Table 4.

Monitoring indicators of exercise-induced fatigue.

Indicator	Variation	Significance	Reference
Exhaustion time	↓	Records the time from the start of the exercise to the onset of exhaustion, reflecting the intuitive performance of exercise capacity	54,55
Organ index	↓	The percentage of organ weight in body weight; an important indicator reflecting the internal organs and their nutritional status	56,57
Lactic acid (pH value)	↑(↓)	One of the products of anaerobic respiration; its pH value affects the metabolism of LA system	58
Blood urea nitrogen	↑	The main end product of human protein and amino acid metabolism, a reflection of the metabolic intensity of amino acids in the body	59–61
Malondialdehyde	↑	The degradation product of polyunsaturated fatty acid peroxides; the reflection of the severity of free radical attack and damage on cells	63
Superoxide dismutase	↑	An important anti-peroxidase in free radical scavenging system; an antioxidant that can reduce oxidative stress caused by exercise-induced fatigue	64,65
Testosterone	↓	Maintains muscle strength and quality; maintains bone density and strength	66,67
Glutathione peroxidase	↑	Catalyzes the reduction of H2O2; protects the integrity of cell membrane structure	64,68
Cortisol	↑	Increases gluconeogenesis, protein, and fat metabolism; is related to the damage of biological energy caused by intense exercise	69–71
Creatine kinase	↑	The reflection of the degree of skeletal muscle injury; it is positively correlated with the degree of muscle injury, which directly affects the body’s aerobic and anaerobic metabolism during exercise	71–73

↑: up; ↓: down.