I work with a CompuTrainer to study the relationship between actual load (watts), cadence (I count), and perceived effort. PS – the pace is low because I had to stop pedaling to take a non-fuzzy photograph. Photo by FitOldDog.
I loved that book!
“If you decide to try to understand your cardiovascular or aortic stent, and it’s potential impact on your blood flow, remember that the heart is not a pump that sends blood around a system of rigid pipes, it is but one (sorry, two) of many driving components of the cardiovascular system, which would probably be best considered as one, highly integrated, continuous pumping network, employing a panoply of energy storage and loss systems, which almost certainly include the thixotropic (non-Newtonian) properties of the blood itself.”
by FitOldDog today. (PS you don’t need to know any of this to listen to your body!)
Hi folks, welcome!
The cycling mantra for optimal cadence tends around 90 rpm, but this might not apply to those with non-compliant (stented) arteries, in FitOldDog’s opinion. For optimal performance as an older athlete, you have to work it out for yourself, with all of the expert advice you can lay your mind on, and please be aware that your body is the ultimate expert on such matters.
The cycles of life come and go, with Spring following Valentine’s day, and so on. The rpm is fixed, so accept it and enjoy.
You can only suck (or push – it’s the same thing) so much fluid through a rigid straw, due to pressure differences between the ends of the straw. The straw is non-compliant – it’s rigid, unlike your arteries, be they coronary (heart) or iliac (legs – as in my case). Add a stent and you have a rigid straw, and no matter how hard your heart, aorta, and all the rest, try to drive blood through your stent into your legs during systole (diastole for the heart vessels), the rigidity of the graft places an upper limit on flow rate due to pressure drops across your stent. The efficiency of blood flow to your legs, whilst riding a bike, is almost certainly impacted by this fact. But how?
You have to work out who is to be taken most seriously when it comes to exercise, your doctor, your coach, or your body – you know my call.
So! Just because skilled athletes and coaches say your cadence should be 90 (0r whatever), this may not apply to you. I did a simple experiment on this today, which is reported in more detail in my training diary, and simply put the result was:
Spinning, relaxed, at 70-75 rpm on my trainer bike, permits me to hold a higher wattage with less burning in my legs than at 90 rpm.
There are many possible reasons for this observation, but what really count for me as an athlete with a stent are what works and what is safe. I wonder about the optimal heart rate for a cardiac stent?
-k @FitOldDog
Very interesting. My graft is likely more rigid than the original as well. In my classes, we have been sprinting- I can get to 117 rpm with others at 130-140. Pulse still a round 140. I’d like to be able to measure corresponding power.
Hi Pauline, it seems that you could get a rough estimate of power output as you run (though I’m not sure there is a gizmo for this yet; maybe there is). Plenty about it on the web e.g. http://www.topendsports.com/testing/running-power.htm May your sprints be fun. Sounds as though Bob is (was?) having a great time in Tucson. -k
Hi Kevin,
Interesting stuff, as always. I am reminded of hydraulic lock (http://en.wikipedia.org/wiki/Hydrolock). While I realise that the circulatory system does not use pistons, it is a system of valves, pipes and pumps (the heart, various other large and small muscles) and they all need to work in unison or the system is liable to suffer from pressure variations that affect its efficiency and integrity (kind of biological hydraulic lock). Invariably exercise using major muscle groups has the potential to compromise blood flow efficiency as muscles perform multiple, sometimes imcompatible, functions. Add in the complication of a mechanically inflexible stent and it is just one more complexity to consider.
I find your discussions interesting for a range of reasons, not the least of which is that you recognise the need to find the most efficient and effective ways to get your particular system of valves, pipes and pumps to work so that you minimize the potential for problems while maximizing athletic performance, I particularly enjoy your analysis of the variables. I just wish that more medical professionals would follow your discussions as they provide great insight that I don’t often hear from ‘the professionals’.
Hi Glenn, the hydrolock reference was interesting, and I sure don’t want to kink my stent that way. Biology is so fascinating, and we know so little. When it comes to ‘the professionals’ and my blog, I find that the majority are silent, and most of them probably don’t know I exist. I’m just a weird old veterinarian to most of the ones that do, I think, but I love thinking about these things. Guess that is why I went into research. I sure appreciate your encouragement. Wonder how I’ll do in Placid? I guess the chips will fall where they may, but I’m really enjoying getting back into shape. Kind Regards, Kevin
Interesting. I have a stent in my right coronary artery. I would never countenance any experiment on its response (or lack of response) to over-vigorous exercise. I have carried out a lot of repair work in buildings. On a second call out for a burst pipe the first place to check is the initial repair as it is usually the repair that is almost always the weakest point.
