If you are doing strength and cardio on the same day, putting the strength work first tends to give better lower-body numbers — several meta-analyses report results pointing that way. You arrive at the gym, warm up on the treadmill for twenty minutes, then head for the barbell. That routine may be costing you something.

A 3.96 kg difference in the lower-body 1RM

Combining strength training with endurance training has long been called concurrent training in the sports science literature. And the fact that attempting both can blunt strength gains compared with strength work alone has been debated for decades as the interference effect. The question of order comes out of that debate: how much of the interference can be avoided?

In 2018, the British researcher Eddens and colleagues published an analysis pooling prior studies of intra-session exercise order, and reported that performing strength before endurance favored lower-body dynamic strength, with a pooled difference of 6.91% in change. In a meta-analysis published the same year, Murlasits and colleagues reported that lower-body 1RM was higher by a pooled mean of 3.96 kg when strength came first, while gains in aerobic capacity were not affected by the order.

The shape of it is this. Reversing the order costs you on the strength side; the endurance side is indifferent. So when in doubt, putting strength first is the choice that leaves less on the table. Only one side carries the risk, and it is worth getting your bet on the right side.

Are you confusing a warm-up with cardio?

Why do so many people enter the gym in the opposite order? Probably because "warm-up" and "cardio" live in the same mental drawer. Five easy minutes on the bike is a warm-up; a twenty-minute run is cardio. The first is preparation, the second is training in its own right and takes something out of you. They are entirely different in nature, and yet the second sits at the top of the session wearing the face of the first.

There is another reason order gets treated lightly: time. Try to fit everything into ninety minutes after work and you end up taking whatever machine is free. The constraints of the facility overwrite the constraints of the body. This is worth consciously pushing back on. If the same ninety minutes yields a different result purely from how it is arranged, that is an improvement available for free.

As we wrote in our piece on Zone 2, there is real value in doing cardio slowly and at length. Put that slow, long work before the strength session, and you run out of gas at the moment you have to pick up the bar. Place the high-intensity work in the part of the session where you are not yet tired. As rules go, that is the whole of it.

Rearrange the week

  1. If both fall on the same day, put strength first. Save cardio for the finish. Since only the order changes, it costs no extra time or money.
  2. Keep the warm-up to five or ten minutes of easy movement. Separate the bike that warms you up from the cardio that trains you.
  3. When you seriously want both to progress, split them across days. The very fact that the interference effect has been debated suggests there is a limit to how well they cohabit.

Stacking high-intensity work raises the load on joints and heart. If you have any concerns about your condition, don't push it — talk to a doctor before raising the intensity.

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