He doesn't need to every Friday night. But now and then - before a particularly "hot date, or stepping out to a nice club" - Edward Dennis' veins cry out for it, and he'll do a quick one. With each arm. Then ten or 20 more.
He means bicep curls, of course. Dennis, a 25-year-old mortgage broker from Parkville, is one of untold numbers of young men who hit the weights just minutes before they hit the town, a routine that creates a fleeting enlargement of upper body muscles - and swells the ego to boot.
"You get bigger, tighter," Dennis said. "Your arms bulge out a little bit."
Not everyone confesses so readily to this furtive self-inflation, which some personal trainers say can temporarily increase bicep diameter by as much as a quarter of an inch, add definition to muscles and plump veins.
"The process is called The Pump, OK?" said David Levin, owner of Max-Out Personal Training in Reisterstown. "Nobody talks about it. It's just something that is."
Men have pumped since prehistoric times, when cave men "dragged around dead mastodons" before promising dates - or so claimed Stephen Perrine, the editorial creative director at Men's Health magazine, which last spring published an article on pumping technique.
Professional body builders have long appreciated the power of The Pump, Levin said, but only in recent years has that knowledge trickled down to the male populace, which is increasingly body conscious.
The Pump is now the metrosexual equivalent of the Wonderbra.
The point of pumping is, of course, to attract attention, particularly from potential partners.
"You're looking a little bigger, you're feeling buff," said Justin Roman of Frederick, who sweated until closing time at the Gold's Gym at the Power Plant one recent Friday night before heading out with friends. "All the girls notice. They grab onto your arms."
But the girls may not grasp what's going on - which is basically a kind of false advertising.
"You have probably been dating much smaller guys than you thought," said Perrine.
The Pump is accomplished through clandestine sets of push-ups or late-night gym work, any kind of exercise that involves relatively light weights and lots of repetitions.
The mechanics are simple: Biceps swell after a few sets of curls because blood floods into the working muscles, supplying oxygen and sugar, according to Dr. Luis Queral, chief of vascular surgery at Mercy Hospital.
But this increase in size is sadly "very transient," said Ilya Leyngold, a medical student at Johns Hopkins who quit pre-going out pumping after he noticed that the visible effect lasted only an hour or two. By the end of a night out, biceps deflate like leaky beach balls.
For the fake muscle to make a prolonged public appearance, "you have to do it at home, not even shower and then leave," he said.
This post-shower pumping is a bit tricky, because sweatiness can counteract the allure of bloated muscles. Some men lift immediately before leaping into the shower, then do a refresher set of push-ups.
Others work out on the way out, hitting the health club before the nightclub - sometimes in evening attire. Late on Friday nights at Baltimore's Downtown Athletic Club, men occasionally materialize on the weight machines "wearing really nice shirts," according to Brandon Rivera, a part-time trainer there.
The Pump is a running joke among them. "They say, 'I just got to fill out this shirt a little more," Rivera said.
It's even possible to pump - or "get swole" as it's also called - en route to a date. The truly motivated can clench their stomach muscles while driving to a woman's house or - while she's putting the finishing touches on her makeup - do some dips with a kitchen chair to jack up the triceps, according to Kenneth Reed, owner of Fit for Life Personal Training in Randallstown.
Sounds like a pain in the glutes, but The Pump is an unavoidable part of man's evolutionary strategy, said Perrine, the Men's Health editor.
A man's size reflects his strength, and "in addition to intelligence, personality and willingness to walk little old ladies across the street, a man's ability to protect and move mattresses" matters to women, he said.
There is even evidence of cross-species pumping. The Andean Cock-of-the-Rock, a bright orange rainforest bird, performs a similar ritual when attempting to attract females.
"They expand their feathers and lift their wings out," said Adrian Forsyth, author of A Natural History of Sex. "They actually puff themselves up. And then they dance, they bob, they make noises," a display eerily reminiscent of the twentysomething bar scene.
To be fair, even women sometimes succumb to The Pump. Some of the fiercest pre-event pumping occurs in the hours right before weddings, as brides strive to make their backs and arms look more defined in plunging gowns, according to Andrew Bloom, who owns Homebody's Inc. in Owings Mills.
The effect isn't as striking because women's bodies are typically less muscular. And although they may experience a tightening of the muscles that improves posture, even smaller-built men may not look significantly different from pumping - especially beneath the loose-layered clothing fashionable today.
Even in the tightest T-shirt, The Pump "isn't going to turn your Average Joe into the governor of California," Perrine said.
More important is that pumpers feel transformed afterward. This is due in part to the rush of blood and hormones that accompanies a workout - a kind of chemical confidence boost - as well as a shift in self-perception born of believing you look better. This magic feather effect endures far longer than the period during which muscles are actually engorged.
When men feel confident physically, they are more likely to exercise the most important muscle of all - the larynx.
No matter how many reps you do, Reed said, "if you don't have the raps" - the right way of talking to somebody - "you're not going to have any luck anyway."
Some serious body builders disdain pumpers - "nightclub muscles," one said scornfully - and noted that, ultimately, the technique can hurt the physique, particularly because drinking and dancing are not conducive to muscle growth. Workouts actually weaken muscles, so afterward the body should be treated to a comfortable night's rest and plentiful helpings of protein and carbohydrates. ("Beer doesn't count," said Todd Swinney, a Millersville personal trainer.)
The Pump also repels some women. Twenty-five-year-old Courtney Flannery isn't attracted to men who advertise their muscles, "even if they actually have them." But pumpers are worse because "they are showing off something that isn't real and making themselves something they're not," she said after her own workout at Quest Fitness in Lutherville.
Perhaps a better strategy is the one employed by Scott Lofgren, who lifted weights and played a vigorous game of basketball at the Johns Hopkins University student gym on a recent Thursday evening.
Like the pumpers, Lofgren was preparing for a night of drinks and partying. But the college senior wasn't trying to supersize himself - quite the opposite, in fact.
"I got to keep the gut down," he said.