Effect of magnetic field mitochondrial regulation technology combined with low-load blood flow restriction on the strength of lower limb muscle groups

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 magnetic stimulation group (high-load squat training + magnetic stimulation), blood flow restriction group (low-load blood flow restriction squat training), combined group (low-load blood flow restriction squat training + magnetic stimulation), and control group (high-load squat training). The trial lasted 4 weeks, with training three times per week, and low-frequency pulsed magnetic stimulation (1.5 mT, 3 300 Hz) was administered every 48 hours. After the trial, changes in maximal strength, explosive power, and strength endurance of the lower limb muscles were observed among groups. RESULTS AND CONCLUSION: Fifty subjects completed the trial and were included in the analysis. ① After 4 weeks of intervention, the maximal strength, explosive power, and strength endurance of the lower limbs in the magnetic stimulation, blood flow restriction, and combined groups significantly increased. ② In terms of maximal strength increase, blood flow restriction was superior to magnetic field mitochondrial regulation technology; low-load blood flow restriction also enhanced distal muscle strength, while magnetic field mitochondrial regulation technology had the advantage of improving maximal strength without fatigue accumulation. ③ In terms of explosive power increase, both technologies had similar effects; magnetic stimulation was more advantageous for explosive power in single-joint movements, while low-load blood flow restriction training was more advantageous for explosive power in multi-joint coordinated movements. ④ In terms of strength endurance increase, magnetic stimulation technology, due to its mitochondrial function regulation, effectively improved muscle fatigue resistance. The results suggest that the combined application of magnetic stimulation and low-load blood flow restriction can produce synergistic effects on maximal strength, explosive power, and strength endurance of the lower limbs. This technical approach may provide a novel and efficient auxiliary training protocol for lower limb muscle strength enhancement in postoperative rehabilitation and sports injury patients who cannot undergo high-intensity resistance training.

1. Introduction

Decline in lower limb muscle function is closely associated with multiple major health risks, such as falls, loss of mobility, and increased mortality [1]. In the current trend of innovation in sports science, peripheral physical intervention technologies, as auxiliary means to enhance muscle strength training, are driving a paradigm shift in sports training and rehabilitation medicine. Low-frequency pulsed magnetic field, as an emerging non-invasive physical factor intervention, exerts its core mechanism by activating the classical transient receptor potential channel 1 (TRPC1) through specific magnetic stimulation parameters, thereby triggering a calcium-mitochondrial axis cascade. This physiological process upregulates the transcriptional activity of peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α), significantly enhancing mitochondrial biogenesis and myogenesis. Notably, the calcium influx induced by low-frequency pulsed magnetic fields can specifically activate the calcineurin (CaN)-nuclear factor of activated T cells (NFAT) signaling pathway [2], triggering a key molecular switch for skeletal muscle adaptive remodeling, successfully mimicking the metabolic adaptation characteristics induced by exercise training, and providing a series of physiological support and adaptive changes to skeletal muscle function and structure. Experimental evidence shows that low-frequency pulsed magnetic field intervention can promote muscle fiber hyperplasia and injury repair at the tissue level [2-4], enhance ATP synthesis efficiency at the cellular metabolic level [5], improve contractile force at the biomechanical level [6], and exhibit systemic regulatory advantages by modulating whole-body fat metabolism homeostasis [7]. Based on this mechanism, Chinese researchers have previously observed that magnetic stimulation can enhance maximal voluntary contraction and strength endurance of local muscle groups, with muscle strength maintenance and attenuation effects consistent with resistance training [8-10]. Moreover, skeletal muscle structural indicators also showed beneficial changes, and it was verified that combining magnetic stimulation with moderate- to high-load leg resistance training can effectively induce lower limb skeletal muscle hypertrophy, leading to greater gains in lower limb muscle strength.