Does too much cardio lower testosterone?

Moderate cardio will not lower your testosterone, but chronic, excessive endurance training can. The blanket claim that cardio kills testosterone is one of the most persistent gym myths, and the real answer is more useful than the scare story.

In normal amounts, cardio helps your hormones rather than harming them. Moderate aerobic exercise improves your body composition and insulin sensitivity and lowers the visceral fat that converts testosterone into oestrogen, all of which support healthy levels. A man who walks, cycles or runs a few times a week alongside lifting is doing his testosterone a favour, not a disservice.

The genuine exception is the endurance extreme. Men training at very high volumes, at marathon and ultra-distance levels, especially while under-eating, can show measurably lower testosterone. But the cause is usually not the cardio itself. It is the chronically raised cortisol and the energy deficit that come with hours of training and too little food or recovery. Sports scientists call this low energy availability: when you burn far more than you take in for long enough, the body reads it as a stress state and dials hormone production down. The same thing rarely happens to someone doing two or three sensible sessions a week.

So the real question is not whether cardio lowers testosterone, but whether your overall training load and nutrition are sustainable. Volume without recovery is the problem, not movement, and the fix overlaps with the basics that raise testosterone.

The type of cardio matters less than the total load. Short, intense intervals and steady-state sessions are both fine in sensible amounts; what tips a man into trouble is sheer volume stacked on top of lifting, work and too little food. Fasted morning cardio is fine for most, but doing hours of it while dieting hard is exactly the energy-deficit trap that suppresses hormones.

What to do: keep cardio in your routine, since it is good for your heart, your waistline and your hormones. Just avoid burying yourself in high-volume endurance work while under-eating and under-recovering. Pair it with strength training, eat enough to fuel it, and prioritise recovery. Done that way, cardio is an asset to your testosterone, not a threat.