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fitness in your twenties

Fitness and Working Out In Your Twenties

Adolescence is the age of rapid growth along with hormones bursting at the seams. If the teen years are meant for growing then what do the twenties have in store for your level of fitness? This is part two on our series of fitness through the decades: the twenties.

Working Out In Your Twenties

This is part two on a series that talks about fitness through the lifespan. Part one talked about what it means be a teen and how it relates to fitness. Because of the developing body, the teenage years are one of the best times to take advantage of the growing body. You’ve got hormones running wild and neural connections being made. It really is the best time to pack on muscle and develop strength and agility. If adolescents is the best time to take advantage of fitness, then what do the twenties have in store?

Adolescents generally lasts from around the ages of ten and finishes up between the ages of twenty to twenty-five. If fitness is something that you didn’t really take advantage of as a teen, don’t worry, it’s not too late. For those that did take advantage of their adolescence, the twenties are a time to hone your skills and develop your fitness even further.

Recapping Adolescence:

Adolescence is marked by a surge of growth hormones – allowing one of the best times to take advantage of developing muscles, strength, and power. Neurological connections are also still being developed at a rapid rate. Taking advantage of neurological pathways can enhance performance, balance, agility, and all around body awareness. The body also becomes more efficient with its metabolism – the body uses oxygen better and is able to support higher intensities of cardiovascular exercise and weight training. As adolescents ends towards the early twenties, the body goes through a period of neurological pruning. This “pruning” is literally what it sounds like – unused neurological connections get “pruned.” This is why using adolescents to develop neurological connections can really help someone develop skills and body awareness.

Coming Out Of Adolescence – Your Mid-Twenties

I’m sad to say it, but, once body structures reach their maximum capacity (and that happens when puberty officially ends), genetically influenced declines in the functioning of organs and systems and biological aging begins. Sorry, dude. Aging begins within the level of the DNA of the body’s cells. It happens for a couple reasons – your genetics and also the cumulative effects of random events that damage genetic and cellular material. There’s those pesky free radicals and naturally, the telomeres (protective tips of DNA at the end of chromosomes) shorten…eventually to the point that causes cells to not be able to replicated anymore. Then there’s the protein fibers that make up the body’s connective tissue – they start to become less elastic. This leads to the loss of flexibility in the skin and organs such as the lens of the eye, clogging of the arteries, and damage to the kidneys. But slowing this can be linked to regular exercise and a vtamin rich, l, healthy diet.

Growth Hormone:

In your twenties secretions of your growth hormones also starts to decrease. This leads to a gradual loss of muscle and bone mass. One big growth hormone that starts to decrease around age twenty-five is testosterone. The decrease is gradual at first and not that significant – but nonetheless, it’s a decrease of about ten percent each decade after the age of twenty-five (2).

Cardiovascular and Respiratory Systems:

Surely but slowly, your heart muscle starts to become more rigid. Your maximum heart rate begins to decrease which limits your heat’s ability to meet the body’s oxygen requirements when stressed by exercise. The average heart rate decline starting at age twenty-five is from six to ten beats per decade (2). The same stiffening happens in your lungs and chest muscles making it more difficult for the lungs to expand to full volume. The average VO2 Max decreases an average of five to fifteen percent per decade in both men and women (2). A decrease in hormones can also start to see a slow decline in the number of blood plasma, red blood cells, and total blood volume as well.

As far as your kidneys are concerned, after around age twenty, there’s also about a ten percent reduction in blood flow to your kidneys per decade (2).


Nerves aren’t as stimulating as they used to be. Fast twitch muscle fibers responsible for speed and explosive strength slowly begin to decline in number and size to a greater extent than slow twitch muscle fibers (which support endurance). Tendons and ligaments slowly stiffen which reduce speed and flexibility of movement. After peake bone mass is obtained, the rate of bone less is about 0.7% per year in men and about about 1% in menopausal women (2).

Immune System:

The capacity of the immune system to offer protection against diseaes also decreases through adolescence and declines after around age twenty. Party responsible is the shrinking of the thymus gland. The thymus gland is responsible for developing your body’s T cells which help fight infection. After puberty the thymus gland starts shrinking and actually becomes inactive later in life.

Metabolic Rate:

The basal metabolic rate, which is the amount of energy the body uses at complete rest starts to drop off as well. Reason being is the number of active cells start to drop off after puberty. This can lead to an increase in weight gain. The trend is for people to keep eating the same amount of calories they take in during their early twenties even though though their caloric requirements start to decrease. Curious on how many calories you need? See our article on calorie intake.

The Good News:

Research remains pretty consistent on peak athletic activity. Athletic tasks that require speed of limb movement, explosive strength, and gross body coordination typically peak in the early twenties. Those sports that depend on endurance, arm-hand steadiness, and aiming, usually peak in the late twenties and early thirties – mostly because these skills require either stamina or precise motor control that take longer to perfect. If fitness was a part of your teens and early twenties, you can hone your skills and athletic abilities – it’s no secret that many professional athletes commonly have the peak of their careers between twenty-five to thirty years of age.

Physical activity does prevent aging when compared to inactive people. Vital capacy (the amount of air your lungs can take in at one time)can be much larger and the heart can also be much more effective at delivering blood to the body than people who don’t exercise. Training also slows muscle loss, increases speed and force of muscle contraction, and leadds fast-twitch fibers to be converted into slow-twitch fibers which support long distance performance and other endurance skills.

The best news of all is that the declines in health are usually so gradual that they are hardly noticible at all. Unless of course, you really don’t take care of yourself – and I’m pretty sure we can all name at least one person who looked like they were thirty-five when they were twenty-five.

Making The Most Of Fitness In Your Twenties

Up until around age twenty-five or so your flexibility, hormones, heart, lungs, muscles and bones are at their best. Now is the perfect age to capitalize on your body that’s optimally functioning. The time you put into fitness and nutrition during these years will propel you into a healthier future keeping you leaner, limber, stronger, and faster longer than thsoe who do nothing. Don’t fall into the fast food trap that tends to extend from your adolescent years into your twenties. Learn to love fruits and vegetables now and your body will thank you in your sixties.

Get Your Basic Fundamental Movements Down:

Develop your techniques in squatting, deadlifts, and presses. Don’t neglect flexibility. While your body in your twenties is great at recovery, you don’t want to risk repetitive motion injuries. In between mastering your basic human movements, also familiarize yourself with the different types of stretching.

Keep Yourself Limber:

One of the biggest physical aspects that people neglect is stretching and joint mobility – something that only gets worse with age. Why not keep yourself as flexible as possible? You’ll develop stronger lifts become more explosive and be able to move more weight at more efficient speeds. Your body will thank you down the road.

What Not To Do Physically In Your Twenties:

Nothing. If you’re not doing anything, then that’s a big problem. Metoblic loss issues become aging issues. Next to the adolescent years, the decade of the twenties is the best time to capitalize and hone your skills to launch yourself into the thirties. Next up: fitness for the decade of the thirties.

Have a question about fitness in the twenties? Leave a comment.


1. Berk, L. Development Through The Lifespan. Boston: Pearson Education Inc. 2007. 431-438
2. 1090, 238



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