HR Mythbusting

cbjesseeNH

When not riding my bicycle with powermeter, I wear a Heart Rate Monitor. The classical advice in texts of the 80s/90s was to not exercise at 90%+ HRMax as the risk of injury is greater. This risk was not well explained and the advice may have been directed at those seeking initial fitness from sedentary lifestyles, but no such disclaimers were made - probably due to legal concerns.

Now one sees information from highly regarded sources indicating normal training levels are expected to achieve HR > 90% HRMax http://www.cyclingpeakssoftware.com/power411/levels.asp

Is/was there any support for this claim of added "risk" at > 90% HRMax?

If not, is there any support for the lack of any added "risk" in exercising at > 90% HRMax? (for an otherwise healthy individual who trains hard).

Even further, is there evidence for benefit of training at 90%+ HRMax? (Which just might be that to acheive training at FTP or higher power, HR will likely exceed 90% HRMax).

Practically speaking, I do it all the time, as do others, I'm sure, but I was looking for some studies that address the matter more thoroughly than anecdotal experience.

What got me wondering, is when I'm in a hot indoor spinning studio, cranking at a HR greater than I would expect if riding known power ranges on a bike with adequate colling, am I getting some sort of excessive "physiological strain" from the temperature-induced high HR but less gain from the lower power?

Snuffleupagus

You're going to see stresses of 90% or greater in a race situation right?

The goal of training should be to prepare you for the efforts you're going to subject yourself to...if anything training your body to handle maximal efforts will keep you safer when doing those same maximal efforts in a group.

acoggan

Even in a healthy individual, the risk of a significant cardiac event (e.g., heart attack) increases with increasing exercise intensity. That said, in a healthy person the risk of such complications is very low, such that high intensity exercise is not contraindicated.

Pendejo

Exactly. If it doesn't kill you it will make you stronger!

cbjesseeNH

I did find the following: RPE drift during cycling in 18 degrees C vs 30 degrees C wet bulb globe temperature (http://www.ncbi.nlm.nih.gov/sites/entrez?Db=pubmed&Cmd=ShowDetailView&TermToSearch=17369793&ordinalpos=5&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVDocSum ) which suggests RPE was higher (as was HR) at higher temperatures. What I'm looking for is whether the next day's ride is compromised by the prior day's ride at high temperature.

While we've had hot rides, I really can't say whether a ride at 90F instead of 70F had longer lasting recovery impact.

iliveonnitro

Wouldn't it be the opposite? Riding in 90F heat makes L5+ work nearly impossible for me (except race situations) meaning that the intensity is usually lower than that which is possible on a 70F day.

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My club: University of Illinois-Chicago Cycling

Sillyoldtwit

How does this square with RD's philosophy that the heart will take anything you throw at it? That is, other things will give up ghost before the heart lets you down.
Apologies to RD if I've misquoted him.

Naturally, as I'm a few weeks away from 65 now, it would be nice to know that I'm not heading for a Do you have the time Andy to clarify what you are saying in your short passage - perhaps explaining (with some evidence) in more depth?
And is the risk greater for the older cyclist?

I'm sure your statement has raised alarm bells in other senior citizens' minds, if not in the younger cyclist too.

Tyson

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Pendejo

It's just a statistical fact that your heart attack risk goes up with age, and is higher during exercise, and is proportional to the stress on the heart. You can't get away from that. During a treadmill/stress test they monitor your heart as the exertion increases - the heart may function normally until a certain stress level is reached.

And even if your heart has always functioned normally at a certain elevated HR, it's not a guarantee that it won't go on strike the next time you hit that HR.

The bottom line is this: in a given moment, your risk of dropping dead while exercising is greater than if you were inactive. But if you exercise your risk of dropping dead over X number of years is lower than if you don't exercise.

I'm afraid RD's dictum that the heart will take anything you throw at it is wrong: it does, until it doesn't.

Sillyoldtwit

Very comforting Pendejo!!! Maybe I won't even see this guy coming.

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frenchyge

If you ride fast enough, he'll never catch you.

Sillyoldtwit

I think it is time we got this thread into some perspective.
Things in life, be it your car, your iPod, or your heart don't go on strike for no reason. I think I'm safe in saying there is always some underlying reason.
In the case of the human heart, perhaps there is a congenital defect, a hardening of the arteries, fatty deposits on the walls of the arteries etc.
Of course individuals differ, but I think the rate at which your heart recovers from strenuous excercise is a good indicator of the health of the organ.
My heart after being worked at 160BPM (high on average for someone of 65) drops like a stone to under 120bpm in about 45 secs.
With all due respect Pendejo, I feel you have perhaps over simplied matters, and dare I say, been overly alarmist.
When I was younger, a good friend I used to run with everyday, upon reaching the ripe old age of 30, decided he should quit running because he was concerned it might be damaging his heart.
He is still alive but grossly overweight, and his worries were probably unfounded. Yes, he's managed the quantity, but what about the quality?!?!?

Tyson

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cbjesseeNH

Digging through my HR books from the 80s/90s, I find that the more scientific and exercise physiology ones don't have any warnings, but that the Sally Edwards ones do, but mostly mentioning the potential for overuse injury rather than a Major Adverse Cardiac Event (MACE).

I was, in any event, more interested in non-lethal negative stress on training efficacy rather than "The Big One" or damage to the heart itself.

My inquiry seems to evolved to more a question of whether, when HR is eleveated into the 90%+ range by environmental factors (heat, etc), rather than power output, is the accompanying elevated RPE associated with an expected longer recovery time the next day?

That is, if a standard training ride (say, a loop you often ride solo) at given normalized power usually elicits HR in in 90%+ only when bashing the steep section(s) and/or intervals - but you find HR at 90%+ on the shallow grades when it's 90-95F and humid, when it's usually 75-85%, do you need to cut wattage to avoid lasting effects on recovery over the next 48hr?

I guess if you expect hot rides/events, you might want to train for them to accomodate to heat, but I'm more thinking the exceptional day(s) when the highs spike. You can push it to the point of failure, but do you get added training effect from elevated HR/RPE without elevated power, get none, or actually reduce/inhibit the training effect by the higher physiologcal "cost" of a hot ride?

Not quite the same things as watching a horror flick to elevate HR, as you are exercising and pushing RPE and HR, but not pushing Power.

frenchyge

If I'm reading you correctly, I'd say yes the recovery time will be longer. I know that when I ride hard on a hotter day then it takes my body longer to come around, but see below.



The physiological stress may be higher because of the heat, but that doesn't increase the training effect of the ride. Just because your body is working hard to keep itself cool doesn't mean that your leg muscles are going to adapt for greater power as a result. As you say, though, if you expect the heat to be a factor in your events, then it would be a good idea to train in those conditions so that your body can adapt in other ways (besides pushing the pedals harder) for better performance during those events.

frenchyge

I think you're right, although it may not known or may be an interaction of multiple effects which makes it hard to pin down to a specific 'cause'.


Perhaps, although those tend to be included as risk factors since they don't necessarily cause the heart to suddenly stop functioning. People have heart attacks at many different ages and under all types of situations, so it's probably a bit difficult to pin down a specific, common cause.

While I agree with the statement that you quoted from RD as a pithy, practical guideline for HR cycling training, I wouldn't take it as comprehensive medical advice.