During exercise, most people seem to have an instintive desire to grip with their hands, even in exercice where the hands and arms are not involved, and this is a pratice that should be avoided. Muscular contraction increase blood preasure, but there is no relationship between the mass of muscle involved in the contraction and the resulting elevation in blood preasure.
il donne ensuite des examples d'élévation de la pression sanguine et :
But the most dramatic effect on blood preasure is caused by maximal contraction of the muscles that produce gripping with the hands, blood preasure in this case is so high it is difficult to measure. For obvious reasons, such elevation of the blood preasure should be avoided, and can be avoided; do not grip during exercise, instead, maintain the hands in a loose, semi-relaxed position.
voila en gros ce que Jones dit ... bien qu'il conseille tout de meme à ceux qui veulent développer parfaitement les avant-bras de faire du grip, mais à leurs risques et périls... bon Jones est un perfectionniste, peutêtre trop, donc c'est certainement vrai que les exos de grip sont les pires niveau élévation de la pression sanguine, est-ce vraiment dangereux au point de devoir être évité ?...