The first rudimentary exercise equipment used by U.S. astronauts was a simple bungee cord device, first flown on Gemini IV in 1965. Pulling the rubber cord required 70 pounds of force.
The Apollo astronauts took along the commercially developed Exer-Genie on several missions, but reported mixed success. Mike Collins complained after his Apollo 11 flight, “If you got a good workout on the Exer-genie, it got so hot that you couldn't really touch it.” Pete Conrad was also frustrated by the device. He told NASA debriefers, “I tried after the Apollo 12 flight to learn how to use the Exer-Gym right. And I never did like it.”