# Static loads on human body

1. Sep 17, 2011

### mahkum

Hii guys

here something tricky, have a go on this one....

I am required to model the human body so that I can analyse the static loads, (comparing the pilates position and the abdominal sit-up position) (pictures of positions attached)
Using the body mass ‘M’ of 94 kg and a body height ‘h’ of 1.73 metres, to establish which exercise requires the most effort from the abdominal muscles to hold the position and by what factor.
The table shows the details of body parts so that comparison between the two positions can be performed.

Table:
Body Parts
Mass in terms of M, the person’s mass

Thighs 0.2M
Shanks + feet 0.13M
Trunk + arms 0.59M

Length, I, in terms of h, the person’s height

Thighs 0.24h
Shanks + feet 0.29h
Trunk + arms 0.332h

Position of cetnre of mass along from upper end of the body part

Thighs 0.43/
Shanks + feet 0.47/
Trunk + arms 0.50/

For the purpose of this question, the mass and position of the hands and arms can be considered to be part of the trunk. Place the origin at the join between the bottom of the trunk and the top of the thighs, i.e. where the abdominal muscles act. Assume that the angle the legs in the pilates position makes with the floor is 60o, whereas the angle the head and neck make with the floor is 45 o.
For the sit-up exercise, the trunk is at 30 o to the floor and the legs are bent so that the knee joint makes a 90 o bend.

a) Give valid assumptions on how you model the body components
b) Sketch clear, fully labelled free-body diagrams of the two positions, showing the known and unknown external acting forces and moments
c) Provide accurate equilibrium equations by resolving the loads and moments
d) Calculate the unknown external loads and moments
e) Calculate the moment provided by the abdominal muscles to achieve the position

I have no equations, nor any attempts, coz dont know where to start

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