Conditioning programs that address maximal

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1 BRIEF REVIEW STRENGTH TRAINING FOR THE WARFIGHTER WILLIAM J. KRAEMER 1,2 AND TUNDE K. SZIVAK 1 1 Human Performance Laboratory, Department of Kinesiology; and 2 Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut ABSTRACT Kraemer, WJ and Szivak, TK. Strength training for warfighter. J Strength Cond Res 26(7): S107 S118, 2012 Optimizing strength training for warfighter is challenged by past training philosophies that no longer serve modern warfighter facing anaerobic battlefield. Training approaches for integration of strength with or needed physical capabilities have been shown to require a periodization model that has flexibility for changes and is able to adapt to ever-changing circumstances affecting quality of workouts. Additionally, sequencing of workouts to limit overreaching and development of overtraining syndromes that end in loss of duty time and injury are paramount to long-term success. Allowing adequate time for rest and recovery and recognizing negative influences of extreme exercise programs and excessive endurance training will be vital in moving physical training programs into a more modern perspective as used by elite strength-power anaerobic athletes in sports today. Because warfighter is an elite athlete, it is time that training approaches that are scientifically based are updated within military to match functional demands of modern warfare and are given greater credence and value at command levels. A needs analysis, development of periodized training modules, and individualization of programs are needed to optimize strength of modern warfighter. We now have knowledge, professional coaches and nonprofit organization certifications with continuing education units, and modern training technology to allow this to happen. Ultimately, it only takes command decisions and implementation to make this possible. KEY WORDS strength training, military, periodization, resistance training, tactical Address Correspondence to William J. Kraemer, william.kraemer@uconn. edu. 26(7)/S107 S118 Ó 2012 National Strength and Conditioning Association INTRODUCTION Conditioning programs that address maximal strength and power are increasingly being recognized as potentially important components of military fitness (34). Historically, and even today, focus of conditioning in military has been on aerobictype endurance training. Part of this arises out of ease of implementation of such programs and simplicity of exercise prescription when training large numbers of soldiers during a physical training period. Additionally, physical training has often been geared toward performance on aerobic components of annual physical fitness tests, rar than on real-world mission requirements. However, because recognizing and adequately addressing demands on warfighter is an ever-evolving challenge due to diversity of physical, psychological, and environmental factors faced on battlefront, pivotal role of well-designed total conditioning programs is clearly apparent. There is no doubt that a warfighter s maximal strength and power will dictate magnitude of force and power in submaximal high-intensity endurance performances, literally translating into better performance on modern-day battlefield. Progressive heavy resistance training remains primary modality to improve an athlete s maximal strength and power. With this comes need for resistance training equipment and facilities to implement properly designed programs. Although weight rooms and conditioning facilities are found on almost every base, size of facilities and sophistication of equipment may not meet requirement to train every soldier. Although soldiers in United States assigned to specialized units (i.e., Special Operations Forces) now have access to strength and conditioning facilities under Tactical Human Optimization, Rapid Rehabilitation, and Reconditioning (THOR3) program, se same resources are not available to conventional military units, limiting type of training that can be conducted with large numbers (e.g., 100+) of soldiers. Furrmore, need exists for properly educated, trained, and certified professionals within each unit to effectively implement specialized programs needed for different military occupational skill sets and to identify differential demands of each individual soldier that must be addressed for optimal progression and physical development. Herein have evolved historical conflicts surrounding military physical training, as concepts such as individualization, sophisticated equipment, and training VOLUME 26 SUPPLEMENT 7 JULY 2012 S107

2 Strength Training facilities are not only resource and time intensive but also simultaneously philosophically challenging. Out of this vacuum of understanding of optimal resistance training programs have evolved competing influences such as commercial fitness programs that have extensive advertising campaigns that play on warfighter s tough mentality and ever-present need to cut fat and get ripped to meet military s body composition requirements (2). Furrmore, se programs are randomly administered and not individualized or put into context of or physical and psychological demands placed on warfighter. However, promises of quick results cannot be ignored as a key factor in success of se programs in attracting warfighter s attention, including commander and junior leaders at company, platoon, and squad levels. Although se commercial programs have value, y do not incorporate workouts within a progressive, periodized model; a method that has been well established as an effective means of training athletes for optimal performance while