A case study on the importance of individualizing training based on metabolic thresholds.
Age group athletes must strike the balance between their training outcomes and the competing priorities that vie for their attention (think jobs, families, relationships—life!).
In this case study, we'll examine how a 48-year-old cyclist used Tyme Wear to individualize his training resulting in a 22% increase in power output in just 4 months.
Studies have consistently shown that individualized training generates on average a 2.5x greater fitness improvement for the same amount of time spent (image 1). For time-crunched athletes, making efficient use of limited training time in order to yield the biggest performance improvement possible is key. Tyme Wear helps its users accomplish this by measuring their metabolic thresholds and how to apply them in their training. This enables each user to individualize their training to their current fitness level at all times. Allowing them to be more efficient, and ultimately go faster for longer.
Endurance comes down to fuel source & efficiency
Endurance performance is determined by the total amount of work that can be produced, and how efficiently that work can be produced from your available fuel; fat and carbs.
Our Metabolic Thresholds are simply benchmarks of how efficiently our muscles are burning their available fuel. The First Ventilatory Threshold (VT1) benchmarks the transition when we’ve reached our maximal fat utilization. Fat is our most abundant and efficient fuel source. The Second Ventilatory Threshold (VT2) benchmarks the transition when we can no longer efficiently utilize carbs. Carbs are a scarce and inefficient fuel source. Optimal endurance training targets these inefficiencies so that our muscles adapt to output more work more efficiently which enables us to go faster for longer.
We can use our Metabolic Thresholds to improve two key capabilities: 1.) Burn more fat and continue burning it at higher intensities, and 2.) Increase the efficiency of carb consumption by improving our ability to use a by-product of carb consumption, lactate, as a fuel source. Giving our muscles the appropriate training duration and intensity to bring about these adaptations can dramatically improve our ability to endure.
Image 3: Shifting the ventilation curve to the right towards higher efficiency and output by training at our individual metabolic thresholds.
The challenge for athletes is to know what training intensity brings about these adaptations for them at any given time. The importance of getting this right for each individual is the underlying driver for why 2.5x greater fitness is achieved when training is individualized. For example, if an athlete is trying to increase their fat utilization but then exceeds their VT1 intensity during training, they won't improve their ability to consume fat. They will also have less impact on their mitochondrial growth as compared to training closer to their VT1. To learn more about your thresholds and setting your intensity targets, read our blog here.
Case Study: Michael, 48 year-old cyclist
A great example of the improvement that can be achieved when using individual thresholds is from one of our users, Michael. He is a 48 year-old cyclist who was a high level cyclist earlier in his career and is now an avid enthusiast road, cross-country, and mountain biker.
Michael’s initial threshold test was performed using Tyme Wear in August 2022 and showed that he was pushing too hard on his ‘easy’ days and thus not getting the full benefit of the time spent training at those intensities. He set a goal to improve his base endurance.
“Up to now, I was setting my endurance zone, to 135-150bpm and 140-160W. I will revise this down and go even slower.”
When an athlete is in this ‘grey zone’ they are not getting the metabolic benefits of the low-intensity end of the spectrum where mitochondrial growth, fat utilization, and muscle capillary growth occur. Nor are they optimizing the adaptations of high-intensity work including lactate utilization and increased muscle strength.
Adjusting his intensity and sticking to the plan
Michael adjusted his workout intensity to target his VT1 threshold that was obtained from his Tyme Wear test results. Over the coming months, he completed between 10-15 hours/week of low-intensity VT1 workouts.
"At the beginning, an outside ride felt awfully slow, and especially on climbs it takes quite some discipline to stay in range."
He logged workouts with Tyme Wear on a regular basis throughout the 4 months and we can see from his breathing data that he was consistent at staying in and around his VT1. Interestingly, he got more consistent over time at staying around his VT1 as can be seen in the difference in his time spent plots from September-October vs November-December.
Image 3: Time spent as measured by his Minute Ventilation in September and October.
Image 4: Time spent as measured by his Minute Ventilation in November and December.
Results
After 4 months, Michael took another Tyme Wear threshold test to check his progress. The results showed an unequivocal improvement in his base endurance. He was now outputting 22.4% more power at his VT1.
His VT2 power had not increased which is to be expected when someone doesn’t train at VT2, but his Minute Ventilation dropped a whopping 10% at his VT2. This drop in Minute Ventilation indicates that in addition to output more power at VT1, he was also consuming carbs more efficiently at higher power outputs.
For Michael, this means he can last longer at his VT2 power output.
Image 5: Minute Ventilation (VE) vs Power Output from his Tyme Wear threshold tests in August ‘22 (blue) vs January ‘23 (red).
Image 6: Comparison of results between August and January: VT1 Power increased 22% and VT2 VE dropped 9.5% for the same power output.
Conclusion
Knowing your current metabolic thresholds is the key to individualizing training and improving it. In the absence of accurate physiological data, training intensities are largely based on heart rate and athlete tolerance, both of which are variable and frequently lead to overtraining and injuries. As we saw in Michael’s case, once the right physiological data is known in order to individualize training, adherence to the correct training intensities allows athletes to become more metabolically efficient, enabling them to perform at a higher level, and with fewer setbacks due to overtraining and injury.
Get started and adapt your own training based on your unique metabolic thresholds.
Arnar Larusson
Arnar Larusson is the Co-Founder and CEO of Tyme Wear, a smart shirt that tracks breathing to help athletes measure their unique metabolic thresholds and individualize their training to them. Prior to founding Tyme Wear, Arnar did research at Harvard University where he helped develop the first soft exoskeleton that lowered the metabolic cost of walking. Prior to that, he helped to develop prosthetic limbs for Paralympians at Össur. Arnar is a triathlete, ultra-marathoner, and a former basketball player on Iceland’s youth national team. He holds a degree in Mechanical Engineering from the University of Iceland.