Hello everyone. Welcome to the latest episode of The Matchbox Podcast powered by Ignition Coach Co. I’m your host, Adam Saban, and on this week’s episode we’re talking to the founder and CEO of Tymewear, Arnar Larusson about all things training with ventilation metrics.
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Alight let’s get into it!
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Intro/ Outro music by AlexGrohl - song "King Around Here" - https://pixabay.com/music/id-15045/
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Summary
This episode features Arnar Larusson, founder and CEO of Tymewear, talking about why breathing may be the missing signal in endurance training. The discussion centers on how ventilation can give coaches and athletes a more reliable view of internal workload, training zones, fatigue, and perceived exertion than heart rate alone.We also hear from Adam and Dizzle as they pressure-test the practical side of the tech, from zone setup to high-intensity work to whether the strap holds up in winter layers.
Key topics
- Arnar Larusson shares how an engineering background in prosthetics and exosuits led him to endurance physiology and eventually to building a breathing sensor for athletes.
- The core idea behind Timeware is that lab-grade insights about ventilation, thresholds, and metabolic output were not accessible in the field, so the company built a way to bring that signal outside the lab.
- Arnar explains why he sees heart rate as only one limited piece of the performance picture, especially when it is affected by heat, altitude, fatigue, and fueling.
- The episode breaks down why ventilation is a stronger reference point for training zones because it is more directly tied to what the muscles are doing.
- Arnar walks through the evidence behind poor zone estimation using population averages, including the problem of large error margins and high non-responder rates.
- Adam and Dizzle dig into the relationship between breathing rate, RPE, and how the strap could help athletes better calibrate effort in real time.
- The conversation covers why ventilation is especially useful for endurance work and threshold work, while power remains the better guide for short VO2 max intervals.
- Arnar explains how the strap’s dedicated breathing sensor differs from estimating respiration through HRV, especially once exercise intensity rises.
- They discuss how fatigue, race load, altitude, and heat can distort heart rate and power, while ventilation often stays the steadier anchor.
- The episode also touches on practical use cases like winter clothing interference, dynamic zones, and how the product may help coaches understand athlete readiness and training response.
Timestamps
00:00 - Introduction to Arnar Larusson and the breathing sensor concept
00:34 - Arnar’s engineering background and the path from prosthetics to exosuits
01:29 - Why lab-grade breathing data mattered in the field
02:49 - The gap between lab testing and real-world athlete feedback
04:43 - Why breathing became the missing performance metric
05:01 - Timeware’s launch timeline and the Vital Pro Strap rollout
06:02 - Why heart rate alone is too limited to guide training
07:24 - The problem with population-based training zones
08:51 - Why true VT1 and VT2 zones matter more than estimated percentages
10:15 - Breathing as a cleaner signal than lactate or heart rate
11:41 - Why ventilation works as a foundation for interpreting other metrics
13:40 - The breathing rate and RPE connection
15:20 - How breathing rate can help objectively estimate perceived effort
16:22 - Using resting breathing data to set reserve and calibrate effort
17:38 - Why the strap complements heart rate instead of replacing it
18:35 - How ventilation helps distinguish fitness gains from fatigue effects
20:31 - Why power, heart rate, and ventilation can diverge during long efforts
22:39 - Why ventilation stays stable at altitude while power and heart rate shift
24:02 - How coaches think about custom heart rate zones versus ventilatory zones
26:22 - Ramp testing and how the app builds zones from multiple signals
27:52 - How heart rate responses vary by athlete, fitness, and season
28:58 - Jonas and the Visma example of a large VT1 shift in one month
30:19 - The psychology of getting attached to old training numbers
31:14 - Breathing as a grounding metric for effort perception
33:48 - Why ventilation is closer to a continuous lactate signal than heart rate is
35:48 - Why lactate is useful but delayed and influenced by fueling status
37:30 - The lactate cascade versus the near-instant response of ventilation
39:21 - Which ventilation averaging window works best for different workouts
40:05 - Does fatigue change ventilation, or just power and heart rate?
42:22 - Why stable ventilation can indicate fitness gains even when power rises
45:55 - Backyard ultra example showing breathing rate rising while ventilation stayed flat
48:16 - How coaches can use the data to adjust pacing and training interventions
49:02 - Why fresh legs can still show higher ventilation after racing
50:27 - Listener question on VO2 max workouts and how to use ventilation data
51:13 - Why power or pace is still best for guiding VO2 max intervals
52:39 - Why ventilation shines for endurance and threshold work
54:14 - Why standard VO2 max estimates can badly overstate actual capacity
55:06 - How the app’s zone testing improves confidence in training targets
56:27 - Using breathing rate as an RPE-style guide during hard intervals
57:40 - Winter clothing, bib shorts, and sensor interference
60:22 - Dynamic zones and the neural net designed to handle external interference
62:06 - Can ventilation reveal illness or respiratory issues?
64:29 - Anecdotal signs of infection, allergies, or asthma in the signal
65:14 - Current and upcoming integrations with major head units and platforms
67:18 - Why the strap includes both heart rate and a dedicated breathing sensor
68:39 - Why HRV-based respiration estimates break down during exercise
69:39 - Where listeners and coaches can get involved with Timeware
