Here's what usually happens when people try to get fit quickly. They go to a few classes or decide to do high-intensity workouts that are quick hits for 20-30mins tops, 3-4x/week. It's short enough, and they feel that if they are sweating and on the brink of throwing up by the end, they are "getting in great shape."
This can yield some decent benefits in about 2-3 weeks, but overall cardiovascular health and strength improvements start to plateau after this. It's hard to consistently keep that intensity, even if you are an elite athlete. They still have lower-intensity days and rest days between high-intensity work.
When going all out, guns blazing, you risk getting injured and overstressing the body, where recovery will be needed. If you want to get in better shape, you need to be consistent over time, and you should start that in the winter rather than last minute.
Returning to the high-intensity Tabata-style workouts, they give quick results with a plateau and then drop-off
The things that take a long time to build up usually take a long time to diminish. This is where being consistent over a period of time to get fit comes into play, as it will be much easier to maintain in the long run, even if you have a small hiatus. To get in shape the way you see it, you must ask yourself, "What is my primary goal." That could mean having better cardio, being stronger, leaner, or just moving better. Pick one, and then you can choose another as a secondary goal to work on as you go.
You may need to spend 6-8 weeks building up your primary goal, and then you can start to maintain those qualities by sprinkling in specific workouts to that goal 1-2x/week while you focus on the secondary goals. This allows you to not drop off in one area while you build up another. You can see that this could take a few months and sometimes a year, depending on what you need to build to get in shape. Taking shortcuts can only help you for so long. The journey allows you to build up experience and a larger pool of resources to draw from.
To provide context, many people look at cardiovascular fitness as a means of getting in shape, so I provided some guidelines on how that may look over a period of time.
When building up our endurance, it is important to know that we should refrain from really short and intense bouts of training cycles such as 20s on 20s off style training at the start. These can be useful later on but will not provide you with the proper foundation as you advance.
The best way to start is to improve the engine by having a bigger gas tank to draw from as we advance. This is done with low-intensity, long-duration-based exercises. These would include continuous exercises for 30-60min, such as riding a bike, walking, jogging, and swimming, to name a few. If you are working to improve your jogging overall, you may want to start with some light bike work and walking, especially if you have not done anything in a while. You may need to be building some strength and stability within the joints to support the impact of running.
Perform the continuous-based activities for 6-8 weeks 2-4x/week. After this time frame, lower these activities to 1-2x/week and add in some higher-intensity work. These would be small intervals at 80-85% of your maximum heart rate. (Quick max heat rate calculation is 220 minus your age). These intervals can be a faster jog, more resistance on a bike, climbing uphill, etc. You would perform these 1-2x/week at intervals for 10-15s on and 45-60s off, slowly building the number of sets you can do weekly (These should have a 2-day rest period in-between).
After 4 weeks of this work, you can start to add in maximal, all-out work 1-2x/ week (3-4 day rests in between) for short bouts of 3-5s with 60-90s rest periods, for 2-3 weeks total. With all that being said, you will now be in a much better place long term and easy to maintain, as long as you keep the low-intensity work in 1-2x/week.
Building slowly with long-duration work will improve your heart's ability to circulate blood flow, decrease resting heart rate, and improve recovery times. If you have a bigger gas tank, you can have more resources to pull from when doing quicker bursts that take up more energy, allowing you to do more work before getting depleted. The other benefit of the low-level activity is that it acts like a small tickle to keep filling the tank back up after your pull from it. As a result, your recovery times will be quicker, you will have more ability to repeat bursts, and you will be more efficient.
Hopefully, that gives you a running start. Let me know if you have questions or need help with goals other than conditioning.
Dr. Peter Dionisopoulos is the owner and founder of Dynamic Performance & Rehab. He has worked with many high-level athletes and military personnel, but his true passion is to help active adults maintain their lifestyle by providing information and potential solutions to their aches and pains so they can continue with the activities they love.