1. Running too much too soon. Coming back from an injury? Now's the time to take things slowly to stay healthy. Follow the standard rule of upping your mileage by only 10 percent each week.
2. Refuelling badly. After hard runs, grab a high-carb snack, then a meal with carbs and protein to rebuild muscle.
3. Forgoing SPF. Up to 20 minutes of sun exposure a day can be good for you—but you need sunscreen on runs longer than that (even when it's overcast).
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4. Ignoring your core. Participants in a Journal of Strength and Conditioning Research study who did core exercises four times a week for six weeks ran a 5K 30 seconds faster than those who didn't
5. Starting a race too fast. Hold your horses! Not holding back early in a race can ruin your PR hopes. Consider using a GPS watch so you'll know your pace—and be able to adjust it—before the one-mile mark.
6. Being your own doctor. Runners tend to be hyperaware of their bodies, self-medicating with ice or ibuprofen to treat aches and pains. But minor injuries could turn into serious ones. Instead, see a doctor sooner rather than later. If the pain has lingered for three days, schedule an appointment.
7. Skipping stretching. It's okay to nix stretching before a run—in fact, static stretching when your muscles are cold is a no-no—but loosening your muscles post-run can help prevent injury
8. Not getting enough zzzz's. Studies show logging too few hours of sleep can impair your running while compromising recovery, immunity, and mental sharpness. Because everyone requires different amounts of sleep, log your sleep time in your training journal and look for patterns specific to you. Once you figure out what works for you, shoot for that number—and try these tips to get even better sleep—as often as possible.
9. You never rest. Overtraining can lead to a host of problems, from injury and slower times to illness and a loss of motivation. Every training program should have a rest day plus two to three easy-effort days per week to balance tougher workout days. It's okay to cross train, but reward yourself with a day of total rest to give your muscles much-needed rebuilding and recovery time.
10. Fixing it all. There's plenty of advice on how to become a better runner, but try to focus on what's manageable. Remember: You likely started running to feel better, not to become stressed.