Why a year in the gym still leaves you breathless and slow when you play sport

Plenty of people go to the gym three or four times a week, and after a year they've built muscle and their weights have gone up. But as soon as they play a ball sport or go for a run, they're out of breath within minutes and their feet can't keep up. The first reaction is that they haven't trained enough, so they add more sets and more weight. Why, after a year of training, do they still get more breathless the longer they run and slower the longer they play?

Because fitness comes in separate pieces. Strength is one piece, cardio fitness another, and speed, jumping and change of direction are each pieces of their own. Machines and dumbbells mainly train strength and muscle; they don't carry the other pieces along. Whichever piece you don't train is the one you'll be missing when you play.

First, the breathlessness. Of 17 studies in which young adults aged 20 to 40 did only strength training, just 3 found a clear improvement in cardio fitness – and mostly in people who started from a low base.

Cardio fitness needs its own training – and when you train it, it really does improve. Pooling 28 studies and 723 adults aged 18 to 45: compared with people who didn't exercise, steady-state running improved it by 4.9 more (4.9 more millilitres of oxygen per kilogram of body weight per minute), and interval running by 5.5 more. This is key.

Next, the slowness. In a study of 36 men training twice a week for 6 weeks, those who did straight-line sprints got faster in a straight line but improved only a little at changing direction; those who did shuttle change-of-direction work got faster at changing direction, with no clear change in straight-line speed. Even within running fast, straight-line speed and change of direction have to be trained separately.

So what should you train? Four things.
Keep the strength work: squat, push, hip hinge and pull – full-body sessions twice a week.
Train cardio fitness specifically: bodyweight circuits of 20 seconds on, 10 seconds rest; run 1 minute, walk 1 minute.
Jumping and landing: first learn to land softly with stable knees, then progress to continuous jumps.
Speed and change of direction: short sprints, plus sudden stops, turns and restarts.

When you play sport, is it your breathing that goes first, or your feet? Tell me in the comments.