How to Avoid the Post-Illness Over-Training Death Spiral

You’re just getting over an illness, feeling maybe 80% healthy, but you are more than desperate to start training again. You fear losing fitness and you want to make up for lost time, so you head out for your first few rides or runs and you feel out of shape. You notice that your heart rate is unusually high compared to your power or speed, and that you are breathing a bit harder than usual, considering your effort – both totally normal after a layoff. What you do next can make or break your season: Go one way and you’ll be back on track in the shortest possible time. Go another and set yourself on a downward spiral towards several months of below-par performance.

If you are like me, you are tempted to go right back to your normal, pre-layoff power zones and speeds, but that’s a mistake because of two interacting factors: First, lactate threshold (LT) power is reduced by as much as 25% for 2-3 weeks after an illness – even a mild one – while lactate threshold heart rate is often reduced by 10 beats or more. Second, excessive training near or above LT suppresses rather than boosts LT.

The Death Spiral – How to Wreck Your Season

After an illness, your old Zone 2 (aerobic endurance) power or heart rate, which was safely below LT, is now closer to or possibly even above your suppressed LT. That means riding or running at your old normal speed or power is now too hard, even if you can convince yourself that it feels easy. Many athletes, feeling that their performance is down post-illness, push harder. If you return to training at normal power or pace too soon after an illness, you set yourself on a vicious circle path: Riding harder than you should suppresses LT, reducing the speed you can sustain below LT, so you ride at or above LT even more, further suppressing LT…

The Upward Spiral of Return from Illness

To return as quickly as possible from illness, and no quicker, you must be patient. First, do only short recovery rides or days off until you are 100% over the illness. You may start to train while you still have a residual cough, as that can sometimes linger for several weeks after the germs are defeated, but absolutely do not train while you have any aches, fatigue, spaciness or the sort of low energy that indicates that you are still sick. Start to train again only when you feel 100% rested and recovered. Be honest with yourself about whether you really feel normal.

When you start to train, start easy. Take one day strictly in Zone 2 by feel for each day you were off with the illness – including the days you should have taken off but didn’t – up to six days. Zone 2 by feel means you want the effort to feel like Zone 2 before the illness, which will mean riding a lower power and heart rate than before the illness. If you are not good at training by feel, your old Zone 1 (Recovery Zone) is probably okay. After a longer illness, you’ll need to do some rebuilding and use your body awareness to know when it’s time to increase intensity again.

After any length illness, the first days back on should be short as well as low-intensity. If you are doing a four-day re-entry, two short Zone 2 by feel rides and two medium-length ones would be ideal. The later days of a longer re-entry can be as long as your normal rides, but still at a Zone 2 by feel pace.

Keep It Low End for Re-Entry

Even if you do everything right, your power zones will be too high for the first few weeks after an illness, so obey your heart rate monitor, or train by feel for that period. During the re-entry days, stay in the low end of your normal aerobic endurance heart rate zone, rather than your normal power or speed zone, even if that means going incredibly slowly. If you start to feel your breathing accelerate or any heat in your legs back off by another ten beats per minute.

During the recovery period after an illness, it really pays to be body-aware. If you are breathing harder than normal or feeling heat in your legs at lower power than normal, that is an unequivocal indicator that you are not fully recovered and should still be training at reduced power.

Power can be reduced for several weeks even after what seems like a short and trivial cold. It’s best to train by feel rather than your old power zones during this period.  If you must do a hard race during the period of suppressed power, expect to need extra recovery time. Stage racing before power is 100% back to normal risks further suppressing LT and delaying full recovery for additional weeks or months.

If you are patient and allow your LT time to creep back up, you can be back up to full speed about three weeks after a short illness. Any effort to get back on track sooner runs the risk of crashing your season and can’t accelerate your return to fitness anyway, so be patient, keep the intensity down, and ride the upward spiral.

Head Coach Scott Saifer is getting over a cold as he writes this and is doing everything he can to keep himself off the bike. He’s available to help endurance athletes for all levels and abilities come back from set-backs and take their performance to the next level.