Bryan Johnson reports 51-day dunk-training changes

On 11 September 2026, Bryan Johnson posted a progress report from a 51-day programme to dunk a basketball at age 49. He reported ground-contact time falling from 267 milliseconds to 167 milliseconds, a 37% reduction. He also reported an 87% improvement in reactive strength, a 45% reduction in knee valgus under impact, and a shift from muscular braking to Achilles-tendon recoil. The post does not define the testing device, number of trials, footwear, warm-up, body mass, jump height, assessor, statistical method or comparison condition. It also does not show the raw series behind the percentage changes. The reported measures may be relevant to jump performance and injury mechanics, but a single person receiving a multicomponent training programme cannot establish which exercise, recovery practice or measurement change caused them. The report gives no injury outcome and no evidence that the programme changes healthspan or longevity. It is therefore recorded as a self-reported, instrumented n=1 performance update. The claims remain Johnson’s own public measurements, not a controlled training study or proof of a safe way for older adults to increase power.

In 51 days: 37% reduction in ground contact time; 87% improvement in reactive strength; 45% reduction in knee valgus under impact.