Āé¶¹“«Ć½

Health

The remarkable science-backed ways to get fit as fast as possible

A better understanding of what happens to our bodies when we get fitter can unlock ways to speed up the journey – and it might be simpler than you think

By Grace Wade

22 July 2024

Āé¶¹“«Ć½. Science news and long reads from expert journalists, covering developments in science, technology, health and the environment on the website and the magazine.

Watching an athlete at their peak is thrilling.Ā Fulfilling one’s own athletic potential, not so much. Getting fit is hard and painful – orĀ so we assume.

This article is part of a series on fitness that answers eight questions about exercise and its influence on our bodies and minds. Read more here.

But that isn’t necessarily the case. In fact, research shows that anyone just starting to exercise more than they are used toĀ will see improvements surprisingly quickly, regardless of the workout they choose. Better yet is the discovery that there are ways to speedĀ up the fitness journey.

The key to improving fitness is, in essence, simple. You need to exceed your ā€œhabitual loadā€, which is a fancy way of saying doing more activity than you are accustomed to. ThisĀ will stress your body and force it to adapt.

When it comes to starting cardio exercise asĀ aĀ beginner, ā€œone of the first things that happens is you get more blood volumeā€, saysĀ  at the University of Michigan. Within 24 hours of working out, this increases by up to due to water retention, which increases the amount of blood plasma, boosting the amount of oxygen that can be supplied to the muscles. After twoĀ weeks of training, peak blood volume is normally reached, which is about .

Energy-producing structures within our cells called mitochondria become more numerous and efficient around this time as well. Small blood vessels known asĀ capillaries begin rapidly proliferating withinĀ muscles, too, improving the body’s ability to deliver oxygen to tissues. One found that capillary density expanded by about 20 per cent after two months of a cycle training programme.

These shifts enhance the maximum rateĀ atĀ which the body can use oxygen, a measure known as VO2 max, says at the University of Glasgow, UK. Changes in VO2Ā max typically occur around six to eight weeks into training. By the third month, it can improve by approximately 10 per cent, he says.

Getting stronger

Muscle also adapts rapidly. within muscles involved in regulating inflammation and removing waste products that accumulate as a result of the stress of exercising. It doesn’t take long to build muscle strength either, at least if you are a beginner. ā€œEveryone gets stronger in their first three weeks because your nervous system learns how to talk to your muscles better,ā€ says Lane. With repetition, the nerve signals from the brain get quicker, and muscles become better at responding to them, generating greater force more rapidly, says Gray.

Exercising also builds brawn by tearing muscle fibres, allowing them to build back stronger. In a sense, you literally become ā€œrippedā€. This takes a bit longer, though, so theĀ greatest improvements in muscle size andĀ strength don’t happen

All of this suggests that exercise should feelĀ aĀ bit easier within two to three months ofĀ your first workout. But several factors mean this varies from person to person. The most significant influence is genetics. Our genes determine about half our aerobic fitness, says Lane. ā€œSome people, no matter how much they train, their VO2 max won’t shift very much,ā€ says Gray. ā€œThen, you’ll get the very annoying people that will do the same training as you and their VO2 max will fly off the charts.ā€

AgeĀ isĀ another factor, with . Prior physical activity makes a difference, too, as people who have previously trained are able to rebuild muscle faster than those who are just starting out.

Two women using the battle ropes in the gym. Exercising builds brawn by tearing muscle fibres, allowing them to build back stronger

Exercising builds brawn by tearing muscle fibres, allowing them to build back stronger

Shutterstock/Standret

A wide range of exercises can improve fitness within a few months, provided they are done three to five times a week for about 30 to 60 minutes. For instance, 12 weeks of endurance training such as cycling , roughly the same as a strength training programme ofĀ theĀ same duration. However, one regime seems to trounce all others in terms of gettingĀ fit quick – both fromĀ an aerobic andĀ strength perspective – byĀ stressing ourĀ physiology in just the right way to induceĀ maximal adaptation.

High-intensity interval training

High-intensity interval training (HIIT) involves exercising at near maximum effort in repeated bursts of up to a minute, with short rests in between. This regime was devised in the 1990s by Izumi Tabata and his colleagues at the National Institute of Fitness and Sports in Kanoya, Japan. They showed that a 4-minute workout, with repeated cycles of 20 seconds of intense work then 10 seconds of rest, done five days a week for six weeks resulted in than moderate, hour-long workouts done over the same time frame.

Since then, many trials have confirmed the power of HIIT. ā€œIf you want a quick increase [inĀ fitness] over four to six weeks, purely intervals would do the job,ā€ says Lane. The keyĀ is working as hard as you can during the intense intervals. Just six HIIT sessions over two weeks significantly improves VO2 max andĀ endurance capacity, but, remarkably, aĀ  found similar improvements couldĀ be achieved if these HIIT sessions wereĀ squeezed into a five-day period.

at the Norwegian School ofĀ Sport Sciences in Oslo says beginners shouldĀ start with two to three HIIT sessions perĀ week. You can intersperse these with longer-duration endurance activities, such as jogging or swimming, to further boost results, he says. Once you notice that your strength has plateaued with HIIT, you can add two or three full-body strength-training sessions, says Lane.

However, the best exercise is ultimately theĀ one you will be able to stick with, not necessarily the one that leads to the quickest improvements. ā€œWe sometimes get in the weeds with what is the perfect plan, but IĀ thinkĀ for most people, we just need to getĀ outĀ there and get moving,ā€ says Gray.

The trick is to continuously challenge yourself. If you do, you may be surprised to discover your own peak performance.

Topics:

Sign up to our weekly newsletter

Receive a weekly dose of discovery in your inbox. We'll also keep you up to date with Āé¶¹“«Ć½ events and special offers.

Sign up
Piano Exit Overlay Banner Mobile Piano Exit Overlay Banner Desktop