Absolutely not. In fact, quite the opposite; depending on the type, duration and intensity of a training session, they can actually be the opposite of what an athlete wants to ingest.
Yes, it will vary a bit from person to person, but keep in mind that the higher the intensity of a session, the more blood that is diverted away from the gut and to the skeletal muscles in order to provide them with fuel.
On the flip side, if you’re doing a long, aerobic effort, this is a situation where solid food may come in handy. If I’m doing an early season base ride of four to five hours, for example, I might bring along some paleo friendly yams with sea salt in a zippie bag, along with some coconut oil.
However, for the short/hard/fast sessions and certainly when I race, I personally opt not to go with solids.
Incidentally, it’s not only solids that can wreak havoc with your gut; choosing the wrong sugars, those which don’t empty at the proper rate from the gut into the bloodstream, can also create a situation where you’re putting the calories in your mouth, but they’re not getting to the muscles fast enough.
Ever had a ‘sloshy’ stomach? That’s exactly what’s happened, in that case. The calories are going in, not emptying from the gut, staying in the stomach too long and as you continue to ingest more of the wrong sugars, the gut slowly begins to distend and an unplanned trip to the porta potty becomes inevitable; and the race may be a downward spiral from there on in.
Other factors to consider are climate (if you’re in a hot environment and sweating profusely, dehydration becomes and issue as well, resulting in even less ability to digest solids) and your personal fitness goals (if your goal is to achieve a leaner physique, fasted training can be integrated for some of your training in order to optimize for the body to become more efficient at utilizing fat as a substrate; the thing to remember, however, is to ease into this. Don’t head out for a six hour ride with no fuel!).
As with everything else pertaining to fueling for training and racing, practice, practice and then practice some more to see exactly what works for you, and what doesn’t.
Finding this out well before race day will allow you to rest assured when you toe that start line that you’ve taken care of everything in your control to avoid bonking and GI distress, and can plan on a day with optimal fueling.