Injuries, pool closures, off season - a swimmer may be away from the pool for a number of reasons and in that case they might end up losing swim fitness.
Elite swimmers are well aware of the fact that progress is hardly linear. While there might be long and consistent periods of time where a swimmer makes constant progress, at some point they might have to stay away from the pool for a period of time. Whether it be due to illness, injury, pool closure, off season, or just plain distractions as far as life is concerned, it can all cause disruptions in the training schedule.
Meanwhile, swimmers also need periods of rest and recovery in order to allow the body and its muscles to recover from fatigue. As such, athletes would want to know how long does it take for the body to lose swim fitness and how big of a break hampers their training seriously.
Well, the research suggests that highly trained, experienced, and very fit endurance athletes can lose fitness quickly, in periods of 2-4 weeks. Meanwhile, as far as those with lower starting fitness levels and shorter training histories are concerned, they may be able to withstand 2-3 week layoffs without a significant fitness loss.
However, on the flip side of the coin, the losses in gains are expected to level off after about eight weeks in highly trained individuals. This allows them to maintain higher fitness levels when compared to more sedentary individuals whose recently gained fitness gains are completely lost.
This fitness, however, only accounts for the VO2 max level which dictates the extreme level of endurance in athletes. It doesn’t concern with swimming techniques and the nature of the swim.
Consistent years of swimming results in muscle memory being formed and while aerobic fitness can be lost more quickly in more highly trained athletes, the multi-factorial nature of swim-specific fitness will likely withstand less of a hit in more highly experienced swimmers.
It has been regularly proven that swim speed depends on a variety of factors when it comes to aerobic fitness. Therefore, maintaining these fitness levels with some kind of engaging activities like treadmill run, hiking, biking, or even backpacking on trips will allow an individual to compensate for the losses better in case of a break from the pool.
It goes without saying that age also plays a role in this fitness loss. At one end of the spectrum, when looking at pure muscle strength, youth ages 10-13 were able to withstand a four week detraining period without any loss. At the other end, older (65–75 year old) men and women sustained greater strength losses than their younger (20-30 year old) counterparts over a longer time period.
While these studies are dictate on muscle losses, it is also a known fact that VO2 endurance also decreases with age and continued endurance training can help cut the losses by about half.