behind it, so that it drills deeper into the abdomen and will therefore travel at a lower velocity.

 

How you choreograph the kinetic linking determines how you use the force and K.E at your disposal; a bigger/ stronger man has more of each to play with.

 

 

Maybe this will be of interest too, to illustrate how strength scales with weight with proper training. This is the Chinese national Olympic Weightlifting team.

 

 

The limiting factor is actually neurological, there's a limit to the ability of the nervous system to activate muscle.

 

This is why lifts as a multiple of bodyweight reduce as you move up through the weight classes, and at super heavyweight, you'll often see people add more mass to their bodies (in the form of muscle) from year to year than they add to their lifts.

 

A heavier athlete though will have a lower VO2 max and therefore poorer cardiovascular endurance. The best way is to tire out the big guy, but the hard part is surviving that long. Even then, big, strong guys are very, very durable.

 

When I had a real world encounter with a dangerous big guy, I didn't have the chance to tire him out as I'd always naively expected I'd be able to.

 

If you have the space for a home gym, 30 minutes each day is enough time to allow for decent strength and cardio training.

[jeremy]

Wow! This has become super interesting! The whole reason I wanted to lower the weight of my sword with a bohi is because first of all it had sentimental value to me , this sword was acquired through my sensei in Japan from the swordsmith while I was there in 2009, my first trip to Japan ever , and secondly my elbow tendonosis/tendonitis got so bad I needed to start using a lighter sword.  I have tendonitis all over my arms. Left arm tennis elbow , right arm golfers and distal biceps tendonitis , been training in JSA for over ten years and being 40 years old doesn't help , as well as training empty hand since 2007. I had to give up weights years ago because of all the tendonitis/tendonosis problems too 😫

[mas4t0]

1 hour ago, jeremy said:

Wow! This has become super interesting! The whole reason I wanted to lower the weight of my sword with a bohi is because first of all it had sentimental value to me , this sword was acquired through my sensei in Japan from the swordsmith while I was there in 2009, my first trip to Japan ever , and secondly my elbow tendonosis/tendonitis got so bad I needed to start using a lighter sword.  I have tendonitis all over my arms. Left arm tennis elbow , right arm golfers and distal biceps tendonitis , been training in JSA for over ten years and being 40 years old doesn't help , as well as training empty hand since 2007. I had to give up weights years ago because of all the tendonitis/tendonosis problems too 😫

 

Have you been under the care of a physiotherapist and sports doctor?

 

Depending on your strength level, a flexbar might be all you need to fix tennis elbow. If that's not enough, a loadable leverage bar/ Thor's hammer would be the next step.

 

This is exactly why higher volume and higher rep ranges are not recommended. You get negligible strength gains which plateau very early and repetitive strain problems!

 

Rest (properly, no Iaido) and then add in low volume compound barbell exercises like what's laid out above. Its the mostly likely thing to fix your tendonitis.

 

Read Starting Strength ASAP and visit a physio and sports doctor, you'll not regret it.

 

Strength training is not about exhausting your body, causing pain or wear and tear. It's about signalling the need for more strength so that your body rebuilds stronger.

 

Ideally you want to signal as efficiently and painlessly as possible, which is what proper strength training methodology is all about.

[Stephen]

Id take up swimming to.