Training and Programming
Ask a room of lifters why they skip cardio and most will say it costs muscle. Ask them for the study and they will not have one. The belief comes from a real finding, stretched far past what it showed.
Cardio and lifting compete for recovery. That is true. Whether it matters depends on how much of each you do, what kind, and how you arrange them. At the volumes most people in a gym actually run, the cost is close to zero and the benefit is large.
In 1980, Robert Hickson published the study that started it. Three groups trained for ten weeks: strength only, endurance only, or both. The strength-only group got stronger throughout. The combined group matched them until about week seven, then plateaued and slipped.
Look at what the combined group did. Six days a week of hard cycling or running, up to 40 minutes, on top of five days of heavy lifting. Eleven sessions a week with no periodisation. Almost nobody trains like that, and the interference showed up only in the last three weeks, when accumulated fatigue caught up.
The lesson was "too much of both, done badly, costs strength". It became "cardio kills gains". Those are different claims.
Two large analyses matter.
A 2012 meta-analysis by Wilson and colleagues pooled 21 studies. Concurrent training did reduce hypertrophy, strength and especially power compared with lifting alone. The effect grew with cardio frequency and session length, and running interfered more than cycling.
A 2022 meta-analysis by Schumann and colleagues in Sports Medicine, with better-controlled studies, found something narrower. Concurrent training did not meaningfully compromise muscle growth or maximal strength. What it reduced was explosive strength, the ability to produce force quickly. That matters for sprinters and jumpers. It matters much less for someone chasing a bigger squat and more muscle.
Running involves repeated eccentric loading. Every stride lands with force, and that produces muscle damage in the legs that competes with recovery from squats and deadlifts. Cycling is concentric, with almost no landing impact.
Wilson's analysis found this directly. Running had a stronger interference effect on leg hypertrophy and strength than cycling. If your cardio choice is open, a bike, a rower or an incline walk interferes least. If you run because you like running, keep it and manage volume.
The clearest rule from the research: if you must do both in one session, lift first. Doing cardio before weights reduces the quality of the lifting that follows, particularly on lower body days.
Separating them by several hours, or by a day, is better still. Studies that split sessions by six hours or more show less interference than back-to-back sessions. When that is not practical, a short cardio block after the lifting is fine.
The workout planner engine places cardio around lifting days based on how many days you can train, which removes most of the guesswork about arrangement.
Interference scales with volume. In the studies that found real effects, cardio ran four to six days a week at 30 to 40 minutes or more of hard work.
Two or three sessions a week of 20 to 40 minutes, mostly at a conversational pace, sits below the level where hypertrophy suffers in any study worth citing. Add one interval session if you want it. Above that, particularly with running, start watching leg recovery and lifting performance.
High-intensity intervals cost more recovery per minute than steady work. One or two HIIT sessions a week is plenty for most lifters, and doing them on the same day as legs is the arrangement most likely to hurt.
The deficit should come mainly from food, not from cardio. Trying to burn off 500 calories a day on a treadmill is inefficient, hard to sustain and the most likely way to interfere with lifting.
A practical order:
Cardio in a cut is a lever, not the engine. Most stalled cuts are a food problem, and the progress bottleneck engine is built to find which one before you add another hour on the bike.
Anabolic steroids raise blood pressure, thicken the heart wall, drop HDL and raise ApoB. Regular aerobic work is the single most effective thing that pushes back on those changes, and it is the one most enhanced lifters skip.
A floor of 150 minutes a week of moderate cardio, in three to five sessions, is the sensible minimum. Zone 2, the pace where you can hold a conversation, is enough. The point is cardiovascular health, not fat loss, and the interference cost is a bargain against the alternative.
For a five-day schedule with muscle as the priority:
Three cardio blocks, none of them before legs, none of them running if leg growth matters to you.
Cardio at two to four sessions a week does not measurably reduce muscle or strength. Running interferes more than cycling. Lift first if they share a session, separate them when you can, and keep interval work away from leg days. On a cut, the deficit comes from food and cardio is the second lever. If you are enhanced, cardio is protecting the organ that fails first.
Not at moderate volumes. Meta-analyses show two to four cardio sessions a week have little or no effect on muscle growth or maximal strength. The interference seen in early research came from very high volumes of both.
After. Cardio before lifting reduces lifting quality, especially on lower body days. Separating them by several hours or onto different days is better still.
Cycling interferes less with leg muscle growth because it involves no landing impact. Running produces more muscle damage in the legs and competes with recovery from squats and deadlifts.
Two to three sessions of 20 to 40 minutes at a moderate pace, plus daily walking. One interval session a week is fine. Keep hard cardio away from leg days.
No. A calorie deficit from food does most of the work. Cardio and steps add expenditure and help, but a stalled cut is usually a food problem, not a cardio shortage.
Yes. Anabolic steroids raise blood pressure, thicken the heart wall and worsen lipids, and regular aerobic training is the most effective counter to those effects. A minimum of 150 minutes a week is a sensible floor.
This article is educational and is not medical advice. See the medical disclaimer.
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