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Hello, fellow biomechanists. We are currently investigating new ways to
measure efficiency in baseball pitching. Our basic idea is to
quantitatively determine maximal ball velocity with minimal stress
(force and torque) on the elbow and shoulder. For instance, a pitcher
who throws 90 miles per hour (mph) and has 100 N of force at the
shoulder is clearly better than a pitcher who throws 90 mph and has 200
N of force. However, it is rarely that cut and dried. It is more often
the case that there are two people such that one throws 90 mph and
exhibits 100 N at the shoulder and 70 N at the elbow while another
throws 80 mph and exhibits 75 N and 60 N at the elbow. The risk/reward
struggle between injury and performance makes it hard to decide how much
force/torque is too much. Moreover, we are not looking just to compare
two people but rather to establish a database of the most efficient and
the least efficient pitchers. We potentially have a large number of
subjects, we just need some help in figuring out how to classify them.
As a corollary to this optimization method, we were thinking of
establishing a metric such as:
Efficiency Metric = A*Ball Velocity - B*Shoulder Force - C*Shoulder
Torque - D*Elbow Force - E*Elbow Torque
The above equation is just an example, as we may have more than four
kinetic values. While this equation would be fantastic, especially
since it is linear, we realize the difficulty in assessing the metric
and the coefficients, as well as the potential for non-linearity. What
should the form of the equation be? How do we use the data we currently
have (ball velocity kinetic values) to determine values for the
coefficients A,B,C,D, and E? We have determined that body weight and
other anthropometric values may be confounding factors, so we also need
to know how to control for that since we have a wide range of ages and
abilities (10 to 40 years old, youth to professional) in our pool. Do
we also need to factor in tissue strength of ligaments, and is specific
data available that correlates tissue strength to body weight, height,
and other anthropometric measures? At these initial stages, we don't
want to overcomplicate things, but we do want a fairly accurate way to
measure who is getting the most out of their body. We would appreciate
any suggestions from all areas of biomechanics, kinesiology, and other
related disciplines. Perhaps those involved in gait analysis who
measure running economy may be able to provide some substantive
feedback.
Dave Fortenbaugh, M.S.
Biomechanist
American Sports Medicine Institute
833 St. Vincent's Drive Suite 100
Birmingham, AL 35205
davef@asmi.org
(205) 918-2119 Office
(205) 639-9515 Cell
measure efficiency in baseball pitching. Our basic idea is to
quantitatively determine maximal ball velocity with minimal stress
(force and torque) on the elbow and shoulder. For instance, a pitcher
who throws 90 miles per hour (mph) and has 100 N of force at the
shoulder is clearly better than a pitcher who throws 90 mph and has 200
N of force. However, it is rarely that cut and dried. It is more often
the case that there are two people such that one throws 90 mph and
exhibits 100 N at the shoulder and 70 N at the elbow while another
throws 80 mph and exhibits 75 N and 60 N at the elbow. The risk/reward
struggle between injury and performance makes it hard to decide how much
force/torque is too much. Moreover, we are not looking just to compare
two people but rather to establish a database of the most efficient and
the least efficient pitchers. We potentially have a large number of
subjects, we just need some help in figuring out how to classify them.
As a corollary to this optimization method, we were thinking of
establishing a metric such as:
Efficiency Metric = A*Ball Velocity - B*Shoulder Force - C*Shoulder
Torque - D*Elbow Force - E*Elbow Torque
The above equation is just an example, as we may have more than four
kinetic values. While this equation would be fantastic, especially
since it is linear, we realize the difficulty in assessing the metric
and the coefficients, as well as the potential for non-linearity. What
should the form of the equation be? How do we use the data we currently
have (ball velocity kinetic values) to determine values for the
coefficients A,B,C,D, and E? We have determined that body weight and
other anthropometric values may be confounding factors, so we also need
to know how to control for that since we have a wide range of ages and
abilities (10 to 40 years old, youth to professional) in our pool. Do
we also need to factor in tissue strength of ligaments, and is specific
data available that correlates tissue strength to body weight, height,
and other anthropometric measures? At these initial stages, we don't
want to overcomplicate things, but we do want a fairly accurate way to
measure who is getting the most out of their body. We would appreciate
any suggestions from all areas of biomechanics, kinesiology, and other
related disciplines. Perhaps those involved in gait analysis who
measure running economy may be able to provide some substantive
feedback.
Dave Fortenbaugh, M.S.
Biomechanist
American Sports Medicine Institute
833 St. Vincent's Drive Suite 100
Birmingham, AL 35205
davef@asmi.org
(205) 918-2119 Office
(205) 639-9515 Cell