There is still a lot of debate about the right time for cardiovascular training.
Before the weight training session, after, or during a separate, dedicated session? How long, at what intensity and for what purpose? Let’s go through the different possibilities point by point.
Doing a long cardio session before a resistance training session is totally counterproductive, since it would mean emptying your glucose reserves which should have been used for the weight training session!
A short 5-10 minute workout, on the other hand, warms up the entire body, which will help prevent injuries from cold muscle training.
On the other hand, it is very important afterwards not to forget to warm up locally according to the muscles used (warming up the joints and muscles), for example before a pectoral session, rotate the shoulders, elbows and wrists , then do a long and light series (15/20 repetitions at 50% of his max) for each muscle used, for example a series of bar curl (biceps), one of pushdown in pronation (triceps), a series of l- flies (for the rotator cuff, to stabilize the shoulders) then a few light sets of the upcoming exercise (e.g. bench press)
Finishing your weight training session with 15/20 minutes of cardio at moderate intensity allows you to restart your normal blood circulation and oxygenate your muscles, which will optimize muscle recovery.
Doing a slightly longer cardio session at moderate intensity (30 to 45 minutes) allows the use of lipids as a source of energy and therefore helps in the loss of fat, as long as you have not consumed carbohydrates during training, but this is not recommended if you want to maintain or build muscle. This is therefore a possibility to consider only during a diet / dry period, and it will be very important to eat a protein rich meal (or a powdered protein shaker such as whey isolate) at the end of the session. In my opinion, this is not the best option.
In addition, cardio after a weight training session decreases lower body strength. Not optimal for progression!
Doing cardio outside of a weight training session can be a good thing if its objective is to improve cardiac performance (VMA, VO² max), and in this case it is interesting to combine a classic training (speed continuous and moderate intensity) with interval training (alternation between sprints and moderate running for example).
What about a cardio session to lose fat?
It is classically recommended, in order to use your lipids as a source of energy, to do long cardio training sessions (at least 45 minutes) and at low intensity.
In truth, even if indeed this type of training uses fat, the concern is that in the long term it lowers testosterone levels in favor of an increase in cortisol, which blocks the loss of fat (unless you practice weight training on a regular basis).
To overcome the problem of the rise in cortisol levels it would be necessary to drink a drink rich in high GI carbohydrates, but in this case it would no longer be the lipids that would be used so the interest is zero.
It is much more productive to increase your testosterone levels with weight training!
During dry periods, it may be beneficial to do cardio to increase the number of calories burned during the day. But if your work is already physical and / or you mostly walk or cycle, then the benefit of cardio for drying out will be low.