Q: We have many types of machines in our gym; for example, we have two types of lying leg curl machines and two types of standing leg curl machines. What formula do you suggest for converting the weight used on one machine for another?
A: When comparing machines that use pulleys, you have to take the ratio of the circumference of the pulleys used and compare it to their diameters (like pi). With Hammer Strength equipment, which uses lever arms instead of pulleys, just divide any weight you lift on those machines in half and that’s what you can do on another machine. Seriously, I don’t have any special formulas, but if you’re an experienced trainer, you should be able to estimate during the warm-up sets for any new exercise what you can lift on your heaviest sets. Also, if you keep accurate records and frequently change your exercises (by the way, the Poliquin Strength Institute has eight leg curl machines), when you return to a specific machine you should be able to determine how much you can lift based on past results.
Editor’s note: Charles Poliquin is recognized as one of the world’s most successful strength coaches, having coached Olympic medalists in 12 different sports, including the U.S. women’s track-and-field team for the 2000 Olympics. He’s spent years researching European journals (he’s fluent in English, French and German) and speaking with other coaches and scientists in his quest to optimize training methods. For more on his books, seminars and methods, visit www.CharlesPoliquin.com. IM