between frame 86 - 89 i think mebe u should put an anticipation pose (lower pose/ a preping low bounce for the upward lift)

89 spine pose should be more like 95 spine pose (as if the spine is leading the movement, + arms straight (heavy weight is lifted with legs, not bent arms)

98 shift weight backwards abit more in stand(holding weight pose)
the rule about center of mass between feet is, when weight is lifted the center of mass position is sahred by both the character and object, the center of mass moves forward (towards the object) hence leaning backwards to shift the center of mass backwards ( back towards the center of hips) the size and shape of the object will change where its center of mass is comaperd to the characters and hence its combined position aswell.

the walk afterwards is light (the object is not very heavy) because the arms are bent (means they are strong enough or object is light enough for the arms to take the weight easily)

by starightening the arms it will lower the objects weight closer to the characters center of mass (between hips/ belly button area) the spine will have a better fulcrum for more power (levers and torque, mechanics) = heavyer weight

sorry im not making very much sence.
just try a pose with straight arms, more spine bend back, wide stance.
check you tube for weight lifter (the never have bent arms caus its not strong enough)

ok now im gona shut up now caus im confusing even myself