Physical Fitness. MAJ Tanja C. Roy, SP USA * ; COL Barbara A. Springer, SP USA ; MAJ Vancil McNulty, SP USA ; LTC Nikki L.

Transcription

1 MILITARY MEDICINE, 175, 8:14, 2010 Physicl Fitness MAJ Tnj C. Roy, SP USA * ; COL Brbr A. Springer, SP USA ; MAJ Vncil McNulty, SP USA ; LTC Nikki L. Butler, SP USA ABSTRACT Totl force fitness is stte in which the individul, fmily, nd orgniztion cn sustin optiml wellbeing nd performnce under ll conditions. Physicl fitness, n importnt component of totl force fitness, is the mount of physicl trining required to chieve physicl work cpcity. Due to the ustere environments nd high physicl work cpcity required for mission tsks, militry service members must sustin more dvnced level of physicl fitness thn the civilin popultion. To meet these high demnds, physicl fitness trining must be split into four components: endurnce, mobility, strength (including core strength), nd flexibility. Both erobic nd nerobic trining need to be utilized. The four components of physicl fitness trining plus performnce testing nd injury surveillnce/prevention must be well understood nd included s prt of ll militry physicl fitness progrms to ensure our service members re prepred to meet the physicl demnds of the mission without incurring injury. INTRODUCTION Totl force fitness is stte in which the individul, fmily, nd orgniztion cn sustin optiml well-being nd performnce under ll conditions. Physicl fitness is one component of totl force fitness, which lso includes psychologicl, behviorl, medicl, nutritionl, spiritul, nd socil helth. Consistent regulr exercise cn hve positive impct on socil helth, depression, generlized nxiety, nd sleep deprivtion. 1 5 With the interdependencies of the ctegories of totl force fitness, it is very importnt tht militry service members be physiclly fit. The physicl fitness level required by militry service member is higher thn tht of the generl popultion due to the diverse nture of militry missions nd the lrge lods crried by service members. Currently, service members must perform missions in ustere environments over 6- to 15-month periods. Missions executed in these diverse environments require lrge vriety of physicl skills. The purpose of this rticle is to discuss how to develop nd mximize service members physicl fitness by erobiclly nd nerobiclly trining the four components tht mke up physicl fitness: endurnce, mobility, strength (to include core strength), nd flexibility; how to use injury surveillnce nd prevention strtegies to trin without incurring injury; nd to outline current inititives to improve physicl trining. * 15 Knss Street, Bldg 42, Ntick, MA Little River Turnpike, Suite 230, Alexndri, VA Blckhwk Rod, E-4435, Aberdeen Proving Ground, MD Leesburg Pike, Suite 684, Flls Church, VA Previous presenttions: Totl Force Fitness for the 21st Century meeting, December 6 9, 2009 t the Uniformed Services University of the Helth Sciences. The opinions or ssertions contined herein re the privte views of the uthor(s) nd re not to be construed s officil or s reflecting the views of the Army or the Deprtment of Defense. DEFINING PHYSICAL FITNESS Wht is physicl fitness? The U.S. Deprtment of Helth nd Humn Services seprtes physicl fitness into two ctegories: helth-relted fitness nd performnce-relted fitness. 6 The generl public focuses on helth-relted fitness, which is the mount of physicl trining required to reduce the risk of disese or injury. Militry members focus on performncerelted fitness, which is the mount of physicl trining required to chieve physicl gol, such s climbing mountin or mneuver chlks nd chins on n ircrft crrier. Wht exctly is militry physicl fitness? According to the Army Mnul FM 21-20, Physicl Trining, Wr plces gret premium upon the strength, stmin, gility, nd coordintion of the soldier becuse victory nd his life re so often dependent upon them. To mrch long distnces with full pck, wepons, nd mmunition through rugged country nd to fight effectively upon rriving t the re of combt; to drive fst-moving tnks nd motor vehicles over rough terrin; to mke ssults nd to run nd crwl for long distnces; to jump into nd out of foxholes, crters, nd trenches, nd over obstcles; to lift nd crry hevy objects; to keep going for mny hours without sleep or rest ll these ctivities of wrfre nd mny others require superbly conditioned troops. 7 To put it more succinctly, militry physicl fitness is the bility to physiclly ccomplish ll spects of the mission while remining helthy/uninjured. Becuse there re vritions in militry missions/tsks, it is importnt to djust physicl fitness trining ccordingly. Helth-relted fitness is therefore the sme for ll militry members, but performnce-relted fitness differs depending on the mission. An Air Force lod mster who spends 10 hours dy loding plnes needs to trin differently thn scout who is tsked to ptrol 15 miles through the mountins of Afghnistn. Militry fitness trining needs to be designed to specificlly complement the mission tsks required by the service members. This is referred to s specificity of trining. 14 MILITARY MEDICINE, Vol. 175, August Supplement 2010

