The Army, Marines, Air force and Navy all have physical fitness standards because they understand the absolute minimum fitness level required the do the job. When you take the PT (physical training) test generally you wear the appropriate PT uniform. When on mission the uniform the service member wears is often different and as such can have a negative effect on overall performance. There are many factors that indicate fitness from flexibility, strength, endurance, agility and so on, some more specific measures are Ventilatory Threshold, Lactic Threshold and VO2 max.
VO2 max is a metric used by athletes to determine the efficiency with which an individual utilizes oxygen. VO2 max is one measure that indicates an athletes ability to undergo sustain cardiovascular effort. The tests to determine VO2 max vary significantly from very complicated and exact to simple and general. Here we see a simple VO2 max calculation based on run time and distance.
Distance: 2.00 miles
Time: 13minutes 00seconds
Velocity: 9.231 MPH
VO2 Max: 47.63
This calculation is based on distance and time that is a more rudimentary calculation but has the ability under normal circumstances to give an accuracy of over 90%. Here a 47.63 indicates a high fitness level placing this individual in a relatively small percentage of fit athletes. This calculation is not exact as run economy and style play a role but for our purposes it will work.
Ventilator Threshold (VT) is the point at which the athlete has difficulty talking under a workload because their air exchanging capacity has been met due to oxygen uptake requirements. One reason it is important to understand VT is because VT is a nonlinear requirement that increases disproportionately with workload. The VT and VO2 max become excellent indicators of the fitness level of an operational service member. As workload increases by increasing the weight load such as putting the service member in combat kit the VT, VO2 max and aerobic threshold are met much sooner therefore their capacity for work decreases at a disproportionate rate.
Utilizing the same test as above the same individual would perform the same test to a different outcome. Assuming the Tactical athlete wears 25lbs. of body armor and a 10lbs. weapon system the results of the above test can look quite different.
Distance: 2.00 miles
Time: 16minutes 00 seconds
Velocity: 7.500 MPH
VO2 Max (equivalent): 37.47
The individual above is certainly still the fit person in the first example but the capacity to do work with the combat equipment on has decreased dramatically. To put this into perspective; the individual who would have scored 100 out of 100 on an Army run test has the equivalent fitness with combat gear that a person with 22% less fitness has. This becomes very important when engaged in an asymmetric war scenario where the enemy wears no combat kit only carries a weapon system. In this environment it becomes the highest priority for the tactical athlete to have the absolute highest level of fitness possible because when encumbered the playing field will be tilted in favor of the non affiliated insurgent or terrorist.
Also of note is the fact that the weight required by operations will have an even greater effect on the smaller less muscled service member who has less capacity to compensate for the increase in weight as a percentage of total body weight.
The take away message then becomes the importance of full spectrum fitness for the tactical athlete with an emphasis on cardiovascular work in full combat kit as well as anaerobic exercise to compensate for the disproportionate load increase. As a service member it is important to understand and be familiar with limitations brought on by the encumbrance. Understanding the operational equivalent fitness level should motivate a service member to push beyond normal societal fitness standards and strive toward a goal of fitness superiority that will provide an edge in combat or at least decrease the deficit.