For many people — including myself — it’s a daily struggle to get in sufficient exercise.

Luckily, there has never been more support for those who want to get in shape or stay fit. The themed 5K race has quickly become a staple for many in their quest to get fit in a palatable way. With themes ranging from the Color Run to the longer, more arduous Tough Mudder, there are plenty of choices for the masochist in all of us.

Running is more popular than ever. According to Running USA, more than 8 million runners finished a 5K race in 2013 in the U.S. Amazingly, more than 500,000 people finished a full marathon.

In an era when more than one-third of the U.S. adult population is obese, the trend of using running to get fit is an encouraging sign. Many get hooked and begin to want to run more than just a 5K race. It seems to be in vogue to be training for a marathon.

Unfortunately, for those who consistently participate in long-distance races, there have been some discouraging studies that suggest all of this running isn’t as healthy for us as many make it out to be.

A recent study of people who participated in the Twin Cities Marathon suggests that runners “paradoxically” had a greater amount of coronary plaque compared to the sedentary control group. Another study from Britain regarding lifelong elite athletes yielded similar results, suggesting that half of older lifelong athletes in the study exhibited some heart muscle scarring.

Though these studies are ongoing and not conclusive, they are worth considering. Like most things, it seems moderation in exercise is wise. For me, that’s all I need to hear to put off those marathon plans for another year. Or two.