Eligibility Criteria:
Healthy
Inclusion Criteria:
• Aged 20\~85 years old
Exclusion Criteria:
* Severe uncontrolled metabolic diseases (e.g., hyperthyroidism, diabetes, hypertension, hyperlipidemia, etc.)
* Severe pulmonary or cardiovascular diseases (e.g., pulmonary hypertension, chronic obstructive pulmonary disease (COPD), heart failure, cardiac arrhythmia)
* Presence of a cardiac pacemaker or a history of myocardial infarction within the past six months
* Severe musculoskeletal or neuromuscular disorders (e.g., advanced arthritis, limb amputation, post-polio syndrome, Parkinson's disease)
* Unstable vital signs (e.g., systolic blood pressure ≥180 mmHg, diastolic blood pressure ≥90 mmHg, requiring vasopressors, or resting heart rate \>100 bpm)
* Prone to bruising
* Recent inflection \< 1 month
* Pregnancy
* Kidney function impairment
* Cancer
* Simultaneously participating in other research
CKD
Inclusion criteria:
* Aged 20\~85 years old
* eGFR\< 90 ml/min/1.73 m2 over 3 months
* Stable condition without worsening in the past 3 months
* Ability to understand and follow verbal commends and cooperate with an exercise training program
Exclusion criteria:
* Severe uncontrolled metabolic diseases (e.g., hyperthyroidism, diabetes, hypertension, hyperlipidemia, etc.)
* Severe pulmonary or cardiovascular diseases (e.g., pulmonary hypertension, chronic obstructive pulmonary disease (COPD), heart failure, cardiac arrhythmia)
* Presence of a cardiac pacemaker or a history of myocardial infarction within the past six months
* Severe musculoskeletal or neuromuscular disorders (e.g., advanced arthritis, limb amputation, post-polio syndrome, Parkinson's disease)
* Unstable vital signs (e.g., systolic blood pressure ≥180 mmHg, diastolic blood pressure ≥90 mmHg, requiring vasopressors, or resting heart rate \>100 bpm)
* Abnormal blood biochemical parameters (e.g., white blood cell count \<2500/mm³, hemoglobin \<8 mg/dL, total bilirubin \>3 mg/dL, liver enzymes (GOT/AST, GPT/ALT) \>3 times the upper limit of normal, platelet count \<75,000/mm³
* Sensory or motor dysfunctions that affect walking ability
* Diagnosed systemic diseases under ongoing treatment (e.g., systemic lupus erythematosus, cancer, malignancies).