The Link Between Pedal Cadence And Heart Rate On The Bike

Why Care About The Link Between Pedal Cadence And Heart Rate?

It’s About Being Aware Of What’s Going On

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Maintaining high pedal cadence is tough with PowerCranks.

When you ride a trainer bike there are two main sources of data collection, the dashboard and perceived effort. My old trainer is set up with PowerCranks. Great tool, but take care not to strain a hip flexor.

Is 90-95 the most efficient pedal cadence on the bike?

Most coaches say so!

Question the obvious.

It is becoming ‘obvious’ that the most efficient cadence on the bike is around 90-95. Based upon things I have been told by coaches and read it on the Internet.

But is this true all the time? I doubt it. During long trainer rides you have plenty of time to explore your cycling skills. Such skills include pedal cadence. Such exploration passes the time nicely. Increases your focus on what you are doing (riding a trainer), and perhaps will lead to something that improves your racing skills.

I noticed today, during a 2-hour trainer ride at 140 watts (my zone 2 wattage), that my heart rate was clearly linked to cadence in a highly consistent manner.

Watching heart rate and pedal cadence on the trainer bike

Comparison of dashboard of the trainer at 140 Watts on Computrainer control, at high (left) and low cadence showing higher heart rate at higher cadence.

My approach to this ride was to carry out a repeated sequence, to share load between fast (glycolytic, anaerobic) and slow (oxidative, aerobic) muscle fibers. I used a workout cycle of 10 min at 90-95 cadence, followed by 5 min at 50 rpm.

I noticed the following pattern:

Cadence     Heart Rate     Watts

90-95            114-119           140

49-54            104-110          140

This pattern was consistent for all eight repeats of my ride sequence.

I wondered why this is so.

My proposed hypotheses concerning pedal cadence and heart rate:

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  1. The CompuTrainer is giving a false reading for wattage (I doubt this).
  2. The whole-body physiology of fast twitch (oxidative) versus slow twitch (glycolytic) fibers modifies blood lactate or some other metabolite in such a way as to modify the associated heart rate.
  3. The heart rate (cardiac cadence) is entrained by the pedal cadence as a result of linking signals, such as differences in pulsatile venous return rate or neural connections.
  4. High cadence takes greater mental concentration (for me, anyway), and as the brain uses about 25% of whole-body blood flow, the higher cadence requires greater cerebral flow expending energy for brain function (I’m grasping at straws now).
  5. Heart rate is not a good indicator of effort expended, assuming that it is the same at high or low cadence based on an identical wattage of 140.
  6. Other? – Ideas?

You may wonder about the value of such an observation, which is the whole point of this line of thought. Maybe, if you want to rest your legs (they tire at low cadence) use higher cadence, and if you want to rest your brain, which becomes exhausted by the constant mental effort of pushing forward in a race, use a lower cadence. It’s worth a try anyway.

Take care on the roads!

FitOldDog

Today’s workouts:

WorkoutPLAN Coach: Chris Hauth
 Bike
Duration: 02:00:00
Description:
nothing hard here – just steady Z2 cycling

Comments

  1. Kevin
    Great observation. What you say is true. Lower cadence = lower metabolic output.
    Many studies have shown that a cad or 50-60 is the most efficient. But what those studies dont take into account is muscular endurance and overall riding fluidity nor how the movement of pedaling aids in blood transport.

    I dont agree with most of the work that has been done showing ideal cadences. Most of those studies are flawed.

    So whats your ideal cadence? Its whatever you train for. No one is born to pedal at 90 or even 110 rpm.

    It is a learned skill.

    Most riders can easily train to ride at a cadence of 85-110rpm. Lower rpms will lead to less endurance and more overall muscle and body fatigue.

  2. Also Short bouts of lower cad during your ride does really give a rest. Its a good way to calm your aerobic system for a minute or two.

