Can rebuilding lower limb musculature help out an ailing heart ?

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Older individuals are more likely to have heart function problems and also lower limb muscle loss caused by sarcopenia. Can rebuilding the musculature of the lower limb assist with cardiac function and improve general health ?

 

Increased venous return to right side of heart results in greater stroke volume from left ventricle and so flow of blood around body.

Starling mechanism involves atria contracting and preloading ventricles> stretching the cardiac muscle before ventricular contraction.

Venous return reduced if lower limb muscle lost to aging but this can be reversed by progressive resistance exercise . Muscles in foot play key role in venous foot pump but are amongst most affected by aging.

 

So if venous return from the lower limb is reduced in the elderly because of skeletal muscle loss, can restoring skeletal muscle restore better venous return ? Can't seem to find much on this topic .

Also ,to avoid confusion the sentence "Venous return reduced if lower limb muscle lost to aging but this can be reversed by progressive resistance exercise" in post #2 would be better written "as venous return from the lower limb may be reduced if muscle is lost due to aging, but muscle loss due to aging can often be reversed by progressive resistance exercise" .

It needs to be remembered that venous return from the lower limb is likely not just about overcoming gravity but also a significant centrifugal effect produced during gait.

I am not an expert in this area of physiology but find it to be of great interest.

 

eISSN 2765-5628
pISSN 1598-6756

• New Treatment of Varicose Veins through Muscle Regeneration of Lower Leg Muscles (Especially Calf Muscle) Without Removal of Varicose Veins
  
  Ki Ji Lee, M.D., Ph.D.
  Author Affiliations
  Correspondence to : Ki Ji Lee, 15 Saemal-ro, Guro-gu, Seoul 47848, Korea, Deparment of Pediatrics, Woorisoa Seoul Hospital
  Tel: 02-858-0100, Fax: 02-856-0032
  E-mail: leekiji@naver.com
  Abstract
  
  Go to
  The calf muscle pump is the motive force enhancing venous blood return from the lower extremity to the heart. It causes displacement of venous blood in both vertical and horizontal directions, generates ambulatory pressure gradient between the thigh and lower leg veins, and bidirectional streaming within calf perforators. Ambulatory pressure gradient triggers venous reflux in incompetent veins, inducing ambulatory venous hypertension in the lower leg and foot. Bidirectional flow in calf perforators enables quick pressure equalization between deep and superficial veins of the lower leg; the outward (into the superficial veins) oriented component of the bidirectional flow taking place during calf muscle contraction is not a pathological reflux but a physiological centripetal flow streaming via the great saphenous vein into the femoral vein. Calf perforators are communicating channels between both systems, making them conjoined vessels; they are not involved in generating pathological hemodynamic situations and do not cause ambulatory venous hypertension. Pressure gradient arising during calf pump activity between the femoral vein and the saphenous remnant after abolishing saphenous reflux triggers biophysical and biochemical events, which might induce recurrence. Thus, abolishing saphenous reflux removes the hemodynamic disturbance but simultaneously generates a precondition for reflux recurrence and the return of the previous pathological situation; this chain of events has been termed the hemodynamic paradox. But this review showed that varicose veins could be improved quickly through lower leg muscles (especially calf muscle) regeneration by increasing mitochondrial cellular energy (adenosine triphosphate) of leg muscles without removing varicose veins.

Which group of clinicians should be looking after calf and foot musculature in older adults ?

 

The plantar venous plexus is located on the plantar surface of the foot and is made up of large diameter veins . During gait these vessels fill with blood which is then expelled back towards the heart with high force during weight acceptance. A typical volume of blood is estimated as being between 20-35ml of blood. It is worth noting that this pump operates just as well in the cavus foot as the planus foot, but more of that later.

It has been suggested that the foot pump acts as a primer for the calf pump and even that it contributes just as much to venous return as the calf pump itself. The musculature in the thigh also contributes to venous return.

The following may not be backed up by the literature and can best be described as my opinion based on what I have read.

Venous return from the lower limbs, powered by skeletal muscle function, has a huge role to play in cardiovascular function.

The human heart has four chambers 2 atria and 2 ventricles . The atria have a number of functions one of which is to contract and fill the ventricles with blood just before these contract sending blood to the lungs ( right ventricle) and oxygenated blood to the rest of the body ( left ventricle) .

Taking the left side of the heart ; when the atrium contracts it fills the left ventricle and this filling action stretches the muscles of the ventricle (preloading ) which then contacts ejecting more blood than it would if the muscle had not been pre-stretched.

