The Navy SEAL Physical Fitness Guide - Uniformed Services ...

Anaerobic PowerHow much strenuous work can you sustain without oxygen? Most people can dovery little for more than a couple of minutes. It is very important to realize that most peoplecannot work for very long at even 90% of their maximal aerobic capacity. This is becauseeveryone has a threshold at which the balance between aerobic and anaerobic energysystems begins to favor the anaerobic; your muscles cannot extract enough oxygen toproduce the required energy. This is called your anaerobic threshold; the turning point canbe monitored by the accumulation of lactate in your blood. Of course, your body will knowwhen there is too much lactate, because once lactate goes above a certain value, it starts toaccumulate and unless you decrease your work rate, you will become too tired to continueworking.This anaerobic threshold, or “break point” varies among individuals, but rangesbetween 60% and 100% of your VO 2max ; all SEALs should be able to work at 70% of theirVO 2max for an extended period, and should have a break point above 70%. Conditioningprograms for SEALs should strive to raise the anaerobic threshold or break point to as highas possible, because that means you can work at a higher rate for a longer period of time.Interval workouts stress the anaerobic energy systemsand will increase your anaerobic threshold and power.Interval and fartlek workouts for running and swimming are described in theirrespective chapters, and such workouts for other forms of exercise are described later in thischapter.Determination of Work RateOne common denominator across all types of cardiorespiratory conditioningprograms is exercise intensity and work rate. The term exercise intensity typically refers tohow hard you are working as a percent of your maximal aerobic capacity. For example, youcould work at an intensity equivalent to 50% (easy), 70% (moderate), or 90% (strenuous)of your maximal aerobic capacity or maximal heart rate. You will learn how to estimateyour maximal aerobic capacity below, but on average, a maximal capacity of 45 to 55 mlof oxygen/kg/min and a maximal heart rate of 200 beats per min would be typical for a 20to 29 year old SEAL. Table 3-1 presents the relation between exercise intensity, oxygenuptake, and heart rate for a 20 year old SEAL with a maximal heart rate of 200 and amaximal oxygen uptake of 55 ml of oxygen/kg/min. Easy exercise would use 25 to 30 ml34 Cardiorespiratory Conditioning