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Heart Rate Training with 2:21 Marathoner Jason Cherriman

By April 26, 2019May 20th, 20232 Comments
runner winning a marathon race, 1 arm in the air

“Consistency first, volume second, and maybe some more specific workouts if necessary. That gets phenomenal results, you don’t stress your body too much, the results you get from building your aerobic engine are significant” – Jason Cherriman  

Jason Cherriman (Strava) is a 38 year old elite runner from Leeds in the UK. His current marathon PB is 2:21:51 and he is trying to break 2:20 at the London Marathon this Sunday!

A recent podcast guest Jonathan Walton brought up Jason’s website Running Obsessive and I was blown away by the detail and thought he puts into his training and publicly shares for others to learn from.   

In today’s Extramilest Show, he shares many recommendations for marathoners of different levels who are looking to improve. We take a deep dive into heart rate training, aerobic development, measuring various data points, heat training, tapering and much more.   

Background stats Jason:

  • His max heart rate tested in a lab is 198
  • His vo2max during the test was 70
  • MAF hr is 147 (180 – 38 + 5)
  • In the past 10 weeks he ran an average of 111 miles (179km) per week, that’s about 14 hours a week, 2 hours a day
  • 75 to 80% of his runs at low HR (140 or below)
  • His average HR during marathon races is 174 to 177
  • PR’s – marathon in 2:21:51, half marathon in 68:55, 10k in 32:05 and 5k in 15:37.

Question of the day, what was one of your key takeaways from this conversation. Please let me know in the comments!


  Show notes

  • Jason’s background, a bit overweight in his twenties [3:15]
  • His stress fracture injury [5:30]    
  • How he combines running while working full time, being a husband and dad to 2 young daughters [6:10]
  • Jason’s first marathon experience in 2009 at the Hamburg marathon in 3:13 [8:20]  
  • Bonking spectacularly at mile 17 {11:20] 
  • Jason’s approach for his next marathons from there [12:45]
  • Current PR’s [16:40]
  • How Jason has been able to continue improving from 3:13 marathon to 2:21 marathon so far [17:59]
  • How Jason goes about Heart Rate Training [22:00] 
  • Jason’s VO2Max 70, Max HR 198 and MAF 147 [24:35]
  • Measuring aerobic efficiency [27:00]
  • The fine line between stress and fatigue levels [28:00 ]
  • Data analysis with Elevate Strava plugin with fitness vs fatigue [31:20] 
  • Marathon tapering data and thoughts [34:30]
  • Power meters on a bike vs running [35:30]
  • Jason runs with a Garmin watch 645 [37:10]] 
  • Calculating fluid loss + calories lost, so burn rate at different intensities. (540 * fluid loss(kg)) / (distance(km) * body mass(kg) * 0.75). For example, a run Jason did recently: (540 * 1.27) / (12.9*65.45 * 0.75) = 1.08kcal/km/kg [39:10]
  • Thoughts on carb depletion and carb loading around a marathon [41:20]
  • His average HR during marathon races is 174 to 177 [44:12]
  • How Jason trains for heat acclimatization [45:00]
  • Training to reduce your body temperatures, improving sweat rate, developing sweat glands, increase VO2Max, etc [46:00]
  • Floris’s experience with sauna training with heart rate monitor [50:50]
  • How much sleep Jason gets per night [52:20]
  • Aerobic efficiency – number of beats per mile [53:50] 
  • Tanda equation for marathon prediction times [55:30]
  • How Jason goes about rest days and limiting chance of injuries [56:25]
  • How Jason previously got a stress fractures by building too quickly and training too fast [58:45]
  • Jason’s experiment with plant based diet [59:40]
  • The nutrition that works best for Jason in his training cycles [1:00:35]
  • Tracking nutrition on an app 1:00:45
  • 50-60% carbs, rice, potatoes, muesli, grains, fish, vegetables, fruits  [1:01:30]
  • Cross training and why Jason doesn’t do much of it [1:03:50]
  • What Jason would do differently if he was a full time athlete [1:04:38]
  • Peak training weeks with 14 – 15 hours of running, up to 130 miles / 209km a week [1:05:10]. 
  • His favorite speed training workouts [1:06:36]
  • His race strategy going into the London Marathon on Sunday with Sub 2:20 goal [1:09:42]
  • The best way to start a marathon on race day [1:11:05]
  • What Jason does when he hits tough spots in a race [1:13:20]
  • Jason represented England in the 2016 Toronto Marathon [1:15:30]
  • Recommendations for other marathoners looking to improve [1:17:20]
  • Other races on Jason’s bucket list and transitioning into Ultra distances [1:20:45]

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  • Todd says:

    These stories about 2:21 marathoners are very inspiring, but they are far from applying to me personally. I am a 54-year old runner who has been running for two decades. Before I started MAF training four months ago, I was running 8:20 miles on my long runs. Now, after four months of running at my MAF heart rate — even allowing for an extra 5 beats/min because of experience — I haven’t yet broke an 11:00 mile. You’ve said many times in your videos to be patient, but after four months of this my patience has run out.

  • Flo says:

    Hi Todd, thanks for your feedback. I’m trying to share different types of runners here on previous blog. Several 4+ hour runners who have over time improved. That being said, several lessons from recent guests Jason Cherriman, Josh Sambrook and Jonathan Walton can also apply to runners at other levels.

    For your running in particular, it sounds like something is blocking your progress. Here is a long detailed blog post on this exact topic: https://extramilest.com/blog/7-reasons-why-some-athletes-are-not-making-progress-with-maf-training-and-what-to-do-about-it Any thoughts what could be causing your lack of aerobic progress? If you go out for a run and after a 20 minute warm up breath comfortably through your nose on your run, what’s that HR vs your MAF HR?

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