While outdoor riding is fast and fun, it doesn’t translate very well to retaining running fitness. If you’re injured and don’t have access to an Alter G treadmill or swimming pool, setting your bike up on a trainer or signing up for a spin class at your local gym is the next best way to rev your aerobic engine. Staying stationary for an hour or more in a controlled environment can be mind numbing, but it’s far more effective at replicating running workouts than dealing with the incessant interruptions of road cycling.
I’ve found that my spinning sessions need to be one-and-a-half times longer than my usual running workouts to achieve a similar stimulus. So, for example, to replicate a 60-minute recovery run on the roads I’ll spin for 90 minutes at an equivalent effort. Sometimes I’ll use a heart-rate monitor to keep tabs on myself, finding that my heart rate is usually about 15 beats per minute lower on the bike than when running. For harder efforts such as interval sessions and tempo runs, the same principle applies: 3:00 intervals at 5K effort get bumped up to 4:30 at an equivalent effort or heart rate; a typical 30-minute tempo run on the roads is 45 minutes at the same effort on the bike.
For my own training, as well as with the athletes I coach, I prefer the use of a spin bike for specific sessions rather than a bike trainer because the resistance can easily be controlled and you can get out of the saddle to replicate a running motion when doing intervals. I’ll have athletes work mostly at a low to medium resistance and keep a high cadence (90-100 RPM) to engage the right running muscles and maintain good turnover.
The absence of impact in spinning facilitates a quick recovery and allows you to go harder more often than you could or should when running. While rehabbing my way through a case of posterior tibial tendinitis less than six weeks out from the 2008 Boston Marathon, I literally spun my way to the starting line, mixing up interval workouts and tempo “runs” on the bike every other day for three weeks (zero running!) to maintain my hard-earned fitness. In the end, I finished less than two minutes off my personal best and have been a big believer in the benefits of spinning ever since.