Question: I ride six days per week, totaling about 120 miles. I also love to run on my easy cycling days, doing 30 minutes three times per week. This combination has helped me shed 70 pounds. When I run, I push my heart rate past my lactate threshold. Will running at this intensity plus cycling hard eventually burn out my cardiovascular system? My legs feel fine. — Bob C.
Coach Fred Matheny Replies: Risk varies with the individual, but the general rule is to be careful with any type of crosstraining.
The body has a limited capacity for exercise. If you focus on riding, you need plenty of recovery time built into your schedule. Running is fun, but even an easy run isn’t rest. If you’re going above your lactate threshold on runs, you’re not recovering, you’re adding even more to your total load.
The issue isn’t cardiovascular stress. Your CV system can handle nearly anything you throw at it.
Instead, it’s a question of muscular stress. Your muscles drive your CV system, so they’re the first to go. This is especially true with running, which can introduce various overuse injuries into the rest/recovery equation.
Running on the same day as cycling is okay if you’re training for duathlons or triathlons. But you have to be very careful about monitoring the overall stress load.