--- title: This Week in Health: The Risk of Running Marathons description: The hidden dangers of running a marathon and the sad science of loneliness are among the biggest stories in health this week canonical: https://time.com/4718515/running-risk-vitamin-d-cancer/ author: Alexandra Sifferlin article:opinion: false article:content_tier: free article:published_time: 2017-03-31T13:00:15.000Z article:modified_time: 2026-02-23T04:07:29.705Z article:section: Health og:title: This Week in Health: The Risk of Running Marathons og:description: The hidden dangers of running a marathon and the sad science of loneliness are among the biggest stories in health this week og:url: https://time.com/4718515/running-risk-vitamin-d-cancer/ og:site_name: TIME og:image: https://static.time.com/v3/assets/bltea6093859af6183b/blt3bdb81f73c1ced57/6988c09797cdff71b16b001e/running-photo.jpg?branch=production&width=3840&quality=75&auto=webp&crop=16:9 og:image:width: 1200 og:image:height: 675 og:image:alt: Close up of trainers running through mossy terrain og:type: article twitter:card: summary_large_image twitter:title: This Week in Health: The Risk of Running Marathons twitter:description: The hidden dangers of running a marathon and the sad science of loneliness are among the biggest stories in health this week twitter:image: https://static.time.com/v3/assets/bltea6093859af6183b/blt3bdb81f73c1ced57/6988c09797cdff71b16b001e/running-photo.jpg?branch=production&width=3840&quality=75&auto=webp&crop=16:9 ---  # This Week in Health: The Risk of Running Marathons by [Alexandra Sifferlin](https://time.com/author/alexandra-sifferlin/) ## Alexandra Sifferlin Mar 31, 2017 1:00 PM UTC  Close up, low angle shot of a female runners trainers, running through mossy terrain in Iceland. Blue trainers, black running leggings with backlit sunshine. Close up, low angle shot of a female runners trainers, running through mossy terrain in Iceland. Blue trainers, black running leggings with backlit sunshine.Getty Images by [Alexandra Sifferlin](https://time.com/author/alexandra-sifferlin/) ## Alexandra Sifferlin Mar 31, 2017 1:00 PM UTC Marathon-running is a popular pastime, but new research released this week found that it’s particularly stressful for [one part of the body](http://new.time.com/4714344/running-marathon-kidney-injury/). We also learned that if you want to mix-up your workouts, you may want to consider [kickboxing](http://time.com/4712881/kickboxing-fitness-workout/). Here’s what else caught our attention in health news this week. (Sign up for our [newsletter](http://time.com/newsletter-health) for more.) ## [**The hidden risk of running a marathon**](http://time.com/4714344/running-marathon-kidney-injury/) There’s no doubt that running is healthy aerobic exercise. But some people who run marathons show signs of short-term kidney injury after the race, a new study shows. ## [**Your cold feels worse when you’re lonely**](http://time.com/4715823/cold-symptoms-sick-loneliness/) As if getting sick wasn’t enough of a bummer, a new study found that feeling lonely can make cold symptoms feel extra terrible. ## [**Do ovulation kits really help you get pregnant?**](http://time.com/4712786/ovulation-kit-pregnant-pregnancy/) Ovulation kits claim to help identify a [woman’s most fertile window](http://time.com/4585194/women-fertility-pregnancy/) during her monthly cycle. Here’s everything you should know before trying one. ## [**Lead exposure can lower IQ later in life**](http://time.com/4713970/childhood-lead-exposure-iq/) Kids who have high blood lead levels tend to have lower IQs and socioeconomic status in adulthood. The U.S. has laws in place to limit the bad health effects caused by lead, but exposure remains a health threat. ## [**How kickboxing can change your life**](http://time.com/4712881/kickboxing-fitness-workout/) For better balance, power and agility, kickboxing is one of the very best workouts. Here’s why you should consider this calorie-torching exercise. ## [**What you should know about vitamin D and cancer**](http://time.com/4714335/vitamin-d-supplement-calcium-cancer/) Vitamin D has been linked to healthier bones, and new research suggests the vitamin may also play a role in reducing the risk for cancer. However, just how strong the link is remains up for debate. ## [**A paralyzed man can move his arm with his brain**](http://time.com/4715028/paralysis-brain-arm/) This week research revealed a breakthrough: scientists restored the ability of a paralyzed person to move his limbs by commanding them with his brain. [Watch the video](http://new.time.com/4715028/paralysis-brain-arm/) to see how it works. ## [**Where Americans exercise the most**](http://time.com/4716180/exercise-map-america/) How active are people in your community? 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