Power and heart rate monitors

[The Doctor]

I would like to clear up a few misconceptions regarding power meters and heart rate monitors as there have been a few posts in the past 6 months related to this issue.

 

There is no argument about the benefit of training with a power meter. Power meters provide the athlete and coach with significantly more data than a heart rate monitor alone. Monitoring performance changes over time and identifying fatigue is significantly easier with both power and heart rate measurement together. If you want to maximise your training then a power meter is always going to benefit you more than a heart rate monitor, PROVIDED that you use it correctly.

 

The question that arises is whether it is more beneficial to train at a particular power output value or heart rate zone.

 

Until recently there have been no peer-reviewed scientific studies comparing heart rate to power based training. NONE!

 

We recently completed a study which investigated a high intensity training protocol using either heart rate or power. Although each group of subjects trained at identical averge power outputs and heart rates throughout the study, the heart rate group improved their VO2max and peak power output to a greater extent. Although the power values during each interval did not differ, it seems that the particular power curve during heart rate based intervals provided a greater training stimulus (The heart rate intervals started at higher power and finished at lower power than the very constant power ouput of the power based intervals)

 

This study is in review in an iternational peer reviewed scientific journal and will be publsihed in due course.

 

The above study is only applicable to the particular session that we used - 8 x 4min at 80% PPO with 1.5min rest or 8 x 4min at 91% max HR with 1.5min rest (80PPO = 91% max heart rate for this group of athletes)

 

Whether or not the same applies to other training sessions (longer or shorter intervals or lower and higher intensities) remains to be seen but the science has not been done yet.

 

There are some training sessions that by their nature will necessitate the use of a power meter. T-max intervals (which have been proven to provide the greatest training stiumulus in very highly trained athletes) can only be performed using a power meter or ergometer. Similarly, Blowout sessions also require a power meter.

 

In conclusion:

 

If you want to have the best training tool, then purchase a power meter. However, using it incorrectly MAY provide you with a lower training stimulus than a heart rate monitor.

 

If in doubt, perform your intervals by either adhering to a heart rate zone or alternatively by aiming for an average power output during each interval (instead of rigidly sticking to a prescribed power value). Then use the power data to monitor your training load, adaptation and fatigue (get a good coach or use cyclingpeaks software).

 

 

 

 

[Riccardo]

Awsome summary.I just recently purchased a Powertap unit and can see the advantages,particularly when having to do intervals.power reading is immediate,whereas heart rate would take time to reach designated intensity.I still prefer the power route,now that I have tried both,but it would seem that you are a person in the know and as such accept your opinion.

[Riccardo]

Have just checked your details out.Have met you before at your work place and cannot doubt for one bit what you said.

[BikeMax]

 

 

 

I would like to clear up a few misconceptions regarding power meters and heart rate monitors as there have been a few posts in the past 6 months related to this issue.

 

There is no argument about the benefit of training with a power meter. Power meters provide the athlete and coach with significantly more data than a heart rate monitor alone. Monitoring performance changes over time and identifying fatigue is significantly easier with both power and heart rate measurement together. If you want to maximise your training then a power meter is always going to benefit you more than a heart rate monitor' date=' PROVIDED that you use it correctly.

 

The question that arises is whether it is more beneficial to train at a particular power output value or heart rate zone.

 

Until recently there have been no peer-reviewed scientific studies comparing heart rate to power based training. NONE!

 

We recently completed a study which investigated a high intensity training protocol using either heart rate or power. Although each group of subjects trained at identical averge power outputs and heart rates throughout the study, the heart rate group improved their VO2max and peak power output to a greater extent. Although the power values during each interval did not differ, it seems that the particular power curve during heart rate based intervals provided a greater training stimulus (The heart rate intervals started at higher power and finished at lower power than the very constant power ouput of the power based intervals)

 

This study is in review in an iternational peer reviewed scientific journal and will be publsihed in due course.

 

The above study is only applicable to the particular session that we used - 8 x 4min at 80% PPO with 1.5min rest or 8 x 4min at 91% max HR with 1.5min rest (80PPO = 91% max heart rate for this group of athletes)

 

Whether or not the same applies to other training sessions (longer or shorter intervals or lower and higher intensities) remains to be seen but the science has not been done yet.

 

There are some training sessions that by their nature will necessitate the use of a power meter. T-max intervals (which have been proven to provide the greatest training stiumulus in very highly trained athletes) can only be performed using a power meter or ergometer. Similarly, Blowout sessions also require a power meter.

