Using myokines and mitochondria-related biomarkers to explore the effects and mechanisms of high-intensity interval aerobic and resistance exercise interventions combined with hypoxia on muscular mass/function and neurocognitive performance in older adults with sarcopenia

Intervention Arm 1: HIIT/RE under Hypoxia Description: Participants in this group undergo 60 minutes of hypoxic breathing (resting) followed immediately by 30 minutes of exercise. The exercise consists of either High-Intensity Interval Training (HIIT) on a treadmill or Resistance Exercise (RE) using resistance bands targeting both upper and lower limbs. The intervention is conducted over a total of 8 weeks with a frequency of 3 sessions per week. Administration and Monitoring: All sessions are conducted in a one-on-one format under the direct supervision of a physiotherapist. Exercise intensity is assessed and monitored using the Rating of Perceived Exertion (RPE) scale to ensure participants reach the target effort levels. To monitor adherence, a session attendance checklist is maintained by the supervising physiotherapist for every participant throughout the 24-session program. Intervention Arm 2: HIIT/RE under Normoxia Description: Participants in this group undergo 60 minutes of breathing normal room air (normoxia) followed immediately by 30 minutes of exercise. Similar to the hypoxic group, the exercise involves treadmill-based HIIT or RE using resistance bands for upper and lower limb strengthening. The program duration is 8 weeks, with 3 sessions per week. Administration and Monitoring: Sessions are delivered one-on-one and are supervised by a physiotherapist. The level of intensity is consistently assessed using the RPE scale. Adherence is strictly monitored via a session attendance checklist to track completion of the 8-week intervention.