I think the author had in mind acceleration and g-forces, although the two concepts are related.

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przeciążenie

pozorny wzrost ciężaru samolotu, statku kosmicznego powstający wskutek zmian przyśpieszenia ruchu samolotu w locie krzywoliniowym»

http://sjp.pwn.pl/sjp/;2509553

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g-force (with g from gravitational) is a measurement of the type of acceleration that causes weight.

Since g-force accelerations indirectly produce weight, any g-force can be described as a "weight per unit mass" (see the synonym specific weight).
https://en.wikipedia.org/wiki/G-force

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This is a force that acts on a body as a result of acceleration or gravity and is described in units of acceleration equal to one G. For example, a 10 pound object undergoing a G-force of 5 G experiences 50 pounds of force. The force of gravity on Earth is used as a baseline for measuring these forces of acceleration.

http://www.skyandspacetravel.com/speed_gforce.html