SUNDERLAND – Emily Mailloux wants to confuse your muscles and keep you interested.

“It can get very boring, 30 minutes straight on a treadmill,” said Mailloux, founder of Commonwealth Strength (CStrength), a new gym in town. “Changing stimulus and getting people to do different things, muscle confusion, is the sweet spot.”

Mailloux opened CStrength at 110 N. Main St., opposite the Blue Heron Restaurant, this month after running the gym in her basement during the coronavirus pandemic. For over two years clients came one at a time, the low ceilings were a challenge, but Mailloux built a devoted client base and a workout philosophy: no boredom and useful muscles.

“Somebody came to me the other day and said, ‘I helped a neighbor move a couch. Because of you and because of our training, it felt so good and I was able to help.’ This is people in their 60s,” Mailloux said. “People…talk about how the training has benefited them in their real life. That’s exactly it, that’s why we’re here.”

The gym, a large and a small space, features unusual gear, slam balls and battle ropes, kettle bells and steel maces. The non-traditional tools are still weighty, but allow for more variety of motion during an exercise. That fits with Mailloux’s credo that an exercise should develop the specific muscles a client needs to meet the daily demands of life.

“How heavy is your child?” Mailloux asked. “If your kid weighs 20 pounds then we’ll train with a 20-pound kettle bell so you get…what it feels like to move around with a safe good form.”

Mailloux worked at Boston gyms for more than half a decade, also knows good form for a standard bicep curl and CStrength has a rack of dumbbells for individual use. The emphasis is more on group workouts, small and medium classes. The schedule features two session types, the most common being Mailloux’s version of a standard gym offering, a core muscle workout in a small group.

“Small group strength training, I’m calling it Foundations,” Mailloux said. “It will be a…well balanced, full body workout that you’ll be sharing with at least three people, but never more than six.”

One class Mailloux leads is Animal Flow, featuring primal movements like crawling, lunging and throwing. A client recently characterized it as hard yoga. Other classes, with a maximum of 10 people, include Balance in Motion, Mobility and Recovery and classes working with kettle bells and steel maces.

The mace was a weapon of the Dark Ages.

“It’s something new, but it’s also fun. You’re swinging the mace around your head and you feel like a badass,” Mailloux said. The mace is unbalanced, heavier at one end, and challenges different muscles. “The weight is asymmetrical on a mace, so you have to counteract and balance significantly better. Now you’re confusing your muscles and getting different results.”

The coronavirus pandemic forced fitness businesses into different practices. Mailloux began working with one client at a time, still an option at CStrength, but also staged workout classes over the internet. Career demands make virtual classes a better option for some clients, though sessions may be more difficult to lead over Zoom. A client may not have weights or equipment at home.

“Training is hard to do through a screen,” Mailloux said. In the early days “we were working with what they had, equipment at home. Some people had a single set of dumbbells. We were using household objects to create different movements.”

Classes are scheduled to fit into modern lifestyles. Most occur in the early morning, around noon and in the evening, just after rush hour. Individual coaching is an option and the fees can be split between two clients sharing the workout. Private session fees are on a sliding scale from $55 to $80. Semi-private sessions are $35 to $50 per person. Unlimited group classes are $180 monthly and unlimited Foundation classes are $220 monthly.

One thing you won’t find at CStrength is mirrors. Looking good is important, but at the new gym the emphasis is on community, having fun and making workouts a social occasion.

“Everybody likes to work out with other people better than alone,” Mailloux said. “As you come to the same classes, and keep seeing the same faces, that’s a way to meet other people.”

Commonwealth Strength is located at 110 N. Main St., across the side street from the Blue Heron Restaurant. The company has a Facebook page and a website, commstrength.com.