2 Physicl fitness trining cn be split into four mjor components llowing for the diversity of trining necessry to ccomplish mission tsks: endurnce, mobility, strength, nd flexibility. is the body s bility to continully ccomplish the sme tsk in repetitive fshion, such s loding supplies onto ship. is the bility to move the body in spce with the precision necessry to negotite n obstcle. An exmple of this is climbing wll. Strength is the bility to generte force ttempting to overcome resistnce such s lifting n mmunition cn. Finlly, flexibility is possessing the optiml joint rnge of motion such s required to rech overhed. All four spects of physicl fitness re importnt nd essentil in creting physiclly well-blnced, injury-resistnt, nd mission-fit service member. Militry fitness progrms need to be bsed on the mission tsk-oriented fitness philosophy. In fct the most recent physicl fitness guidnce from the Army nd Mrine Corps plces n emphsis on this philosophy. 8,9 It isoltes individul tsks performed by the service member during mission nd breks them down into their physicl components. An exmple of this tsk brekdown is when squd hs to ptrol through Bghdd, sprint through the mrket, kick down door, nd stedy their wepons to fire. Mny spects of fitness re being utilized to ccomplish this mission. The service member must possess the erobic endurnce to wlk the distnce of the ptrol while wering combt ger. Sprinting through the mrket plce nd jumping through the window require not only the nerobic bility to sprint but lso the bility to chnge directions quickly to negotite obstcles. Kicking down the door requires strength. The service member s overll VO 2 mx must be high enough to llow him or her to ccomplish ll of these tsks without ftiguing. Filure to ccomplish ny tsk in the sequence puts the service member in dnger nd could result in deth. Therefore, suboptiml or poor physicl fitness in service members is much more serious thn in n thlete nd trining should reflect this. An bsolute work lod is the mount of work required to ccomplish tsk. A tsk my require 3 L/min of oxygen consumption. If the service member s VO 2 mx is 4 L/min, then he or she is working t 75% of his or her mximl cpcity. By improving the service member s physicl fitness, or mximl cpcity, ny given tsk will represent lower reltive work lod, i.e., it will be esier. The min purpose of physicl trining in service member is to decrese the reltive work lod required to complete mission tsks. The secondry purpose of militry physicl trining is to increse the service member s overll medicl fitness, psychologicl fitness, nd resistnce to injury ( Fig. 1 ). COMPONENTS OF PHYSICAL FITNESS FIGURE 1. Mission tsks cn be seprted into the four different components. Trining these components while using injury prevention strtegies cn result in well-blnced, uninjured, physiclly fit service members. is the body s bility to continully ccomplish the sme tsk in repetitive fshion. Proper endurnce trining will increse the service member s bility to perform repetitive tsks t lower reltive work lod; ptrolling 10 miles will become esier. is erobic trining which is dependent on the body s bility to tke in nd utilize oxygen, VO 2 mx. The Americn College of Sports Medicine (ACSM) nd the Americn Hert Assocition recommend minimum of 30 minutes of modertely vigorous erobic ctivity for minimum of 5 dys week for dults under the ge of However, prticiption in physicl ctivity bove the minimum nd within the guidelines will increse the helth benefits. 10,11 Since the militry requires service members to perform chllenging physicl tsks, they should perform more thn the minimum durtion nd frequency of erobic trining. Exmples of endurnce trining re long-distnce running, swimming, foot mrching, cycling, low-weight, high-repetition strength trining, nd stirmster. Distnce, durtion, repetition number, nd speed need to be incresed grdully to reduce the risk of injury nd increse performnce. A very generl exmple would be incresing the distnce run only 10% per week. is the bility to move the body in spce with the precision necessry to negotite n obstcle, such s entering window. trining is designed to increse the service member s speed, blnce, jumping, nd bility to chnge direction. Anerobic trining cn improve mobility. This involves trining with tsks tht tke no more thn 5 minutes. Exmples of mobility trining include jumping, sprinting, nd climbing. Plyometrics (jumping exercises) hve been shown to be effective in incresing verticl jump height more thn strength trining lone Speed (sprint) trining over 11 weeks with 3 4 sets of 3 sprints of 10 m incresing to 50 m hs been shown to increse jump height, jump power, jump length, squt strength, sprint speed, nd gility. 15 MILITARY MEDICINE, Vol. 175, August Supplement

