Sustained rhythmic movement raising breathing and heart rate. Trials show higher aerobic capacity, lower blood pressure, better blood sugar control, mood, sleep and thinking; higher fitness tracks fewer deaths. Costs are dose-shaped: overuse injury in beginners, irregular heart rhythm and more fatty deposits in heart arteries at very high volumes. (Full Review)
| Marker | Target | Why |
|---|---|---|
| VO₂max | Above the 75th percentile for age and sex | Strongest single predictor of all-cause mortality |
| Resting heart rate | 45–60 beats per minute | Tracks vagal tone and training status |
| Heart rate variability | Deviation from a rolling 7-day personal baseline | Distinguishes productive training load from accumulated stress |
| Blood pressure | 110–120 / 70–80 mmHg | Primary vascular outcome of cardio training |
| HbA1c | 4.8–5.4% | Tracks glycaemic response to training volume |
| Fasting insulin | 2–5 µIU/mL | Detects insulin-sensitivity gains before HbA1c moves |
| hs-CRP | Below 1.0 mg/L | Tracks systemic inflammation and recovery status |
| Ferritin | 50–150 ng/mL | Detects iron deficiency that caps aerobic adaptation |
| ApoB | Below 80 mg/dL, or below 60 mg/dL with existing plaque | Best available marker of atherogenic particle burden |
| Lipoprotein(a) | Below 30 mg/dL (75 nmol/L) | Identifies inherited risk unmodified by training |
| Coronary artery calcium score | 0 Agatston units | Quantifies established coronary plaque before vigorous protocols |
| Testosterone (men) / cycle regularity (women) | Total testosterone 500–800 ng/dL; regular ovulatory cycles | Earliest marker of low energy availability |
Cadence: Daily resting heart rate and variability; fitness retest 8–12 weeks then 6–12 monthly; blood panel annually; coronary calcium imaging 3–5 yearly