mitigating risk of injury and nonfunctional overreaching or overtraining. At present, although more hires of National Strength and Conditioning Association Certified Strength and Conditioning Specialists are being made each year in U.S. military, physical training programs in most typical units are designed by junior leaders at company, platoon, and squad levels. They rely on ir own personal experience with training, muscle magazines, or commercial fitness programs without input from a properly educated and certified professional. In addition, military leaders are often influenced by lay fitness publications that may not represent cutting edge research in field of exercise science. Owing to large numbers of soldiers to be trained (e.g., 100+), limited time and facilities, result is that most fitness programs are based on local muscular endurance, calisnics, and running as primary forms of physical training. In addition, many commercial entities attract soldiers during off duty hours, and this can add additional stress to an already demanding training schedule that includes unit physical training (2). The cumulative stress of both mission demands and extensive physical training can contribute to injury and nonfunctional overreaching concerns when a lack of individualization and periodized training needed for rest and recovery is missing from training schedule equation. CHALLENGES FOR RESISTANCE TRAINING IN THE MILITARY The primary objective of any resistance training program is to improve physical performance and prevent injury by strengning muscles and associated connective tissues (25). Improvement in physical performance requires a careful examination of demands of a sport or particular position or in this case demands of soldier s given military occupational specialty. Thus, basic goals for any resistance training program are to improve maximal strength and power because se are basic hallmarks of neuromuscular fitness. It is upon se two fundamental pillars of neuromuscular fitness that one can n extend and expand physical capabilities to include local muscular endurance and task specific performances. To optimally design a resistance training program, a trained professional is needed to assess performance requirements of particular occupational specialty and overlay it with current capabilities of individual warfighter (6). Additionally, once program is designed, implementation does demand proper instruction on exercise techniques, spotting, and monitoring of physiological demands placed on soldier during different workouts incorporated in a properly periodized program. Ideally, although not currently employed, unit training time must be allocated for teaching advanced exercise techniques (e.g., exercises used in a program: squat, deadlift, power clean). Educational aspects of a program are also needed in areas of nutrition, sleep, alcohol, and smoking, which can all impact physical development and recovery. Here again, commercial shortcuts for needed equipment, supervision, professional background, nutritional supplements and a growing increase in excessive tobacco and alcohol use all make for dramatic challenges in optimizing a resistance training program for warfighter. Once basic core physical capabilities of strength and power development have been addressed, one can n develop program variations that build upon se fundamentals and furr address performance characteristics needed for a given military occupational specialty. However, programs that start with specifics and ignore basic core elements of strength and power limit optimal development over time and set stage for injury. The fundamental principles of proper progressive overload, specificity, and periodization cannot be ignored in any program that seeks to optimally prepare individual warfighter for physical demands of ir occupational specialty (25). THE PHYSIOLOGICAL BASIS OF STRENGTH AND POWER DEVELOPMENT To understand exercise at its most fundamental levels and how external demands of any exercise interact with neuromuscular system, it is important to understand concept of size principle. This is paramount for understanding maximal strength and power development because too often exercise is not defined in careful enough terms to be effective for intended outcome. Thus, it is important to develop a basic understanding of underlying physiology at work when one exercises or trains neuromuscular system. Size Principle The term was coined by Professor Elwood Henneman of Harvard University who made a series of his own initial observations in late 1950s and by late 1970s solidified basic concept that governs motor unit recruitment, size principle (4,9). It is fundamental principle that is S108

3 paramount in understanding seminal basis of exercise and even more important in understanding resistance exercise and training. To produce more and more force in a muscle, re is a demand for orderly recruitment of more and more motor units (i.e., alpha motor neuron and its associated muscle fibers). Thus, size principle dictates that lower amounts of force require fewer motor units than higher amounts of force. With resistance training, it is amount of resistance used in an exercise that dictates how many motor units in that muscle are needed to move weight in desired pattern of a lift. In practical terms, importance of this principle is stunning and often times not appreciated! The amount of muscle that is trained by an exercise is directly related to amount of external resistance that is used. Strikingly, many workouts do not train all of available motor units. Thus, basic core concept of specificity of training is based in motor unit recruitment and thus size principle! If proper