Health-Related Physical Fitness Level From Smartwatches

Inclusion Criteria: Group 1 (Aerobically Trained) * 20-60 years old * actively training or competing over the past 2 years * 3 or more days of vigorous activity accumulating approximately least 1500 MET min/week or 7 days of any combination of walking, moderate, or vigorous intense activities achieving a minimum of 3000 MET min/week Group 2 (Strength trained) * 20-60 years old * actively training or competing over the past 2 years * 3 or more days of muscle-strengthening exercise at an intensity of approximately 5 out of 10 Group 3 (Not actively training) * 20-60 years old * actively training or competing over the past 2 years * 3 or more days of muscle-strengthening exercise at an intensity of approximately 5 out of 10 Group 5 (High flexibility) * 20-60 years old * Sit-and-reach performance is categorized as "very good" or excellent based on the American College of Sports Medicine's sit-and-reach evaluation criteria (Table 4.16 of ACSM's Guidelines for Exercise Testing and Prescription 9th edition). Exclusion Criteria: Exclusion criteria are the same for all groups. * History of cardiovascular disease (Cardiac, peripheral vascular, or cerebrovascular disease) * History of stable or unstable angina * History of cardiac dysrhythmias causing symptoms or hemodynamic consequences * History of hypertrophic cardiomyopathy * History of cardiac valvular disease (e.g., aortic stenosis) * History of pulmonary disease (Chronic obstructive pulmonary disease, asthma, interstitial lung disease, or cystic fibrosis) * History of pulmonary embolus * History of suspected or known aneurysm * History of metabolic disease (Diabetes mellitus (type I or II), thyroid disorders, renal or liver disease * History of renal disease * History of neuromotor, musculoskeletal, or rheumatoid disorders that are exacerbated by exercise * Current acute systemic infection, accompanied by fever and body aches. * Pain or discomfort in the chest, neck, jaw, arms, or other areas that may be due to myocardial ischemia (lack of adequate circulation) * Shortness of breath at rest, during daily activities, or with mild exertion * Dizziness or syncope (fainting) * Orthopnea (breathing discomfort when not in an upright position) or paroxysmal nocturnal dyspnea (interrupted breathing at night) * Ankle edema (swelling) * Palpitations (abnormal rapid beating of the heart) or tachycardia (rapid heartbeat) * Intermittent claudication (cramping pain and weakness in legs, especially calves, during walking due to inadequate blood supply to muscles) * Known heart murmur (atypical heart sound indicating a structural or functional abnormality) * Unusual or unexplained fatigue * Severe arterial hypertension (i.e., systolic blood pressure of \>200 mm Hg and/or a diastolic blood pressure of \>110 mm Hg) at rest.