My favorite “course” when I was at CU was the physiology colloquium. It wasn’t a typical class in that it only occurred once a week and wasn’t just for the students but also to keep the faculty up to date on the latest and greatest research going on. Every week a different CU faculty member brought in a presenter from around the world that does similar work to give a short talk on their research. The topics varied greatly across the semester spanning topics like biomechanics, exercise physiology, sleep, immunology, and stress physiology.
Despite the focus of each week the most interesting part of each colloquium was often the questions following the talk because of their integrative nature when you combine the various fields of everyone in the room with that of the speaker. “How do immune responses to commensal bacteria influence mental health?” “How does maternal stress during gestation influence offsprings’ sexual orientation?” More silently, “How does ____ relate to climbing?”
I have a few favorite talks but the most applicable to the majority of people reading this (unless only my mom reads it) was a talk done by Alan Light from the University of Utah. Dr. Light is a fatigue researcher of multiple decades and climber of probably more that presented on Sensory Muscle Fatigue and Pain. He started with an intro about the psychological and physical components of fatigue then showed how the physical is relayed by two types of sensory neurons. One responding to low concentrations, another to high concentrations, of the three metabolites in the extracellular matrix of skeletal muscle tissue: ATP, lactate, and protons. No one metabolite seems to elicit the neuronal responses but rather all three work in conjunction through specific receptors (check here if you care which or want to read more) to forward the fatigue message on to the brain.
These two types of sensory neurons seem to be responsible for a rapid, primary response for “awareness” that metabolites are building up aka your heading up the steep section of a route and start feeling a little burn. Then a secondary, delayed group of neurons firing once the three metabolites have built up to a higher, “painful” level aka cue the Adam Ondra banshee screams and Chris Sharma yells.
My question to Dr. Light is easy for any climber to relate to, “What’s the flash pump?”
Why are you shot for the day if you quickly go to a high level of activity? Is it a cardiovascular/ lymphatic mechanism? Why does it last so long!? I feel so weak now…am I going to die?
50 Words for Pump. Photo: Khristian Lukianov
His answer is speculative but full of interesting thoughts and ties to research related to chronic fatigue syndrome. These are only partially my ideas and mostly paraphrases. “The molecular detectors for fatigue are quite plastic,” he starts. It’s likely that many receptors and signals are capable of modifying them. One player could be a G-protein coupled adrenergic or serotonergic receptor that normally is not inserted into the membrane (there is another receptor that is normal unactive). However, if activated, potentially by high levels of metabolites that could have been cleared with increased blood and lymph flow with a warm up, these receptors could quickly become functional by being inserted into the membrane (getting too pumped before warming up activates this receptor). Once this happens it’s possible you’re sensitized to become fatigued rapidly until the receptors are removed from the membrane, accounting for the long period of time until you aren’t rapidly fatigable. Relating to the real world, chronic fatigue syndrome patients may have a higher expression of these sensitizing receptors residing on the membrane, instead of normally in vesicles inside the cell, predisposing them to premature fatigue all the time.
These are just interesting ideas and paraphrases I thought I’d share and are likely only a small piece of what’s going on so feel free to share any thoughts.