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HR, fatigue and changes during long ride

graemevetgraemevet Posts: 61
I know that if fatigued from multiple days of exercise it may be normal to experience a reduction in maximum HR.

I've also noticed that during a long ride - 100 miles+ it is significantly harder to raise my heart rate for the same level of perceived exertion. For example on the first climb of the day its easy for me to hit 178-188bpm but at the end of a ride its around 160-170 for the same effort.

Is this a sign of fatigue or it is a mental thing - it feels harder at a lower intensity when I'm tired?

Posts

  • milemuncher1milemuncher1 Posts: 1,472
    graemevet wrote:
    I know that if fatigued from multiple days of exercise it may be normal to experience a reduction in maximum HR.

    I've also noticed that during a long ride - 100 miles+ it is significantly harder to raise my heart rate for the same level of perceived exertion. For example on the first climb of the day its easy for me to hit 178-188bpm but at the end of a ride its around 160-170 for the same effort.

    Is this a sign of fatigue or it is a mental thing - it feels harder at a lower intensity when I'm tired?

    You don’t want to be raising your heart rate out of Zone 2 for any length of time, on a long’un. 178-188 ain’t most people I know’s zone 2. Your body is trying to tell you something, it’s best to listen.
  • graemevetgraemevet Posts: 61
    Thanks, I know. Sometimes its unavoidable - powering up a monster hill is usually a good way to do it!

    I generally potter along at 140bpm for endurance rides.

    As an example on the FW this weekend - Kirkstone pass - max HR 177 (bit of nervous excitement!), 110 miles later, Blea Tarn - max HR 155-160 and it felt bloody hard!
  • milemuncher1milemuncher1 Posts: 1,472
    graemevet wrote:
    Thanks, I know. Sometimes its unavoidable - powering up a monster hill is usually a good way to do it!

    I generally potter along at 140bpm for endurance rides.

    As an example on the FW this weekend - Kirkstone pass - max HR 177 (bit of nervous excitement!), 110 miles later, Blea Tarn - max HR 155-160 and it felt bloody hard!

    It sounds like the route planning was ‘off’ for that distance, for an amateur event. Every year I organise a series of 300Km ‘Audax’ distance rides. A big part of it is making sure the routes are ‘interesting’, without putting too many climbs that will require HR / Power going too high for too long. It takes a lot of self discipline from the riders, to resist ‘smashing it’ when they feel fresh enough, because if they do, they’ll be in trouble in the last 100Kms. If you want to get round this sort of distance, without ending up feeling like censored / causing serious issues to yourself, up to and including a VasoVagel reaction, which is very nasty, you have to learn to reign yourself in, early on. Shorter ‘sprint’ distance events require a totally different approach, and totally different route / rider management.
  • sungodsungod Posts: 12,699
    could be as simple as depleted energy reserves - it's easy to expend energy much faster than the body can replace it

    if you are taking in carbs with the optimum glucose/fructose mix you can get maybe 90g/hour, which is 360kcal/hour

    but unless you are taking it easy, every hour you'll have a deficit, how much depends how hard you're pushing, it's 'easy' to burn energy 2-3x faster that you can take it in, more if you really try, i.e. you'll have an energy deficit

    typically humans have c. 2000kcal glycogen reserve, this is the fast access fuel that's needed to sustain higher effort, human fat energy reserve is bigger, but fat can't sustain high effort

    as the hourly deficit mounts, your glycogen will be depleted, once reserves drop low enough your performance will fall off, go too low and you'll literally fall off!

    you can improve things by training and carb loading before sustained effort, if you start without your reserves at max you'll run out earlier than your potential allows
    my bike - faster than god's and twice as shiny
  • milemuncher1milemuncher1 Posts: 1,472
    sungod wrote:
    could be as simple as depleted energy reserves - it's easy to expend energy much faster than the body can replace it

    if you are taking in carbs with the optimum glucose/fructose mix you can get maybe 90g/hour, which is 360kcal/hour

    but unless you are taking it easy, every hour you'll have a deficit, how much depends how hard you're pushing, it's 'easy' to burn energy 2-3x faster that you can take it in, more if you really try, i.e. you'll have an energy deficit

    typically humans have c. 2000kcal glycogen reserve, this is the fast access fuel that's needed to sustain higher effort, human fat energy reserve is bigger, but fat can't sustain high effort

    as the hourly deficit mounts, your glycogen will be depleted, once reserves drop low enough your performance will fall off, go too low and you'll literally fall off!

