1. In the beginning, man created treadmills. These personalized conveyor belts allowed fitness-crazed humans to work out any time of the day or night in the comfort of their own homes. With treadmills, they could avoid workout obstacles like traffic, darkness, cold, snow, heat, pollution, unwashed clothes, angry dogs and angry neighbors. Finally, there were no excuses for missing a workout.

2. The humans soon found other uses for the treadmill. These alternative uses often served as excuses for missing a workout.
[After the jump, fast-forward to the treadmills of the future.]


3. Over time, technological advancements created time- and energy-saving devices that allowed modern societies, especially in North America, to achieve more by doing less. The amount of physical labor that the average person did in a day decreased exponentially, causing scientists to cite sedentary work as a factor in skyrocketing obesity rates. A few ingenious humans, who were skilled with tools, addressed this problem by constructing treadmills that allowed them to exercise while working.
This photo shows Duane Primozich, the vice president and general manger of Best Life (the diet and fitness plan developed by trainer Bob Greene), on a "treadmill desk" he built using a cordless drill, a screwdriver, a hacksaw and a wrench. Primozich started working this way two and a half years ago, after a physical therapist told him that sitting for long periods of time was exacerbating his excruciating back pain. He now logs up to 15 therapeutic miles during the course of each workday. Like the diets of the hunter-gatherers of the past who would comb the savanna for hours in search of sustenance, Primozich's habit of trekking while typing requires additional calories. Breakfast is a nutritious smoothie with kale, spinach and almond milk, while lunch may involve "a burrito as big as my head."


4. At the same time that Primozich was figuring out how to stay healthy and extend his time on this planet, a few other ingenious humans, who were skilled in biomechanics, were trying to figure out how people could remain fit in space. In the '90s, a NASA scientist named Robert Whalen came up with the idea of a treadmill that could add weight to astronauts' bodies in gravity-free space, helping them to keep their bones and muscles strong during a flight mission. A decade later, his son Sean co-founded a firm that adapted the treadmills for use by ordinary, earth-bound humans who are not skilled with computer technology or astrophysics, and who may even have trouble putting one foot in front of the other. The new AlterG antigravity treadmills are most often used to rehabilitate injured athletes. Instead of adding weight to the body, these machines are valuable for their ability to subtract weight, decreasing the force and impact but still providing the same fitness benefits of running or walking on hard ground. The AlterG treadmills can be found at physical rehabilitation clinics, sports centers and training facilities around the country as well as at the Equinox gym on 63rd Street and Lexington Avenue in Manhattan (for use by members only, and the chain hopes to eventually offer them at other locations, says an Equinox spokesperson). This photo shows a typical office worker of the 21st century who suffers from a running-related foot injury. Here, she is being put through a workout routine with Equinox fitness professional Lindsay Dettbarn, who has been trained to work with clients on the AlterG. The runner is wearing a pair of special shorts, the top of which resembles a neoprene tutu, and is zippered into the airtight "cockpit" of the treadmill. This shot was taken before the true takeoff, so she is still striking the ground with about 70 percent of her body weight. In about 20 minutes, she will be leaping and sprinting at only 10 percent of her body weight. She will not resemble a Buzz Aldrin acolyte or an Alvin Ailey dancer, as hoped, but she will feel like a significantly lighter, more agile, more spry version of herself. She will not experience any foot pain, despite running at the fast-for-her pace of 6 minutes per mile. Because she doesn't feel like she's exerting herself that intensely (she was still able to take notes—albeit messy ones—to write this post), she will be surprised to see that her T-shirt is soaked with sweat after 30 minutes. The return to her full weight will feel like a letdown. For this reason, says Dettbarn, the AlterG is a great motivator for those who are overweight but committed to exercise: By moving through space at a lighter weight, they will effectively experience their future.