loading of musculature is not addressed in a total conditioning program, unused (nonactivated) muscle tissue remains essentially untrained. Thus, although every motor unit does not need to be and should not be trained in every workout, using only part of one s motor unit array in an exercise training program limits optimization of training. Therefore, need exists for a resistance training program that consists of different loading and metabolic training workouts sequenced in a periodized approach to be a part of every total conditioning program in military. Going back to basics, each motor unit can be composed of different numbers of muscle fibers and also different sizes of muscle fibers leading to principle of recruitment by a type of sizing effect. In addition, each muscle can be of a different fiber type profile. The average person presents an array of to 60 40% type 1 or type 2 muscle fibers in ir muscles (31). However, some muscle such as postural muscles (e.g., abdominal) are dominated by type 1 muscle fibers due to functional needs. Additionally, a different array of motor units that is beyond typical ranges can be seen in elite athletes, such as high percentage of type 1 fibers in elite marathon runners or higher percentages of type 2 muscle fibers in elite sprinters locomotor muscles, giving m obvious genetic advantage for oxidative capacity and speed, respectively. Some individuals have a low number of muscle fibers that can dictate amount of lean tissue mass y can develop (e.g., a marathon runner or some women s upper body musculature). Muscle size is dictated by number and type of motor units present in a given muscle, which has implications for magnitude of strength and power development (i.e., some women and men have fewer muscle fibers in ir upper body musculature, thus limiting magnitude of upper body strength). Thus, inherent body structure and capabilities are determined by muscle fiber number and type and impact physical performance. However, regardless of individual genetic differences, everyone can benefit from a progressive heavy resistance training program to optimize strength and power capabilities. Dramatically important for commanders and not clear enough to many responsible for physical training of soldiers is that, if one only trains with light weights, n only a small amount of motor unit pool is recruited to meet demands of workout protocol. Again this means that many motor units (and ir muscle fibers) are not trained despite perception of intense exercise with rigorous high repetition resistance training or long duration endurance training. The only or way such motor units can be activated is by depletion of metabolic substrate (i.e., glycogen) but in this type of recruitment, high force or power is not part of external force demand and even with high numbers of repetitions (e.g.,.125 repetitions) strength is only minimally developed (1). This is especially a concern in exercises that are for large muscle groups that contain large numbers of motor units (e.g., squat or deadlift). Even more alarming are or systems that are left untrained because it is a fact that adaptations in ligaments, tendons, and bone are only realized by translation of forces placed on muscle. Light resistances (e.g., high repetition maximums [RMs] or training percentages of 20% of 1RM or lower) are less effective in training total mass of muscle and connective tissue. Thus, this has a direct influence on role that resistance training can play in injury prevention if such tissues are not fully trained in an exercise program. Additionally, light resistances (e.g., 25 30RM) will not result in hypertrophy of even type 1 motor units that are used (3,29). This is because high electrical impulses (hertz) needed for hypertrophy and which are seen with neural activation and electrical discharge of motor neurons recruited when using heavier loads (e.g., 8 11RM, 3 5RM, or 90% of 1RM or greater) do not exist when using light resistances (e.g.,.20rm)! Anor staggering omission by many in ir understanding of exercise is that motor unit activation dictates physiological demands placed on body. Basic to exercise physiology, it must be clear that number of motor units recruited in a specific manner will dictate amount of involvement of various physiological systems (e.g., metabolic, endocrine, autocrine, immunological) needed to support this specific recruitment pattern. This fact is often times missed when exercise demands are discussed. Thus, contribution of a given system will be related to motor unit recruitment pattern from long-term repetitive use of type 1 motor units in long duration endurance exercise to brief high-intensity heavy resistance training loads used when performing 5 sets of 2 repetitions at 95% of 1RM. The physiological stress of each workout will be dictated by specific demands imposed and training adaptations will follow coined term of specific adaptations to imposed demands (SAID) principle. Metabolic homeostasis and damage and repair requirements are all dictated by demands VOLUME 26 SUPPLEMENT 7 JULY 2012 S109

