Abstract: BACKGROUND: The magnetic field mitochondrial regulation technology has been proven to enhance skeletal muscle function. Low-load blood flow restriction training can effectively induce adaptive growth of muscle strength through metabolic emergency mechanisms. Currently, both technologies have become hotspots in the application and research of skeletal muscle function improvement and treatment. However, the differences in their effects on muscle strength enhancement and whether their combined application can produce a synergistic effect remain unclear. 
OBJECTIVE: To observe the differences in the effects of low-frequency pulsed magnetic stimulation (1.5 mT, 3 300 Hz) and low-load blood flow restriction training on muscle strength enhancement and the impact of their combined intervention on lower limb muscle strength. 
METHODS: Fifty-six healthy subjects were recruited and randomly divided into the magnetic stimulation group (high-load half squat training), the blood flow restriction group (low-load blood flow restriction+half squat training), the combined group (magnetic stimulation and low-load blood flow restriction+half squat training), and the control group (high-load half squat training). The intervention lasted for 4 weeks, with subjects in each intervention group receiving low-frequency pulsed magnetic stimulation (1.5 mT, 3 300 Hz) every 48 hours, three times a week. After the intervention, changes in the maximum strength, explosive power, and strength endurance of the lower limb muscles in each group were observed. 
RESULTS AND CONCLUSION: Fifty subjects were included in the result analysis after completing the trial. (1) After 4 weeks of intervention, all three intervention groups showed significant increases in the maximum strength, explosive power, and strength endurance of the lower limb muscles. (2) In terms of maximum strength growth, the blood flow restriction group had a better effect than the magnetic field mitochondrial regulation technology. Low-load blood flow restriction also enhanced the strength of distal muscle groups, while the magnetic field mitochondrial regulation technology had the advantage of increasing maximum strength without fatigue accumulation. (3) In terms of explosive power growth, both technologies had similar effects, but magnetic stimulation was more effective in promoting explosive power in single-joint movements, while low-load blood flow restriction training was more effective in improving explosive power in multi-joint coordinated movements. (4) In terms of strength endurance growth, magnetic stimulation technology, due to its regulation of mitochondrial function, was more effective in enhancing the anti-fatigue ability of muscles. To conclude, the combined application of magnetic stimulation and low-load blood flow restriction can produce a synergistic effect on the maximum strength, explosive power, and strength endurance of the lower limbs. This technology protocol can provide a new and efficient training method for enhancing lower limb muscle strength for patients who cannot perform high-intensity resistance training, such as those in postoperative rehabilitation or with sports injuries. 

Key words: lower limb muscle strength, blood flow restriction training, low-frequency pulsed magnetic stimulation, mitochondria, TRPC 1