This is speculative ; The heart may beat /contract via active and passive mechanisms. The active component involves the ATP/ oxygen burning, contractile components of the cardiac muscle and the passive component is reliant on the elastic tissues in the cardiac muscle mass being stretched and then recoiling. This stretch/ recoil mechanism requires little oxygen ( blood via coronary arteries) and is powered largely by atrial activity and the pressures generated during venous return via the skeletal activity.

As physical activity becomes more demanding so the proportion of blood pumped by active contraction of the ventricles verses passive contraction will change in favour of passive elastic recoil doing more of the work . Therefore, as higher cardiac output is required so venous return becomes more important.

Perhaps the hearts of older people, with reduced calf, foot, thigh musculature, might struggle to utilize the "free" pumping action of the which depends on venous return.

Oxygen cheap and expensive ventricular activity ? Simultaneous sure, but which may be thought of as distinct components.

 

Bringing this back round to the foot, it's pretty clear that the pumping mechanism in the foot engaged during weight acceptance, the venous foot pump, has an important role to play in venous return and therefore, in my opinion, in cardiac function during gait /standing.

So what? Well , the venous foot pump needs a healthy intrinsic musculature to function properly . Blood is still pumped out of the feet of paraplegic patients when they bear weight on their feet, but flow is poor and erratic.

The muscle function in the calf and foot can be improved in the elderly with progressive resistance exercise and therefore circulatory problems linked to sarcopenia could be regarded as a modifiable risk.

Foot calf strengthening will likely improve venous return, cardiac function, and possibly postural hypotension. Postural hypotension can lead to falls, especially in the first 60 seconds or so after standing from a seated position.

 

"Surprisingly, the single best predictor of a senior citizen falling is toe strength. In a prospective study of 300 older adults, Mickle et al. (3) discovered that non-falling seniors had 20% more toe strength than the seniors who fell. Interestingly, there was no difference in quadriceps or ankle strength between the fallers and the non- fallers, confirming that toe weakness, not generalized weakness, is responsible for the falls. Unfortunately, toe weakness is extremely common in senior citizens: compared to their younger peers, older adults have toe strength declines of more than 35%, which greatly increases the risk of falling (4)."
Tom Michaud

Reduced toe strength may negatively impact a persons ability to maintain balance and avoid falling through a mechanical mechanism but I believe other factors need to be considered. Reduced toe flexor strength may mean reduced intrinsic muscle mass and a poorly functioning foot pump . This in turn might lead to postural hypotension when moving from seated to standing, increasing the risk of fainting or dizziness and a fall. Apparently, the connection between the skeletal muscle pump and falls is presently under investigation at Newcastle University, UK .

A healthy foot pump can move a volume of between 20-35 ml of blood out of the foot with enough force to lift a column of blood all the way to the heart. 2 feet could equal as much as 70 ml of blood (the same as the volume of blood pumped from the left ventricle during a single beat body whilst at rest ).

 

Ok, so let's assume, for now, that the plantar venous plexus has an important role to play in venous return and that this might make the mechanism important in cardiovascular mechanics, postural hypotension, and falls prevention.

But how does the plantar venous pump work ?

We can forget "necking down" as emptying a viscoelastic tube of fluid by stretching it is not possible in the context ,valves or no.

The vessels of the plexus lie within the intrinsic muscle mass of the foot and so it's a pretty safe bet that what happens to the muscles during weight acceptance is what drive the pump. It could be muscle contraction or it could be muscle compression through weight bearing ,but either way muscle needs to be there . Replace muscle with a defuse fatty infiltrate and the pump will be diminished whether the mechanism is contraction , compression, or a combination of the two.

As with diabetic feet, the feet of older people have less contractile muscle mass than healthy younger people.

Both the feet of older people ( Mickle et al) and those of diabetics with neuropathy ( Hohne et al), can be strengthened by resistance exercise, indeed Hohne managed to increase intrinsic muscle mass as well as strength, employing an exercise regime of just 10 mins 3x a week ( as best I can remember !) .

The venous foot pump is greatly diminished in the affected foot of hemiplegic patients but still exists as reduced erratic outflow . Exercise will not restore the intrinsic foot musculature of a hemiplegic patient but it can be restored in diabetics and older people . If it can be stored it can almost certainly be prevented in the first place.

Falls can absolutely destroy the confidence of older people and cost health services a huge amount of money.

 

From a previous thread but worth reposting IMO .

From Fox and Gardner, emptying of veins on weight bearing. This includes the dorsal veins which probably empty via the mechanism outlined in the video linked to below.

1. scotfoot, Mar 24, 2024Report
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   scotfootWell-Known Member
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   scotfoot, Mar 24, 2024Report
   #21Reply
3. 
   scotfootWell-Known Member
   Venous foot pump , dorsal aspect ,a theory 20210320 110916
   
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