3 It is importnt tht speed trining incorporte chnges in direction s well. If service member is trining to ccomplish running tsks tht require quick directionl chnges, the principle of specificity of trining should be pplied; nmely, trin by sprinting in stright line s well s with multiple directionl chnges. Using only stright sprint trining results in increses in stright speed but not chnge-of-direction speed nd vice vers. 16 Therefore, combintion of the two trining techniques is needed. 17 Strength The purpose of strength trining is to increse the service member s bility to generte force nd power, thus lowering the reltive work required to complete mission tsks. Muscle strength is the mximum force creted by muscle, muscle endurnce is the bility to crete force repetitively or sustin it, nd power is the bility to crete force quickly cross distnce. Hence, strength is required to lift 40-lb box, while power is the bility to move the box 4 feet in 1 second. Mny weight trining regimes re bsed on one-repetition mximum (1 RM). This is simply the most weight tht the service member cn lift once. Novice individuls should begin with 60 70% of their 1 RM for 8 12 repetitions nd 2 3 sets. 18 However, once service member hs been strength trining for 6 months or more, 80% of 1 RM is needed to continue to increse one s strength nd 85% hs been shown to be most effective in thletes. 18 It is importnt to remember tht even though 80% is stted to be the most successful, this effectiveness is mximized when incorported into periodized weight trining progrm. 19 Periodiztion is phsed trining progrm using vriety of sets, repetitions, weights, nd exercises. The strength progrm gol lwys needs to be considered. For mximum strength to increse, one of three things must hppen: (1) the lod must increse, (2) repetitions must increse, or (3) rest periods must be lengthened. 18 For muscle endurnce to increse, repetition speed should be incresed nd rest time reduced. 18 If the gol is to increse power, light lods (0 60% 1 RM for lower body nd 30 60% 1 RM for upper body) re used with fst repetitions. 18 The mount of rest time between sets vries, depending on the gol of the weight lifting progrm. 19 If the gol is for mximum one-time strength, such s lifting hevy csulty, then the rest periods between sets need to be longer, t lest 2 3 minutes nd often up to 5. 20,21 If the gol of the progrm is to increse endurnce, such s lifting more boxes, then the rest period should be shorter, less thn 1 minute for sets of repetitions nd 1 2 minutes for repetition sets. 22,23 For power, such s pushing up out of the prone, rest periods should be 3 5 minutes between sets. 18 Bllistic exercises use very fst explosive movements nd re most effective when trining power. 18 It is importnt to remember tht mximum strength, muscle endurnce, nd power re ll inter-relted nd generl progrm should include spects of ech one. ACSM recommends tht weight lifting be performed 3 4 dys week. 18 It is importnt to remember tht this does not men tht ech muscle group is stressed every dy. When performing whole body routine, the service member should lift mximum of three times week or, when using n upper nd lower body split workout, the service member should lift 4 dys week: upper body 2 dys nd lower body 2 dys. 18 Core strength is the endurnce strength of the bdominl nd bck muscles nd should be included s the foundtion of ny physicl fitness progrm. Low musculr forces pplied t specific res long the spine during core strengthening will drsticlly increse the lod crrige cpbility of the spine (combt ger or lifting lods). 24 Since this submximl coctivtion must be mintined regrdless of which component is being trined (endurnce, mobility, strength, or flexibility), endurnce is much more importnt thn overll strength for mintining nd incresing lod crrige cpbility. 25 Core stbility is the biomechnicl building block upon which ll other trining rests. Core stbility is lso importnt becuse low core strength is ssocited with high prevlence of low bck pin (LBP) nd higher core strength is ssocited with less reoccurrence of LBP; ptients were 12 times less likely to hve recurrence in LBP for 1 yer fter receiving core stbility trining The core muscles must be conditioned to increse the lod crrige cpbility of the spine, reduce the risk of injury, nd keep the body biomechniclly efficient. Flexibility Flexibility is the fourth physicl fitness component. The purpose of flexibility trining is to mintin or chieve optiml muscle length tension reltionships cross joints tht enble service member to perform militry-specific tsks with less likelihood of injury or undue difficulty. Hypo- or hyperflexibility cn be detrimentl. Poor flexibility is relted to injury in the Achilles tendon, hmstrings, ptellr tendon, plntr fsci, nd iliotibil bnd For individuls who require incresed flexibility, sttic stretching (motionless stretches held for seconds) should be done t the end of the fitness session. 