As stated in the previous passage, the local work turnover in the muscle i.e the fatigue/straining of the muscle is crucial. This is the impetus for the muscle to adapt e.g. the increase of muscle mass and strength. If you proceed to the next repetitions too early - you do not wait until the cardiovascular system has finished its first recovery phase - not everything will have gone "down to zero" again and with every repetition the pressure rises.

Relation between blood pressure and performing single repetitions

On the one hand, this is risky, if correlating risks exist and on the other hand, as soon as the cardiovascular system runs "at full speed" (you breath rapidly and heavily, accompanied by breathlessness during exercise) the oxygen is redistributed. From then on, you feel an all round fatigue which includes the muscles as well. Too much energy is turned over in the entire body and the muscle is forced to perform a (for adjustment of the muscle) work load that is typically not ideal due to an oxygen shortage. As a consequence, one needs more time for the recovery of the entire body, the subsequent hours are wasted time. This is frustrating because time passes during a period in which one is too exhausted to do anything else. The time that is used to take a break or to breathe in between training without weights, can last from 10 to 60 seconds; depending on the state and the extent of comorbidities.

Particularly, for patients with diseases of the right heart and pulmonary hypertension, 45 to 60 seconds are reasonable. When it comes to respiration, one must have the general feeling that the air "goes down" entirely and runs without pressure or wheezing. It is reasonable, too, to control the intensity by counting in breaths.