Need For Passive Flexibility?

[Chris Hobbs]

Reading through the forums I haven't found a good answer to the following question so I thought I would start  a new topic. Basically, why even bother developing passive flexibility, why not simply put the time into active flexibility training?

 

What would be the disadvantage to solely working active flexibility? It seems like that is where we want to end up anyway. Acquiring a range we don't have strength within doesn't seem conducive to GST so why spend any time on passive flexibility?

 

- Chris

[Joshua Slocum]

Active flexibility is limited by passive flexibility. And passive flexibility decreases the risk of injury from pulling/overstretching a muscle. 

[Joshua Naterman]

1) You can't build strength and control in a range of motion you cannot access.

 

2) You build passive ROM faster than you build active ROM.

 

 

 

Given these two statements, which I believe are fairly irrefutably true, why would you not work on both?

[Chris Hobbs]

Active flexibility is limited by passive flexibility. And passive flexibility decreases the risk of injury from pulling/overstretching a muscle. 

 

Wouldn't passive flexibility set one up for further injury due to the tissue easily making it into a ROM that it has no strength/stability within?

 

1) You can't build strength and control in a range of motion you cannot access.

 

2) You build passive ROM faster than you build active ROM.

 

 

 

Given these two statements, which I believe are fairly irrefutably true, why would you not work on both?

 

If one is working a straddle split for example they will be actively pulling their legs apart - and let's use bands for the load. Over time wouldn't the available ROM increase because the strength within their current ROM had increased enough to allow access to that new range?

 

- Chris

[Joshua Slocum]

Wouldn't passive flexibility set one up for further injury due to the tissue easily making it into a ROM that it has no strength/stability within?

 

Injuries tend to occur when a muscle is extended beyond its normal range of motion with excessive force. Since most actions tend to occur within a 'normal' range of motion, passive flexibility essentially gives you more leeway before entering the danger zone. 

 

 

However, if you are working towards the extremes of your range of motion, passive flexibility greatly in excess of active flexibility could be dangerous for exactly the reason you have described. 

 

 

If one is working a straddle split for example they will be actively pulling their legs apart - and let's use bands for the load. Over time wouldn't the available ROM increase because the strength within their current ROM had increased enough to allow access to that new range?

 

- Chris

Yes, but your abductors (legs apart muscles) would be actively fighting your adductors (legs together muscles). Increasing the passive flexibility of the adductors would allow the abductors to move the legs even further before encountering resistance. A large component of flexibility is neurological: the muscles reflexively contract once they elongate past a certain poinit to prevent injury. This restricts your accessible range of motion. Part of the effect of passive stretching is that when you move your limbs beyond the range of motion your body currently considers "safe", you can train your your muscles to allow for a greater range of motion before triggering the stretch reflex.

[Chris Hobbs]

Injuries tend to occur when a muscle is extended beyond its normal range of motion with excessive force. Since most actions tend to occur within a 'normal' range of motion, passive flexibility essentially gives you more leeway before entering the danger zone. 

 

I guess what I am thinking is that as the active flexibility ROM increase that their would be a corresponding increase in passive flexibility ROM naturally. Thus you would always have your same leeway of passive > active as a buffer zone.

 

Yes, but your abductors (legs apart muscles) would be actively fighting your adductors (legs together muscles). Increasing the passive flexibility of the adductors would allow the abductors to move the legs even further before encountering resistance. A large component of flexibility is neurological: the muscles reflexively contract once they elongate past a certain poinit to prevent injury. This restricts your accessible range of motion. Part of the effect of passive stretching is that when you move your limbs beyond the range of motion your body currently considers "safe", you can train your your muscles to allow for a greater range of motion before triggering the stretch reflex.

 

Why does it need to be increasing the passive flexibilty of the adductors? Why couldn't it be active flexibility work to increase their ROM as well? Seems like the latter would be safer for the body anyway since if we are devloping active flexibility within the abductor muscle we would want a corresponding amount of active flexibility within the adductors to remain in balance.

