Question: Relationship between Temperature & TSS

They measure training stress. The important word there is training. That doesn't mean that the ride wasn't sressfull. I live in Phoenix and ride to and from work. The other day it was 117 when I rode home. If I rode very hard I would start to overheat. So the overall TSS for the ride was low. The next morning I was exhausted with a ton of residual fatigue from the heat. It wasn't training related. It didn't help me get faster. I just got worn down from the heat.

There is a recent article on 53x12.com on the Tour commenting on the decreased VAMs in the Pyrennean stages where Ferrari states that output tends to decline about 1% for every degree over 22 degrees C.

(I sure wish he would write a book someday)

I notice more cardiovasular stress when it's above 25 degrees (and particularly when humid) but my muscular stress goes way down when it's above 26 degrees. I get less sore the next day or over a period of days if it's above 26 degrees. Since I'm more limited by muscular stress than cardiovascular, I prefer temperatures of 26-28 and about 30-40% humidity. 70% humidity+ and I start sweating like a pig, and my power drops.

-Bikeguy

bikeguy said:

I notice more cardiovasular stress when it's above 25 degrees (and particularly when humid) but my muscular stress goes way down when it's above 26 degrees. I get less sore the next day or over a period of days if it's above 26 degrees. Since I'm more limited by muscular stress than cardiovascular, I prefer temperatures of 26-28 and about 30-40% humidity. 70% humidity+ and I start sweating like a pig, and my power drops.

-Bikeguy

So you're talking about 82F? as being hot? my my. Yesterday the high was 47 and the low was 34. Humidity was only 27% so I guess it was a dry heat 😉 If I waited for a 28 to ride in it would be Sept.

Jerryz wrote:

So you're talking about 82F? as being hot? my my.

No, I'm estimating that my 40 k TT time is probably best at about this temperature.

It hasn't reached 28 degrees here at all. I wish, I could use a nice hot day to go to the beach and get some sun.

-Bikeguy

bikeguy said:

I notice more cardiovasular stress when it's above 25 degrees (and particularly when humid) but my muscular stress goes way down when it's above 26 degrees. I get less sore the next day or over a period of days if it's above 26 degrees. Since I'm more limited by muscular stress than cardiovascular, I prefer temperatures of 26-28 and about 30-40% humidity. 70% humidity+ and I start sweating like a pig, and my power drops.

-Bikeguy

The distinction between muscular and cardiovascular stress iis something of a myth for cyclists, like that old nonsense about 'lower cadences shift stress from the CV system to the muscles'. At any given intensity (power output) your body has to convert a certain amount of energy, and this is accomplished in the same way regardless, although certain cadences can be more economical than others, resulting in higher or lower rates of 'central function' if you will. My guess is that people who attribute fatigue to one thing rather than another are just psychologically more aware of that aspect of their fatigue.

L.

Biker-linz wrote:

like that old nonsense about 'lower cadences shift stress from the CV system to the muscles'.

It doesn't shift the stress, just creates a new one! Also, higher blood pressure I'm sure with a lower cadence at equal power output.

Biker-Linz wrote: At any given intensity (power output) your body has to convert a certain amount of energy, and this is accomplished in the same way regardless, although certain cadences can be more economical than others,

Yeah, all studies of cadence have shown higher economy at 60 rpm then 90 rpm. What does that mean? Less oxygen consumed per watt (as you well know). Unfortunately, muscle fatigue sets in more quickly at 60 rpm than at 90 rpm, at least with intensities closer to maximum aerobic power.

resulting in higher or lower rates of 'central function' if you will.My guess is that people who attribute fatigue to one thing rather than another are just psychologically more aware of that aspect of their fatigue.

I don't know anything about that... but I get less sore muscles and can ride more consecutive days when it's warmer... without going into a phase of overreaching. No psychology here... just a drop in performance. Solution: wear warmer clothing.

bikeguy said:

Biker-linz wrote:
Yeah, all studies of cadence have shown higher economy at 60 rpm then 90 rpm. What does that mean?

