Which factors would negatively impact the body’s digestive system?

This is an extremely loaded question! There are an infinite amount of factors that play into how well or poorly you digest your food. Here are some I think are major ones:
State of your digestive system
·        Probiotics - the presence of good bacteria is so important in properly processing your food; ingesting fermented foods regularly or taking probiotic supplements will help boost the number of probiotics in your system; pretty much everyone can benefit from supplementing with probiotics or eating probiotic rich foods as taking antibiotics or eating conventionally grown meat, fruits or vegetables can decrease the healthy flora
·        Enzymes - enzymes are crucial in helping you break down the food in your stomach; some people choose to supplement with enzymes while there is a differing school of thought that if you supplement with enzymes, your body develops a reliance on it and does not produce their own; I tend to take enzymes when I have a heavier meal to act as support
What you eat
·        Quantity of food- the more you eat, the more work your body has to do; I'm pretty sure anyone can relate to overeating
·        Quality of food– as stated above, conventionally grown food can have additional chemicals that can throw off the balance of your gut
How you eat
·        Food combining - this is an extensive topic but basically the more complicated your meals are, the harder they are to digest; general food combining rules: eat fruit alone and on an empty stomach, don't combine protein and starches
·        Mood/mindset when you're eating - eating when you're happy is a way better digestive experience than eating when you're sad, angry, or stressed; being able to mindfully eat also helps
·        Mood/mindset when you're cooking – this is a little woo-woo but cooking when sad, angry or stressed imparts that property to the food and can cause issues; one time I cooked a meal for my husband when I was very upset at him, he had a stomach ache that night; another example – mom's home cooking – nothing can replace it because your mom puts her love into it
·        Environment you are eating in - eating in a quiet environment vs. a loud one can effect your digestive system
·        Chewing – chewing your food thoroughly is so important to helping your digestive system because you don't have anything like teeth in your stomach that will help breakdown food
·        When you eat – eating too late, before strenuous activity and in the middle of the night are some of the times that can create poor digestion

From the list of individual sports in which an individual can compete, like swimming, diving, running, ice skating, wrestling, gymnastics, golf, tennis, skateboarding, in-line skating, biking, martial arts, and bowling, I think that swimming would be the most strenuous to play because it requires strength in specific muscle groups, endurance, and lots of power.