4 Strength Training placed on body for specific patterns of motor unit recruitment and in this process both motor units and associated physiological systems are trained with repetitive exposure to stimuli. Figure 1 overviews this important concept of motor unit recruitment in translation of size principle to resistance exercise. Although resistance exercises should not be performed to failure because of joint stress and potential for injury resulting from technique failure, figure shows that amount of load used impacts level of motor unit recruitment seen (i.e., a greater percentage of 1RM used in an exercise recruits a greater number of motor units), going up recruitment order in an orderly fashion from low to high threshold motor units (4). The same process occurs even when available motor units are small or composed of primarily type 1 endurance type fibers as seen in abdominals or hand musculature. Differences between large and small muscles are related to amount of rate coding needed to achieve maximal voluntary contraction levels. Interestingly, even with eccentric actions such orderly recruitments continue to exist. When both high-intensity aerobic endurance and strength-power programs are used simultaneously one can see a problem with exercise compatibility in which type 1 motor units and ir muscle fibers make no changes in cross-sectional area with heavy resistance training and improvement in anaerobic power is also nullified (18). Thus, integration of training so as not to create ineffective programs is also a part of optimal program design and implementation. ACUTE PROGRAM VARIABLE DOMAINS Since 1983, acute program variables have been overviewed many times, and each variable really represents a cluster of many different variables that were derived from Figure 1. A diagrammatic view of motor units in a muscle. Each filled in circle represents a different type and size of motor unit with larger circles depicting more muscle fibers in a given motor unit and different color depicting motor unit containing different fibers (type 1 or type 2). The dashed circle represents a potential group of motor units that are affected if trained with both high-intensity aerobic and strength and power exercise workouts (compatibility). a multivariate cluster analysis of features that were reported to be part of workouts in different weight training programs over past millennium. Neverless, y still provide a quantifiable profile of a given resistance training workout. Owing to fact that modern training technology using periodized programs uses a wide variety of different workout combinations to address different physiological needs of individual, such a domain paradigm is helpful in analyzing effectiveness of a given workout (6). Before any exercise prescription process, a needs analysis has to be undertaken to determine biomechanical specificity for movement patterns to be trained, metabolic demands, and potential sites of injury that need to be addressed to limit injury or prehabilitate movement patterns that will be under most stress (6). The functional needs of soldier, given ir particular military occupational specialty, must be matched as well to create a conditioning program focused on what has been termed anaerobic battlefield. This approach is likely most important perspective to have to reduce heavy reliance upon long distance endurance training, which is ineffective in training strength and power, as core component of military fitness programs. Choice of Exercise To meet specific demands of soldier s occupational specialty, a need exists for what might be called standard closed chain structural exercises such as squats, box lifts, pulls, etc. Normative lifts that address symmetry around each joint (e.g., push and pull) and use both upper and lower body musculature are paramount for muscle balance (25). Including both unilateral and bilateral exercises in a program also allows for equity of development of musculature on both sides of body. Employing both concentric and eccentric muscle actions is also vital for optimal training and results in longer maintenance of adaptations with detraining or minimal training stimuli (5). The use of free weights as dominant modality in a program better influences multidirectional control of external resistances likely to be experienced in natural environment and helps develop balance under load and stability with movement. Important to exercise choice is that equipment fit is appropriate so that full range of motion and optimal performance of exercise can be achieved. The choice of exercise will dictate what angles are trained and in what manner, because S110

5 se mediate resistances used and motor unit recruitment that results. The exercise choice dictates primary mechanical (i.e., movement) patterns that body will experience, which are n influenced by or acute program variables. Thus, choices made within acute program variable paradigm are what define workout. Order of Exercise The order of exercises in a workout will dictate resistance load that can be used and quality of motor unit recruitment. Typically, large muscle group exercises are placed at beginning of a workout to allow greatest amount of resistance to be used. One can n progress to smaller and smaller muscle group exercises where order is not as impactful on resistance used (30). A host of different exercise order combinations have been used from circuit weight training protocols (e.g., arm n leg or arm-arm n legleg) to complex training that endeavors to optimize recruitment of one set of motor units by stimulating anor (e.g., heavy 5RM squats before maximal vertical plyometric jumps for power). The order of exercises in a workout should not be random but rar should have a planned purpose, dictated by specific goals of training program (i.e., training for maximal strength and power vs. training muscular endurance). Remember, fatigued motor units are not as effective in force and power production. Intensity/Load/Resistance Used Classic to concept of resistance training is amount of external load to be lifted (6,25). Higher intensities have been associated with greater gains in strength (23). Again based on size principle, heavier loads are needed to recruit more motor units. The force velocity curve also impacts this discussion of