You should not straighten your legs in a sitting position:
you already spend day after day in this position, which leads to heavy loads on your knees, because straightening your legs can do more harm than good.
Alternatives:
Barbell press
There are not so many people who are able to do the bench press safely. And it does not always depend on the level of training, but may be related to your personal characteristics. Leading a sedentary lifestyle, it is difficult to prepare yourself for this kind of exercise. Therefore, choose the best alternative:
Lifting from a prone position
Lifting your torso is accepted by everyone who wants to return their forgotten abs cubes. But the truth is that when lifting, we use little of the abdominal muscles, unlike the thigh muscles, which can lead to excessive load on the lower spine. For those who sit all the time, this is not the best solution.
Alternatives:
Bench press
This is one of the regulars' favorite exercises, but you are a keyboard regular and it almost certainly does not suit you and can only harm and bring injury.
Alternatives:
Traction in front
In general, it is difficult to think of a reason why anyone would need such a movement. If it is included in your exercise cycle, review it and find out why you go to the gym. Unnatural movement is a direct path to damage.
When choosing your training program, you should choose exercises, taking into account both goals and possible risks. The absence of spectacular exercises will pay off handsomely by the absence of injuries and the constant improvement of your physical form.
5 Exercises Computer Guy Should NOT Be Doing [ Jamie Nischan ]
P.S.
During the discussion in the comments, it turned out that many of our readers do not agree with the content of the article and therefore, perhaps, it is worth treating it with caution.