Total, external and internal work for human movement

ABSTRACTS

OF THE EIGHTH ANNUAL CONFERENCE AMERICAN SOCIETY OF BIOMECHANICS Held in Tucson,

THE KISEMATICS

ASD

Kl;VETICS

Arizona,

3-5 October

OF SWINGING

The purpose

was to develop

Cam camera operating conditions: during

a spike mallet flexion during

spike condition, 200 m

hammer

the sledge condition

of trunk

a profile

s- ’ compared

with 280 m

swinging

the spike condition.

of the downswing

s- ’ developed

for the spike mallet

company

views of hammer

head. The movement

Although

with the spike mallet. Torques

than for the sledge. The output

two

was greater

showed similar speed

prior

acceleration

to impact

with the

of the sledge head was

at the lumbar

from

A Lo

under

of the trunk

its movement

The terminal

employee.

swinging

both performances

stopped

HARIhIERS

Urbana-Champaign)

male railroad

sagittal

the trunk

decreased its displacement.

OF RAILROAD

of Illinois.

for a skilled

was used to obtain

head and a sledge hammer

than during

the majority

whereas the trunk

to be 35”,, greater

of hammer

at 100 frames s-*

1984

TWO TI.PES

MARLENE ADRIAN and GERALD SMITH (University

OF THE

spine were estimated

this subject

can be a model

for

emulation.

TOTAL,

EXTERNAL

AND INTERNAL

SERGEI Y u. A LESHINSKY (Biomechanics

Different

methods currently

Among

these methods

However

used to calculate

mechanical

one of the most popular

the reason for this discrepancy

MOVEMENT

The Pennsylvania

energy during

movement

is to sum up ‘external’

analysis of the simplest example ofa one-link

To find out

WORK FOR HUMAN

Laboratory,

movement

a mathematical

State University)

give radically

and ‘internal’

work

shows the incorrectness

description

of a moving

different

results.

to get ‘total’

work.

of such an approach. multi-link

model

was

undertaken. It was shown that some components other

and required

W”,,, = %,Vn~l

no energy

of external

supply.

+ %rrmai. he unintentionally

INDIVIDUAL

MUSCLE

and internal

But if one follows includes

AND JOINT

energy always fluctuated

the traditional

the cncrgy

FORCES

total

work.

i.e.

cost of these lluctuations.

ACROSS

K. N. AFT, B. F. MORREY and E. Y. CHAO (Biomechanics

out of phase with each

way of calculating

THE ELBOW

Laboratory,

Mayo

Clinic,

IN SPORTS Rochester,

MN

55905.

U.S.A.) Knowing

the individual

information

muscle and joint

forces across the joints

can not only be used to assist in the design ofathletic

the mechanism

and management

ofsports

injuries.

forceanalysis

is presented. A new optimization

is introduced

to resolve the indeterminate

moments and joint

A BIODYNAMIC

MODEL

procedures,

In this study, the development

approach, problem

angles at the elbow during

in sports is significant training

running,

based on minimizing

for a unique

solution.

in several respects. This

but also for understanding

ofan

analytic

model for elbow

the upper bounds of muscle stress, By using the data of intersegmental

the results of major elbow muscle I’orces can be calcclated.

INDUSTRIAL

PUSH/PULL

R. 0. ANDRES. D. S. BLOSWICK and D. B. CHAFFIN (Center for Ergonomics.

FOR INVESTIGATING

The University

Ann Arbor, A sagittal pulling:

plane biodynamic

the risk of back injury

compressive

force,

Laboratory

validation

while

model

the slip hazard experiments

MI 48109, U.S.A.)

has been developed

and the risk of slipping. is surmised

were

designed

TASKS of Michigan,

to predict

two risks associated

The risk of back injury

with cart pushing

is assessed by predictions

from

predictions

of the required

and

performed

to

compare

coefficient

model

and

of Lj/SI of friction.

predictions

with