Alan Calvert's Milo Barbell Company began to offer its adjustable barbells at the turn of the 20th century, giving rise to progressive resistance training. Before then, bodybuilders lifted fixed weights. "When people could change the plates and incrementally add weight, it made it easier for them to see their progress and train," says Jan Todd, a professor in the Kinesiology and Health Education department at the University of Texas at Austin. Today, plate-loading free weights and machines such as chest presses, shoulder presses, and leg curls save gym owners countless square feet of floor space.
Thaddeus Fairbanks built the first platform scale in Vermont in 1830. The invention ushered in a new, important motivator: knowledge of one's weight. Regular weighing remained uncommon until the insurance industry became intrigued by the metric; insurers wanted to know their clients' weights because heft had been linked to an increased risk of death, writes science journalist Gina Kolata in her book Rethinking Thin: The New Science of Weight Loss—and the Myths and Realities of Dieting. The bathroom scale, with its promise of privacy, appeared at the turn of the 20th century. Another key staying-slim tool would soon follow: the full-length mirror.
From the Greek words for "beautiful" and "strength," calisthenics was practiced in ancient Greece and had one of its first American advocates in Catharine Beecher, who founded a girls school in Hartford, Connecticut. Beecher taught a system of calisthenics there that she devised, incorporating principles from Per Henrik Ling's Swedish gymnastics as well as music. The body-weight-as-resistance exercises intended to improve the coordination, health, and general vitality of females were recognized as beneficial to men as well; they remain an important part of military fitness regiments—and, really, the regimen of any gym-goer.
Gatorade's blend of carbohydrates and electrolytes debuted at the University of Florida in 1965. Inspired by a desire to help the Gators' football players, who were suffering the negative effects of dehydration after playing for hours in the heat, the drink replaces lost salts and helps athletes stay hydrated. "It made everybody all of a sudden aware that we need to hydrate," says Todd. "It's hard to believe, but it wasn't always that way."
The modern athletic shoe evolved from the plimsoll shoes of 19th-century England. Early shoes included Charles Goodyear's mid-19th Century invention of vulcanized rubber not only on the soles—which were quiet, allowing wearers to "sneak" around—but also at the toes, preventing the big toe from breaking through. Keds became the first mass-market athletic shoe in 1916, and various performance-enhancing design changes followed. The most famous was perhaps the Nike waffle sole, invented when University of Oregon track coach Bill Bowerman poured rubber onto his family's waffle iron.
When the 10-speed bicycle came to the U.S. from Europe with its additional options, increased ease of use and streamlined design that reduced drag and added speed, baby boomers fell in love. By the early 1970s, a full-on bicycle craze had begun and manufacturers like Schwinn were facing shortages. "I remember all of a sudden, everybody seemed to want a 10-speed bike," says Todd. Suddenly, biking wasn't just for kids. The 1980s would bring the modern stationary bike, an update of the crank-operated Gymnasticon of the late 18th century. Countless sweaty Spinning classes would follow.
Its namesake is a mill operated by a person or animal treading the steps of a wheel to grind grain. And the physical labor continued through the years: Prisoners sometimes walked early treadmills in 19th-century England and in New York at the Bellevue Penitentiary, where they generating power. By the 1960s, research by Kenneth Cooper led to the idea that the treadmill could be an important tool for aerobic exercise. Today, some treadmills have returned to their roots as sources of power. Gyms like the Green Microgym of Portland offer treadmills that harness the power of walkers and runners to generate electricity.
In the late 19th century, physiologist Charles-Edouard Brown-Sequard discovered he felt "rejuvenated" after injecting himself with testicular extracts from dogs and guinea pigs. Decades later, in 1935, scientists isolated and chemically synthesized testosterone (two of them, Adolf Butenandt and Leopold Ruzicka, won a Nobel for their work). Anabolic steroids, synthetic derivatives of testosterone, were used as performance enhancers among Olympic weightlifters in the 1950s. Although now illegal in professional athletics due to their long-term negative health affects and performance-altering effects, steroids grab the spotlight every sports season with the stars that take them spurring no shortage of controversy along the way.
Before personal trainers rose to their current level of ubiquity, weightlifters who'd watched Ah-nold at Gold's Gym in the 1977 film Pumping Iron would ask gym employees—or the guy in the best shape—for help. Today's trainers "trick" muscles through periodization—changing up a workout so the body doesn't have time to adapt—while also providing accountability, injury prevention, and general guidance. Some exercises involve complex movement patterns, says Mike Fantigrassi, a specialist with the National Academy of Sports Medicine. As with a sport like golf, "it takes coaching to do something right if you haven't done it before," he says.
This little sensor that fits in a Nike+ shoe (or that may be worn on a runner's own pair) enables tracking of performance indicators like speed and distance, as well as the ability to map a route. It relays information via a voice that becomes both pedometer and pace coach, providing real-time feedback and encouragement on the route. There's also the ability to select a "power song" for an extra boost. Users of the system can upload their workout information to the Web to track their progress and plan a training schedule. Users can also join an online running community, giving runners access to one of the most important tools of training: competition. —Jennifer Weiss