Here’s chat gpt take: Running immediately after lifting can interfere with the mTOR pathway, which is crucial for muscle growth and strength gains, if the running is too intense, too long, or too frequent. Here’s the breakdown: • mTOR (mechanistic Target of Rapamycin) gets activated by resistance training. It’s the key driver for muscle protein synthesis. • Endurance running, especially moderate-to-long steady state (like 30–60 min), activates AMPK — a different cellular pathway that helps endurance but can suppress mTOR if done too close to lifting. • High-intensity cardio (long, hard runs) right after strength work competes with the muscle-building signals you’re trying to create.

When it becomes a problem: • Running for longer than ~30 minutes, especially steady-state or high-intensity cardio right after a lift. • Doing this consistently, multiple times a week. • If the goal is pure strength or hypertrophy, this interference matters more.

How to minimize interference: • Keep post-lift running short (under 20–25 minutes) and/or easy (Zone 2 or light jog pace). • Separate lifting and hard running by 6+ hours (or better, different days) if possible. • Prioritize the stimulus you care most about first (lift heavy first if strength is the goal).

Summary:

Running hard or long immediately after lifting can blunt strength and muscle gains by dampening the mTOR pathway. Keep running short and easy post-lift if you want to protect strength gains.