Cellular processes are messy. They produce copious amounts of harmful waste products and damaged parts that can accumulate inside the cell, creating havoc and even cell death. A recent study found that resistance training activates critical cellular cleanup processes in muscles, facilitating waste disposal and supporting muscle cell health.

The study had two phases: an acute exercise phase with intense workouts to trigger an immediate muscle response and a six-week adaptation phase to see how muscles adjust to repeated mechanical stress. In the acute phase, participants performed resistance exercises, including leg extensions, leg presses, and drop jumps, using heavy weights and incorporating eccentric movements. During the adaptation phase, they performed the exercises at a lower intensity twice a week, allowing the muscles to adapt to the consistent workload gradually. Researchers took muscle samples before and after these sessions at the start and end of the study, analyzing changes in critical proteins and focusing on a cellular protein called BAG3.

BAG3 facilitates a cellular cleanup process called chaperone-assisted selective autophagy, or CASA. Unlike ordinary autophagy, which generally recycles various cell parts, CASA specifically targets and breaks down damaged or misfolded proteins with the help of unique proteins called chaperones. BAG3 is one of these chaperones. Under resting conditions, two phosphorous molecules tether BAG3 in place, keeping it inactive.

However, the researchers found that when cells experienced mechanical stress, the phosphorous molecules released BAG3, activating it and allowing it to perform its chaperoning job. Notably, BAG3 release was essential for eliminating damaged mitochondria—a process called mitophagy—in skeletal muscles.

These findings suggest resistance exercise supports cellular health and mitophagy by boosting in-house cleanup processes. Learn more about mitophagy in this clip featuring Dr. Guido Kroemer.