This is an example of an interval session recorded with Powertap. It's meant to be 5 x 4minute intervals at 250Watts with a minute recovery in between (except I got carried away on the third interval and did 5 minutes by mistake).
The black line is power, red is heart rate, green is cadence, and blue is speed (pretty irelevant as it was on the turbo).
Anyway it demonstrates a couple of benefits of power over heart rate. Firstly, the heart rate takes a good two or three minutes to catch up with the effort you're putting in, so if you were doing these intervals on HR you would have to guess the effort to reach the target HR. Secondly, each interval ends up at a higher HR, so if you were doing them at a target HR the power you were putting out would reduce each time.
[img]http://i85.photobucket.com/albums/k75/jrhemming/Intervals.jpg[/img]
Heart Rate Monitors
22 posts
• Page 2 of 2 • 1, 2
by Matthew Ives » Thu Sep 14, 2006 6:21 am
[quote]Matt - I think I fall well in to the rough guide type of rider Very Happy
heheh...me too.Except for rough you can add 'skint', so I won't be getting apower meter any time soon
Jon: can't see your picture/graph but what you say about the lag is spot on and also the observation you make about HR going up on each subsequent interval. After each interval, it's easier and easier to get the heart rate up and it also seems to creep up higher after each one.
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by Toks » Thu Sep 14, 2006 10:11 am
[quote]You asked about doing sessions on feel. The problem is feel is not specific enough. On feel, a recovery ride is usually done too hard where with a HRM you have the data to stop that. The same with all training sessions I guess.
I gotta disagree about riding on 'feel'. Its actually surprisingly accurate especially for anyone who's used a heart rate monitor for a period of time. I can generally guess my av hrt to within a few beats on my regular training route. Like Jon I only use mine occassionally. Last year I actually think it was hindering my progress when racing and training because I was so obsessed with staying in a specific zone. So hence there were days I could've pushed a litte harder despite feeling good but didn't coz my heart rate monitor said I had reached 90% of my max...
Also when I've taken a week off the bike my heart rate will often be up to ten beats higher than it normally would under threshold training circumstances. So if you're sticking to you're hrm training zones you'll be putting less effort than you should be to stay in the zone. If you were training on`feel` this wouldn't be a problem.
In addition, its quite possible to ride moderately hard for three days in a row and on the 3rd day your heart rate av may have fallen by nearly ten beats. Again if you a 'zone junky' you're gonna get caught out and may even attempt to ride harder to get your hRt up. When in fact by riding on 'feel' you'll instintively know that you're putting in the required effort.
On top of all that you should consider Cardiac Drift (heart rates tendency to rise over time probably as your core body temperature increases), alcohol, caffine, illness, anxiety and dehydration will all be a factor on your heart rate...
On the positive, regularly measuring your wake up heart rate is always useful - when its five beats or so up on its average for a couple of days it generally means your a little tired or perhaps becoming ill. Also as your general fitness increases its nice to see your average heart rate fall; and again fall quickly after very intense efforts. Also HRM are a great way to reign in overexuberance on long climbs and perhaps on cyclosportivs and long flattish TT's...So would I still get a heart rate monitor? Yes of course -just don't let it become your religous training guru
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by Robh » Thu Sep 14, 2006 12:56 pm
Jon, what sort of workout are you attempting?
4 X 5mins are usually VO2 type workouts with 5 mins rest but your doing 1 min... or it might be LT workout based on your 1 hr power?
4 X 5mins are usually VO2 type workouts with 5 mins rest but your doing 1 min... or it might be LT workout based on your 1 hr power?
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by Andrew G » Thu Sep 14, 2006 6:49 pm
Cheers Jon and Toks. I think I'd still ride mainly on feel but use a HRM more as you suggest, an aid not a dictator. Typical bloke - don't like being told what to do 
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