particular resistance choice to be made and refore also impacts training of muscular power (10,15). The equation for muscular power is as follows: watts = force 3 distance O time. By spreading out this equation, one can see that both force component and velocity component need to be considered when training strength and power. There is an interrelationship between force and power in that as force component of equation is increased so is power, but this is specific to velocity movement is trained at. Thus, periodized programs use a variety of workouts that train entire force velocity curve to lift whole curve up and to right for optimal training adaptations (Figure 2) (20,25). Number of Sets The number of sets acts as a volume dial on a workout. Although repetitions performed will be dictated by resistance load used, number of sets will determine extent of exposure of activated motor units to a particular load (27,28). Although a topic of much debate arising out of commercial mythologies of 1970s, it is now apparent that programs can use a variety of set schemes within a periodized program. However, single sets are really only used for higher Figure 2. The goal of most training is to use a variety of resistance loads that train whole force velocity curve from heavy loads to explosive exercises with lighter loads moving entire force velocity curve up and to right in concentric force velocity domain curves depicted. repetition training or for recovery workouts when a lower volume of total work is desired. Rest Between Sets and Exercises The amount of rest between sets and exercises becomes metabolic dial for a workout that must be carefully manipulated. Dialing up too much metabolic glycolytic intensity too quickly in a training program progression can lead to adverse symptomatology (e.g., nausea, dizziness, and vomiting) that is not indicative of a good workout. Although short rest workouts can be an effective component in a periodized training program, y must be gradually integrated and properly progressed. This is based upon development of body s buffering capacities which only takes about 1 or 2 workouts a week over an 8-week period of time, so more frequent use of short rest workouts for this aspect of physiological adaptation is overkill and can lead to types of nonfunctional overreaching. The stress of short rest (#1 minute) is dramatic with epinephrine (adrenaline) increases that are 2 3 times higher than that seen in maximal treadmill exercise (12,13,17) (Figure 3). In addition, anabolic and catabolic hormones increase to support dramatically high metabolic demands of workout protocols (12,13). Such short rest workouts really require a rest day after workout or accumulation of physiological and psychological stress increases. It has been demonstrated that a 4-day workout plan with heavy day on Monday, metabolic day on Tuesday, rest Wednesday, strength and power on Thursday VOLUME 26 SUPPLEMENT 7 JULY 2012 S111

6 Strength Training Figure 3. Responses of catecholamines after a short rest, high-intensity exercise workout performed by trained bodybuilders and powerlifters as control subjects could not make it through workout (18). Increases at 5 minutes after workout, catecholamines were significantly higher by magnitudes compared with maximal treadmill exercise test results immediately after. With exponential decay of catecholamines after exercise, magnitude of immediately postexercise concentrations were apparently dramatically higher. This workout protocol produced some of highest lactate and catecholamine concentrations after exercise that have been reported in literature. Thus, care must be taken when prescribing such exercise protocols and recovery allowed in subsequent workouts. and anor metabolic day on Friday can be completed along with sprint intervals on Monday and Thursday and 40- to 45-minute endurance days on Tuesday and Friday using a split workout of running in morning and lifting in afternoon after about 6 hours of rest and proper nutrition (18). However, even here price to be paid is a loss of adaptive increases in type 1 muscle fiber size and no anaerobic power increases after 3 months of training. This might be mitigated by reducing oxidative stress by using only one sprint interval training day. Furrmore, even when short rest workouts can be tolerated, care must be taken to check and monitor exercise technique because its disintegration is more probable, resulting in excessive microtears and injury to tissue. Short rest workouts in weight room and sprint interval training on track (with high metabolic demands, high levels of oxidative stress, free radical formation, and cortisol increases) must follow careful prescription so as not to create physiological distress conditions from too many stress stimuli hitting body, thus creating an increased potential for overreaching conditions (7,32,33). The heavier resistance, longer rest that is needed to optimally recruit motor units. Although so-called strength-endurance is an important fitness characteristic, one cannot lift same absolute resistance with large muscle mass exercises with both short (1-minute) and long (5-minute) rest period lengths. Thus, one really is training with relatively lighter loads when short rest period lengths are used; refore, if strength is primary target for improvement, longer rest periods are needed in a workout when attempting to lift heavy weights (e.g., $90% of 1RM). Table 1 overviews rest period lengths for different load requirements. EXERCISE COMPATIBILITY/ CONCURRENT TRAINING Almost inherent in every military training program is challenge of training both aerobic and anaerobic metabolic systems. The motor units that are recruited