When jumping, however, the arms are not a major limitation for speed, and this mode of locomotion also favors speed for the following reasons:
- the arms always work together, making their power the highest possible (roughly twice that of other modes). In addition, their role is only to absorb impact during landing; they are not needed to provide any impulse.
- the impulse is produced instead by both legs together, which allow them to provide all their power with a full extension.
- the movment is less tiring on the hip area because of the succession of grouping and ungrouping of the body.
- finally, the alternating rest of anterior and posterior limbs is improved. [ndt: it is not entirely clear if this means the limbs are allowed to rest better or if their posture on the ground is more stable. Both might be relevant.]
In galopping, one of the impulses is made with a diagonal with one arm and the other arm works alone, having a very violent contact with the ground. The attainable speed depends on the resistance capacity of that arm; subjects with strong arms may reach their maximum speed with galopping as well as with jumping, although galopping is more tiring after a certain distance because of the fall on a single leg at the end of the move.
In summary, jumping or hopping is the fastest and least tiring QM mode for most subjects. Only a certain body conformation and large amounts of flexibility can make galopping faster. This preference to imitate hopping quadrupeds is largely due to the flexibility and ease of movement of the posterior limbs, and the limited effort required of the anterior limbs. At full running speeds, a trained quadrupedist can bring the feet to land forward of where the hands hold, making long individual jumps that can exceed two meters [ndt: 2m = 6 feet].