35 If sttic stretching is performed before the min exercises, there is often decrese in performnce In fct, one study shows tht mximum voluntry muscle contrction ws still reduced 9% n hour fter stretching. 42 Hence, to void performnce decrements, stretching is best done t the end of work out. It is importnt to note tht it is possible to be too flexible. 43,44 Those who re hyperflexible do not need to stretch these muscles, s it will not reduce their likelihood of injury. NON-PERFORMANCE-BASED BENEFITS OF PHYSICAL FITNESS There re mny non-performnce-bsed benefits to being physiclly fit besides ccomplishing the mission. The risk of crdiovsculr disese, thromboembolic stroke, hypertension, type 2 dibetes mellitus, osteoporosis, obesity, colon cncer, brest cncer, nxiety, nd depression ll decrese with n increse in physicl ctivity. 11 trining increses 16 MILITARY MEDICINE, Vol. 175, August Supplement 2010

4 cpillry density in working muscle, rises blood volume, nd decreses hert rte during exercise. 45 Mechnicl loding of the skeletl system through impct or weight lifting will help increse bone formtion in young dults nd slow the rte of bone loss in older dults. 10 Fitness progrms tht include resistnce trining improve dynmic stbility nd preserve functionl cpcity Fitness trining lso improves psychologicl well-being s well s work performnce. 46,50 52 The end result is tht fit service members re physiclly nd psychologiclly helthier nd more productive. TABLE I. Stndrd Physicl Fitness Tests of Ech Service Service Event Time/Distnce Component Air Force Push Ups 1 minute Sit Ups 1 minute Run 1.5 miles Wist Circumference None Army Push Ups 2 minutes Sit Ups 2 minutes Run 2 miles Mrine Corps Abdominl Crunch 2 minutes Pull Ups/ Flexed To exhustion Arm Hng Run 3 miles Nvy Push Ups 2 minutes Curl Ups 2 minutes Run 1.5 miles Sit nd Rech Flexibility A swim or ellipticl event cn be substituted for the Nvy run. MEASURING PHYSICAL FITNESS Once unit physicl fitness triners understnd the four components of physicl fitness nd how to crete nd implement fitness progrm, there needs to be method to mesure the service member s nd unit s physicl fitness. Physicl fitness needs to be mesured nd monitored to ensure tht service members re improving or mintining the required level of fitness to perform their mission tsks with reduced reltive work lod. There exist numerous vlidted tests to mesure ech component individully. Militry fitness tests re not currently designed to mesure ech component. However, the militry physicl fitness test design is constrined by ese of dministrtion, miniml requirement for equipment, field settings, nd time required to dminister. Currently, ech militry service is using its respective physicl fitness test composed of some vrition of distnce run, push ups/pull ups/flexed rm hng, nd sit ups ( Tble I ). Note tht only endurnce nd flexibility re currently being mesured on stndrd fitness tests. However, current tests re esy to dminister nd roughly correlte to endurnce nd strength performnce. In the mjority of studies, the 2- nd 3-mile run hve shown good or excellent correltion to VO 2 mx in subjects. 53,54 A 1-mile run hs shown poor to good correltion with VO 2 mx. 54 Previous studies on push ups indicte good correltion with totl upper body strength nd endurnce. 54 The Mrine Corps hs dded combt fitness test (CFT) to complement their stndrd physicl fitness test (PFT). The Mrine Corps is currently the only militry service evluting the components of mobility nd strength ( Tble II ). The CFT is designed to test tsks similr to those found in combt environment. Since service members tend to design their physicl trining round the fitness test, the idel fitness test would reflect ll components required for mission tsk ccomplishment. The performnce mesures in Tble III provide possible set of tests to ssess ll four components. This set is only one exmple; mny combintions of tsks could be used. A complete fitness test could be chieved with severl single events or events could be combined into n obstcle course, similr to the CFT. The gol is to mesure mobility, strength, nd endurnce in the entire body nd monitor how they chnge over time. The Mrine Corps dministers the PFT once yer nd seprtely dministers the CFT lter in the yer. The Air Force, Army, nd Nvy currently dminister their single fitness tests twice