Not making any gains at the gym? Blame your pressing work deadlines and relationship woes. Persistent stress can impair your muscles’ ability to recover from a hard workout, according to new research in Medicine & Science in Sports & Exercise.
In the study, University of Texas researchers surveyed undergraduate students about their current stress levels. The participants then performed a lower-body heavy-resistance exercise to failure. During the hour following the exercise, students with higher chronic stress scores took longer to recover their maximum strength than their unworried classmates.
“Your body is in a state of physical stress after a tough workout,” says study author Matt Stults-Kolehmainen, a postdoctoral associate and clinical faculty member at the Yale Stress Center. Think about it: Your heart rate elevates, breathing increases, temperate rises, glucose levels drop, endorphins surge, and human growth hormone flows.
A tough lifting session also creates microtrauma–or thousands of tiny tears–to your muscle fibers. In essence, your body is a complex machine that needs to fire on all cylinders to effectively recover from a difficult workout. (Get more valuable fitness tips and workout advice sent straight to your inbox by singing up for our free Personal Trainer newsletter.)
But if you want to pack on muscle and increase strength, mental stress can slow your fitness adaptations. (Though energy levels, soreness, and fatigue were not influenced by stress, the study found.) While researchers aren’t exactly sure how it plays a role, they believe stress may cause an inadequate inflammatory response, says Stults-Kolehmainen. And inflammation helps heal the microtrauma so you can build stronger, bigger muscles. Previous research has also shown that stress can increase your chances of sports-related injury and slow recovery after illness or surgery.
Now, we’re not telling you to skip the gym if you’re stressed out. “Exercise can actually help you cope with stress, as long as you dial down the intensity,” Stults-Kolehmainen explains. So if you usually perform three intense lifting sessions a week, shoot for one tough workout and two moderate workouts instead. Allow for a couple days recovery after an intense workout, he recommends, or else you’ll continue to see poor results and put yourself at risk of injury. (Discover hundreds of doctor-approved, do-it-yourself fixes for every sports injury imaginable in The Athlete’s Book of Home Remedies.)