 

Regarding the stretch reflex, is there any research out there showing that increasing active ROM doesn't move your passive ROM point forward? I have spent a fair bit of time doing some searches and reading various studies and such, but haven't come across anything specific to this. I suppose it makes some sense that there wouldn't be much, if any, as most focus on passive flexibility training simply because it is easier to obtain.

 

- Chris

[Joshua Slocum]

I guess what I am thinking is that as the active flexibility ROM increase that their would be a corresponding increase in passive flexibility ROM naturally. Thus you would always have your same leeway of passive > active as a buffer zone.

 

This does happen a little bit because your abductors will stretch your adductors at the extreme of your active ROM. But it will not be nearly as efficient as if you had done dedicated adductor stretching. 

 

 

Why does it need to be increasing the passive flexibilty of the adductors? Why couldn't it be active flexibility work to increase their ROM as well? Seems like the latter would be safer for the body anyway since if we are devloping active flexibility within the abductor muscle we would want a corresponding amount of active flexibility within the adductors to remain in balance.

 

Active flexibility work is constrained by the passive ROM of the opposing muscle (e.g. how far it can elongate before triggering the stretch reflex) and the active ROM of the contracting muscle (e.g. how far it can contract and still apply force). Increasing your active adduction flexibility doesn't help with your active abductive flexibility, because it doesn't affect how far your adductors can elongate before reflexively contracting. However, you do want to improve the active ROM of the adductors so that you have appreciable strength even when they are highly elongated. This is one reason why PNF stretching is a particularly good method for training passive flexibility. 

 

 

Regarding the stretch reflex, is there any research out there showing that increasing active ROM doesn't move your passive ROM point forward? I have spent a fair bit of time doing some searches and reading various studies and such, but haven't come across anything specific to this. I suppose it makes some sense that there wouldn't be much, if any, as most focus on passive flexibility training simply because it is easier to obtain.

 

- Chris

 

As I said above, it does, just very slowly compared to dedicated passive flexibility work. 

[Chris Hobbs]

Active flexibility work is constrained by the passive ROM of the opposing muscle (e.g. how far it can elongate before triggering the stretch reflex) and the active ROM of the contracting muscle (e.g. how far it can contract and still apply force). Increasing your active adduction flexibility doesn't help with your active abductive flexibility, because it doesn't affect how far your adductors can elongate before reflexively contracting. However, you do want to improve the active ROM of the adductors so that you have appreciable strength even when they are highly elongated. This is one reason why PNF stretching is a particularly good method for training passive flexibility. 

 

So my thought on the above is that if one were to focus on developing active flexibility in both the adductors and abductors simultaneously that the corresponding increase in passive flexibility that happens naturally through building active flexibility in that muscle group would continue to move both along incrementally.

 

I get that it isn't as fast as dedicating a chunk of time to passive, but I wonder if it would be safer and more effective longer term in as much as being flexibility that sticks with you as opposed to going away when routines aren't kept up. After all, strength tends to stick around, so if the range you had access to was attained via a purely active means then by that strength sticking around the flexibility should maintain also.

 

Or am I missing some component of how this works?

 

- Chris

[Aaron Griffin]

Thomas Kurz suggests working passive flexibility immediately after active flexibility work is ideal. /shrug

[Joshua Slocum]

So my thought on the above is that if one were to focus on developing active flexibility in both the adductors and abductors simultaneously that the corresponding increase in passive flexibility that happens naturally through building active flexibility in that muscle group would continue to move both along incrementally.

 

I get that it isn't as fast as dedicating a chunk of time to passive, but I wonder if it would be safer and more effective longer term in as much as being flexibility that sticks with you as opposed to going away when routines aren't kept up. After all, strength tends to stick around, so if the range you had access to was attained via a purely active means then by that strength sticking around the flexibility should maintain also.

 

Or am I missing some component of how this works?

 

- Chris

Eventually your active flexibility reaches the end of your passive flexibility. At that point you can make no further gains in active flexibility until your passive increases. You are unlikely to be able to make significant gains in that area without dedicated passive stretching. You can't get a very good stretch solely through contracting opposing muscles. Also, if your passive flexibility lapses, so will your active flexibility, because you can't move your limbs (much) past the point where the stretch reflex is triggered.

