Don’t keep the same workout routine, volume, and intensity. If you kept doing a similar routine of hard workouts and recovery days, similar loads of volume and intensity, then you could probably stay reasonably fit all of the time. Again, as mentioned above, if you did that, you might open yourself up to increased long-term risk of injury by overworking some muscles, joints, and connective tissue while under-utilizing others. But there’s more than that. If you’re always keeping a moderate stress on your body, you can adapt and progress for a while, but eventually you’ll plateau and see the same fitness achieved on an ongoing basis. If you want to see higher peaks in your fitness, then you need to consider toning things down, giving your body a little extra rest, and then have a stretch of progressive training that will hopefully culminate in a higher level of fitness than what you’d otherwise achieve. So, most athletes find good success taking the off-season months to slowly build up a bigger, broader foundation of strength, endurance, and aerobic efficiency, so that they can add on an extra bit of maximal aerobic capacity and anaerobic capacity work, finally reaching their best potential for that point in time.
Don’t keep the same dietary habits or put on too much extra body weight. Inevitably, if you’re engaged in heavy training and abruptly stop, then it may take days or even a few weeks for your appetite to adjust to the lower energy demands placed on your body. That’s fine; don’t worry about it. But, try to do what you can to mitigate the damage. Don’t shut down your training but keep eating 3000 or 4000 calories a day like you might have been doing when engaged in heavy training. Try to establish good eating habits that will provide a lot of nutrition without encouraging your body to put on extra weight. If you’re not doing high-intensity workouts and races, then you don’t need high-octane fuel sources (i.e. refined carbohydrates and sugars). If you’re not engaged in a high volume of training, then you don’t need nearly as many calories to keep your body happy and healthy. You don’t need to worry about digesting food quickly before your next workout or race, so you don’t need to ever worry about avoiding lower density foods with higher fiber content. So, consider cutting back on the refined carbohydrates you might want for intense workouts and races, in favor of fruits, vegetables, nuts, fish, legumes, some meat, and maybe some dairy. Definitely look for ways to eat as many vegetables as you can, while also keeping additives to a minimum. It’s one thing to have a great salad, it’s another one to have an extra 500 calories of croutons and salad dressing on top. Always remember, you’re never going to put on extra weight by eating too many vegetables, but they are generally the ones most universally associated with increased longevity and reduction in risk for various health problems, so you might as well spend most of your time grocery shopping in the produce section.
Don’t worry. Don’t worry about losing fitness when you tone things down or take a break. Don’t worry if you put on a couple of pounds. Don’t worry if you get busy and take more days off than you planned or expected. 6 months from now, in all likelihood, it won’t matter. It will matter if you get worried and keep training straight through the off-season, never take it easy, and never shy away from high-intensity workouts, because you might end up stale physically or mentally, perhaps burnt out or even hurt. Try not to focus on things that you might consider negative, and instead try to be positive and look for ways that you can move towards your goals even if you’re not actively pursuing a hard training routine. When you’re not out training as much and you’re taking extra days off, consider doing a few minutes of core work to strengthen the part of your body you might neglect a little bit when you’re competing more regularly. Look for areas of your diet where you could improve things. Do a bit of cross training to get a mental break from your sport and to enjoy playing around with others. Or engage in other hobbies you have. After all, the athletic adventures we seek out are supposed to be fun, provide an outlet for our drives to be competitive and to better ourselves, and they should be rewarding, so as much as we want to do well, succeed at achieving our goals, and maybe beat some of our competition, we don’t ever need it to add stress or concern to our mental lives.
Don’t do too much LSD. Doing higher volume training sessions and keeping those sessions at a steady, moderate intensity can be great for building up aerobic endurance and efficiency preserving glycogen stores and increasing your fat-burning capacity. But doing long training sessions at a really low intensity, or doing long stretches of training only at a steady pace will not help you out. You should never do only long-slow distance training. For one thing, for a competitive athlete who’s been engaged in an endurance sport for more than a year or two, there is little fitness to be gained from doing truly slow training in any volume. This is a little less of a concern for runners, because running tends to encourage athletes to operate at intensities closer to their threshold pace most of the time (say, 80-100% of their threshold pace). If you’re a runner whose half-marathon pace is 7 min/mile (about 1:32 pacing), then it’s likely that a lot of your general endurance running is done somewhere around 7:40-8:20 min/mile pace (80-90% of half-marathon pace). For cycling there is much more of a propensity for athletes to have a much bigger range of intensity at different times. For a lot of cyclists, their average wattage for one of their long rides might be as low as 50-65% of their threshold wattage, which is relatively low. But at the same time, during that ride, they may have a few dozen relatively modest efforts of 30s to 2-3m up to or above their threshold wattage. Such is the nature of cycling, where it’s very natural for a lot of cyclists to ease into an easy pace and then kick a little bit harder on every little rise or headwind section without paying much attention to the big differences in intensity. And even more extreme, cyclists necessarily coast into stop signs, traffic lights, and down hills, so it’s not uncommon for a rider to coast 10, 15, even 20% of the time. In general, these two phenomena can be viewed as a good thing, because it naturally helps cyclists to develop strength and anaerobic fitness if they’re routinely doing short hard efforts up hills and after stops, but it also means that they may have to focus more if they’re trying to get in an efficient endurance boosting ride.
Don’t do only your sport of choice. Whatever your chosen sport is, you don’t want to train by only ever doing that singular activity. Of course, if you’re a cyclist, cycling will be the most specific activity that you can do to improve your race-readiness. Likewise, if you’re a runner, running will get your fitness dialed in for the events you’re getting ready for. But, when you’re months away from competing, you need to make sure that you’re building your overall fitness, strength, and working to keep a balanced, flexible body and prevent injury. If you only do one sport all of the time, then you’ll almost certainly be developing some muscles while neglecting others, creating imbalances that may or may not create functional inefficiencies down the line or even injury. Consider mixing it up, building a better balanced musculature, increasing flexibility, and stressing your body in ways that you don’t normally, keeping it stronger all-around.
Don’t do too much intensity. Even though hard efforts are a necessary and integral part of developing race-readiness, and improving fitness generally, it’s good to cycle through periods of higher and lower intensity training. That’s definitely not to say that hard efforts will be absent from off-season training, it just shouldn’t be the focus. Presumably, for most endurance athletes, leading into and during a competitive season, training will include heavy doses of high-end aerobic and anaerobic workouts. These stress your body a lot and push it to maximize the potential that you’ve built up over the previous months that you’ve been building up foundational fitness. All of those miles of steady and high-endurance training, all of those tempo and threshold efforts, the strength training and cross training you may have done during the pre-season and early-season months, will all culminate after a few months of hard training in your best race-ready fitness and performances. If you spend your off-season skipping strength, endurance, and aerobic workouts in favor of maximal aerobic-capacity workouts, anaerobic workouts, hard race-rides, etc. then you’re not getting the most long term benefit to your fitness that you could. Basically, there’s only so much time that you have to train and a finite capacity that your body has to absorb workouts and grow stronger from them, so you want to build the biggest foundation of strength, endurance, and aerobic efficiency that you can during the off-season, so that when you pile on top end fitness later, you’ll reach a higher peak. If you do too much high intensity work instead of foundational work, then you may see more fitness early on, but only see it deteriorate or stay flat throughout the season rather than reach a new high-point for you.