How fit are YOU for your age? Experts say how you perform in four simple exercises is the ultimate indicator...so where do you score?

You might ace your weekly spin class, or be able to lift super heavy weights - but does that mean you're physically fit?

Meeting the basic fitness recommendations for your age is crucial, as being slightly below par can lead to a dramatic increase in heart disease risk. 

Now, experts at the University of California Los Angeles and mega-gym Equinox have detailed the four science-backed exercises that best indicate your fitness levels.  

Your performance of each of the movements - which include push ups and running for a mile - measure how much your muscle mass, mobility and cardiovascular systems have declined. 

Fitness experts from Equinox have computed a handy chart (below) that tells you exactly where you should be for your age in upper body strength.

Starting at age 30, you begin losing anywhere from three to eight percent of your muscle mass per decade, according to endocrinologists from the University of Southern California. 

'Exercise is the closest thing we’ve found to a magic pill for combating the effects of aging,' said Linda P Fried, the dean of Columbia University Mailman School of Public Health. 

Michael Crandall, a certified strength and conditioning specialist at E by Equinox gym, told the Wall Street Journal that the four 'test' exercises monitor strength, cardiovascular efficiency and mobility. 

VO2 max is traditionally calculated by monitoring the amount of oxygen that you take in while running for several minutes at top speed, as above.

First, to test your aerobic fitness, identify your VO2 max, which is a measure of the maximum oxygen your body is able to take in and use when you're doing cardio. It measures the efficiency of the body's cardiovascular system. 

Traditionally, you'd have to go to a lab under a instructors' supervision to determine your VO2 max - and run on a treadmill with a mask over your nose or mouth to measure the amount of gas you're taking in and putting out. 

But physical therapists have developed two versions of this test that you can do at home. One involves running at your top speed for twelve minutes and the other involves walking a mile at a brisk pace. 

For an average 25 year old American woman, a good score would constitute taking in 2544-2775 milliliters of oxygen per minute. A poor score would constitute taking in 1773-2236 milliliters of oxygen per minute.

For the average man of the same age, a good score would is 3851-4168 milliliters of oxygen per minute, while a poor one is 2990-3262 milliliters of oxygen per minute.

In a lab, this is measured by a mask that can monitor oxygen levels, as well as the amount of CO2 you're expelling. At home, and without a special mask, the mark of adequate VO2 max is that you can complete the exercises without stopping.

Push ups are a great way to measure your upper body strength as they require several muscles to complete the move.

Second, to measure your upper body strength, the experts recommend push-ups. 

Though this may seem like a simple exercise, it involves a broad swath of muscles and is a good indicator of how well your muscles can move your own body weight, Equinox's Crandall said. 

Placing your hands under your chest, shoulder-width apart and your feet in a plank position, lower yourself to the ground until your arms are bent past 90 degrees before pushing back up.  If you're not able to do this in the standard position, you can start on your knees instead. 

See how many you can do in a row. Your fitness for the push-up test will depend on your age group and gender.  

According to Equinox, a good result for a 31-40 year old woman year would be 15 push ups in a row or more, a poor result would be 10 or less. 

 A good result for a 31-40 year old man would be 29 pushups or more, and a poor result would be 15 or less. 

Side planks give you an idea of how stable your core is and how likely you are to maintain a good sense of balance in later life.

Third, to measure your core endurance and stability, Crandall recommends a side plank. 

This involves arranging your feet on top of one another and pressing your body off the ground while balancing on one arm. 

If you're able to hold this position for more than 45 seconds,you're definitely fit, regardless of your age. But if you're not able to maintain the position for longer than 20 seconds, you should work on your core strength, Crandall said.

Core strength is incredibly important as you age for maintaining posture and balance, as well as staving off back and neck pain, according to Harvard Men's Health Watch. 

Finally, the last test is important for measuring your mobility, and involves you trying to stand from a seated position without using your hands. 

If you can lunge to the ground, rotate your hips to sit and then reverse that path to stand back up without using your hands, then you pass the test. A 'good' score is a passing score, regardless of your age. 

Suzi Schulman, a chiropractor from New Jersey, demonstrated this test in a TikTok clip (above). 

This movement is something that is innate to children, but adults tend to practice less as they age, according to research from Herlev‐Gentofte University Hospital in Denmark. This means that generally speaking, the older people get, the less muscle strength they have for this sort of movement. 

'A person’s ability to balance remains stable until the age of 40 but declines gradually thereafter,' according to Kwon-Young Kang, a physical therapist from Wonkwang Health Science University in Korea. 

So if you're able to nail it, it's probably a good sign for your longevity, Schulman said.