If you drink coffee every day, does caffeine stop working for exercise?

Short answer

No. People who already drank 351 mg a day still got faster with caffeine before exercise. But when the same dose is taken every day, the boost is biggest on day one and shrinks over 2 to 4 weeks.

If you drink coffee every day, does caffeine stop working for exercise?
'Daily coffee → tolerance → no pre-workout boost' — does this formula hold?
A common claim: daily coffee drinkers get so used to caffeine that taking it before exercise does nothing. We checked whether how much you usually drink changes the pre-workout effect.
Usual intake did not change the effect
Across 60 studies, heavy drinkers still benefited
An analysis that pooled 60 caffeine studies found that caffeine before exercise improved endurance, power and strength. How much people usually drank each day did not change this effect. It held for men and women, and for people who trained regularly and those who did not.
People drinking 351 mg a day still got faster
No difference from those drinking 58 mg a day
40 people were split by usual daily intake: 58 mg, 143 mg and 351 mg. With caffeine before exercise, a roughly 30-minute bike time trial was about 53 seconds faster than with a placebo, with no difference between the three groups. In a strength study of 24 people, the effect was no different between the 65 mg and 235 mg groups.
But daily dosing shrank the effect
On the same daily dose, day one was the strongest
11 people who had cut out caffeine for a month took caffeine every day for 20 days (about 210 mg for a 70 kg (154 lb) person). Peak cycling power was about 4% higher than with a placebo for the first 15 days, then the gap disappeared. The boost was biggest on day one and got smaller day by day.
After 4 weeks of daily caffeine, the effect fell about 7%
The placebo group kept its full effect
18 people who rarely had caffeine took caffeine or a placebo every day for 28 days. In the daily caffeine group, the work done in 30 minutes after a pre-exercise dose dropped from 383 to 358, about 7% less. The placebo group kept the full pre-exercise caffeine effect.
Still, it never disappeared
People on caffeine every day for 8 weeks still improved
In a study where 80 people took caffeine or a placebo every day for 8 weeks, the daily caffeine group saw a smaller pre-exercise effect. Even so, caffeine before exercise improved 3 km run times and sprint power in every group at every time point. A short break from caffeine made the reduced effect bigger again.
Bottom line: the effect survives daily coffee
The formula breaks at 'tolerance → no effect'
Heavy coffee drinkers still performed better with caffeine before exercise. The effect was clear up to about 420 mg for a 70 kg person; above that, there was no difference from a placebo. But on the same daily dose, the boost is biggest on day one and shrinks over 2 to 4 weeks.