 

In conclusion:

 

If you want to have the best training tool, then purchase a power meter. However, using it incorrectly MAY provide you with a lower training stimulus than a heart rate monitor.

 

If in doubt, perform your intervals by either adhering to a heart rate zone or alternatively by aiming for an average power output during each interval (instead of rigidly sticking to a prescribed power value). Then use the power data to monitor your training load, adaptation and fatigue (get a good coach or use cyclingpeaks software).

 

 

 

 

[/quote']

 

Interesting post - thanks.

 

A few questions;

 

1. Were the results of the study significant ?

 

2. How many subjects ?

 

3. Are you saying that the average power output for the HR group was the same for each interval as the average power for the power group in relative terms, but only the way the interval was ridden lead to the different results ?

 

4. If the answer to 3 is "yes" then did you not experience any power drop off at all over the 8 intervals in the HR group whilst maintaining a steady HR ?

 

5. What was the Normalised power for each group during each interval  -

I suspect the HR group may have had a nigher NP due to harder start and higher peak

so TSS would have been higher leading to a greater stimulus and so more

response  (i.e the sessions were not equal) ?

 

6. What were the control conditions to ensure that recovery, diet, work stress etc were identical for both groups ?

 

7. How do you account for genetic ability and it's impact on performance improvements ?

 

8. If, as you say, that the way an interval is ridden alters the effectiveness of that interval, then it would be relatively easy to ride that interval in the way you describe using power alone. I am not sure what the relevance of HR is to the conclusion of your study and why or how you link the use of HR to riding an interval in a particular fashion.

 

It seems to me that your study has set out to prove that by riding an interval at a variable power may lead to greater performance benefits than riding the same interval at a constant power ?

 

Cheers

 

Peter

BikeMax2008-04-16 03:32:46

[Rocket Man]

Cool stuff Doc.

 

Here's a few other variables to throw in - (HRM plus SRM).

 

1. An interesting measure of "fitness" is the ratio of power over heart rate. It correlates with how bad it feels at a given power output. Without exception early morning training produces a significantly lower ratio than afternoon (ie lower power for the same effort).

 

2. There is a strong negative correlation between cadence and power irrespective of the duration - lower cadence  produces more power (peak and average) for the same heart rate.

 

3. The ambient temperature has a significant impact on sustainable power.

 

4. The load characterisitcs of most trainers change as the exersise progresses so performance can either appear to increase or decrease.

 

5. The load characteristics of most trainers changes with ambient temperature so you may find better performance on colder days.

 

6. With carefull planning you can always set a PB - cool day, low cadence, high loading, operate at high heart rate etc...

 

It seems to me that the number of variables that affect performance make it very difficult to measure your current state of readiness for a race. Of course basic things like overtraining do show up easily but to be certain that you're 5% fitter/faster/VO2maxed or LT'd since a previous measurement is very difficult to achieve...

 

 

[PPWTF]

Not wishing to steel your post, but you seem like the people to ask....

I am seriously researching a return to full time study, having take a 1 year break from work. I am trying to figure out how i would go about get into a work position in an elite sports environment (having a long term view/plan).

I know everyone always answers sports science degree. or that you have to have a competative sporting background, but all the sports science grads I know ended up doing personal training at Virgin active type places..... and I've never been a pro-am level sportsman.

What would you recommend as a line of study, what is the most targeted approach to take? Very interested to hear your thoughts

[BikeMax]

 

Not wishing to steel your post' date=' but you seem like the people to ask....

I am seriously researching a return to full time study, having take a 1 year break from work. I am trying to figure out how i would go about get into a work position in an elite sports environment (having a long term view/plan).

I know everyone always answers sports science degree. or that you have to have a competative sporting background, but all the sports science grads I know ended up doing personal training at Virgin active type places..... and I've never been a pro-am level sportsman.

What would you recommend as a line of study, what is the most targeted approach to take? Very interested to hear your thoughts

[/quote']

 

Tough call - I would certainly say that in order to work in an elote sports environment that a good level of ex physiology is a prerequisite - but that points you back to the sports science degree. One other thing you might look at is American College of Sports Medicine - I did this after my degree in around a year and it is very focused in terms of sports performance. The issue may be the entry qualifications but you would have to discuss this with them.

 

The issue here that is the bigger one is that, regardless of your qualifications, there is not much of an environment in elite sports to support this type of person. In cycling for example, the Brits, US and Aussies have high performance institutes solely focused on performance in this sport and that consist of ex phys, ex psych, docs etc.

