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Cardio before weights ruins your gains (exercise order matters)

This one is partly true. When cardio and lifting share a session, doing the weights first gives somewhat better lower-body strength gains, but order makes no measurable difference to muscle growth, aerobic fitness or body fat. How much and what kind of cardio you do matters more than when.

What the science says

  • Lifting first gives better lower-body strength Moderate evidence

    Eddens' 2018 meta-analysis of 10 studies found that resistance-then-endurance sessions improved lower-body dynamic strength about 7% more than the reverse order. Murlasits' 2018 meta-analysis agreed, with about 4 kg more gain in lower-body 1RM when strength came first.

  • Order changes muscle growth Limited evidence

    Eddens' meta-analysis found no effect of exercise order on lower-body hypertrophy, static strength, maximal aerobic capacity or body-fat percentage.

  • Order changes aerobic fitness Limited evidence

    Murlasits' 2018 meta-analysis found no difference in VO2max between strength-first and endurance-first sessions.

  • Cardio type and amount drive the interference Moderate evidence

    Wilson's 2012 meta-analysis of 21 studies found that adding endurance work reduced strength, power and hypertrophy gains compared with lifting alone, with running interfering more than cycling and the effect growing with endurance frequency and duration.

What to do instead

Put whichever quality you care about most first; if strength is the priority, lift first or split the sessions, and keep cardio volume sensible.

Strength is the priorityLift first, then cardio
Endurance is the priorityCardio first is fine; aerobic gains are unaffected by order
Muscle growthOrder does not matter much; total volume and effort do
Reduce interferencePrefer cycling over running near leg sessions; keep cardio frequency and duration moderate
Warm-up5-10 minutes of easy cardio before lifting is not the same as a full cardio session

Who should be careful

Combining hard cardio and heavy lifting raises fatigue; build up gradually. People with heart conditions or other medical issues should get clearance from a doctor before starting vigorous training.

Frequently asked questions

Should I do cardio before or after weights?

If lower-body strength is your priority, lift first: two 2018 meta-analyses found modestly better strength gains with that order. For muscle growth, aerobic fitness and fat loss, order made no measurable difference.

Does cardio kill gains?

It can reduce them somewhat, according to a 2012 meta-analysis, especially running and when cardio is frequent and long. Moderate amounts still allow good progress.

Is a short cardio warm-up a problem?

A brief easy warm-up is not what these studies tested; they compared full endurance sessions before or after lifting.

Scientific references

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