Sorry if this answer appears twice?? I'm afraid you are mistaken with regard to research into economy and cadence. Economy increases with increasing workload, see:
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=15232702

and probably
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=15503124

This probably explains why 60 rpm is the most economical cadence for *untrained* cyclists, but that most economical cadence rises with fitness (as does freely chosen cadence). It also highlights another problem: sub-elite cyclists who emulate their heros by adopting unnaturally fast cadences might be doing themselves few favours.
Re. your idea about low cadences and increased BP I think it's unlikely; do you have any references that I could look at??

L.

So Linz,

Are you saying that the stress induced from heat has a positive training effect? That is not my experience here in the summer heat of Arizona. But that's not a scientific study more my personal observation. I find that by and large fi I ride int he heat of the day I can't ride as hard as I can otherwise. So I doubt that there is a positive training stress. And yes I do believe that thermal stress is different. And no I have no study to back that up. But have you ever tried to work very hard at high temps?

jerryz said:

So Linz,

Are you saying that the stress induced from heat has a positive training effect?

Goodness no, quite the opposite! :eek: 🙂 No, I was just being pedantic on the subject of cycling physiology. I just hear a lot of people saying things like 'my legs are strong but my lungs let me down' and then make training decisions based on very misguided interpretations of their own physiological 'short-comings'.

L.

Response to Biker-Linz:

Biker-Linz: economy to me means how many joules per km are required, and this is minimized by riding at low (60 or even lower) cadence and low power output, regardless of fitness level. The studies you link to involving ramped tests to V02 max are not the best way to minimize calories burned per unit distance covered. I am fully aware that fatigue sets in later in a ramped test if cadence is increased as approaching V02 max, as I mentioned in the previous post. I even purposefully increased my rpm's during my OWN V02 max ramp test as I came to what I estimated as over 80% of V02 max!!!!!

Biker-Linz wrote: I just hear a lot of people saying things like 'my legs are strong but my lungs let me down' and then make training decisions based on very misguided interpretations of their own physiological 'short-comings'.

I hope you didn't mean to imply that I made such a statement?

Bikeguy wrote: Since I'm more limited by muscular stress than cardiovascular, I prefer temperatures of 26-28 and about 30-40% humidity. 70% humidity+ and I start sweating like a pig, and my power drops.

Perhaps I should define what I mean by greater muscular stress: means I get freakin more sore the next day. When I say I'm limited by muscular stress, that means my training time is limited by quite a bit of soreness post ride, which I experience less of if the temp outside is 25+.

What I mean by not limited by cardiovascular stress: means I'm not huffing and puffing and my lungs aren't cramping up (ventilatory threshold perhaps?). Since I don't do ramped tests to failure out on the road, this isn't a problem.
I also don't do as many, after experiencing pericarditis last fall. The pericarditis was aggravated by attempting to hold any significant fraction of V02 max, but is OK now.

-Bikeguy

Biker-Linz said: I just hear a lot of people saying things like 'my legs are strong but my lungs let me down' and then make training decisions based on very misguided interpretations of their own physiological 'short-comings'.

Hrrrrmmmmmm.... I'd be interested in discussing some of these shortcomings, or rather just increasing my one hour TT time. At this current point, I basically just take time off or do recovery rides when I get really sore, other then that, I don't make any modification to my training program as I really have no need to. Since I don't have any janeiros to pay you, I would appreciate any other advice I can get, and I accept all donations.

-Bikeguy

Hey bikeguy,

First up I need to make a confession. I went back and re-read your original post this morning regarding heat and increased CV stress and I have to admit I slightly misinterpreted what you had written. You are correct, there is certainly a greater central stress when temperatures are high. As for muscle stress being less, do you own a power meter? I just wondered if you were using a HRM, as HRs at a given intensity are higher in the heat. This could mean that you were just exercising at a lower intensity without realising it.
Re: the Foss paper. I think you've misread the paper, they performed submaximal as well as maximal tests. Just to avoid any confusion, cycling economy is defined as the power output which corresponds to a given rate of O2 consumption, units are Watts per Litre per minute.

Very sorry to hear about your pericarditis- is all ok now?

L.

Biker-Linz:

BL wrote: Re: the Foss paper. I think you've misread the paper,

I don't have access to the full version. Keep that in mind.

BL wrote: they performed submaximal as well as maximal tests.

I know, from the abstract.

