ATC 336: In-Depth Sweet Spot Bike Training Guide for Ironman and Beyond, Going From Too High Heart Rates to MAF Focus for Master’s Athletes, and More

January 14, 2022


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Greg asks:

Sweet spot training: How much and how far out for Ironman?

Hey guys! I am curious to hear Lucho talk more about sweet spot training on the bike for Ironman. I am 42 with a cycling background and have done some triathlons but starting training for my first full Ironman in 2022 and feel like sweet spot training makes sense for me on the bike, but I can’t find much information on this approach and just wanted to hear more from you guys.

When you should start this in the training cycle? How much time spent in this sweet spot zone per week? What other bike workouts complement this type of training? Are there times it should be avoided? Thanks so much for any input!

What the coaches say:

  • Sweet spot on the bike is applicable to athletes who need lower volume training.
    • e.g. 8hr/wk or less on the bike; or if you’re training for Olympic distances races
    • It’s not for everyone- it does add a strong stimulus and added risk for some!
    • Look at TP TSS- if you’ve 1hr to bike, is Z2 going to stimulate you if you’re already pretty bike fit?
  • Sweet spot is
    • Mid Z3 and higher, don’t go over Z4.
    • It is 84-97% of FTP
    • If you’re doing Z3/Z4 sweet spot- must realize the stress is higher than usual Z2 training.
    • It’s like tempo-plus, higher stimulation of muscle tendon than pure tempo.
    • Meanwhile not much muscle stress at Z2- so volume matters to get the stimulus, i.e. 3hr minimum if doing Z2 but less with sweet spot.
  • Can implement sweet spot in the base period.
    • Weekday rides could be: 45-60min high Z2/low Z3 into sweet spot but not over Z4; weekends 4-6hr Z2 ride.
    • Sweet spot is supplementing Z2 work, it’s slightly harder effort but still aerobic.
    • Don’t fear tempo/sweet spot; it is not true intensity nor will it mess up your fat burning or base training.
  • When should you start this in training cycle?
    • Immediately if coming in fit…. 
    • But if not that fit, you can tweak it and still achieve the goal: Can be as simple as 10 x 1 min /1 min off at sweet spot watts (a lower risk workout).
    • Watch TSS- only bumping it a little bit not crushing yourself.
    • So, do sweet spot in base, not mid-season build, and it is for time-crunched athlete
  • Caveat: sweet spot not good for run training or runners.
    • Running too hard is the biggest mistake we make (however, tempo ok!)
  • How much time spent in sweet spot?
    • You can try to predict it but we’re not some machine so there’s an intuitive nature to it.
    • When getting into a sweet spot workout: you can be a bit tired and its still ok, but adjust intervals, if you don’t feel good back it off.
    • Don’t get locked into trying to hit a data point if it’s not the day!
    • With sweet spot, train to fatigue- i.e. do as much as you can…
    • For example of a 3-day block of descending intensity:
      • Get on the bike and do as much as you can, hold watts till “it sucks” then back off, and repeat intervals.
      • Next day, that feels too hard? stick to Z3/tempo but not as hard as sweet spot.
      • 3rd day now just do Z2- and this is more quality because you’re tired now.
      • You can use fatigue to complement the next workout.
  • How much time per week at this zone?
    • As much as you can handle without it screwing up the rest of your training!
  • Word of caution: Sweet spot the day before a run can screw up a run.
  • Complementary bike workouts:
    • Z2 rides, sweet spot will increase FTP- don’t mix sweet spot with FTP, Z5,Z6.
    • However if you want to raise FTP to raise sweet spot wattage, this is not a complement to your current sweet spot training.
  • Sweet spot WILL increase FTP in itself, so don’t overdo it by doing quality more than this.
  • When you reach your IM build period (after base):
    • Back off sweet spot a bit, and edge more toward a polarized approach as training goes on (z1/Z2 and Z5-Z7 or VO2 power).
    • A traditional linear periodization training cycle is about 8-week blocks that include:
      • Base: 18-26 weeks out and the time to do sweet spot if coming in bike fit (20-28 weeks with longer taper).
      • Build: 10-18 weeks so now do less sweet spot, start work more polarized with more time in either Z1/low Z2 or Z5/Z6- can still do sweet spot just be on top of recovery (and also things like not running hard).
      • e.g. Lucho says he is not running or swimming hard at all, all Z2/MAF focus in those sports.
      • In this build you can stimulate VO2 but not crush it, don’t need to wreck your world.
        • *minimal effective dose- VO2 max 8-9 minutes TOTAL.
    • Specificity: The last 10-12 weeks abandon polarized/Z5 and go back to sweet spot because this is still considered specific and complements IM wattage/Z2.
  • Is the “gray area” really that bad?
    • Not if you’re using data to guide you! You will be forced to back off and not get stuck there.
  • Nutrition considerations:
    • If you are going to do sweet spot, you better factor in calories… as well as other markers of holistic health, don’t start this kind of training if you’re drained and worn down already.