The problem as I see it is that of testing to the point of catastrophic failure. You can by definition learn not a jot from that!
Hi Trevor, you are missing the point.
My Ironman goal is always to feel good at the end of the race, able to enjoy pizza or whatever is available, with friends and family. If I feel, during the race, that this will not be the case, I pull out and enjoy my food sooner. The exception was Lake Placid 2012, which I did as an experiment to see how far I could go (without risking life and limb) on a purely ‘paleoid’ diet. It was a great experiment that I enjoyed a lot, leaving me healthy enough to finish the Louisville Ironman one month later, third in my age group, and in the company of Nigel – what could be better than to race with your kid?.
My work on the bike is designed to find the conditions that minimize risk, whilst maximizing enjoyment and the benefits of exercise. My peers are falling apart, one by one. My aneurysm, and the related hyperlipidemia, are almost certainly genetic, and one of them would have killed me already, I’m sure, if I didn’t do what I do, so there is a net gain of almost 4 years, already.
To each his own.
Cheers,
Kevin
A note on stents – a thought experiment if you may
Aortic stents and some types of vigorous exercise (A variation on wave erosion of a shore)
As I understand things arteries are not rigid plumbing pipes. They have flex and they are elastic in response to waves of pressure that pass through the fluid within them.
These waves of pressure are not simple sine waves but are complex in form somewhat like waves upon an ocean. There is the main wave, the heart beat driven wave, like the ocean roller and then there are other waves from other forces exerted upon the system. These come from body movements and external shocks etc..
An artery supported by a rigid stent has less flex and is not elastic in the way an unsupported artery is. At the end of any stent there is an inherent weak region. This is the junction between the free artery with flex and elasticity and the reinforced artery. This is a zone of most stress.
The simpler the wave form at this point the less scope there is for weakening of the artery wall by shock waves much like there is less coastal erosion with normal seas lapping a shore and greater erosion in the havoc of a storm with its more complex wave patterns. Also the erosion that does take place is at its greatest at borderlines between two differing strata. Like between supported and unsupported arteries.
For this reason I argue against exercise that increases complex pressure wave patterns within blood vessels and suggest exercise that is more regularly rhythmic. That is that swimming is probably better than cycling and running.
My knowledge of wave theory comes from the trade cycle theories of economics not from physics but waves are waves for all that.
Hi Trevor, you’re correct, in that the interface between the stent/no stent region, especially the upstream region, is that of greatest risk. Thus the spikes holding it in place near my renal arteries. The complexity of the wave forms, including those of actual fluid flow (which, in the case of visco-elastic blood are probably far from simple), pressure and pressure bounce back waves, almost certainly played a role in my stent-induced hypertension (now essentially self corrected). Based on many years of studying fluid mechanics, in both Newtonian and non-Newtonian systems, I suspect that we have almost no understanding of the structure of this complex flow system, as is related to pulse rate, transition from high to low compliance, and the like. So, everyone is guessing, especially yours truly – guessing often.
The swim, I suspect, due to core spiral forces, may actually be more dangerous than the bike, when it comes to stent displacement and the induction of potentially fatal endoleaks. However, that said, I consider the greatest risk to come from not enjoying life – I ran my benefit/risk equation, and came out with an acceptable result.
I think about stent stability quite a bit, but I suspect it is time to just put into practice my chosen approach and enjoy my sport.
This is why I loved Gary Gartner’s comment so much:
https://athletewithstent.com/2014/02/20/fitolddogs-training-diary-day-66-221-learning-train-smart-bike-abdominal-aortic-aneurysm-stent-graft/#comment-9402
Thanks again for your concern. Isn’t life interesting?
-k
You ran an equation!!! Well all hale equations then. Sorry like econometrics equations are a substitute for reasoned thought. I retire from reason. Lost causes are a waste of time.
Equations permit a dynamic understanding of reasoned thought – they are a tool that helps to balance the input variables. Not the solution.