3-second maximal contractions are a minimal strength-building exercise: one maximal effort, usually a slow, resisted weight lowering, on most days; a seconds-long add-on, not replacing fuller strength work. The best-supported benefit is modest strength gain in untrained muscles within a month; one daily effort does not appear to build muscle size. Main risks: blood-pressure and eye-pressure surges, especially with breath-holding, and soreness from many efforts. Lasting benefits remain uncertain. (Full Review)
| Marker | Target | Why |
|---|---|---|
| Resting blood pressure | Below 120/80 mmHg | Screens pressure-surge risk |
| Handgrip strength | Men 40 kg or more; women 27 kg or more | Tracks whole-body strength |
| Five-times sit-to-stand time | Under 10 seconds | Leg power, fall-risk proxy |
| Trained-muscle strength | No established target; gain of 10% or more from own baseline at 4 weeks | Confirms response |
| Creatine kinase (CK) | Below about 200 U/L at rest | Detects excess muscle damage |
| Intraocular pressure | 10–21 mmHg, or the individual glaucoma target | Guards against eye harm |
Cadence: Baseline before starting; strength tests at 4 weeks, then every 3 months; blood pressure at 4 weeks, then every 3–6 months; CK only if unusual muscle pain, weakness or dark urine appears; eye pressure only with glaucoma or ocular hypertension