Inclusion Criteria:

1. Aged 18 to 25 years.

2. Currently active or trained competitive roller skaters with regular roller skating-specific training experience who meet at least one of the following criteria:

   1. Hold a Chinese National Athlete Grade II classification or higher; or
   2. Have completed at least 2 years of continuous roller skating-specific training, maintained systematic training during the previous year, and participated in provincial-level competitions.

3. In good general health, without known cardiovascular, peripheral vascular, respiratory, neurological, metabolic, or coagulation disorders, a history of thrombosis, severe varicose veins, severe hypertension, or other conditions that may affect the safety of blood flow restriction training or high-intensity exercise testing.

4. No acute or unresolved chronic injury involving the joints, muscles, ligaments, tendons, or bones of the lower limbs, and no clinically significant lower-limb pain that would interfere with roller skating, jumping, or balance testing.

5. Able to safely complete roller skating-specific testing, jump and balance testing, cycle ergometer-based fatigue induction, and standardized roller skating-specific fatigue induction.

6. Intact and healthy skin on the thighs, without wounds, infection, skin disease, severe allergy, or other conditions that may interfere with blood flow restriction cuff placement or surface electromyography electrode application.

7. Stable sleep, training, and recovery status during the week before testing, without evidence of marked fatigue, inadequate recovery, persistent muscle soreness, substantial performance decline, severe sleep insufficiency, or serious psychological distress.

8. A pain score of 0 to 3 on the Numeric Rating Scale and a pretest rating of perceived exertion of 12 or lower.

9. No use during the previous week of medications, nutritional supplements, or sports supplements that may affect cardiovascular function, muscle metabolism, blood lactate, heart rate variability, neuromuscular activation, fatigue responses, or exercise performance.

10. Familiar with the roller skating-specific testing procedures and able to follow all testing and training instructions.

11. Willing to undergo blood flow restriction training and all required assessments.

12. Able to understand the study procedures, provide written informed consent, and voluntarily participate.

Exclusion Criteria:

1. Age outside the range of 18 to 25 years or failure to meet the required roller skating training, athlete classification, systematic training, or competition-experience criteria.
2. Cardiovascular disease, peripheral vascular disease, respiratory disease, neurological disease, metabolic disease, coagulation disorder, history of thrombosis, severe varicose veins, severe hypertension, circulatory impairment, or another contraindication to blood flow restriction training or high-intensity exercise testing.
3. Acute lower-limb musculoskeletal injury or an unresolved chronic injury that prevents safe completion of the testing or fatigue-induction procedures.
4. Clinically significant lower-limb pain, severe sleep insufficiency, inadequate recovery, suspected overtraining, serious psychological distress, or another condition that may compromise participant safety or data validity.
5. Use during the previous week of medications, nutritional supplements, or sports supplements that may affect the study outcomes.
6. Skin wounds, infection, skin disease, severe allergy, or another condition affecting blood flow restriction cuff placement or surface electromyography electrode application.
7. Inability to understand or comply with the study procedures or to safely complete the required surface electromyography, force-platform, Y-Balance, jump, and fatigue-induction assessments.
8. Refusal to undergo blood flow restriction training or any required study procedure.
9. Failure to provide written informed consent.