 

Apart from SSISA (which is a great facility ;-) there may be limited opportunities.

 

[JasonW]

I'm inclined to agree that riding to a floating avergae power value is more beneficial than riding to a static value which negates onces ability to push oneself.

 

The problem that I have with HR training is that one can simply not tell whether you are still in the same zone that you were in when you started, or possibly even which zone you started in!

 

For example you could set out to perform a 20 min L4 (threshhold) interval, but would typically start in L5 (VO2 max) and then drift down to L3 (tempo) by the end. You think that you have performed a constant effort as your HR has stayed the same.

 

The advantage of the power metre is that it allows you to aim at and validate your efforts to ride in a defined zone.

[PPWTF]

Thanks very much for your reply Peter.

 

I guess the only clear advantage of getting older is that you do get more patient, and coupled with the reality of knowing you can't take over the world tomorrow, you're so much more prepared for what comes next.

 

I know that if I do follow though with this that it is a very long term thing (taking a year out has been eye opening to say the least).

 

Thankfully there's plenty of motivation; 14 years of work before deciding that enough was enough and that i might actually benefit from doing something I actually want to do, that maybe that I should seriously rethink what I expect out of my job, makes for a pretty powerful driving force :-)

 

 

PPWTF2008-04-16 03:19:28

[BikeMax]

 

Thanks very much for your reply Peter.

 

I guess the only clear advantage of getting older is that you do get more patient' date=' and coupled with the reality of knowing you can't take over the world tomorrow, you're so much more prepared for what comes next.

 

I know that if I do follow though with this that it is a very long term thing (taking a year out has been eye opening to say the least).

 

Thankfully there's plenty of motivation; 14 years of work before deciding that enough was enough and that i might actually benefit from doing something I actually want to do, that maybe that I should seriously rethink what I expect out of my job, makes for a pretty powerful driving force :-)

 

 

[/quote']

 

I second that for sure - after 15 years in the corporate world, I am now doing something I love (But the money sucks ;-)

 

[The Doctor]

Peter

 

The reason I placed the post was to clear up the misconception that we at SSISA are somehow against power meters. As you can see, it is actually quite the opposite.

 

The study that we undertook was not "set out to prove" anything. We saw a gap in the research that has been done and decided to investigate.

 

We have no vested interest in the outcome and the trial was conducted under strict ethical conditions as are all research trials conducted through the University of Cape Town.

 

I appreciate that you will naturally have some bias and therefore adopt a fairly aggressive stance. Instead of trying to find fault with the resaerch, why not show some evidence to counter our findings (there is none!)

 

In response to your questions:

 

1) Yes

 

2) 20

 

3) Yes

 

4) No. The heart rate group was encouraged to reach the target heart rate in all intervals. The average values validate this.

 

5) Normalised power is a term used by Cyclingpeaks and is not a scientifically validated term. A similar term would be training impulse or TRIMPS. The answer then is yes. Although the average power and heart rate values were identical, the TRIMP values for the heart rate group were higher. As many coaches prescribe power based intervals and ask the athlete to sustain a fixed power throughout the interval, our findings validate the advice that fixing power output may result in a lower training stimulus than fixing heart rate.

 

6) The training and testing conditions were strictly controlled. Each athlete performed the performance tests at the same time of day, under stable climactic conditions in a temperature, pressure and humidity controlled laboratory. Other factors were also controlled

 

7) There is no method to account for genetic variability but both groups were randomly assigned and matched for performance data prior to participation.

 

8) Answered in my previous post

 

Please do not post any similar questions. You can have a copy of the journal when its published and then you can have a go at the study. However, I anticipate your approach will be somewhat biased.

[Slowbee]

 

Please do not post any similar questions. You can have a copy of the journal when its published and then you can have a go at the study. However' date=' I anticipate your approach will be somewhat biased.

[/quote']

 

sheesh Doc, that sounds a bit harsh!!

 

Its great to read the questions and answers. Not all of us have access to the journo's.

[BikeMax]

 

Peter

 

The reason I placed the post was to clear up the misconception that we at SSISA are somehow against power meters. As you can see' date=' it is actually quite the opposite.

 

The study that we undertook was not "set out to prove" anything. We saw a gap in the research that has been done and decided to investigate.

 

We have no vested interest in the outcome and the trial was conducted under strict ethical conditions as are all research trials conducted through the University of Cape Town.