    • Hi Victor,
      What are your thoughts on my system, which is 30 minute PowerCranks to warmup and engage my hip flexors, followed by repeating sets of 10 min higher cadence, 5 min low cadence, until the end of the trainer ride?
      Thanks for the comments.
      -kevin

      • I would keep the higher cadence sets short. You dont want to be sloppy. I recommend no more than 3 minutes of focused practice. Yes there is science support 2-3 minutes. I think you already know that

        That is of course if the purpose of this workout is to build higher rpm.

        • Hi Victor,
          When working to train my neuromuscular systems to accept a higher cadence I go to 120 -150 rpm, this rate (90-95) is my working cadence on the road. I agree with 2-3 min for high cadence and high load work. I use the 10/5 cycle to mimic hills on rollers.
          -k

  3. Ken Meyer says:

    The higher heart rate at a higher cadence can easily be understood with a simple (thought) experiment, IMO:

    a) put your bike on a trainer
    b) remove the chain
    c1) pedal at 60 rpm
    c2) pedal at 130 rpm

    The useful output in both cases is zero watts.
    The heart rate in the second case is higher because moving the mass of your legs faster requires more power. That is simple physics.

    That is not to say, that a higher cadence has no beneficial effects in racing. But obviously it comes at the price of less energy efficiency.

    • Hi Ken.
      Boy, I wrote that a while ago, when I was still using PowerCranks (they broke!). This really is a fascinating topic. I suspect, for optimal efficiency, that it mainly comes down to balancing the use of slow versus fast twitch muscles. High cadence seems to win out overall, once one can hold it there – sometimes my legs will be spinning, when I am really in shape, and they seem to be doing it entirely on their own, but only at high cadence (90+). It’s like an engine, and it sure feels great – not there, right now.
      Yep, it takes energy to move your legs around. Standing is really costly, I find.
      I wonder if entrainment plays a role in heart rate and cadence?
      I’m not a great cyclist, but I do love getting out there into the country on early morning rides.
      Thanks for the comment.
      Cheers,
      Kevin

  4. I recently installed a power meter on my bike. With the indoor riding season, I needed something to break up the boredom, so did a sequence of constant power runs a different cadence. I started in the center (70 spm) and then worked on both sides alternatively (80, 60, 90, 50) to normalize the effect of fatigue to some degree. Each run was five minutes long. At 150 watts constant power, here is what I recorded…
    Cadence – Heart Rate
    50 spm – 129 bpm
    60 spm – 136 bpm
    70 spm – 138 bpm
    80 spm – 142 bpm
    90 spm – 149 bpm
    I also felt much less stressed at the lower cadence. When the weather warms, I am going to do six 20 minute trials at 150 watts, alternating between 50 and 90 spm to see how my leg muscles fatigue at the two different cadences. It will be interesting… 🙂

    • Hi Joe,
      I enjoyed hearing from you. I often wonder if the spin response is due to physiological entrainment. It’s counter-intuitive, because higher cadence TENDS to lead to more efficient output for a given input – that’s the dogma, anyway. I suspect that age plays a role. I find that it takes me much longer to attain a high cadence in my 70s than I did in my 50s.
      The trick is to listen to your body, I think. Not that you can always trust it – if it can get out of working, it will!
      Do you have a race planned?
      If you do, a coach can be essential, but they are pretty expensive.
      I’ve been training all my life, but Ironman for only 20 years – still learning new things as I go along.
      64 – those were the days.
      If you have specific questions, let me know, and I’ll answer, or attempt to send you to the right ‘expert.’
      Kind Regards,
      kev aka FitOldDog

      • Hi kev,

        Thanks for responding so quickly! It is unusual for me to be the youngster when talking with other cyclist. Looks like I have lots to look forward to.

        I was an athlete in high school (cross country, basketball, track), but life (work, family – all good) were priorities until I retired last year. Been working on getting into shape and then plan on looking for low level competitions in the local area this summer.

