Preventing Glycogen Depletion. As discussed in chapter 2, your body can store only a limited amount of glycogen. With a typical runner’s high-carbohydrate diet, you probably have enough glycogen to get you through a 20- to 22-mile (32 to 35 km) run or a hard interval workout. It takes about 24 to 48 hours to completely replenish your glycogen stores. When you do two hard workouts in a row, therefore, you risk going into the second workout with partially filled glycogen stores, becoming depleted, and having a bad workout. Although glycogen depletion is potentially a problem on the second hard day, with a bit of planning it needn’t be an insurmountable problem. Three hard days in a row, however, would very likely lead to glycogen depletion and a more-prolonged recovery period. By following the hard/easy principle, you give your body time to build up your glycogen stores so you are prepared for the next hard workout.
Preventing Illness. Moderate training makes your immune system stronger. Various studies have found that people who get regular exercise have 20 to 50 percent fewer colds than do sedentary folks. After high-intensity and prolonged exercise, however, the immune system is temporarily suppressed, creating an “open window” during which you’re at increased risk of infection. Although immune function varies greatly among individuals, studies indicate that the immune systems of healthy, well-trained runners are typically suppressed only after exercise lasting more than 1 hour at about marathon race pace or faster. Immune system suppression after high-intensity running has been found to last from 12 to 72 hours. Interestingly, there is evidence that immune system suppression is linked to carbohydrate depletion and that restocking carbohydrate quickly may help restore your immune function to full strength in less time. The clear implication is to not do another hard training session until your immune function recovers from the previous hard session or race. Allowing at least one easy day before the next hard workout typically provides enough time for your immune system to return to full strength.
Minimizing the Effects of DOMS. Contrary to many runners’ beliefs, high levels of lactate (lactic acid) in your muscles aren’t what make you sore for several days after a hard effort. Essentially, all the lactate you produce in a race or workout is eliminated from your body within a few hours. DOMS is caused by microscopic muscle damage that occurs primarily from eccentric (lengthening) muscle contractions, such as when you run downhill. During downhill running, your quadriceps muscles contract eccentrically to resist the pull of gravity and keep your knees from buckling. The resulting muscle damage leads to inflammation, which causes soreness. It takes 1 to 2 days for this process of muscle damage, inflammation, and pain to reach a peak, and the effects can last for up to 5 days. While you’re experiencing DOMS, your muscles need time to repair. The damaged muscles are also weaker, so any workout done before the soreness goes away not only will be painful but also will likely not be intense enough to improve your marathon fitness.
The physiology of DOMS favors an approach of 2 hard days followed by 2 easy days, because it takes 1 to 2 days for DOMS to kick in, then it takes another couple of days for the soreness to dissipate. By doing back-to-back hard days, you may sneak in your second workout before soreness and muscle weakness develop. You would then have 2 days to recover before the next hard effort.
We’ve seen several reasons why you should follow the hard/easy principle in your training and that a hard day doesn’t always have to be followed by an easy day. A pattern of 2 hard days in a row followed by 2 (or more) recovery days may actually allow you to handle, and recover from, more high-quality training. Let’s look at two specific situations in which you should do back-to-back hard days.
During weeks that you race, you need to train but also to rest for the race. In Daniels’ Running Formula, renowned exercise physiologist and coach Jack Daniels, PhD, recommends back-to-back hard days during race weeks rather than alternating hard and easy days (Daniels 2005).
For example, say you’re following a strict hard/easy schedule and have a race on Saturday. If you did a long run on the previous Sunday, then you would run hard Tuesday and Thursday and easy on the other days. Doing a hard session on Thursday, however, doesn’t make sense because you would still be tired from that effort for Saturday’s race. If, however, you do back-to-back harder workouts on Tuesday and Wednesday, as detailed in figure 3.2, you would still get your hard sessions in but would have an extra day to recover for the race. Although this modification still doesn’t provide the optimal amount of time to recover for Saturday’s race, it’s an intelligent compromise that allows you to get your high-quality training while also racing reasonably well.
Another time when you might do 2 hard days in a row is if your weekly schedule is dictated by the Monday-to-Friday workweek. If you’re too busy or fatigued during the week to get in regular high-quality training, then you’ll want to take advantage of the weekend and squeeze in 2 hard days. This situation is detailed in figure 3.3. Hard days on Saturday and Sunday followed by recovery days on Monday and Tuesday provide a strong training stimulus and 2 full days to recover before the next hard effort on Wednesday. Easy days on Thursday and Friday then leave you well rested for another weekend of hard training. Four of the 5 weekdays become recovery days, and you still get in three hard training sessions per week.
This brings us to the time-honored tradition of racing on Saturday and doing your long run on Sunday. If you race 10K or less, you’ll dip into your carbohydrate stores but (assuming that, like most runners, you generally eat a lot of carbohydrate) will most likely not come close to fully depleting your glycogen stores. By eating your normal high-carbohydrate diet, you’ll be reasonably topped up with glycogen and ready to handle your long run on Sunday morning. As discussed in chapters 1 and 7, however, after a tune-up race, your long run should be at a more-relaxed pace. If Saturday’s race is longer than 15K, however, you’ll likely have severely depleted your glycogen stores and may find yourself at less than your best for Sunday’s long run. If you race more than 15K on Saturday, skip the long run on Sunday. In that situation, you’ll be better off by postponing your long run until you’ve recovered from the race.
So far, we’ve considered only the pattern of hard training and recovery within a week. Just as important is the pattern of hard efforts and recovery over the course of your marathon preparation. Week after week of hard training can eventually lead to staleness or overtraining. To adapt optimally, it’s best to have several hard training weeks followed by a recovery week. The training schedules in the second section of this book regularly incorporate recovery weeks.
There are several patterns that you can follow. The correct pattern for you depends on how hard you’re training, your body’s ability to adapt to training, and the sum of other stressors in your life. The most commonly used pattern is 3 hard weeks followed by a recovery week. During the early buildup phase of marathon preparation, some runners can handle 4 high-mileage weeks followed by 1 recovery week. In other cases, 2 hard weeks followed by 1 recovery week is optimal. Again, through trial and error, you’ll have to find the pattern that’s best for you.