yer. INJURY SURVEILLANCE AND PREVENTION It is essentil tht units, commnders, nd other overseeing gencies hve the bility to monitor injuries nd ensure tht specific trining techniques re not disproportiontely incresing injuries. An dequte surveillnce system monitors injury incidence nd llows injury to be tied to mechnisms of TABLE II. Mrine Corps Combt Fitness Test Event Time/Distnce Component Run 880 yds Overhed Lift 2 min Sprint 25 yds Crwl 25 yds Sprint 25 yds Csulty Drg 10 yds Strength Csulty Crry 65 yds Strength Ammo Cn Crry 75 yds Grende Throw Ammo Cn Crry 75 yds TABLE III. Suggested Performnce Metrics to Include All Components in Militry Fitness Tests Metric Mesured Component Push Ups 55 Sit Ups 55 2-Mile Run 55 Illinois Agility Test 56,57 Medicine Bll Put 58,59 Strength Brod Jump 60 Repetitive Squts 61 Pull Ups 62,63 /Flexed Arm Hng64,65 Functionl Movement Screen 66 Flexibility The Functionl Movement Screen is currently undergoing vlidtion in militry popultion. It hs been shown to correlte with injuries in NFL plyers. 66 MILITARY MEDICINE, Vol. 175, August Supplement

5 injury. Idelly, injury dt should be linked to rediness reduction due to injury. From this informtion, medicl providers nd commnders cn identify nd modify injury promoting ctivities, tking steps to decrese injuries nd increse unit fitness, productivity, nd rediness. For injury surveillnce to be optimlly successful, the Deprtment of Defense (DoD) needs to crete stndrd DoDwide injury surveillnce dtbse. Currently, injury surveillnce dtbses re not uniform either in metrics collected or dt entered. In generl, it is recommended tht minimum of four dt points be collected on ll new ptients (mechnism of injury, body region, deploybility, nd unit). Additionlly, fitness scores should be included s prt of the medicl record. The informtion tht is collected must be vilble for nlysis by locl medicl stff to provide commnders with ccurte injury trends nd options to correct the likely cuse of injury. Using surveillnce, the Army identified tht the mjority of injuries occur during trining. Dt collected Army-wide indicted tht physicl trining is the leding cuse of outptient injury visits, ccounting for 25 to 40% of ll injuries. 67,68 In Mrine Corps bsic trining, 78% of the injuries were due to overuse nd significntly correlted to running nd physicl trining. 69 Thirty-six percent of femle Nvy recruits suffered overuse injuries in bsic trining. 70 Musculoskeletl injuries resulted in the most lost duty dys t the U.S. Air Force Acdemy. 71 Of the limited duty dys received by soldiers, 80 90% re from trining-relted injuries. 72 In study of 15,000 deployed soldiers, the mjority of soldiers climed tht physicl trining ws responsible for their musculoskeletl injuries. 73 Reserch hs identified risk fctors for these injuries in service members. Smoking, greter ge, lower musle endurnce, lower fitness level, hyper- nd hypo-flexibiity, lower VO 2 mx, nd higher running milege increse the chnce tht service member will sustin n injury. 44,72,74,75 Once injury surveillnce hs identified injuries, steps must be tken to reduce them through prevention. The Joint Services Physicl Trining Injury Prevention Work Group in 2008 systemticlly reviewed 34 potentil injury prevention strtegies. Six interventions hd strong enough evidence to become recommendtions for implementtion in ll four services: (1) prevent overtrining; (2) perform multixil, neuromusculr, proprioceptive, nd gility trining; (3) wer mouth gurds during high-risk ctivities; (4) wer semirigid nkle brces for high-risk ctivities (such s irborne trining); (5) consume nutrients to restore energy blnce within 1 hour following high-intensity ctivity; nd (6) wer synthetic blend socks to prevent blisters. The first two interventions spek to the widespred overuse injuries cused by n over-relince on endurnce running in the militry s physicl trining progrms. CURRENT PHYSICAL FITNESS INITIATIVES The militry hs ttempted to initite the six interventions mentioned bove s well s severl others gered towrd mitigting dditionl risk fctors. Service members re given counsel on smoking senstion, custom mouth gurds re offered by dentl services, nd synthetic blend socks re issued. All four brnches of the militry hve issued new physicl fitness guidnce with the Army nd Mrine Corps offering the most indepth instruction. The previous Army Fitness Mnul, FM 21-20, ws published in Since then, there hs been further exercise nd injury reserch s well s drstic chnge in the militry s opertionl tempo. This resulted in implementtion of severl locl fitness progrms. In ddition, Army physicl therpists recognized the need for well-rounded fitness progrms nd creted them for severl divisions nd the Rngers. In these progrms, more emphsis hs been plced on strength trining, core strengthening, mobility drills, nd foot mrching thn found in FM The Army recently creted new doctrine for physicl fitness trining using the injury prevention pproch guidnce. TC Army Physicl Rediness Trining (PRT) ws published in Mrch of The emphsis is on well-rounded mission tsk-oriented pproch to physicl fitness nd includes detiled explntions of proper methods for mobility, strength, endurnce, nd flexibility trining. Soldiers prticipting in PRT were 46 52% less likely to suffer n injury when compred to units using trditionl physicl trining while scoring the sme on the Army physicl fitness test (APFT). 