Aerobic -vs- Anaerobic in Track & Field running events…..
Certain conclusions were drawn from some studies in the late 1960’s, early 1970’s that got proliferated into the sport community. That info got set in stone inside people’s brains for several decades.
If you’re willing to unlearn what you think you know about Aerobic -vs- Anaerobic you can advance the ball.

The subject revolves around 1 item, mitochondria……the organelles around brain cells, nerve fibers, and muscle fibers that consume fuel [carbo, fat] to produce energy and utilize oxygen to keep that process going for an indefinite period of time.
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Whether you’re a sprinter or distance runner most of your energy will come aerobically if you have enough mitochondria to make that happen.
If you don’t have enough mitochondria to make that happen then most of your energy comes anaerobically.
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Therefore, its your aerobic fitness level [a.k.a. the number and size of mitochondria], not your event distance that determines which energy system will be the predominant source of energy.
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The more velocity you put into training program design the more mitochondria you produce around brain cells, nerve fibers, and muscle fibers. Note that each year that Usain Bolt ran under 9.7 for 100m he started that season off having run under 45 seconds for 400m.
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Note that in the 1998 season Haile Gabrselassie ran world record for 10,000m 26:22 a few months after running 1500m indoors 3:31, still the #2 time in history.
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Its the mitochondria, not the event distance. Its the things that utilize oxygen [mitochondria], not oxygen delivery [EPO, red blood cells].
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And about myth #2 related to Aerobic -vs- Anaerobic…….Lactic acid isn’t what causes your fatigue.
And the disappearance of lactate within 10 to 20 minutes following your race or exercise at the gym means that lactic acid isn’t what you’re feeling in your legs hours later, a day later, or 2 days later.
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Be willing to unlearn what you have learned.
Put data ahead of dogma.

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background science info —– https://theetgtrackclub.com/documents/TheETGsportscibackgroundMasterOfSport.pdf
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“Little data exist that specifically and accurately evaluate energy system contributions….Considerable information can be found that attempts to do so, but this data has generally been based on data in the 1970’s that inappropriately used oxygen debt to quantify anaerobic energy release.”

“The crossover to predominately aerobic energy system supply occured between 15 and 30 seconds for the 400, 800, and 1500 meter events.”

“These results suggest that the relative contribution of the aerobic energy system during track running events is considerable and greater than traditionally thought.”

M.R. Spencer, et al
Energy System Contribution During 200 To 1500 Meter Running In Highly Trained Athletes
Medicine & Science In Sports & Exercise….Volume 33 #1….January 2001….page 157

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“Denis et al [1992] have reported the ability to sustain supra-maximal work lasting 30 – 45 seconds was related more to muscle oxidative [aerobic] capacity than to glycolytic [anerobic] capacity.”
B. Dawson, et al
Changes In Perfomrance Muscle Metabolites, Enzymes, And Fiber Types After Short Sprint Training
European Journal Of Applied Physiology & Occupational Therapy….Volume 78…1998…page 167

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“…..there have been relatively few investigations of the effects of sprint training on mitochondrial enzymes or aerobic power in humans….”
“The significant increases in Vo2max…..were somewhat unexpected….Changes of this magnitude are usually assciated with training programs involving several hours per week at sub-maximal intensity.”
J.D. MacDougall,et al
Muscle Performance And Enzymatic Adapations To Sprint Interval Training
Journal Of Applied Physiology…..Volume 84 #6….June 1998…page 2141

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“These findings suggest that exercise training increases brain mitochondrial biogenesis…”
J.L.Steiner, et al
Exercise training increases mitochondrial biogenesis in the brain
Journal Of Applied Physiology…….Volume 111 #4……October 2011…..page 1066