to perform both types of exercises (i.e., low and moderate threshold motor units) are ones that are susceptible to diverse opposing stimuli for physiological adaptation. High-intensity endurance training stimulates recruited motor units to optimize size of ir muscle fibers to increase oxidative capacity (typically type 1 slow twitch fibers) by reducing ir size (i.e., cross-sectional area), what might be called exerciseinduced atrophy. Conversely, heavy resistance training results in cellular signaling of recruited motor units (typically type 1 slow twitch and type 2 fast twitch fibers) to increase in size to produce more force. As noted previously, even if high-intensity training is optimized with rest, when both programs are performed concurrently what has been shown TABLE 1. Rest period lengths with different resistance loads. Very very light: 1 min between exercises, increase to reduce stress if more than 1 set, or a higher number of exercises are used in a circuit protocol. Very light: 1 2 min between sets and exercises Moderate: 2 3 min between sets and exercises; high metabolic intensity progression to 1 2 min can be used with understanding that this produces some of highest metabolic stress responses in weight room. Heavy: 4 5 min for handling heaviest resistance loads. Very heavy: use of $5 7 min when maximal lifts are being performed. S112

7 to happen is that type 1 fibers make no changes in ir size, type 2 muscle fibers get bigger, power is compromised, aerobic capacity is not affected, and strength might be reduced in magnitude (18). Thus, real care must be taken when adding high levels of aerobic training duration to a training program (e.g., 4- to 10-mile runs) because it will not help soldier athlete and compromises anaerobic capabilities, which are vitally important for anaerobic battlefield of present. Examining impact of different aerobic training programs, it was shown that when soldiers only ran and even with use of interval training, no improvements in loaded rucksack carriage over 2 miles were observed (19). Thus, addition of a periodized heavy resistance training program is vital to overall physical performance. Various low volume sprint interval type workouts are a better choice to enhance maximal oxygen consumption or aerobic capacity while limiting effects on anaerobic performance capabilities. However, concerns exist if more than two such workouts are done in a week, and long distance running has to be reduced dramatically as well. Table 2 overviews some of training effects of different program combinations. Ordering of Workouts Although a topic of much research, order of workouts may turn out to be a vital consideration in subsequent adaptations to exercise training. The basis of a workout sequence appears to be related to time course of genetic and cell signaling. Preliminary research points to concept that those motor units that are stimulated by resistance exercise have ir anabolic signaling blunted in some manner when immediately or shortly reafter followed by aerobic exercise. Thus, if a combined workout is used, performing an aerobic exercise first followed by resistance exercise may well help to establish a more anabolic environment during repair process. Alternatively, as noted before, one might separate workouts by 6 hours, with, for example, a running workout being done in morning and lifting done in afternoon. The underlying mediating mechanisms and definitive proof for benefit of such ordering of workout modes remain experimental but TABLE 2. The effects of different training programs on muscle fiber cross-sectional area in thigh s vastus lateralis and or performance variables (18,19).* Type 1 Type 2 WG V_ O2 max 2 Mile run 2 Mile RS VJ Endurance only D NC NC I I NC NC Strength training only I I I NC NC I I Both training modes NC I NC I I I I *2-mile RS = 2-mile rucksack carry; WG = 30s Wingate test: peak and average power; VJ = countermovement vertical jump; D = decrease, NC = no change, I = increase. intuitively have some merit in design of workouts done in combination. Workout sequencing within a single day has been a topic that from a practical perspective requires attention when designing training programs. Ultimately, a choice has to be made with more prudent order of performing a workout with less oxidative and free radical stress (i.e., or forms of conditioning focusing on continuous short rest sequences, rar than long duration endurance exercise) before performing a more anabolic workout. Periodization of Training The concept of linear and nonlinear periodization has been discussed at length over years. More important to military is one corollary of periodization that is needed because of dramatic challenges posed by competing mission schedules and differences in individual readiness to train (26). A number of features make concept of flexible nonlinear periodization attractive not only to sport teams but to military because of its rapid ability to alter a given workout on a given day (11). Flexible nonlinear periodization allows for a host of sequence orders while at times mimicking or periodization formats if conditions allow (22,24). Thus, blocks or traditional linear sequences can be used in different mesocycles if warfighter is ready to train and situation is appropriate. The basis for adaptability and refore success of flexible nonlinear programming lies in concept that quality of training is more important than going through motions. Planned nonlinear periodization, although effective, may take longer to stimulate change because of potentially longer cycling required to get enough heavy resistance training days. Thus, use of flexible nonlinear approach allows more freedom to sequence workout days as needed in a mesocycle and defines mesocycle dependent upon conditional needs, allowing for adaptability if warfighter is not capable of workout intensity, volume, or metabolic demands planned. The fundamental basis for nonlinear periodization is that one can have a different workout each day that provides a different physiological stimulus and recruitment of motor units. Additionally, one can use certain types of workouts to provide rest and recovery for motor units that are only passively going through range of motion. Furrmore, different types of workouts allow for variety without noncalculated mix of exercises seen in extreme commercial programs. Finally, if one misses a workout because of mission requirements or illness, one can pick up next VOLUME 26 SUPPLEMENT 7 JULY 2012 S113

