Generally Healthy Active Adults (Baseline)

This is the reference population the other modules modify from. WHO 2020 guidelines and U.S. Physical Activity Guidelines (2nd ed., 2018) for adults (WHO: 18–64):

• Aerobic: 150–300 minutes/week of moderate-intensity, OR 75–150 minutes/week of vigorous-intensity, OR an equivalent combination; spread across the week. More than 300 min/week of moderate (or 150 min vigorous) provides additional benefits.
• Muscle-strengthening: moderate or greater intensity involving all major muscle groups on ≥2 days/week.
• Sedentary behavior: limit sitting; replace with activity of any intensity, including light. WHO launched the 2020 guidelines as "every move counts", and both WHO 2020 and PAGA 2018 dropped the earlier rule that aerobic activity had to come in ≥10-minute bouts — bouts of any length count. WHO also advises doing more than the recommended MVPA to offset high sitting time.

Complementary components (ACSM Position Stand, Garber et al. 2011):

• Flexibility: a series of stretches for each major muscle-tendon group (about 60 s total per exercise) on ≥2 days/week (Flexibility Guidelines (ACSM)).
• Neuromotor/balance: balance, agility and coordination work on 2–3 days/week, especially valuable as people age (ACSM Neuromotor Exercise Recommendation).

Intensity gauges: percent HRmax/HRR, METs, RPE, and the talk test (FITT-VP Applied to Cardio).

• Healthy adults generally do not need medical clearance to begin light-to-moderate activity, and WHO 2020 notes that someone already doing moderate activity can step up to vigorous without consulting a provider (Medical Clearance & Pre-Participation Screening); progress sensibly.
• Tailor by goal (strength/hypertrophy/endurance) using the training-age continuum (Beginner / Novice Trainee → Advanced Trainee).

• Adults 18–64: 150–300 min/wk moderate OR 75–150 min/wk vigorous aerobic (or equivalent).
• Muscle-strengthening, all major groups, ≥2 d/wk.
• Extra benefit beyond 300 min moderate / 150 min vigorous.
• Add flexibility (≥2 d/wk) and neuromotor/balance (2–3 d/wk) (ACSM 2011 stand).
• Minimize sedentary time; bouts of any length count.