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.

There’s no getting around it: winter is here.

Unfortunately, colder temps doesn't just mean layering up for long runs and traversing over slick sidewalks. It could also mean reduced bone strength. 

That’s the word from a new study in Cell Metabolism that examined the link between air temps and bone remodeling. (In case you didn’t know, every bone in your body is in a constant state of turnover, with certain cells degrading and new ones coming in to save the day.)

For the study, researchers placed adult mice in a toasty environment of 93.2 degrees Fahrenheit. In their new digs, the mice’s bone strength and density significantly improved. Then, when the researchers mimicked the hormonal changes that occur in post-menopausal osteoporosis, the mice didn’t lose bone strength like they “should have”. 

But, of course, mice and Spartans aren’t the exact same, so the researchers looked at global epidemiological data on bone breaks. They found that people who live in warmer climates have stronger bones compared with those located in colder temps—regardless of latitude, vitamin D levels, and calcium intake. 

Related: 2 Must-Do Weight Workouts

Warm Temps (All On Their Own) Strengthen Bone

While previous research has shown a link between cold temps and weak bones, it wasn’t clear why one led to the other. Now, researchers have ID’ed what’s going on, and it’s all about the gut microbiota. When the bacteria in your gut adapts to heat, it increases the activity of bone-building osteoblasts and reduces the number of bone-degrading osteoclasts in your body.

How Bone Strength Impacts Performance

Why are we even talking about bone strength in the first place? Because it has huge impacts on performance, explains Sam Stauffer, Spartan’s Director of Training. In fact, research shows that during exercise, your bones produce a hormone, called osteocalcin, that drastically boosts muscle strength and endurance.

Plus, the stronger your bones, the lower your chances of running into exercise injuries during heavy training and competition, he says. While stress fractures are incredibly common in runners, another concern for Spartans is broken ankles. Navigating uneven, unpredictable terrain requires not just strengthening the muscles and connective tissues that make up the ankle joint, but also the bone itself.

Here’s how to train for bone strength, whatever the temps this winter… but especially if you're in a colder climate.

Exercise for Strong Bones (Especially through Cold Winter Temps)

1. Stand Up When You Lift

“Just like your muscles adapt to the stresses placed on them, so do your bones,” Stauffer says. “In response to this stress, they become denser and stronger.” For the greatest benefits, focus on performing strength exercises with free weights in a standing position. Seated exercises won’t fully load your spine, hips, and legs. Progress weights gradually, just like you do for your muscles. The goal is to stress (but not over stress!) your bones.

Related: Max Workouts: Functional Strength Exercises to Boost Your Power

2. Do “Hard” Cardio

Swimming and cycling are great for your heart, but they don’t do much for your bones. For physical activity to stimulate bone growth, those bones have to take the full force of your body’s weight — and then some. Winter’s a good time to focus on weight-bearing, high-impact cardio workouts like running and jumping rope. Just make sure you progress into it by starting ideally in the warmer months and gradually going harder or longer. 

3. Double Down on Plyo

“Plyometric training has a huge effect on bone density,” Stauffer says. Try bodyweight plyos such as depth jumps, bounding, and explosive push-ups. Opt for three or more sets of six to 10 reps per exercise, he recommends. Let your heart rate fully recover between sets, maintaining pristine form and landing mechanics. The goal isn’t to push your cardio or endurance, it’s to progressively and safely stress your skeletal system. If you’re a beginner, stick to two days a week — max — of this type of training.