Physiologist Noah Collins offers insights about why runners fixate on mileage while cyclists fixate on power, why lactate isn’t the enemy and much more!
Should you train by miles or by time? Exercise physiologist and endurance coach Noah Collins, former head physiologist at Carmichael Training Systems and Zwift, makes the case that your body doesn’t know how far you ran, only how long and how hard. He’s a former Category 1 road racer who switched to trail running, and he talks with Zoë Rom and Brendan Leonard about leaving elite cycling, starting over as a beginner, and what years of coaching taught him about the limits of training data.
The conversation covers why runners fixate on mileage while cyclists fixate on power, the client who fired him over round numbers, research linking the gut microbiome to exercise motivation, and why lactate isn’t the enemy. Noah also makes a spirited case against sweet spot training and explains what he prescribes for time-crunched athletes instead. And yes, there’s a practical tip about supplements and highlighter-colored pee.
Check out our winter gear picks here: https://trailhead.ultrasignup.com/gea…
Learn more about Noah’s coaching at RyseOn: https://ryseon.com
More About Noah Collins

Noah Collins has lived on both sides of endurance sport, as an athlete and as a scientist. He started cycling at 14 and went on to race the biggest pro stage races in the country. When his road career ended, he may have sworn off running. If he did, it didn’t last: he’s now a distance runner.
He also has the science to back up the miles. Collins holds degrees in biochemistry and physiology. He has served as head physiologist for Carmichael Training Systems and Zwift, and he runs his own coaching company.
More About The Trailhead
The Trailhead is deliberately not a training show. It isn’t your typical trail running podcast: the hosts aren’t dissecting splits or debating race strategies. Instead, hosts Zoë Rom and Brendan Leonard go straight to the heart (and funny bone) of the sport, celebrating the people, stories and quirks that make trail running special. The tone mixes humor, heart and a little irreverence, and the subjects are the personalities, artists and everyday athletes who give the sport its soul. Catch up on previous episodes however you listen to podcasts.
Show Chapters
0:00 Winter running gear for early darkness
1:39 Starting a sport from scratch
4:57 Meet Noah Collins: from cycling to trail running
6:09 The documentary that got him into cycling
8:28 Fear of failure and first races
10:20 Progress over placement: finishing last every week
14:22 Racing Cat 1 while working full time
17:37 Why he quit road racing
20:12 Why cyclists switch to trail running
22:00 Rolled ankles and rocky trails
23:32 Becoming a beginner again
25:03 Training for fun, not performance
26:58 Coaching with feel, not just data
29:59 Training by time vs. mileage
32:56 How to stop obsessing over distance
38:50 Gut microbiome and motivation to exercise
43:56 Lactate vs. lactic acid: what athletes get wrong
46:10 Is sweet spot training overrated?
49:52 Tempo training for time-crunched athletes
51:24 Are you taking too many supplements?





