Dark chocolate, which contains epicatechin, has the same effect on muscles as a workout at the gym.
Dr Moh Malek studied the effects of the compound epicatechin and found that it appeared to boost energy in muscles, allowing them to exercise for longer periods.
The effect is similar to training in the gym.
The research results were published in The Journal of Physiology.
Improvements in muscle performance were linked with an increase in mitochondria.
Mitochondria decreases in skeletal muscle as we age and this affects us physically in terms of muscle energy production and endurance.
Chocolate may provide an approach to reduce the effects of muscle ageing.
Unfortunately, it is too early to say whether humans get the same benefits as the mice used in the study.