Jennifer M. asks:

53 and MAF—help!

I’ve been dabbling in endurance training and triathlons for the last 10 years or so, basically ever since my kids were older and I had more time to myself again. For a long time I’ve been training by pace and grit while ignoring HR but realizing my training and racing heart rates were just so high (I would see HR in 170s in training and even over 180 in races like half-marathon!). I started working with a coach who applied zone training to my workouts, based off lactate threshold, and my Z2 was set at 140-155. I was running an ok pace at this zone and getting the training done, but not recovering well and still worn down, so after some research I came across MAF method and have been dabbling with my 180-age HR (a whopping 127- yikes!) and I’m STRUGGLING. This has me at a 13:00+ pace on average, usually with walking to keep HR down. I am not signed up for anything this year and self-coached at the moment, but have my heart set on doing an Ironman before I turn 60! I have time, so should I just stick to this low HR and hope for the best? Or with a higher heart rate that I’ve seen in the past should I adjust my MAF? How much run mileage/week would you recommend for someone in my age group?  How long should it take till I expect results with MAF, before adjusting the HR or training? Also- if I’m looking long term at Ironman, what tips now would you have for getting my bike up to speed, I can go all day but I’m sloooow and probably on the weaker side.

What the coaches say:

  • Testing lactate threshold, how was that done? 
  • If you’re doing a 20-30min run TT (or bike TT too), you have to subtract- e.g. Take 95% and subtract 10 watts for the bike
  • These numbers are pretty arbitrary and can be wrong
  • For her, she can stick to MAF if everything else in life feels good and balanced
  • However, it might help to split the difference and set your modified MAF zone at 130-145 HR, that will fulfill that goal and keep it fun and enjoyable!
  • Don’t look at the physiological aspects in a vacuum—if you hate it it’s not going to work
  • Start from a point of building confidence and gaining satisfaction
  • For example regardless of how useful it is, if it’s not sustainable and you hate it, it’s useless
  • It’s not like 140-150 bpm is completely anaerobic
  • How long till you should expect to see results? Give it 3-4 months of this.
  • Along the way you will see subtle increases and training benefits that may not be as obvious as faster pace per mile, pay attention to your body and the signs. For example, just getting less tired for the same training load. Something that once was hard maybe isn’t as hard anymore—that’s a boost in fitness even if not easily measurable! 
  • Monitor recovery… does it improve at this new, revised range?
  • How is nutrition, be sure to think outside the box in how your training is progressing—it’s more than just heart rate and mileage.
  • Maybe not “go all day” on the bike at this point and give the run a shot first. You can still bike just not to the point of draining you and negatively affecting the run.
  • Use data and auto regulation to guide training and not overdo it!

One Comment

  • Taylor says:

    Hey all, thanks for being such a great resource. Just started the MAF method to help train for my first 70.3 four months from now. Committed to being patient with it, even at 12+ minute miles. But I am finding that running that slow causes discomfort in my knees after my run is over. It feels like I’m just trudging along and there is more pressure on my knees and quads while running. Thoughts on how to reduce this discomfort? Or will this go away as I build aerobic base and can run at a faster pace again?


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