Push-up intensity:

It's no easy matter staying in shape when the whole world conspires to keep you looking like Porky Pig's brother. Between frequent business trips out of town; brain-draining, dispiriting 60-hour workweeks; and weekends wasted watching Hope Floats with the girlfriend, you're lucky your body hasn't turned you in to the government's fitness czar on grounds of neglect. Leading a busy lifestyle usually means placing all your hard-earned muscle on the sacrificial altar of "not enough time." However, keeping in shape doesn't have to be so time-consuming, nor inconvenient. No matter how complex your life may get, you already have all the equipment you'll need--well within arm's reach--for staying fit. PUSHING THE LIMIT The classic push-up has survived the ages of iron, Nautilus and Cybex because of its easy access, but convenience isn't the only reason this timeless exercise is still relevant to the guy intent on building a better physique. "No single movement simultaneously strengthens the chest, deltoids, lower back, and triceps quite as efficiently as the push-up," says Kurt Brungardt, author of The Complete Book of Shoulders and Arms. Fear of embedding your teeth into the floor forces you to spend equal time lowering your body as you do raising it back up, a concentrated effort you may not often allow when using free weights. It's this controlled pace that works muscles through three types of muscle-building resistance (concentric, eccentric and isometric) while teaching them to work as a team.