76 The Mrine Corps hs lso been mking huge strides in enhncing its physicl fitness progrm nd issued new guidnce in Along with creting the CFT the Mrine Corps is shifting the focus of its physicl fitness trining to missionoriented tsks s well. The Mrine Corps hs been developing comprehensive combt fitness progrm tht promotes helth nd fitness. 8 The Mrine Corps most recent guidnce recommends tht erobic nd muscle-strengthening ctivities be conducted more often, t higher intensity, nd for shorter durtion s well s points out the need to grdully increse the difficulty of trining. 8 The Air Force hs issued its ltest physicl fitness guidnce in This guide instructs irmen to trin endurnce, strength, mobility, nd flexibility. The Air Force hs incresed its fitness testing to twice yer, is mking the stndrds on their fitness test more difficult this yer, nd is certifying physicl trining leders. The Nvy published new guidnce on physicl fitness trining in 2005, emphsizing its importnce for mission ccomplishment.78 Silors re instructed to trin endurnce, flexibility, nd strength. The Nvy hs strted commnd fitness leders course to crete fitness leders cpble of designing fitness progrms. CONCLUSIONS Physicl fitness is composed of the four components: endurnce, mobility, strength, nd flexibility. Trining should include ll four components supported by foundtion of core strength nd be bsed on mission tsks the service member is required to perform. Proper physicl trining should (1) brek down mission tsks into physicl components, 18 MILITARY MEDICINE, Vol. 175, August Supplement 2010

6 (2) ensure tht ll four components re prt of physicl trining in mnner specific to the mission tsks required, (3) monitor physicl fitness levels nd improvement to ensure performnce is incresing nd reltive work lod is decresing, nd (4) prevent improper trining through injury surveillnce nd prevention. The four components of physicl fitness trining plus performnce monitoring nd injury surveillnce/ prevention must be well understood nd included s prt of ll militry physicl fitness progrms to ensure our men nd women in uniform re properly prepred to ccomplish ny mission sfely nd effectively. ACKNOWLEDGMENTS The uthors cknowledge the ssistnce of the members of the Chirmn s Totl Fitness Conference 2009 members s well s tht of Col Brin McGuire, USMC (Ret.) in creting this rticle. REFERENCES 1. Crmer SR, Niemn DC, Lee JW : The effects of moderte exercise trining on psychologicl well-being nd mood stte in women. J Psychosom Res 1991 ; 35 (4 5) : Hssmen P, Koivul N, Uutel A : Physicl exercise nd psychologicl well-being: popultion study in Finlnd. Prev Med 2000 ; 30 (1) : De Moor MH, Beem AL, Stubbe JH, Boomsm DI, De Geus EJ : Regulr exercise, nxiety, depression nd personlity: popultion-bsed study. Prev Med 2006 ; 42 (4) : Brbour KA, Blumenthl JA : Exercise trining nd depression in older dults. Neurobiol Aging 2005 ; 26 (Suppl 1) : Driver HS, Tylor SR : Exercise nd sleep. Sleep Med Rev 2000 ; 4 (4) : U.S. Deprtment of Helth nd Humn Services : 2008 Physicl Activity Guidelines for Americns, Wshington, DC, DHHS, Deprtment of Wr : FM 21-20, Physicl Fitness. Wshington, DC, Government Printing Office, Deprtment of the Nvy : Mrine Corps Order Wshington, DC, DoD, Deprtment of the Army : Army Physicl Rediness Trining. Wshington, DC, DoD, Hskell WL, Lee IM, Pte RR, et l : Physicl ctivity nd public helth: updted recommendtion for dults from the Americn College of Sports Medicine nd the Americn Hert Assocition. Med Sci Sports Exerc 2007 ; 39 (8) : Kesniemi YK, Dnforth E Jr, Jensen MD, Kopelmn PG, Lefebvre P, Reeder BA : Dose-response issues concerning physicl ctivity nd helth: n evidence-bsed symposium. Med Sci Sports Exerc 2001 ; 33 (6, Suppl) : S Luebbers PE, Potteiger JA, Hulver MW, Thyfult JP, Crper MJ, Lockwood RH : Effects of plyometric trining nd recovery on verticl jump performnce nd nerobic power. J Strength Cond Res 2003 ; 17 (4) : Ftouros IG, Jmurts AZ, Leontsini D, et l : Evlution of plyometric exercise trining, weight trining, nd their combintion on verticl jumping performnce nd leg strength. J Strength Cond Res 2000 ; 14: Newton RU, Kremer WJ, Hkkinen K : Effects of bllistic trining on