If you've ventured out looking for fitness trails for the Lifehacker Fitness Challenge, you may have noticed some mysterious unlabelled equipment. What are you supposed to do with this bar near the ground? This slanted bench? Here are your answers.

It's a beautiful day and we're going on an adventure! For the May instalment of the Lifehacker Fitness Challenge, your mission is to find a fitness trail (sometimes called a parcourse) near you - they're often hiding in plain sight.

Now that we're almost two weeks into our plank challenge, you've probably figured out that some kinds of planks feel harder than others. Tiny changes in your body's position can make a big difference.

"I CAN GIVE YOU MASSIVE ARMS, BROAD SHOULDERS, AND A GIANT SIZED CHEST IN JUST FOUR WEEKS," the Body-Tone pamphlet promises. It is the "World's Fastest Strength and Muscle Building System". It cost $20 in the late 1950s, but today the program is available for free in the Stark Center Archives. I am ready to begin.

If working out is an important part of your routine, frequent travel is likely to blow it into smithereens. You're thrust into unfamiliar places, lack amenities and resources, and often have little control over your schedule. But you don't have to give up on fitness completely. Here are some helpful tips, my fellow fitness enthusiast.

Push-ups look so deceptively easy. Everyone knows how to do them in theory, but when asked to do one, most people make various little mistakes that can cause problems and injuries down the road. These subtle mistakes are common and simple to fix once you're aware.

Video: Ever wish you had better balance? Today's workout gives you a chance to work on that skill. It won't leave you sore or sweaty, though! These exercises are all about neuromuscular training: Getting your nerves and muscles to work together so you can control your body precisely.

Video: Get up from your desk! This won't take long. Welcome to Lunch Break Workout, where we'll share a short workout every Thursday that you can do almost anywhere, with little to no equipment.

Pull-ups and chin-ups are both great strength-building bodyweight exercises, but they're not the same exercise. People tend to use them interchangeably, but the differences are distinct enough that you should avoid lumping them together.

Working out with your partner isn't always easy, especially if you're at different levels of fitness or what you want to focus on isn't the same. These are both reasons why I don't usually work out with my boyfriend, but this weekend we gave a bodyweight couples workout a try and it was really successful!

Maybe you can't go to the gym. Maybe you don't want to go to the gym. Maybe the gym is too darn expensive. Good thing you can turn to your phone for an instant workout. Which app gives the best workouts, though? Today, we find out.

Here's a fun variation on side lunges. The Cossack goblet squat challenges you to balance on one leg while pivoting the other so your toes face up. It's a great workout for the muscles along the outside of your hip...okay, all your leg muscles really.

For a busy parent, kids can be an obstacle to exercise: How can I distract or babysit them so I can get my workout in? But kids can join in a lot of workouts, too -- you just have to pick the right approach for their age and personality.

Parallettes, sometimes also called push-up bars, are a compact version of parallel bars that you can use for more advanced upper body, gymnastic-like exercises in the comfort of your home. Here are some DIY options for parallettes that fit a different range of budgets.

At the beginning of January, I happened upon a video you may have seen: A young woman doing push-ups for 100 days. She starts out "scrawny", but gets stronger. I wanted to do that. So I did, and you can too.

Suspension trainers are like a gym that you can take anywhere. TRX, the current popular darling, is used in homes and boot camps for bodyweight workouts, but the monkii bars 2 gives it a run for its money in both aesthetics and features. Both add a ton more variety to your workouts and let you work out anywhere, but let's see how they stack up in the categories that count.

Push-ups, like vanilla flavours, are reliable, but when you want something different but just as good dips are your answer. Dips also work out your chest, shoulders and triceps, but focus on slightly different parts of those muscles. Combine that with push-ups and you will build awesome chest and "pushing" strength.

Is today the day you're going to start working out more often? Or are you just getting back to what you used to do before all the holiday parties messed with your schedule? Either way, it's time to get started. We've picked out six workouts that are perfect for your first (or second) day back.

If you can hold a plank for ages and crack walnuts with infinite sit-ups, you've got good core strength. But a strong core is more than brute-forcing your way through ab exercises. Your core needs stability to protect you from injury. In other words, you need core strength and core stability.