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

many challenges. It is also a very efficient means of locomotion: the energy cost of bikingis only 20% of walking, but you can travel almost five times faster on a bicycle. Thequadriceps muscle in the front part of the thigh is the primary muscle for high rates ofpower output, and seat height can markedly affect overall muscle involvement. Althoughpedaling rates vary from 40 to 100 RPM, a rate of 70 appears to be the most comfortable.A high pedaling rate offers advantagesin terms of a high power output.All in all, biking is a great alternative to running, and should be considered as asuitable activity for maintaining fitness, even if it is not part of a SEAL’s mission. Bikingcomplements other activities and is often used in rehabilitation from other musculoskeletalinjuries. More details with respect to biking will be provided under the section on stationarycycles.Cross-Country SkiingAlthough cross country skiing is discussed in detail under winter warfare below, itshould be noted that this is an excellent method of training for cardiorespiratory fitness. Itengages almost all of the major muscle groups and thus, the overall energy expenditure maybe as high or higher than when moving the body over the same distance on foot.Importantly, the intensity of the effort varies greatly as a function of the terrain: climbinguphill requires tremendous effort whereas going downhill represents a light load. Highcaliber cross-country skiers have some of the highest maximal oxygen uptakes everrecorded (see Chapter 2). However, the appropriate equipment and environment arenecessary for cross-country skiing.Jumping RopeJumping rope is a great way to maintain fitness on board a ship or in confinedspaces. It can provide a high intensity, cardiorespiratory workout if done long enough andfast enough. If the pace is fast, it is equivalent to running in terms of energy expenditure.Jumping rope does not have to be boring, especially if you use different types ofjumps. Table 3-6 provides the names and an explanation for alternatives to the basic jump.42 Cardiorespiratory Conditioning