How Long Does It Take to Lose Your Fitness?

The question "How fast do I lose fitness when I stop training?" usually comes when cyclists experience illness or an injury that forces time away from training. The other time they ask this question is at the end of a race season when most coaches recommend athletes taking a break from normal training routines.

A decrease in training typically follows three paths that include complete bed rest, doing normal activities without any training or a reduction in training volume and/or intensity.

For this two-part column series, let's focus on taking time off at the end of a competitive race season without injury and without complete bed rest. We will focus on intentional, planned time off—the recovery phase of training periodization.

More: 4 Offseason Cycling Tips

For some athletes, the recovery phase means doing all normal activities except athletic training. For others, recovery means a reduction in training volume and intensity. A third set of athletes may alter volume, but intensity remains as a matter of switching sport activities. An example is when cyclists switch to Nordic skiing. Know that even two-sport athletes will take a recovery phase of some type between sport seasons.

Lost Fitness

When training volume and intensity is significantly decreased or eliminated for long periods of time, compared to prior weeks, fitness is lost. How much fitness is lost and how fast the losses occur depend on many factors, some of which include:

• The volume of training that remains during the time of decreased training.
• The amount of training intensity that remains in the schedule.
• The total length of time the athlete has been fit and training.
• The amount and type of cross training included in the recovery.
• The age of the athlete.

More: Should Cyclists Run in the Offseason?

Training Ceases, Normal Activities Continue

Researchers took a look at seven highly-trained athletes who were either cyclists or runners. These athletes trained for at least 10 to 12 months, five days per week at some 70- to 80-percent of VO2 max. In the experiment, 57 sedentary control subjects were used as comparison.

Researchers looked at physiologic measures that included oxygen consumption, heart rate, cardiac output and cardiac stroke volume. They took muscle biopsies of left gastrocnemius (on the runners) and vastus lateralis (cyclists).

The trained athletes stopped doing athletic training and limited physical activity to the minimum required for their jobs. They also walked less than 500 meters per day.

More: 3 Questions for Your Cycling Offseason

VO2 max decreased by seven percent after 12 days, 14 percent after 56 days and 16 percent by day 84. Cardiac output declined by around 10 percent by day 84, declining by around seven percent after 12 days. Stroke volume decreased by 11 percent in the first 12 days and stabilized at a loss of 14 percent by day 84.

Heart rate increased during the detraining period, which partially compensated for decreases in stroke volume.

Many athletes confused about training seek to achieve the highest heart rate possible during workouts. As athletes achieve fitness, heart rate decreases. This makes achieving higher heart rates during training more difficult.

In separate research, when scientists looked at combined study results, it appears that blood-lactate concentrations increase exponentially when training ceases and a steady state level is reached around the 21- to 28-day mark.

More: Do Cyclists Need to Cut Calories in the Offseason?

Biopsy data

Key enzymes that are essential to aerobic respiration decline and reach their lowest levels by day 56. Interestingly, myoglobin (the primary oxygen-carrying pigment of muscle tissue) and capillary density (affecting the volume of blood flow into muscles) were not affected by the detraining.

Two Phases of Fitness Loss

It appears that there are two distinct phases of fitness loss in highly trained athletes when they cease training. The first phase lasts some 21 to 28 days and is attributed to central adaptation losses. You can think of it as losses to your cardiovascular system.

The second phase is considered peripheral or linked to losses specific to trained muscles and muscle fiber changes.

More: Why Road Cyclists Should Try Cyclocross in the Offseason

Changes in Strength

A separate study examined strength training in two mixed groups of men and women. The first group included those 20 to 30 years old and the second was 65 to 75 years old. The groups followed a strength program for nine weeks and then allowed 31 weeks of detraining to occur.

Using one-repetition maximum and isokinetic strength as the measurements, the study found no significant differences in strength gains or losses between the women and men in each group. This means gender had no effect on the percentage of strength gains and losses.

What's striking is that after 31 weeks of detraining, the young group lost around eight percent of their strength; however, the older group lost around 14 percent. Strength training losses in older athletes is more than in the younger group.

More: Cross-Training for Cyclists: 4 Tips to Keep You Fit

Detraining or the Reversibility Principle

As you probably expected, if you quit training you will lose fitness. Science refers to this phenomenon as detraining or the reversibility principle. Scientists collected results from several studies to find the following average results for two periods of detraining. Short-term (ST) was three weeks or less and longer-term (LT) was 3 to 12 weeks.

1. VO2 max decreased eight percent ST and 18 percent LT.
2. Lactate threshold decreased seven percent ST and 18 percent LT.

The good news is that if you reduce training and keep some intensity in the training mix, you can significantly reduce your losses. This allows for recovery from the racing season without resetting your fitness to zero. This will be covered in Part II.

More: Base-Building for Time-Crunched Cyclists

Ready to ride? Search for a cycling event

---

References

McArdle W., Katch F. and Katch V., "Exercise Physiology, Seventh Edition", Lippincott Williams & Wilkins, 2010, pp. 350, 456, and 526.

Mujika I., Bosquet L.,  "Endurance Training – Science and Practice", I?igo Mujika S.L.U., Vitoria-Gasteiz. ISBN 978-84-939970-0-7, 2012, pp. 101-106.

Lemmer J.T., et al, Age and gender responses to strength training and detraining, Med Sci Sports Exerc. 2000 Aug;32(8):1505-12.