Unpacking 'Within-Session Intensity Regulation': Defining the Concept

In recent blogs and newsletters, I have extensively discussed 'within-session intensity regulation.' I believe that proper within-session intensity regulation is one of the most critical components of the training process. It's a topic I spend a lot of time contemplating, planning for, and researching.

But what exactly do I mean by 'within-session intensity regulation'? In this blog, I'll attempt to clarify this concept.


Imagine you're training for an Ironman. You're currently in the midst of a four-week Specific Strength training block, focusing on (i) accumulating a substantial overall training volume and (ii) engaging in long, tempo runs on hilly terrain. Your training program emphasizes low-intensity sessions below the lactate threshold, allowing you to train extensively and frequently without inducing excessive fatigue (7, 8). The only sessions in your plan that exceed the lactate threshold are (i) a midweek trainer workout involving 8-minute...

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Chelsea Sodaro Wins the Ironman World Championships

Photo Korupt Vision

On Thursday, 6th October 2022, Chelsea Sodaro did something pretty special! She won the Ironman World Championships to become the first American woman to win since Paula Newby-Fraser in 1996. Chelsea and I believed that she would one day win this race (she certainly has all the goods), but for it to happen so soon was a shock for both of us. We talked about the top 3 being excellent, but a win is out of this world! Chelsea’s 8 hours 33 minutes finishing time was the second fastest time ever by a female at Kona. The competition was among the strongest assembled, with Lucy Charles-Barclay and Anne Haug in 2nd and 3rd position. Well done, Chelsea!

This has been one incredible journey, having taken on Chelsea initially when she was just 6 weeks pregnant. But some fundamental principles got Chelsea to that outstanding performance on race day. Of course, the training and data are a massive part of all this. Still, I also wanted to share some more global concepts...

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