The study followed up earlier work that showed how cursing increases pain tolerance, helping explain the common reaction to hitting one's thumb with a hammer.
Dr Richard Stephens, from the University of Keele, in Staffordshire, 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."
The findings were presented at the British Psychological Society's annual meeting 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 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.
