A Kinematic and Dynamic
Analysis of Shoveling Snow
José A. DeFaria
Third Progress Report
April 24, 2016
Problem Statement
11,500 people are
treated in ERs each
year due to injuries
sustained while snow
shoveling
 Are ergonomic
shovels effective at
reducing loading on
the lower back?

Prior Research



Lewinson report measured trunk flexion angles and
showed that angle was decreased using the bent-shaft
shovel
This should also reduce the moment at the base of the
spine, and therefore, the likeliness of muscle strain
Lewinson presented only normalized data. Did not
speak to the extremes of the human population
Adult Human Population


Significant variance in height and weight across the
population.
Findings for the average male are not necessarily
accurate for other segments of the population
Methodology
Maple, a
computer algebra
program, will be used to
simulate the motions of snow
shoveling.
Height and weight can be
defined
Simulated person can rotate
until specified trunk flexion
angle is met, move arms until the
shovel reaches the ground, load
the shovel with snow, and then
complete the prior motions in
reverse
Results & Discussion
Straight Shovel
Bent Shovel
70000
60000
Moment (in*lbs)
50000
40000
30000
20000
10000
0
0

25
50
Time (normalized to % cycle)
75
100
For the average individual, the moment is reduced
using the ergonomic (bent) shovel
Results & Discussion
Straight shovel
Bent shovel
% Reduction
5th percentile female (light)
32,548 in*lb
26,654 in*lb
18.1%
5th percentile female (average)
37,139 in*lb
30,987 in*lb
16.6%
Lewinson average
57,337 in*lb
50,237 in*lb
12.4%
95th percentile male (average)
86,689 in*lb
78,018 in*lb
10.0%
101,421 in*lb
91,922 in*lb
9.4%
95th percentile male (heavy)


Moment is reduced across the population
Larger percent reduction in the lighter individuals
since each individual lifted the same weight of snow,
and this weight is more significant when compared to
a lighter individual
Results & Discussion
(h*w)
(h)
(w)
(h+w)
(h+4w)
(h+2w)
Straight Shovels
59 in // 88 lbs
17%
70%
6%
15%
0%
6%
59 in // 113 lbs
7%
49%
6%
18%
10%
13%
69.69 in // 162 lbs
2%
14%
2%
3%
0%
1%
74 in // 246 lbs
9%
20%
1%
6%
3%
4%
74 in // 297 lbs
12%
32%
2%
7%
1%
3%
59 in // 88 lbs
1%
83%
1%
23%
8%
14%
59 in // 113 lbs
11%
58%
12%
24%
16%
19%
69.69 in // 162 lbs
16%
15%
1%
3%
0%
1%
74 in // 246 lbs
21%
22%
3%
8%
5%
6%
74 in // 297 lbs
24%
33%
1%
10%
4%
6%
Average Variance
12%
40%
3.5%
12%
4.7%
7.3%
Bent Shovel
Other studies
normalized their
findings by height
and weight (h*w)
 Results from this
study show that
while there is a
strong
correlation with
weight, the of
moment to
height is not as
strong.
 Most accurate
normalization
method was by
weight only

Potential Sources of Error
Straight Shovel Bent Shovel Difference (°) Difference (%)
Reference [5]
Reference [6]




Mean (S.D.)
Mean (S.D.)
49.2°
41.4°
(12.7)
(14.4)
84.8°
74.3°
(13.3)
(11.5)
-7.8°
-15.9%
-10.1°
-11.9%
Two prior studies presented vastly different trunk
flexion angles.
The cause of these differences between the two
reports are not clear from their journal articles.
The trunk flexion angles used in Reference [6] were
used in this simulation.
It is possible the Reference [5] angles are more
accurate.
Conclusions
Ergonomic
snow shovel was
determined to reduce
maximum bending moment in
the lower back across the
adult population
This reduction in moment
will lead to decreases back
strain and decreased injuries
Further Work
Future
evaluations
should consider inclusion
of 5th percentile females
and 95th percentile males
Future evaluations
should define how the
trunk flexion angle is a
function of height, as
opposed to simple
presentation of the
average
Any Questions?