Quasipaa spinosa-Derived Parvalbumin Attenuates Exercise-Induced Fatigue via Calcium Homeostasis and Oxidative Stress Modulation in Exhaustively Trained Mice

<b>Background:</b><i>Quasipaa spinosa</i> crude extract (QSce), a natural source rich in proteins such as parvalbumin (PV), has been traditionally used to promote physical recovery. However, its mechanisms in mitigating exercise-induced fatigue remain unclear. <b>Methods:</b> Using a murine treadmill exhaustion model, we evaluated the effects of QS-derived Parvalbumin (QsPV) (30 and 150 mg/kg/day) on endurance capacity, oxidative stress, tissue injury, and muscle function. Indicators measured included time to exhaustion, intracellular calcium levels, antioxidant enzymes [superoxide dismutase (SOD), glutathione peroxidase (GSH-Px)], lipid peroxidation (malondialdehyde, MDA), injury markers [creatine kinase (CK), lactate dehydrogenase (LDH), cardiac troponin I (cTnI)], renal function (blood urea), and muscle force. <b>Results:</b> QsPV-150 significantly increased time to exhaustion by 34.6% compared to the exercise-only group (<i>p</i> < 0.01). It reduced MDA by 41.2% in skeletal muscle and increased SOD and GSH-Px levels by 35.4% and 28.1%, respectively. Serum CK, LDH, and cTnI were reduced by 39.5%, 31.7%, and 26.8%, respectively, indicating protection against muscle and cardiac injury. QsPV also decreased blood urea by 22.3% and improved renal histology, with reduced glomerular damage and tubular lesions. At the molecular level, QsPV restored calcium balance and downregulated calpain-1/2 and atrophy-related genes (MuRF-1, MAFbx-32). Muscle contractile force (GAS and SOL) improved by 12.2-20.3%. <b>Conclusions:</b> QsPV attenuates exercise-induced fatigue through multi-organ protection involving calcium buffering, oxidative stress reduction, and anti-atrophy effects. These findings support its potential as a natural recovery-enhancing supplement, pending further clinical and pharmacokinetic studies.