Muscle strength and stamina can be boosted by turning the air blue, a study has found.
Swearing may help a cyclist struggling up hill to summon up extra pedal power, new research suggests.
Likewise, a good dose of foul language might be what it takes to free that stubborn bolt or jammed bottle top.
Psychologists conducted tests in which volunteers had to swear before intense sessions on an exercise bike, or squeezing a device that measures hand grip strength.
In both experiments swearing rudely led to significant improvements in performance compared with uttering "neutral" words.
The study followed up earlier work that showed how swearing increases pain tolerance, helping explain the common reaction to hitting one's thumb with a hammer.
Dr Richard Stephens, from the University of Keele, who led both teams, said: "We know from our earlier research that swearing makes people more able to tolerate pain.
"A possible reason for this is that it stimulates the body's sympathetic nervous system - that's the system that makes your heart pound when you are in danger.
"If that is the reason, we would expect swearing to make people stronger too, and that is just what we found in these experiments."
Surprisingly, increases in heart rate and other expected changes linked to the "fight or flight" response were not seen in the latest tests.
Dr Stephens added: "Quite why it is that swearing has these effects on strength and pain tolerance remains to be discovered. We have yet to understand the power of swearing fully."
The findings were presented at the British Psychological Society's annual meeting taking place in Brighton.
In the first experiment, 29 volunteers with an average age of 21 pedalled hard on an exercise bike for half a minute while repeating a swear word or a neutral word.
Peak power was increased by an average 24 watts by swearing, the scientists found.
The second experiment involved 52 participants of about the same age undergoing tests of hand grip strength.
Again, the volunteers were asked to swear or utter a less emotionally charged neutral word while measurements were taken.
Swearing boosted grip strength by 2.1 kilograms on average.
Dr Stephens said study participants were invited to use a swear word they would typically utter if suffering a bang on the head.
Common examples included "f***" and "shit".
Allowing volunteers to choose their own swear words ensured the words meant something to them.
The words were uttered in a "steady and clear" voice in order to avoid the emotional effect of shouting.
Dr Stephens said: "It doesn't seem to be related to autonomic (fight or flight) arousal. We have some suggestions about what might be behind this effect which will need further research.
"It could be that it involves the pain relief effect we registered before. Pain perception and pain relief are quite complex things. Swear words have a distracting effect.
"If you're asked to squeeze a hand gripper as hard as you can there's a certain amount of discomfort, and it could be that this is reduced by being distracted.
"Swearing seems to be a form of emotional language. Perhaps it's the emotional effect of the words that leads to the distraction, but this is just speculation at the moment."