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Durability 🚴
In the last year of my PhD at Auckland University of Technology, we asked 12 trained cyclists to ride at 90% of their first ventilatory threshold (VT1) until exhaustion.
Two riders lasted 6 hours.
One stopped after just 2 hours.
What struck me the most?
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Training intensity zones do NOT divide training adaptations into separate categories.
Zone 2 does not increase only mitochondrial density and 1st threshold, just as Zone 5 does not only increase cardiac stroke volume and VO2max.
Here’s what you need to understand. 🧵
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Thresholds and training zones help prescribe exercise duration × intensity and distribute training load, stress, and recovery to maximize overall adaptations across individual sessions, microcycles, and macrocycles.
During exercise, an increase in lactate is a marker of an increase in metabolic perturbations associated with fatigue, rather than its direct cause.
The body doesn't work like a vending machine, where selecting a different button (read training zone) delivers a completely different physiological adaptation.
In this interesting but forgotten study (never cited in durability papers), higher blood cortisol and GH concentrations during prolonged exercise are associated with superior durability.
pubmed.ncbi.nlm.nih.gov/1171…
How might these endocrine responses positively influence durability?
Genetics influence Endurance Trainability.
Chung et al. reported that the number of favourable alleles explained approximately 85% of between-individual variability in improvements in distance covered during a 12-min (Cooper) max test after a 8-week training program.
Anyone can access this full text?
pubmed.ncbi.nlm.nih.gov/9502…
If yes could you please send in message?
Thanks!
Endurance athletes' VO₂max values are an exception.
If you consistently train in an endurance sport, there is a good chance that your VO₂max is higher than that of the average person in the general population.
The endocrine system might be involved not only in durability but also in recovery capacity, two physical characteristics that may themselves be closely linked.







