Fitness Adaptation Takes Four to Eight Weeks of Consistently Progressive Exercise Stress

To become stronger and faster, your muscular system and metabolic systems (what energy your body requires at the moment), need four to eight weeks of consistent work to create fitness adaptations.

Three Things to Know about Fitness Adaptations

  1. Your body requires consistent and progressive stress in the form of exercise.
  2. Having a specific adaptation goal and monitoring your progress goes a long way to helping you achieve fitness adaptations. 
  3. You need to build in recovery in order to let your body “heal” and create the systemic adaptations.
You need time to build the the fitness adaptations in your body to get stronger and faster.

To become stronger and faster, your muscular system and metabolic systems (what energy your body requires at the moment), need four to eight weeks of consistent work to create fitness adaptations. 

I wish I had a dollar for every person who starts a fitness program, then, after a couple of weeks, never shows up again, especially after New Year’s resolutions!

Fitness adaptation takes time, and that’s the reason so many people stop their exercise and training plans after few weeks. 

People with great intentions don’t much in the way of quick results and give up.

They aren’t getting faster or stronger quickly enough, they aren’t losing weight (if that’s a goal), and, in fact, they feel sore and tired most of the time! (A sure sign of doing too much too soon!)

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Fitness adaptations require increased stress and consistency

Fitness adaptation is the process your body REQUIRES before it shifts gears and becomes stronger and faster.

So if you run, ride, strength train, or do yoga once a week, your body realizes you’re not going to require change, so you get tired and maybe sore, and nothing much changes. 

However, if you stress your body several times a week and continue to build more stress by exercising more, your body says, “damn, he/she is serious and I need to make changes in order to keep up with the demand.

That’s when the magic starts to happen. 

The really good news is if you stick with the regular exercise and change in fuel intake, the changes will come!

Fitness adaptations take between four and eight weeks

We can have many different goals when it comes to fitness adaptations and changes. We might want to increase our fat-burning capacity, or improve our muscular strength, or build a bigger engine. 

As an example, one strength training client put a lot of pressure on herself to lose weight in a few weeks.

I wrote on her training plan that her six-week goal was to NOT look at a scale and come into the gym to strength train three or four times a week for six weeks without thinking weight loss. 

You are building new habits, and it takes your body time to adjust. And your body is not going to like the change!

It’s going to protest with soreness and stiffness, especially if you push too much in the beginning.

Depending on your experience, your starting point, and your natural systems, adaptations take between four and eight weeks. 

Some adaptations, like anaerobic capacity/ VO2max work can take just a few weeks, while others, like building aerobic capacity, can take months.

Rate of fitness gains and weight loss

Weight loss – or becoming more fit – is often a goal for runners and cyclists. 

But so many factors affect the rate at which people gain fitness and lose weight, including current BMI, your past weight loss history, hormonal issues, and, especially, genetics. 

Weight loss is not only about reducing calorie intake.

In fact, sometimes, you need to maintain or even increase your caloric intake as you exercise.

I worked with a long-distance swimmer who wasn’t losing any weight despite burning thousands of calories a day training for a series of seven to nine mile races.

His caloric deficit was several thousand, and that’s not sustainable.

When your body doesn’t have enough fuel, it reverts to caveman days and holds onto fat because the lack of food means famine.

The solution?

Eat more carbs. The swimmer needed more fuel as carbohydrates.

He’s since lost weight and lowered body fat since adding more carbs to his diet so that his caloric deficit was more manageable.

The key to weight loss, though, is building muscle as fat melts away. That is the importance of exercise in the process. 

Fitness adaptations change your body

And that leads us to fitness adaptation, and by this I mean the metabolic, muscular, and neurological changes in your body as you exercise and improve nutrition.

Essentially, this means you need to gradually and consistently increase the exercise stress you put on your body to bring about the adaptations you’re looking for. 

For instance, it’s important for anyone who wants to gain strength to hit the gym three times a week, especially in the beginning. 

What happens in your body, to put it simply, is that when you strength train once a week, sometimes two, your muscles think it’s a temporary thing.

If you go to the gym three or four times a week for several weeks – four to eight, depending on the person and their current fitness level – your muscles finally “give up” and surrender. 

Your muscular system says, “We realize now we have to adapt to the new routine in order to produce the energy and fuel to support the work.”

That’s fitness adaptation.

And that’s when you’ll really see the changes in your body. You should see some change in your weight, but you’ll also really see the changes in how your body is shaped.

Fitness adaptations take effort, work, and consistency

This four to eight-week period is not going to be easy.

Your body is going to resist. And you have to be consistent with your goal. 

If your goal is to build power at your second threshold (FTP, Critical Power), you need to stick with the plan of overloading your system with the work, then recovering enough to do it all over again AND allow your body to make the changes. 

If your goal is to increase your speed in a 10k, for example, you need to be consistent in your intervals at your goal race pace. 

You need to continually and progressively overload your muscles as you build that adaptation.

For example, if you always lift with five-pound dumbbells, you won’t get any stronger.

And if you do the same strength exercise every time, you also won’t get any stronger.

Your body needs variety to adapt and grow stronger.

Working with a personal trainer, coach, and/or nutrition expert can really help fitness adaptation, or at least make some of it easier. 

It’s really not complicated, but it is a challenge. 

Fitness adaptations require monitoring and goals

One of the benefits of having a coach or personal trainer is identifying the particular adaptation you’re looking for. 

That way, you can focus your work and see results more quickly by efficiently applying the correct stress to your systems. 

Monitoring and documenting your goal also helps to see changes in your fitness. 

For instance, if your goal is to increase time to fatigue at your Critical Power/FTP, you can write down your current time at FTP, heart rate, and other metrics like Efficiency Factors. 

Then, with extensive intervals (making the intervals longer each time), you can monitor those same metrics to see progress. 

Recovery is allowing your body to marinate with the stress to produce adaptations

The key to all of these adaptations – fitness, metabolic, muscular – is recovery. 

You don’t create adaptations in your systems through exercise; you create adaptations when you recover. 

In a way, your body’s systems marinate in the stress soup (am I mixing metaphors there?) and gradually build back up stronger and better than before. 

Recovery is taking days off. Resting. Sleep is by far the best recovery tool we have!

Building additional stress, then recovering from that stress is the most effective way at creating fitness adaptations that help you reach your performance goals. 

Want to know more about what you can achieve? 

My purpose with Simple Endurance Coaching is to help everyday endurance athletes achieve their goals with more strength, endurance, and mobility. 

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Paul Warloski is a: 

  • USA Cycling Level 3 Coach
  • RRCA Running Coach
  • Training Peaks Level 2 Coach
  • RYT-200 Yoga Instructor
  • Certified Personal Trainer