Which tank pays depends almost entirely on how long the effort lasts. Hold the button on the next screen and watch it happen.
This is Clarence going all out. Press and hold, release when you are done.
He just finished a hard 8 second all-out effort. His phosphagen tank is down to about 55 percent. Pick how long he rests, then watch effort two.
Get him to 93 percent or better. The dotted line is the target.
Short and hard means the phosphagen tank. Give it real rest and it pours again. Cut the rest and you are training something different, on purpose or by accident.
Three systems, running at the same time, in different proportions. The clock decides the mix.
Figures: Harris et al., Pflugers Archiv 1976 (phosphocreatine resynthesis half-times). Gastin, Sports Medicine 2001 (equal aerobic and anaerobic contribution at roughly 75 to 80 seconds). Sprint energy-system splits from PeerJ 2024 and PMC8044429, 2021. Rest-interval power data from Journal of Exercise Science and Fitness 2024. Tank levels and output percentages on screen are an approximate teaching model, not measured values. Placeholder content pending expert review.