Page 133 - Journal of Special Operations Medicine - Spring 2015

An Ongoing Series

The Importance of Physical Fitness for Injury Prevention:
Part 1

Joseph J. Knapik, ScD

ABSTRACT
Physical fitness can be defined as a set of attributes that developed, summarize the data on the association be­
allows the ability to perform physical activity. The attri­ tween fitness and injury in the military, and provide a
butes or components of fitness were identified by testing possible explanation of why higher fitness is associated
large numbers of individuals on physical performance with lower injury risk. This is the first of two articles
tests (e.g., sit­ups, push­ups, runs, pull­ups, rope climbs, on this topic. The first will cover the general concept of
vertical jump, long jumps), and using statistical tech­ physical fitness and then focus on associations between
niques to find tests that seem to share common perfor­ injuries, cardiorespiratory endurance, and muscular en­
mance requirements. These studies identified strength, durance; Part 2 will focus on associations between inju­
muscular endurance, cardiorespiratory endurance, co­ ries, body composition, and flexibility.
ordination, balance, flexibility, and body composition
as important fitness components. Military studies have Fitness Definitions and Development
clearly shown that individuals with lower levels of car­ of the Concept of Physical Fitness
diorespiratory endurance or muscular endurance are
more likely to be injured and that improving fitness low­ Physical fitness has been defined in many ways, as
ers injury risk. Those who are more fit perform activity shown in Table 1, but perhaps the most concise defini­
at a lower percentage of their maximal capability and tion is that provided by McArdle, Katch, and Katch.
1
so can perform the task for a longer period of time, fa­ They define “fitness” as a set of attributes that pro­
tigue less rapidly, recover faster, and have greater reserve vide the ability to perform physical activity. The attri­
1
capacity for subsequent tasks. Fatigue alters movement butes or components that contribute to physical fitness
patterns, putting stress on parts of the body unaccus­ were investigated in a series of studies that began in
tomed to it, possibly increasing the likelihood of in­ the 1930s. These studies had large groups of individu­
jury. Soldiers should develop and maintain high levels als perform a broad array of physical tasks for which
of physical fitness, not only for optimal performance of quantitative performance measures could be obtained.
occupational tasks but also to reduce injury risk. These tasks often included those in the Army Physical
Fitness Test (APFT) but also involved many other tasks,
Keywords: physical fitness, injury prevention, activity, stress, like pull­ups, rope climbs, vertical jumps, long jumps,
cardiorespiratory endurance, injuries, muscular endurance shuttle runs, medicine­ball throws, and the like. Statis­
tical techniques (correlations and factor analysis) were
used to assemble the task scores into groupings that
had common performance requirements. For example,
Introduction
tasks like pull­ups, push­ups, bent­arm hangs, dips, rope
Few Soldiers would argue that a high level of physi­ climbs, and squat thrusts seemed to group together in
cal fitness is important for the occupational tasks that the statistical analyses. Investigators reasoned that these
Soldiers perform. But, higher levels of fitness are also tasks required the performer to repeat movements in­
important because they are associated with lower risk volving muscular force as many times as possible with
of injury. This article will first define physical fitness, a progressive decrease in the number of repetitions that
provide a summary of how the concept of fitness was could be performed. In different studies, this “factor”

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