Let me preface by the fact I've never swam competitively, and it's been a while since I've swam routinely. I do train competitively, and I do eat before training. The two biggest risks with eating before training are:
- Muscle cramps--which in swimming is much more dangerous than with running or cycling, and more likely when the training is sustained such as in all three of these sports.
- Nausea--which if it gets messy requires the pool to be cleaned and maintained before practice can resume.
The nausea can be avoided as long as you stay away from oily, greasy, or whatever your trigger foods are. An example that happened to a teammate when I was on the high school basketball team was sardines before sprinting which resulted in vomiting.
Muscle cramps are understood less, but can be anything from electrolyte imbalances to heavy exertion while the body is trying to digest a meal. It's typically the second issue that your coach is concerned about.
Guidelines for food before training:
- Don't eat a heavy meal
- Eat light fare. Examples are cottage cheese, yogurt, toast and jam, fruit
- BCAAs or Creatine Monohydrate can also provide energy without violating the spirit of your coach's objections.
The goal is to give you some quick energy that isn't going to burn out right away. This is why we stay away from candy, but mix together a couple different energy sources that are easily digested. You also don't want your body to divert a lot of its resources to digestion when you need to train.
My typical pre-training snack is either cottage cheese or yogurt with fresh fruit mixed in, 2 slices of Ezekial bread with organic jelly or jam on it. Either that, or I'll have 10g of BCAAs or a serving of creatine monohydrate.
The food provides energy without weighing me down too much, and I stay energized throughout the training session. BCAAs work by providing amino acids your body needs during exertion in a form that doesn't need to be digested. Your muscles use ATP as their direct energy source. When ATP is consumed it becomes ADP. Creatine monohydrate facilitates reconverting that ADP back to ATP--thus allowing you to maintain energy for longer. If your coach won't like the light fair, then they shouldn't have any problems with the BCAAs or the creatine. Those are liquid, which also helps your hydration.
Preparing for Long Training Sessions
I just read the training regimen which is grueling. To be properly prepared for that, you will need a sizeable meal, but the timing of it is important.
- Between 1-2 hours before training have a good size meal. Try to stay away from greasy or fatty foods, but get plenty of lean protein and a healthy amount of carbs.
- 15 minutes before training, you can have the light fair or supplements
- Use regular Gatorade to maintain hydration particularly between the running and the swimming. It has some sugars and a balanced amount of electrolytes your body will need to keep going.
- After training eat whatever you want. You deserve it.
The only major change to my recommendation is to time your last meal to be no closer than an hour before training but still close enough that the energy from that meal can be used for your training. Staying away from fatty or greasy foods will keep the meal easier to digest so you are ready to train without being weighed down. You can have them after training, but before hand you want protein and carbs. The protein provides longer term energy and the carbs provide the nearer term energy.