    you can improve things by training and carb loading before sustained effort, if you start without your reserves at max you'll run out earlier than your potential allows

    Quite right, one of the most important parts of my bike computer screen ( to me ), on an endurance ride is the estimated calorie burn rate. As you said, Your liver and muscles can only store so much Glycogen, and if you burn it quicker than you replace it, you can end up in trouble, fairly quickly. If you run it down to very low levels, and the fat burn / glycogen burn equilibrium shifts too far to fat burning, as the ‘low hanging fruit’ (Glycogen) runs out. The body has to start relying on Ketones, to keep the brain functioning properly, then you start smelling the ‘pear drop’ smell, and you are in big trouble, fairly shortly afterwards. This is why feeding, and keeping a close eye on Calorie burn rate, H.R. Power, is important, if you want the experience to be enjoyable, and not a chore.
  • graemevetgraemevet Posts: 61
    Thanks everyone. Feeding has been an issue - I really struggle with normal / solid foods and often end up with some...ahem...gastric distress!

    I've managed to get along with a electrolyte/glucose/fructose drink mix that gives me 20 or so grams per hour of carbs if I drink 500ml an hour and I supplement that with another 20g or so from a gel each hour. I know that on the last few long rides I haven't drunk enough and therefore get the double hit of dehydration and negative energy balance.
  • BrakelessBrakeless Posts: 867
    graemevet wrote:
    Thanks, I know. Sometimes its unavoidable - powering up a monster hill is usually a good way to do it!

    I generally potter along at 140bpm for endurance rides.

    As an example on the FW this weekend - Kirkstone pass - max HR 177 (bit of nervous excitement!), 110 miles later, Blea Tarn - max HR 155-160 and it felt bloody hard!

    It sounds like the route planning was ‘off’ for that distance, for an amateur event. Every year I organise a series of 300Km ‘Audax’ distance rides. .

    Which events are those?
  • sungodsungod Posts: 12,699
    graemevet wrote:
    Thanks everyone. Feeding has been an issue - I really struggle with normal / solid foods and often end up with some...ahem...gastric distress!

    I've managed to get along with a electrolyte/glucose/fructose drink mix that gives me 20 or so grams per hour of carbs if I drink 500ml an hour and I supplement that with another 20g or so from a gel each hour. I know that on the last few long rides I haven't drunk enough and therefore get the double hit of dehydration and negative energy balance.
    that puts you way below the ideal feeding level

    everyone's different, but i'd think using drinks is more likely to cause upset due to the higher volume - if you started well hydrated and aren't losing 500ml an hour, eventually something is going to give

    try splitting things

    plain water, or add a lemony zero-cal isotonic tablet, makes it easier to tolerate sweet gels, hours of claggy sweet taste is not pleasant

    see if you can find gels that use just glucose, might be easier for you to tolerate
    my bike - faster than god's and twice as shiny
  • mrfpbmrfpb Posts: 4,478
    You don’t want to be raising your heart rate out of Zone 2 for any length of time, on a long’un. 178-188 ain’t most people I know’s zone 2. Your body is trying to tell you something, it’s best to listen.


    Its this rather than nutrition thats the issue. Get used to going easier at the start. (And you use more calories from fat in the lower zones.)
  • fenixfenix Posts: 5,437
    Sounds to me like you were knackered by the end. If you can;t do the work with your legs then you can;t expect the heart rate to be maxing out.

    I'm taking it the FW isn't your normal day out ?
  • imposter2.0imposter2.0 Posts: 11,003
    fenix wrote:

    I'm taking it the FW isn't your normal day out ?

    Is it anyone's normal day out? ;)
  • graemevetgraemevet Posts: 61
    Ha ha, the FW is definitely not my normal day out! :lol:

    It was only my second >100mi ride since August last year and about double the normal amount of climbing that I'm used to!
  • fenixfenix Posts: 5,437
    I think that explains it then. Your legs are shot so they can't do a huge amount of work so your heart rate won't be elevated as much as it will when the legs are strong.
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