When I started working out, I had a personal music player the size of a dachshund for exercise motivation. I filled it with Rush and Joe Satriani mix tapes to enhance my workouts.

Technology has come a long way since then.

Now I use an iPod Shuffle, which is preferred among fitness folks for its diminutive size, even if it does have a robustness issue when it comes to a little sweat.

One night I recall waking up at 3 a.m., as if from a bad dream, my consciousness shrieking: The battery in my iPod is dead, and I have an early bike ride planned! I had to get up and plug in the thing in order to get back to sleep.

I am a music junkie when it comes to working out, and I know many people who, if their music player is dead, lose their motivation to exercise. Science explains why.

In 2005, British researchers put 18 untrained men and women on stationary bikes and told them to go for it. One group got no music, one got motivational, get-your-butt-in-gear-type music, and the third group got Enya. (I mean I assume it was Enya. The researchers called it “nonmotivational.”)

Published in the European Journal of Sport Science, they found the music listeners blew away the control group (which had no music), and the tuned-in subjects traveled significantly farther. What’s interesting is “no significant differences were observed” between the slow- and fast-music groups. Even more interesting is that though music listeners were working a lot harder, they did not perceive an increased level of effort.

James Annesi, director of wellness advancement at YMCA Metropolitan Atlanta, researched how distractions affect athletic performance. His 2001 study published in the Canadian Journal of Behavioral Science compares use of music with television on treadmills.

“We allowed people to use a wide selection of music channels versus television channels,” Annesi told me. “Almost exclusively, people chose the TV over music.”

Music, television, chatting with a friend or traveling through a scenic vista are all methods of dissociation, Annesi said. “It’s all about removing discomfort. Pain has been engineered out of our culture. In agrarian times we had to exercise or die, but now we need to find ways to manipulate conditions to get people to exercise.”

Dissociation via music is about making us not think about the pain we’re in.

For those who need the motivational kick, music or other distractions can get them to train harder. But for more elite exercisers, music may interfere.

“Elite athletes are associators,” said Jack Raglin, a professor and sport psychologist at Indiana University. “When they’re just logging the miles in training, they can listen to music, and a lot of them do. But for the really intense efforts you have to pay close attention to your body. Music will absolutely interfere with this.”

I ran a 10K race with an iPod in 2008. I’d planned out a specific rockin’ playlist and everything. I felt the distraction held me back from a full effort. The next 10K race I ditched the music and chopped 4 minutes off my time. Now I never listen to music when racing.

There may be other reasons to listen to music, like if your gym plays lots of Nickelback. I also suspect some female weightlifters wear headphones to deter would-be suitors from approaching, and when I posted this question on Facebook I received numerous confirmations.

“Men are less likely to come up and talk to me when I’m listening to music,” said Jessica Morse, a 32-year-old government worker in Ottawa, Ill.

Morse, who is also a fitness competitor in the “bikini class,” explained her motivation. “We have some creepers at my gym, and it’s awkward. I use music as a deterrent.”

James Fell is syndicated fitness columnist and certified strength and conditioning specialist.