How much zone 2 training do you need per week?

Zone 2 training (exercise at which your blood lactate stays between 2 and 4 mmol/L) takes up a remarkably modest share of the weekly programme for elite athletes. In elite cyclists that share was just 7 to 13% of total training volume, while the large majority of time (65 to 91%) was spent in the even lower zone 1. An Olympic rowing pair averaged 17% zone 2, with the remainder likewise at low intensity. Zone 2 is present in all these cases but is clearly not the dominant zone.

That pattern in elite athletes does not necessarily tell us anything about recreational athletes. In national-level youth swimmers, 7 weeks of more high-intensity training at the expense of low-intensity volume produced no performance gain. Lactate threshold speed actually declined in the group that did less low-intensity training. This suggests that a broad base of low-intensity work contributes to maintaining fitness, even in young athletes.

Concrete weekly figures for the average athlete are difficult to derive from the available studies. What does emerge is that elite endurance sports are characterised by a large total volume with the emphasis on low intensity. Zone 2 is one component of that, not the centrepiece. In world-level running, this translated to 150 to 180 km per week with the majority at a low heart rate; zone 2 was just one of several intensity zones within that.

How much zone 2 you personally need depends first and foremost on your total training time. If you exercise 5 hours per week, even 15% zone 2 amounts to just 45 minutes. The studies provide no minimum threshold value for recreational athletes. What they do show is that athletes who traded low-intensity volume for more high-intensity work did not perform better and sometimes performed worse.