        Though I have a competitive streak, it is not near as strong as it was when I was younger. I get more pleasure out of my personal growth and helping others to develop than winning these days, but there is nothing like competition to make the juices flow and to create strong relationships with others.

        I inquired with a coach through Training Peaks, but you are right, it is expensive. Figured I could self coach for a few more years and then when I hit the development wall I can consider coaching. I have read The Cyclist Training Bible and Training with a Power Meter. My annual plan is built around the teachings of Friel and Coggan. Figure that should suffice for a while. I am just barely into the Cat 5 power capabilities at this point. 🙂

        For now I guess I am the GetFitPup… 🙂

        Best Regards,

        Joe

  5. FYI… I am 64 and have only been riding for the last two years, so not highly trained (may influence pedaling efficiency at higher cadence?). I am using Training Peaks and currently about 12 weeks into my annual training plan. My power meter is a 4iiii Precision. Two days a week at the gym working on strength training and three days a week on the bike. Come spring, I will do one day a week at the gym for strength maintenance and will ride four or five days a week (weather permitting).
    It is great to be able to share experiences.

    • Hi Joe, sorry for the delay.
      If you don’t have aortic disease, squats and wall sits are the trick for a strong bike. I’ve used Training Peaks workouts, and they are a great, cost effective, approach.
      For direct conversations with other athletes, Facebook works really well. Lots of great feedback.
      kev

  6. Johan Schoeman says:

    Johan says:
    Aug 30 2017,
    Hi Kevin,
    I am 67 yrs old and I got back on the bike 4 yrs ago after an absence of 40 yrs.
    My MTB and ROAD bike are fitted with a power meter and I use WKO 4 to annalize and record my workout and race data.
    My progress over the past 4 yrs were not to my satisfaction. I am yet to find what sequence of workouts really works for me. Leave alone what to eat and drink best.
    During yr No 3, I purchased a 24 week training program from a top coach in our country.
    During the first week the program prescribed a 2 hr workout at a cadence of 95 to 110 on the first day at very low power. My legs were so soar the next two days, I could hardly walk.
    I wrote to the coach telling him that he did not take my age and level of cycling into consideration. I told him this program is not for me. So I continue to workout as I use to.
    The past two years saw me reading almost very thing possible, from Friel, Coggan, Candian Long distance, how a 64 yr old train for RAAM and the lot.
    The money for a full time coach is not on.
    At the start of my race year No 5, which is 7 weeks ago, I took the 24 week training program on my computer and slowly when through it week by week, and realised the every thing I red was built into this program, the works!!!!
    Yes, after five weeks I could do 3 hrs at 97 rpm 90w and the next day 2 hrs at 95 rpm. at 105 w.
    Yesterday, after 7 weeks into this year, I have done my best ave watts during a two hour workout and equal my best one hour ave power, races include for the past 4 years. My ave cadence during high effort workouts and races use to be 75 rpm. and yesterday my ave rpm was 84 rpm.
    In past years it took me 4 to 5 months plus to reach this level.
    I am convinced that this high rpm work has made a huge contribution.
    So far it seems that this high rpm workouts works for me.
    I would like to hear what you and any other cyclist or coach say about this response in my power and fitness.
    Many thanks
    Johan

    • Hi Johan,
      I remember my races at age 67, when I did my best Lake Placid time. I was coached by Chris Hauth, of AIMP. He included lab work, and used the data to set my load. It worked, even got me to the Boston Marathon in 2009. Cost was over $200/month. Can’t afford that right now!
      That said:
      Cadence for older cyclists – it takes us much longer to warm up, including warming up cadence, swimming, biking or running.
      Listen to your body, not your young coach, world-class athlete on that one.
      A training plan is key, whether you design it, or someone else.
      The best answer:
      Combine data with perceived load, with the latter dominating as you get older, to avoid injuries.
      Ride with someone or a group that is just a tiny little bit better then you are.
      That’s it.
      Oh! Yes! Keep on riding.
      kev

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