preseson preprtion of elite volleybll plyers. Med Sci Sports Exerc 1999 ; 31 (2) : Mrkovic G, Jukic I, Milnovic D, Metikos D : Effects of sprint nd plyometric trining on muscle function nd thletic performnce. J Strength Cond Res 2007 ; 21 (2) : Young WB, McDowell MH, Scrlett BJ : Specificity of sprint nd gility trining methods. J Strength Cond Res 2001 ; 15 (3) : Wlklte BM, O Brien BJ, Pton CD, Young W : Supplementing regulr trining with short-durtion sprint-gility trining leds to substntil increse in repeted sprint-gility performnce with ntionl level bdminton plyers. J Strength Cond Res 2009 ; 23 (5) : ACSM : Americn College of Sports Medicine Position Stnd. Progression models in resistnce trining for helthy dults. Med Sci Sports Exerc 2009 ; 41 (3) : Kremer WJ, Rtmess NA : Fundmentls of resistnce trining: progression nd exercise prescription. Med Sci Sports Exerc 2004 ; 36 (4) : Ahtiinen JP, Pkrinen A, Alen M, Kremer WJ, Häkkinen H : Short vs. long rest period between the sets in hypertrophic resistnce trining: influence on muscle strength, size, nd hormonl dpttions in trined men. J Strength Cond Res 2005 ; 19: Pincivero DM, Lephrt SM, Krunkr RG : Effects of rest intervl on isokinetic strength nd functionl performnce fter short-term high intensity trining. Br J Sports Med 1997 ; 31 (3) : Mrcinik EJ, Hodgdon JA, Mittlemn K, O Brien JJ : Aerobic/clisthenic nd erobic/circuit weight trining progrms for Nvy men: comprtive study. Med Sci Sports Exerc 1985 ; 17 (4) : Wilmore JH, Prr RB, Girndol RN, et l : Physiologicl ltertions consequent to circuit weight trining. Med Sci Sports 1978 ; 10 (2) : Kiefer A, Shirzi-Adl A, Prninpour M : Stbility of the humn spine in neutrl postures. Eur Spine J 1997 ; 6 (1) : Brr KP, Griggs M, Cdby T : Lumbr stbiliztion: core concepts nd current literture, Prt 1. Am J Phys Med Rehbil 2005 ; 84 (6) : Mnnion AF, Muntener M, Timel S, Dvork J : Comprison of three ctive therpies for chronic low bck pin: results of rndomized clinicl tril with one-yer follow-up. Rheumtology (Oxford) 2001 ; 40 (7) : Byrmoglu M, Akmn MN, Kilinc S, Cetin N, Yvuz N, Ozker R : Isokinetic mesurement of trunk muscle strength in women with chronic low-bck pin. Am J Phys Med Rehbil 2001 ; 80 (9) : Greene HS, Cholewicki J, Gllowy MT, Nguyen CV, Rdebold A : A history of low bck injury is risk fctor for recurrent bck injuries in vrsity thletes. Am J Sports Med 2001 ; 29 (6) : Hides JA, Jull GA, Richrdson CA : Long-term effects of specific stbilizing exercises for first-episode low bck pin. Spine 2001 ; 26 (11) : E Puniello MS : Iliotibil bnd tightness nd medil ptellr glide in ptients with ptellofemorl dysfunction. J Orthop Sports Phys Ther 1993 ; 17 (3) : Grrett WE Jr, Cliff JC, Bssett FH 3rd : Histochemicl correltes of hmstring injuries. Am J Sports Med 1984 ; 12 (2) : Kibler WB, Goldberg C, Chndler TJ : Functionl biomechnicl deficits in running thletes with plntr fsciitis. Am J Sports Med 1991 ; 19 (1) : Lech RE, Jmes S, Wsilewski S : Achilles tendinitis. Am J Sports Med 1981 ; 9 (2) : Worrell TW : Fctors ssocited with hmstring injuries. An pproch to tretment nd preventtive mesures. Sports Med 1994 ; 17 (5) : LRoche DP, Connolly DA : Effects of stretching on pssive muscle tension nd response to eccentric exercise. Am J Sports Med 2006 ; 34 (6) : Rubini EC, Cost AL, Gomes PS : The effects of stretching on strength performnce. Sports Med 2007 ; 37 (3) : Ymguchi T, Ishii K : Effects of sttic stretching for 30 seconds nd dynmic stretching on leg extension power. J Strength Cond Res 2005 ; 19 (3) : McMillin DJ, Moore JH, Htler BS, Tylor DC : Dynmic vs. stticstretching wrm up: the effect on power nd gility performnce. J Strength Cond Res 2006 ; 20 (3) : MILITARY MEDICINE, Vol. 175, August Supplement

7 39. Amko M, Od T, Msuok K, Yokoi H, Cmpisi P : Effect of sttic stretching on prevention of injuries for militry recruits. Mil Med 2003 ; 168 (6) : Jones AM : Running economy is negtively relted to sit-nd-rech test performnce in interntionl-stndrd distnce runners. Int J Sports Med 2002 ; 23 (1) : Brndenburg JP : Durtion of stretch does not influence the degree of force loss following sttic stretching. J Sports Med Phys Fitness 2006 ; 46 (4) : Fowles JR, Sle DG, McDougll JD : Reduced strength fter pssive stretch of the humn plntrflexors. J Appl Physiol 2000 ; 89 (3) : Stewrt DR, Burden SB : Does generlised ligmentous lxity increse sesonl incidence of injuries in mle first division club rugby plyers? Br J Sports Med 2004 ; 38 (4) : Knpik JJ, Shrp MA, Cnhm-Chervk M, Huret K, Ptton JF, Jones BH : Risk fctors for trining-relted injuries mong men nd women in bsic combt trining. Med Sci Sports Exerc 2001 ; 33 (6) : Kubukeli ZN, Nokes TD, Dennis SC : Trining techniques to improve endurnce exercise performnces. Sports Med 2002 ; 32 (8) : Stewrt