The first point in the summary of CKC's system that started this post was:
1. Effort. All out, last two minutes of the championship game effort every time you're on the court. Kim has said it's an effort-based system. She's said when done right, players are glad to come out. I see it like interval training -- going really hard for 90 seconds to 3 minutes, then resting, then doing it again. Defense and rebounding are a lot about effort, and we all know what Pat said about offense, defense, and rebounding.
The "interval training" comparison was just an idea. I wondered if there was a basis for Kim's substitution pattern in physiological science. So, I asked ChatGPT for a report. I didn't run this one through multiple, but feel free to double check me. Anyway, here is what I got:
Yes — there
is physiology that makes your “interval training” intuition plausible. But there isn’t a magic cliff at
2:00 where biology flips from “fine” to “wrecked.” What
is real is a
fatigue curve: as an all-out shift gets longer, the stuff that lets you repeat high-power actions (accelerate, stop, jump, press, close out) degrades fast, and the recovery you’d need starts to exceed what basketball naturally gives you unless you sub.
The key mechanism: refueling the “burst” battery (PCr)
Most of the
explosive actions in basketball are powered by the ATP–phosphocreatine system (PCr) plus anaerobic glycolysis. PCr is basically the immediate “battery” that helps you hit repeated bursts.
- PCr recovery after intense work is fast at first (time constants on the order of ~18–30 seconds in healthy people/athletes in many conditions), as long as muscle pH hasn’t dropped too much; acidosis slows recovery. (ScienceDirect)
- In repeated-sprint research, performance recovery tracks PCr recovery: after a brutal sprint bout, PCr resynthesis correlated with how much work athletes could produce when they went again. (PLOS)
Translation to a press-heavy system:
you sub so the player’s PCr can come back up enough to have “pop” again, instead of staying out there while that battery is drained and their bursts turn into jogs, late closeouts, and fouls.
Why “going longer” becomes self-defeating
As you keep the intensity high
without a real break, you lean harder on anaerobic glycolysis and accumulate byproducts (including H+), and neuromuscular output drops. Recovery then takes longer.
A nice way to see the idea: in an intermittent sprint study (team-sport relevant),
shorter recoveries (60s) led to lower mean power than 90–120s, and the authors point out these rest intervals sit between a
fast and slow phase of PCr resynthesis (~20s and ~180s) — meaning you’re getting partial, not complete, recovery. (
ScienceDirect)
That maps cleanly onto hockey-style subs:
sit 1–3 minutes, come back with restored power.
Why basketball specifically rewards short, hard “shifts”
Basketball isn’t a steady run; it’s repeated bursts. Even in normal styles, play is starts/stops and short segments. One sports-science summary notes average play segments around
12–20 seconds, with heavy reliance on anaerobic metabolism layered on top of aerobic support. (
Gatorade Sports Science Institute)
And match data show the game is physiologically taxing: elite players can sit at very high heart rates and show meaningful lactate levels (a marker that anaerobic glycolysis is heavily involved). (
PMC)
Caldwell’s system pushes the game
more toward continuous demand (more pressure, more running, more repeated accelerations). That tends to make
fatigue show up sooner unless minutes are managed.
So does “under 2 minutes” have scientific meaning?
Not as a hard threshold. But it’s a
reasonable coaching heuristic because:
- A 90–120s shift at max press intensity is long enough to get you deep into the fatigue curve (PCr down, glycolysis up, decision-making and footwork deteriorate).
- Off-court time of 1–3 minutes gives you meaningful partial PCr recovery (fast early recovery), which is exactly what you need for repeated high-intensity bursts. (ScienceDirect)