Bl wrote: Just to avoid any confusion, cycling economy is defined as the power output which corresponds to a given rate of O2 consumption, units are Watts per Litre per minute.

I know. A watt/liter/minute value of over 90 is considered elite. However, the articles you linked to do state that economy is better at cadences around 60 rpm, if power is low.

The abstract says itself, that economy is better at low cadences and low power outputs.

quote from the foss abstract: "The results showed that the lowest oxygen uptake, i.e. the best work economy, shifted from 60 rpm at 0 W to 80 rpm at 350 W ( P<0.05"

Sounds to me like economy at a value 0<x<350 watts, that economy is maximized at between 60<x<80 rpm, meaning economy at lower power outputs and cadences is better than at high power outputs and cadences.

It is true that economy at higher power outputs is maximized at higher rpms (the value given of 80 seems a little low, as all hour record attempts are more like 90+ rpm) however, absolute economy is better at low rpms and low power outputs. i.e, if one wanted to cycle 24 hrs continuously, one would choose a lower cadence and power output, to maximize economy than if one were to attempt a 1-6 hr event. Sort of makes sense, because one wouldn't want to spin around at 80+ rpm for 24 hrs.

BL wrote:As for muscle stress being less, do you own a power meter? I just wondered if you were using a HRM, as HRs at a given intensity are higher in the heat. This could mean that you were just exercising at a lower intensity without realising it.

I don't think the intensity is lower, as my speed over an out and back course (abut 40 km) increases. I've done numerous runs over the same course, and I'm faster when it's warmer, even if my heartrate comes up higher.
I don't own a powermeter, nor can I borrow/afford one.

BL wrote: Very sorry to hear about your pericarditis- is all ok now?

I think so, although occasionally I get a strange increase in heart rate ( increases by 40-60%, no pain though) for 2-8 seconds, and I also can feel my heart beating (like a pounding, increased blood pressure).

After experiencing symptoms similar to a heart attack last fall, my heart was monitored in hospital for 7 consecutive days and I did a graded exercise test (although not to exhaustion, maybe 85%) on a bike, and no heart rate abnormalities were found. I also was examined by 2 doctors with an ultrasound to check for heart beat/blood flow (or other problems, I'm not a cardiologist) and nothing was found. They did say my pericardium was very thick, and had some trouble seeing the picture. No cause was found for the pericarditis, although a T-cell count showed an infection/inflammation of unknown type. I experienced some chest pain occasionally, including during exercise for 2 months after, which gradually decreased to normality.

-Bikeguy

In the Foss paper, 80 and 60 rpm are not statistically different in terms of O2 consumption at 200 and 275 W. However, Foss' own explanation for the shifts in economy are related to optimum shortening velocities of different muscle fibre types. If this is the case, then most economical cadence would be related to relative rather than absolute intensity, and would also be affected be muscle fibre make-up. WRT my previous post, I appear to have mistakenly picked up on something which we both agree on :eek: 😄 ! When it comes to cadence selection I honestly believe we don't have the whole picture as yet. I think ideas like central governor theory (or related theories) might fill in the blanks a bit- i.e. that freely-selected cadence might be affected by long-term rather than just short-term considerations of fatigue (as you implied).

L.

biker-linz said:

In the Foss paper, 80 and 60 rpm are not statistically different in terms of O2 consumption at 200 and 275 W. However, Foss' own explanation for the shifts in economy are related to optimum shortening velocities of different muscle fibre types. If this is the case, then most economical cadence would be related to relative rather than absolute intensity, and would also be affected be muscle fibre make-up. WRT my previous post, I appear to have mistakenly picked up on something which we both agree on :eek: 😄 ! When it comes to cadence selection I honestly believe we don't have the whole picture as yet. I think ideas like central governor theory (or related theories) might fill in the blanks a bit- i.e. that freely-selected cadence might be affected by long-term rather than just short-term considerations of fatigue (as you implied).

L.

How would central governor theory help with this? From what I've read, it usefully explains lots of things, but the underlying mechanisms any theoretical central governor are by and large not yet elucidated. It seems a little like an appeal to deity to explain why the planets move, or a really clever way of saying 'I don't know, but it's probably something to do with the brain and/or the nervous system'. Certainly it's helpful in pointing out the cracks in other ex phys hypotheses.