KJ, Mson JM, Kelemn M : Three-yer prticiption in circuit weight-trining improves strength nd self-efficcy in crdic ptients. J Crdiopulm Rehbil 1988 ; 8: Kelemn MH, Stewrt KJ, Gillin RE, et l : Circuit weight trining in crdic ptients. J Am Coll Crdiol 1986 ; 7: Ghilrducci LE, Holly RG, Amsterdm EA : Effects of high resistnce trining in coronry rtery disese. Am J Crdiol 1989 ; 64 (14) : Evns WJ : Exercise trining guidelines for the elderly. Med Sci Sports Exerc 1999 ; 31 (1) : Ewrt CK : Psychologicl effects of resistive weight trining: implictions for crdic ptients. Med Sci Sports Exerc 1989 ; 21 (6) : Norris R, Crroll D, Cochrne R : The effects of erobic nd nerobic trining on fitness, blood pressure, nd psychologicl stress nd wellbeing. J Psychosom Res 1990 ; 34 (4) : Pronk NP, Mrtinson B, Kessler RC, Beck AL, Simon GE, Wng P : The ssocition between work performnce nd physicl ctivity, crdiorespirtory fitness, nd obesity. J Occup Environ Med 2004 ; 46 (1) : Mello RP, Murphy MM, Vogel JA : Reltionship between two mile run for time nd mximl oxygen uptke. J Appl Sport Sci Res 1988 ; 2 (1) : Knpik J : The Army Physicl Fitness Test (APFT): review of the literture. Mil Med 1989 ; 154 (6) : Deprtment of the Army : Physicl Fitness Trining. Wshington, DC, DoD, Roozen M : Illinois Agility Test. NSCA s Perform Trin J 2004 ; 3 (5) : Miller MG, Hernimn JJ, Ricrd MD, Chethm CC, Michel TJ : The effects of 6-week plyometric trining progrm on gility. J Sports Sci Med 2006 ; 5: Wyss T, Hubner K, Mder U : Seted shot put s mesurement of explosive upper body power. In: Interntionl Congress on Soldiers Physicl Performnce. Edited by Häkkinen K, Kyolinen H ; Jyvskyl, Findlnd, University of Jyvskyl, Shrp MA, Knpik JJ, Wlker LA, et l : Physicl fitness nd body composition fter 9-month deployment to Afghnistn. Med Sci Sports Exerc 2008 ; 40 (9) : Hrmn EA, Gutekunst DJ, Frykmn PN, et l : Effects of two different eight-week trining progrms on militry physicl performnce. J Strength Cond Res 2008 ; 22 (2) : Kremer WJ, Nindl BC, Gotshlk LA, et l : Prediction of militry relevnt occuptionl tsks in women from physicl performnce components. In: Advnces in Occuptionl Ergonomics nd Sfety, pp Edited by Kumr S. Burke, VA, IOS Press, Deprtment of the Army : Physicl Trining, Vol FM Wshington, DC, Government Printing Office, Deprtment of the Nvy : Hedqurters United Sttes Mrine Corps: Mrine Corps Order P Wshington, DC, DoD, President s Council on Physicl Fitness nd Sport: The President s Chllenge, Bloomington, IN. Avilble t lenge.org/pdf/2009_pc_brochure.pdf ; ccessed October 1, Eisenmnn JC, Mlin RM : Age- nd sex-ssocited vrition in neuromusculr cpcities of dolscent distnce runners. J Sports Sci 2003 ; 21: Kiesel K, Plisky PJ, Voight M : Cn serious injury in professionl footbll be predicted by preseson Functionl Movement Screen? North Am J Sports Phys Ther 2007 ; 2 (3) : Knpik J, Drkjy S, Jones S, et l : Injuries nd physicl fitness before nd fter deployment by the 10th Mountin Division to Afghnistn for Opertion Enduring Freedom 2007 : Report Number 12-MA-05SD-07. U.S. Army Center for Helth Promotion nd Preventive Medicine, Edgewood, MD. 68. Knpik JJ, Jones SB, Drkjy S, et l : Injury rtes nd injury risk fctors mong U.S. Army wheel vehicle mechnics. Mil Med 2007 ; 172 (9) : Almeid SA, Willims KM, Shffer RA, Brodine SK : Epidemiologicl ptterns of musculoskeletl injuries nd physicl trining. Med Sci Sports Exerc 1999 ; 31 (8) : Shffer RA, Brodine SK, Ito SI, Le AT : Epidemiology of illness nd injury mong U.S. Nvy nd Mrine Corps femle trining popultions. Mil Med 1999 ; 164 (1) : Billings CE : Epidemiology of injuries nd illnesses during the United Sttes Air Force Acdemy 2002 Bsic Cdet Trining progrm: documenting the need for prevention. Mil Med 2004 ; 169 (8) : Jones BH, Knpik JJ : Physicl trining nd exercise-relted injuries. Surveillnce, reserch nd injury prevention in militry popultions. Sports Med 1999 ; 27 (2) : Snders JWPS, Frnkrt C, Frenck RW, et l : Impct of illness nd noncombt injury during Opertions Irqi Freedom nd Enduring Freedom (Afghnistn). Am J Trop Med Hyg 2005 ; 73 (4) : Bell NS, Mngione TW, Hemenwy D, Amoroso PJ, Jones BH : High injury rtes mong femle rmy trinees: function of gender? Am J Prev Med 2000 ; 18 (3, Suppl) : Jones BH, Bovee MW, Hrris JM 3rd, Cown DN : Intrinsic risk fctors for exercise-relted injuries mong mle nd femle rmy trinees. Am J Sports Med 1993 ; 21 (5) : Knpik JJ, Huret KG, Arnold S, et l : Injury nd fitness outcomes during implementtion of physicl rediness trining. Int J Sports Med 2003 ; 24 (5) : Secretry of the Air Force : Air Force Instruction Personnel Fitness Progrm. Wshington, DC, DoD, Deprtment of the Nvy : OPNAV Instruction H: Office of the Chief of Nvl Opertions, Wshington, DC; MILITARY MEDICINE, Vol. 175, August Supplement 2010