Over 40 and hills leave you blowing? The Norwegian 4×4 is the session sports scientists point to: four hard four-minute efforts, once or twice a week, and it raises VO2 max faster than steady cardio. Developed at NTNU in Trondheim, it takes about 40 minutes.
- The session: 10 min warm-up, 4 × 4 min hard with 3 min easy between, 5 min cool-down
- How hard: 85–95% of max heart rate; about 70% in the breaks
- How often: once or twice a week
- Heart condition? See your GP first
How to do it
- Warm up 10 minutes, easy.
- 4 minutes hard at 85–95% of max heart rate. It takes a minute or two to climb.
- 3 minutes easy at about 70%, still moving.
- Repeat to four hard intervals, then cool down 5 minutes.
Finish feeling you could do a fifth. Going flat out “is definitely not how it should be” (NTNU).
Your heart rate zone
Use 211 − (0.64 × age) for max heart rate; 220 − age underestimates it after 30 (Nes et al., 2013). Yours may be 10 beats either side.
| Age | Max HR | Intervals (85–95%) | Recovery (70%) |
|---|---|---|---|
| 35 | 189 | 160–179 | about 132 |
| 40 | 185 | 158–176 | about 130 |
| 45 | 182 | 155–173 | about 128 |
| 50 | 179 | 152–170 | about 125 |
| 55 | 176 | 149–167 | about 123 |
| 60 | 173 | 147–164 | about 121 |
| 65 | 169 | 144–161 | about 119 |
| 70 | 166 | 141–158 | about 116 |
For a real number: once you’re used to hard training, go flat out from two minutes into a third interval; the highest reading is close to your max. Skip it if you have a heart condition.
No monitor: a word or two, not a sentence; about 16 out of 20 for effort (Stensvold et al., 2020).
Treadmill, bike, rower or hill
| Option | Setup |
|---|---|
| Treadmill | Walk or jog at a 5–10% incline |
| Hill | About four minutes to climb; walk down to recover |
| Bike | High resistance, 80–100 rpm |
| Rower | A split you can only just hold for four minutes |
| Running | About your best 3–5 km pace (pace calculator) |
What the research shows
- Healthy men: 7.2% more VO2 max in eight weeks, more than long slow or threshold running (Helgerud et al., 2007).
- Heart patients: big gains in a small 2007 trial (Wisløff et al.), but a 261-patient trial found it no better than moderate training (Ellingsen et al., 2017).
- Over-70s: five years of twice-weekly 4x4s: 3.0% died, against 4.7% on standard advice. A trend, not proof (Stensvold et al., 2020).
- Why it matters: each 3.5 mL/kg/min of extra VO2 max goes with a 13% lower risk of death (Kodama et al., 2009). More in VO2 max and longevity.
Where do you stand?
| Age | Average VO2 max | Middle two-thirds |
|---|---|---|
| 40–49 | 47 | 40–55 |
| 50–59 | 43 | 35–50 |
| 60–69 | 39 | 33–46 |
| 70+ | 35 | 29–42 |
Test yourself: run as far as you can in 12 minutes. VO2 max ≈ (metres − 505) ÷ 44.7 (Cooper, 1968), so 2,400 m is about 42.
How often, and who should be careful
Start with one a week, build to two, never on consecutive days. Keep the rest of your cardio easy.
See your GP first if you have a heart condition, high blood pressure or diabetes, have had chest pain or fainting with exercise, or are over 45 and haven’t trained hard in years. On beta-blockers, go by feel. Stop straight away with chest pain, dizziness or palpitations.
Norwegian 4×4 FAQ
Can I walk it?
Yes. A brisk walk up a steep treadmill incline or hill gets most men over 40 into the zone.
Is it better than zone 2?
They do different jobs: the 4×4 pushes VO2 max up, zone 2 builds the base. Do both.
Can I do it every day?
No. Twice a week is plenty; three is the most the main studies used.
Sources: Helgerud et al., Med Sci Sports Exerc 2007; Stensvold et al., BMJ 2020; Wisløff et al., Circulation 2007; Ellingsen et al., Circulation 2017; Nes et al., Scand J Med Sci Sports 2013; Loe et al., PLOS ONE 2013; Kodama et al., JAMA 2009; Cooper, JAMA 1968; NTNU CERG, exercise advice. General information, not medical advice.
