QUESTION: What is the 75 rule in cycling? I heard someone telling his buddy to remember that rule on a group ride as the pace started to pick up. What did he mean? —Pete L.
RBR’S STAN PURDUM REPLIES: The 75 rule is a training guideline for riders who are seeking to improve their performance and endurance. The “75” is a percentage and the so-called rule is that when training, about 75% of your time should be at or below 75% of your maximum heart rate (MHR), which is the highest heart rate you can achieve. Conversely, only about 25% of your time should be spent working intensely above 75% of your MHR.
The theory behind the rule is that by staying below the 75% of MHR threshold most of the time, you’ll be able to train overall at a higher intensity without overdoing it and injuring yourself.
Our MHR changes as we age. To calculate your MHR for your current age, subtract your age from 220. For example, for a 60-year-old person, the estimated maximum age-related heart rate would be 220 – 60 years = 160 beats per minute (bpm). That, as I said, is an estimate, which can be affected by health factors, but it is a place to start. The 75% threshold would be: 0.75 x 160 = 120 bpm.
If you wear a heart rate monitor when you ride, your MHR is likely to be the highest number displayed on your monitor over the last year. And realistically, a heart rate monitor is the only way to constantly know where you are in relation to the 75% number, as your current rate is displayed while you are riding. Otherwise, you must stop periodically and take your pulse for 60 seconds at your neck, wrist or chest.
But a lot of trainers say that obsessively watching our MHR is irrelevant, especially as we age. See, for example, what RBR’s Coach John Hughes says about this.
In terms of the guy you heard telling his buddy on a group ride to remember the 75 rule as the pace started to pick up, he was probably speaking loosely to mean “Don’t blow the socks off the rest of us!”
For more about heart-rate-based training, see Arnie Baker’s RBR article here.
Stan Purdum has ridden several long-distance bike trips, including an across-America ride recounted in his book Roll Around Heaven All Day, and a trek on U.S. 62, from Niagara Falls, New York, to El Paso, Texas, the subject of his book Playing in Traffic. Stan, a freelance writer and editor, lives in Ohio. See more at www.StanPurdum.com.