12/14/2012
Adaptations to Training or "How will our people pass this new fitness test?" (Part 1)
1.5 mileWe are in the business of ensuring the physical readiness of the folks who safeguard our lives on a day-to-day basis. In the process of performing our duties, we will, on demand, develop tests and standards. These physical readiness tests take one of two forms: physical fitness test battery or job-task simulation tests. (We develop both but don't charge extra for it!) One of the first questions we get during the out-brief is: "How many people will pass (or fail) the test?" This often represents a shift in the administrative emphasis from fitness for duty to avoiding perceived challenges. Public safety is in the business of managing risk and we're not promoting a cavalier approach to another risk, namely potential litigation; but let's be clear on the mission: public safety agencies are tasked with ensuring their sworn members are up to the job.
A valid physical readiness test evaluates either actual job tasks or the physical parameters that underly those tasks. This post will begin a series focusing on the physical fitness test battery that measures the physiological parameters which both underly the job (construct validity) and predict job performance (criterion validity). Specifically, we will explore the tests and the physical adaptations which must take place in the individual officers in order to meet the demands and pass the respective test items. The first test we'll look at is the 1.5 mile run test.
TRAINING ADAPTATIONS
1.5 Mile Run Test
The training we typically call "cardio" is cardiovascular, cardioendurance, or perhaps most correctly termed: cardiorespiratory training. The scientific term to describe the trained condition is maximal oxygen consumption. This refers to the body's ability to take in oxygen, deliver it to the working muscles and use it to produce the energy necessary to sustain activity or exercise.
Maximal oxygen consumption is expressed as VO2max; this is the product of cardiac output times the volume of oxygen extracted per liter of blood [VO2max = Qdot x (a - VO2 diff), where Cardiac output (Qdot) is the product of stroke volume,i.e. the volume of blood ejected from the left ventricle per heart beat or contration, times heart rate or the number of contractions per minute (Qdot = SV x HR)]. An inverse relationship exists between 1.5 mile run times and VO2max, i.e. the faster one can run the distance (the lower the time) the greater one's aerobic capacity (the higher the VO2). Think of all of this as the engine responsible for moving the car (the body in this instance) as fast as possible over the required distance. (We'll come back to this analogy shortly.)
All of the components above adapt in response to training. So, what will it take for recruits or incumbents to pass a 1.5 mile run standard?
Chronic Adaptations to Aerobic Exercise
Cardiac output is increased
Stroke volume is increased
Heart rate at rest and during submaximal activity is decreased (a good thing)
Increased capillary density - for oxygen exchange
Increased mitochondrial density - more energy packs in the muscle fibers
Increased enzymatic activity - for producing energy and eliminating waste by-products
Improved energy storage capacity (ATP-PC, glycogen, triglycerides)
Improved connective strength (ligament/tendon)
Decreased percent body fat
Many exercise studies demonstrate 10-30% improvement in aerobic capacity in 3 - 6 months of regular training. The greatest percent change will occur in the least fit segment of the population and heredity will largely determine the absolute levels of oxygen consumption achieved. Training responses and trainability is similar for men and women.
Let's say for a moment, you have an incumbent who initially tests out at 18:20 for the 1.5 mile run. Given the above estimates, the same person is running between 12:47 and 16:30 (10-30% improvement) in 3-6 months of regular training.
Improved Run Times
Let's go back to our car analogy. There are other ways to enhance the performance of your car: new suspension, tires, and better steering. When we test previously sedentary adults or when the same group begins a new "cardio" program, their initial complaint isn't "Man, my heart and lungs are really tired!" The first things we notice are aches and pains in our feet, knees, hips, and back. The musculoskeletal system is the chassis if you will and it too responds to and eventually adapts to the training. When you put new sneakers on yourself or the car, performance is improved. Strength training of the chassis: legs, back, and upper body will also make the testing and training easier to tolerate and help to bring run times down.
Finally, a little support or coaching in better running form and practice as well time on the road will eventually improve mechanical efficiency which will lead to reduced energy consumption, leading to still better run times.
Conclusion
All too often when we think of "cardio" training or tests, we think of the skinny guys on the road who are all head, heart, lungs, and legs. If we go back to the definition of cardiorespiratory fitness, what we're really talking about is the ability to perform work. Some of the most critical tasks performed by law enforcement officers and firefighters represent very significant work performed with dire consequences resulting from an inability to succeed. The 1.5 mile run just happens to be one of the best field measures of this ability to perform work.
A very modest investment of 3-6 months of training, made by either male or female officer can produce significant gains in aerobic capacity; certainly an important consideration when evaluating the impact of a new test with standards.
Stay Safe, Stay Strong
JS