Men will slow down for sex, but not as much for friendship

When men and women walk together, men slow to match the pace of a romantic partner, but when walking with a female friend men slow some, U.S. researchers say. Cara Wall-Scheffler, a biologist at Seattle Pacific University, and colleagues said the study involved 11 couples, and 14 male and female friends of the pairs -- all ages 18-29 -- to walk several times around a track solo and as couples. People have an optimal walking speed, which minimizes energy expenditure for a given distance, with men tending to have faster optimal walking speeds, the researchers said. The individuals walked around a track alone, with a significant other -- with and without holding hands -- and with friends of the same and opposite sex while their speeds were recorded. The study, published in the journal PLoS One, found men walked faster when they walked alone, but walked at a significantly slower pace to match the females\' paces, when the female was their romantic partner, whether they held hands or not. However, when female partners walked with the male friends, the female partners increased their speeds, while the male friends decreased their speed -- demonstrating a compromise of speed. Similarly, when the male partners walked with the female friends, the female friends increased their speed, while the male partners decreased their speed -- again demonstrating a compromise of speeds, the study said. Lastly, when men walked with other men, they both sped up the pace, while women walked together they both slowed.