In recent years, thanks to the popularity of crossfit and hi (high intensity interval training), we have seen how many exercise-based weight loss activities try to combine a slimming effect of training with minimal time expenditure. and possibilities (of tools, of equipped, economic places). Put simply: maximum yield with minimum expense.
For example, Kayla Itsines bikini body guide, or many ten-minute, twenty-minute, half-hour workouts a day are based on the idea that you can burn many more calories by condensing your workout in a short time, as long as you do it quickly. . This creates anaerobic effort, which leads to an increase in metabolism. There is no need for special equipment for these workouts, nor for the gym.
However, there are cons:  – you must already be trained enough to jump, push-ups or squats in a few seconds of time and in as many repetitions as possible. Penalty the injury, especially to damage to the joints. – if the training is not done in speed, the metabolic advantage is lost, that is: you do not lose weight.– these are workouts that put a strain on the cardiovascular system: therefore, if we are not marathon types and rather we are untrained and sedentary subjects and we get out of breath while climbing stairs, this activity is literally not for us.
There are alternatives that are based on the same principles, but what can we do without playing with our knees, and even if we are not particularly trained? Yes, and they fall within the “low impact hiit” , that is an activity for weight loss that is based on low impact exercises, that is, which are not particularly difficult to do, and do not require a motor coordination that only trained people (and not all , they can do).
The basic idea is always to condense the activity into twenty or thirty minutes at the most, but with less dangerous exercises, always to be carried out in speed.
A good protocol can be the following: 5 minutes of jogging in place, 4 exercises to do, a minute and a half break, repetition of the 4 exercises (second cycle), a minute and a half break, repetition of the 4 exercises, final stretching . Less trained people can do two exercise cycles to start.
The exercises should be carried out with the hiit technique, for example: perform an exercise for 45 seconds, doing as many repetitions as possible. Pause for 15 seconds and then off to the second exercise. If you can’t, it’s also okay to do 30 seconds of an exercise and a 30 second break.

It is the type of exercises to choose that are “low impact”, ie simpler. 
For example, choose 4 to do in one week from these, and another four the second week:
1) high knee walking . Standing, the left leg is raised and the right arm is lowered, so that the left knee and the right elbow meet, then it is done with the right leg and the left knee. Video. 
2) jumping jacks: you do jumps on the spot, closing and spreading the legs and arms in repetition. Video. 
3) boxing with side jog: ten punches forward (as if boxing), do a side run in three or four long strides and then punch ten forward.
4) simplified squats: they are done by raising the arms in a fist over the head, and alternately raising the left and right leg with the knee up, towards the torso. Third exercise of this video. 
5) cross-legged push-ups / push-ups: lying on a mat on your stomach, with your arms crossed, you raise yourself from the floor with your arms. Video. 
6) bridge to the ground: lying on a mat with your stomach in the air, with your knees raised and your feet on the ground, you move your pelvis up and then down. Video. 
7) boxing with forward kicks: punches forward as in boxing, kicking every four punches.
8) bicycle:lying on the back, we move the legs in a whirlpool, mimicking a bicycle ride, and raising one arm towards the opposite leg. Video.

Please note: the videos are in English, but you don’t need to know English. You just have to look at how the exercise is done.
Remember to stretch after and not before the activity.