I'm having trouble figuring out why you would think active flexibility work is safer than passive work. Passive flexibility decreases your risk of injury during normal movements. It is only dangerous if you attempt to perform movements towards the extremes of your ROM without first building enought strength there to safely execute the movement. If you explain your reasoning I could try to clear up any confusion.

[Chris Hobbs]

Eventually your active flexibility reaches the end of your passive flexibility. At that point you can make no further gains in active flexibility until your passive increases. You are unlikely to be able to make significant gains in that area without dedicated passive stretching. You can't get a very good stretch solely through contracting opposing muscles. Also, if your passive flexibility lapses, so will your active flexibility, because you can't move your limbs (much) past the point where the stretch reflex is triggered.

 

I am struggling to understand how your active flexibility could reach the limits of the passive flexibility. It seems like once you totally own a given ROM (in that a sufficient amount of strength is developed within that range) that the upper passive limits would move forward accordingly.

 

I'm having trouble figuring out why you would think active flexibility work is safer than passive work. Passive flexibility decreases your risk of injury during normal movements. It is only dangerous if you attempt to perform movements towards the extremes of your ROM without first building enough strength there to safely execute the movement. If you explain your reasoning I could try to clear up any confusion.

 

There have always been a ton of stretch related injuries across disciplines, and as far as I know all are a result of pushing, or being pushed, too far into that passive flexibility range. I am not aware of any active flexibility type injuries, and would definitely be interested to see some cases if they exist.

 

If the injury risk is at the limits of your ROM, and you need to build strength there to mitigate that risk, it seems that active flexibility training addresses that aspect while by definition being safer as you are only ever entering a range you have strength within. If that range never increases is the only problem I see and it is a very big if that I can't find the answer to in the literature.

 

- Chris

[Chris Hobbs]

Thomas Kurz suggests working passive flexibility immediately after active flexibility work is ideal. /shrug

 

I understand that, and for the case of building passive ROM it makes sense to me. I am questioning the entire premise of passive flexibility being necessary though. I am essentially wondering if one could make progress with only active work and if it would be more ideal for GST than opening up ranges we risk injury within.

 

- Chris

[Joshua Slocum]

I am struggling to understand how your active flexibility could reach the limits of the passive flexibility. It seems like once you totally own a given ROM (in that a sufficient amount of strength is developed within that range) that the upper passive limits would move forward accordingly.

 

The mechanism are entirely separate. Passive flexibility is restricted by the point at which the stretch reflex is triggered in the opposing muscle. Active flexibility is limited by the range in which the contracting muscle has strength. Eventually you reach a point where the contracting muscle moves the limb to a point where the opposing muscle's stretch reflex is triggered. At that point the only way to appreciable increase your range of motion is to push the stretch reflex further back: passive flexibility work. 

 

 

There have always been a ton of stretch related injuries across disciplines, and as far as I know all are a result of pushing, or being pushed, too far into that passive flexibility range. I am not aware of any active flexibility type injuries, and would definitely be interested to see some cases if they exist.

 

To my (admittedly limited) knowledge, the most common stretching injuries are from ballistic stretching; passive stretching is mostly safe. If you have data to the contrary I would like to see it. Those injuries that do come from static stretching are from stretching too hard/too far. The smart way to avoid that risk isn't to cut out static stretching altogether, but to learn how to safely stretch and keep within your limits. 

 

If the injury risk is at the limits of your ROM, and you need to build strength there to mitigate that risk, it seems that active flexibility training addresses that aspect while by definition being safer as you are only ever entering a range you have strength within. If that range never increases is the only problem I see and it is a very big if that I can't find the answer to in the literature.

 

What you need is strength in the opposing muscle, to resist further movement. PNF stretching develops this. Active flexibility develops strength in the contracting muscle. So relying solely on active flexibility would result in less resistance to injury, not more. 

[Chris Hobbs]

Thanks Hari. That clears up a lot of the thoughts I had running through my mind. I appreciate the discourse.

 

- Chris