In this Spartan Fit franchise, we ID the most interesting newly-published research, and talk to an expert about how the findings apply to you, Spartans, specifically.

An injured shoulder means no overhead pressing at all and a cranky knee means you can’t deadlift, period, right? Not so fast. Research has shown that performing unilateral resistance exercises, those that focus on one arm or leg at a time, does have contralateral, or both-side, effects. 

A new study, published in the Scandinavian Journal of Medicine & Science in Sports, looked specifically at the effects of eccentric exercises, those that involve lengthening, or in the case of free-weight exercises, lowering. (Think: lowering a dumbbell in a press, lowering to a chair in a single-leg squat, and lowering a weight to the floor in a single-leg deadlift.) Turns out, when it comes to single-sided moves, eccentric ones have even greater effects on the non-working arm compared with traditional ones.  

In the study, researchers immobilized adults’ non‐dominant arms for eight hours per day over the course of eight weeks. The subjects trained their free arm three times per week. The result: They successfully reduced—and in some cases completely eliminated—strength or muscle size losses in the immobilized arm. 

Eccentric training is so beneficial because it’s “more stressful to our brains,” says Luis Peñailillo, Ph.D., study author and exercise science researcher at the Universidad Finis Terrae in Chile. 

When you exercise, it’s your neurological system that powers each rep. So when you work your right arm, even if your left arm is in a sling, you’re still strengthening the neural connections that feed into it. And increasing how hard your neural system has to work is as simple as lifting more weight or doing something out of the ordinary. Eccentric training checks both boxes: first, you can lower more weight than you can lift, and the heavier the loads you move, the greater your neurological system has to fire. Second, because lengthening-only moves tend to be pretty unfamiliar motor tasks, they require more mental juice.

“Athletes commonly think, ‘If I’m injured, I should do nothing,’ and that’s just not true,” says Sam Stauffer, Spartan’s Director of Training. “Staying active and exercising in pain-free ways can help speed tissue healing and prevent cardiovascular de-conditioning.” Plus, as this study shows, it can squash strength and muscle losses.

Related: Spartans on Science: The Post-Quarantine Training Guide to Prevent Injury

How to Use Unilateral Eccentric Training 

1. Pick Your Exercises

Performing the same moves week over week is pivotal to progressive overload. Through recovery, Stauffer recommends hitting all of your body’s basic movement patterns and adding in some extra exercises that focus on the injured muscle or joint—just on the other side of your body. 

2. Start Small 

Keep tabs on how you’re feeling, stop what you’re doing if you have any pain, and don’t hesitate to reach out to a physical therapist for individualized guidance, he says. After you’ve tested things out with a few light and moderately weighted workouts, incrementally progress to heavier loads, Peñailillo says. 

3. Slow Down

The more slowly you perform an eccentric movement—with quality form—the greater the effects. Try lowering to the count of three, four, or even five, Stauffer recommends.

Related: Spartans on Science: Strong Bones = Stronger Performance (+ 3 Tips for Winter Workouts)

4. Use Your Imagination

To increase neural and muscle recruitment, Peñailillo recommends mental imagery. Visualize your immobilized limb or joint doing the exact same thing as your working one. Research shows that simply imagining yourself moving heavy weights can reduce strength losses following upper-body or even ACL injury through neural adaptations. 

5. Keep With It

Even after you’re all healed up, regular eccentric and unilateral training can effectively reduce the risk of future injury, Stauffer says. Look out for any strength or form differences between your left and right sides.