For most of us, a trip to the gym means running on the treadmill or pumping iron, but there is a new fitness trend can be done from the comfort of your desk. Rather than work your quads and triceps, these gyms stretch your mental muscle. "Brain gyms" consist of a circuit of interactive games that are designed to improve select areas of brain health including memory, concentration and strategic thinking, and just like regular gyms, you pay a monthly membership and have access to personal trainers.

Sheida Rabipour, a PhD candidate in neuroscience at the University of Ottawa, recently published a review on brain gyms and says while more research is required to determine whether brain gyms can lead to improved productivity, they have been shown to advance certain cognitive functions.

Brain training programs target the prefrontal cortex, which is associated with problem solving, strategic thinking, attention and memory. "[These are the areas] that require a higher level of thinking," says Rabipour. "By strengthening these networks, not only will you improve at that particular task but hopefully you will improve in other aspects of mental function that draw on the same network that has now been strengthened as a result of these games that you've been practicing," she says.

Related: How Brain Training Games Can Help You Build Your Business

Here are three things you should know about brain gyms before signing up for a mental workout.

1. It's more than just doing crossword puzzles.
People have been doing games like crossword puzzles to stimulate their minds for decades. But brain training is different from says Rabipour. "Cognitive training programs try to increase the level of challenge. As the levels increase, you add more factors in a very controlled and monitored way," she says. Instruction may show you how to look at a problem differently than you may have previously thought of doing. This is especially true of brain gyms such as cogmed.com in which training is only provided through accredited coaches that provide motivation and monitor results. 

2. Frequency is important.
Brain gyms are designed to be fun and provide a level of entertainment that keeps the user engaged, but this doesn't mean you devote hours each day to working out in your brain gym. Rabipour advises they you should focus on frequency and building a habit, playing games during a lunch hour or while taking a coffee break a few times a week. Some brain-training sites, such as www.HAPPYneuron.com, ask users to make a commitment log in two to three times per week and spent 30 minutes to one hour per session. 

3. Not all brain gyms are the same.
While there are plenty of products on the market that promise to boost your cognitive function, Rabipour advises those shopping for a brain workout to ask whether the program targets the capabilities you're looking to improve and look for independent studies done on the programs. Often, these can be found on the program's website or in scientific journals. "If the website has no studies or evidence to show [their program works], that's a red flag," says Rabipour.

Related: How to Train Your Brain to Stay Focused

Interested in a mental workout? Try these brain gyms:

Cogmed was developed to focus on attention problems caused by poor working memory. Trained coaches support users throughout the training, and program fees are set by each individual Cogmed trainer and vary by location.

CogniFit provides a free assessment in which users participate in ten brain games that target memory, spatial perception, hand-eye coordination, attention and response time. The assessment delivers a detailed report to show your brain's level of fitness. After your assessment, the games become more challenging. The premium plan is $10/month or $90/year.

HAPPYNeuron 's interactive games target memory, attention, language and strategy. There are over 3,500 hours of training available, and virtual coach suggests specific training sessions adapted and customized to the user's needs based on their performance. A three-month membership costs $29.95. 

Before registering for Lumosity, you're asked to choose a particular aspect of each of five cognitive areas: speed, memory, attention, flexibility and problem solving. From your responses, and your age, Lumosity builds a personalized training program. The three-day trial is free while a monthly subscription is $14.95 (or $6.70 per month for a yearly subscription).