 

I appreciate that you will naturally have some bias and therefore adopt a fairly aggressive stance. Instead of trying to find fault with the resaerch, why not show some evidence to counter our findings (there is none!)

 

In response to your questions:

 

1) Yes

 

2) 20

 

3) Yes

 

4) No. The heart rate group was encouraged to reach the target heart rate in all intervals. The average values validate this.

 

5) Normalised power is a term used by Cyclingpeaks and is not a scientifically validated term. A similar term would be training impulse or TRIMPS. The answer then is yes. Although the average power and heart rate values were identical, the TRIMP values for the heart rate group were higher. As many coaches prescribe power based intervals and ask the athlete to sustain a fixed power throughout the interval, our findings validate the advice that fixing power output may result in a lower training stimulus than fixing heart rate.

 

6) The training and testing conditions were strictly controlled. Each athlete performed the performance tests at the same time of day, under stable climactic conditions in a temperature, pressure and humidity controlled laboratory. Other factors were also controlled

 

7) There is no method to account for genetic variability but both groups were randomly assigned and matched for performance data prior to participation.

 

8) Answered in my previous post

 

Please do not post any similar questions. You can have a copy of the journal when its published and then you can have a go at the study. However, I anticipate your approach will be somewhat biased.

[/quote']

 

Easy there boy :-)

 

If my post or questions came across as agressive then I am sorry - that was certainly not my intention.

 

If you post something like this on a forum then you ought to expect to be asked some challenging questions without getting defensive. All "peer reviewed" research needs to be able to stand up to scrutiny.

 

Whether or not you use TSS, NP or Trimps, the bottom line is that it looks like the intervals were not the same in terms of training load, and so I would not expect the same response in terms of performance.

 

I am surprised at your assertion that many coaches prescribe intervals to a fixed power level - my experience does not bear this out, as most of the guys I have worked with use a target "range" to prescribe intervals, and in an interval of the duration you tested, it is normal to see a higher load at the start with a gradual decline over time - hence similar to your HR group.

 

The bottom line is that "interval pacing" is not dependent or indeed related to HR but how you choose to ride the interval.

 

 

 

 

 

[Rocket Man]

Although each group of subjects trained at identical averge power outputs and heart rates throughout the study' date=' the heart rate group improved their VO2max and peak power output to a greater extent. [/quote']

 

Doc, did you look at why this happens?

 

I know from track training programs that 4min intervals aren't going to help your VO2 or max power very much. But shorter, higher intensity intervals are far more effective. Is it not the case that your constant heart rate subjects were actually doing a totally different program from the constant power guys? By that I mean that they were getting more peak power training during the period that they were raising their heart rate. I'm guessing that there would be a 30% higher peak power for the HRM subjects.

 

Given the number of intervals they were doing the power subjects were training TT capability whilst the heart rate subjects were training peak power with active recovery...?

 

[The Doctor]

Sorry Peter

Its difficult to gauge the tone in the written form.

Feel free to ask questions at your leisure.

[The Doctor]

Although each group of subjects trained at identical averge power outputs and heart rates throughout the study' date=' the heart rate group improved their VO2max and peak power output to a greater extent. [/quote']

 

Doc, did you look at why this happens?

 

I know from track training programs that 4min intervals aren't going to help your VO2 or max power very much. But shorter, higher intensity intervals are far more effective. Is it not the case that your constant heart rate subjects were actually doing a totally different program from the constant power guys? By that I mean that they were getting more peak power training during the period that they were raising their heart rate. I'm guessing that there would be a 30% higher peak power for the HRM subjects.

 

Given the number of intervals they were doing the power subjects were training TT capability whilst the heart rate subjects were training peak power with active recovery...?

 

 

Rocket Man

 

4 minute intervals have consistantly imrpoved VO2max and PPo by between 3 and 6 percent over a 4-6 week period. There are about 6 different studies that have proven this.

 

The fact that they are doing short bursts of "supra-maximal" training at the start of each interval is the reason that we summised that they improved to a greater extent than the poewer group.

 

By the way, the improvement in 40km TT time was the same for both groups 2.1% vs 2.3%.

 

Peter - Using a power band would have restricted the maximum power in the early part of each interval, something that didn't happen in the heart rate group.

 

Remember that this study only applies to that particular type of session. Someone out there needs to do more research for LT type sessions to see whether staying in a power band is providing more benefit or whether "preloading" the interval to get the heart rate up is going to provide a greater training stress or impulse.

 

Training studies are time consuming and exhausting (not just to the athletes)