Length-tension and force-velocity relationships

[stronghold]

I have just started reading BRS physiology and found that those concepts are not explained well, at least to me. For example, it states that tension would be high when there is overlap between thin and thick filaments. But when muscle length is reduced then thin filaments collide and tension is reduced.
I found that latter part is somewhat confusing. To my understanding, decreased length means more overlap between filaments, bur how the tension would decrease then?
I hope you could explain those principles and relatinships

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[stronghold]

Looks that was low yield or whar?

 

[Ycut]

I have just started reading BRS physiology and found that those concepts are not explained well, at least to me. For example, it states that tension would be high when there is overlap between thin and thick filaments. But when muscle length is reduced then thin filaments collide and tension is reduced.
I found that latter part is somewhat confusing. To my understanding, decreased length means more overlap between filaments, bur how the tension would decrease then?
I hope you could explain those principles and relatinships

there is active and passive tension
when muscle fiber is stretched to certain optimum length there is maximal overlap (active tension) + muscle elastic recoil force (passive tension)=maximal contractile force

when length is reduced maximal overlap is occuring but passive tension decreases
when length is increased theres no maximal overlap anymore =decreased active tension (decreased contractile force) but passive tension increases

 

[stronghold]

Thanks man...but it's still not clear to me. Maybe the problem is in definition; Length, active tension, passive tension, total tension, isotonic, isometric, preload, afterload. I would be grateful if you explain them to me

 

[Ycut]

think of muscle fiber like stretching a rubber
it has its elastic recoil force (passive tension) which is added to active tension (generated by cross links between thick and thin filaments)

when muscle fiber is stretched to some optimal length, maximal cross bridge formation is still possible and the two forces which are active tension and passive tension add up and maximal contractile force is generated

when u overstretch the muscle fiber (beyond that optimal length) number of available cross bridges decrease but increases elastic recoil force. Despite this, contractile force generated is small when compared to above example due to fact that number of cross bridges (active tension) plays a major role in contraction than elastic recoil of stretched muscle fiber (passive tension)

when fiber is not stretched (original length) the maximal cross bridges are available but there is no passive tension generated which when compared to first example has lower contractile force

 

[stronghold]

Thanks man!!