8 Strength Training workout sequence easily, modify it and continue on. One is not anchored to a set pattern outside of desired goal for that mesocycle of 6 12 weeks. If necessary workouts cannot be accomplished to meet goals of a specific mesocycle, a new one is created to allow for continuation of training. The Flexible Nonlinear Program Approach For consistency, terminology of flexible nonlinear approach is similar to that of classic periodization. The biggest period of time being dealt with is a macrocycle, typically 12 months, next phase is mesocycle, which can range between 6 and 12 weeks and is mutable based on schedule. The smallest period of time is microcycle, which is unique aspect of nonlinear programs and this is 1 day! Over a given mesocycle, a combination of workouts are planned to reflect primary goal of mesocycle, but workouts can differ more dramatically when compared with a typical week using more classic periodization models. Finally, workout decisions for a given day are made dependent upon individual s readiness to train and this is determined with simple tests before workout or by comparing workout logs and prior workout performances (11). Again, goal is to promote quality and also allow for recovery to reduce potential for overreaching (leading to overtraining syndromes), which compromises soldier s readiness and can result in a loss of duty time because of sickness or injury (21,33). The Workout Sequences Many different workout sequences are possible within construct of flexible nonlinear approach, but this will depend upon goal of a particular workout design with its combination of workout variables, how that particular TABLE 3. An example of a planned nonlinear periodization training program for a 10-day cycle within a mesocycle that can be changed as needed to allow optimal training.* Changes can be made based on readiness for training for a particular workout. This protocol uses a 5-day rotation (a 7-day rotation, etc. can also be used). Monday Wednesday Light 1 set 12 15RM Very heavy for major exercises: 6 sets of 1 2RM Friday Monday Heavy 3 sets of 3 6RM Power day: 10 sets of 1 2 reps at 45% of 1RM Wednesday 4 Sets of 8 10RM (metabolic training, with short rest) Endurance training is mixed in with care taken when using high glycogen depletion runs *RM = repetition maximum. Endurance training must be integrated into program in proper sequence order and with adequate rest. workout fits into goal for mesocycle and how it n fits into yearly or macrocycle training profile. In this process, not all soldiers will progress at same rate, but general workout styles may be similar, unless a decrement is noticed in workout performance on a given day, requiring a default move to a less stressful workout or rest. Table 3 shows a 10-day mesocycle with different combinations of workouts that can be chosen which create a continuum of intensity, volume and rest period length interactions within range of chosen exercises. Within mesocycle, guiding principle is to address overall goal for that mesocycle. One can alter it based on capability of warfighter to perform workout schedule. In some cases, array of workouts will include less variance, for example, Monday heavy, Tuesday heavy, Wednesday rest from lifting, Thursday power, and Friday metabolic training. If a workout cannot be accomplished at level needed, it can be switched out to a low volume recovery light workout or complete rest to avoid nonfunctional overreaching. Remember this is a training program approach to conditioning and implementation is related to situations that exist and needed individualization for warfighter, military occupational specialty, and unit demands. Mesocycle Plans Using unit s yearly training plan or modular scenarios for Special Operations Forces (based around deployment cycles), one can create a basic plan based on best available knowledge. Next goal of mesocycle for a given period of time is developed based on types of individuals who will use program. Thus, for a given unit, one may see 2 or 3 different mesocycle plans based on current fitness levels, injury history, experience with resistance training and mission operational tempo. This approach allows one to address what each soldier and unit needs while not overshooting m with program workouts that cannot be performed because of low fitness levels, lack of knowledge of exercise techniques, or more often, time constraints and competing unit training demands. By modifying workouts within a given mesocycle to adapt to se training limitations, injuries typically seen even with functional exercises (when performed inappropriately) can be avoided. Once a planned cycle is created, it is n challenged by situational demands as to wher it can be accomplished. If it can be done, S114

9 plan moves forward within a week or mesocycle. If a workout planned for a Monday cannot be done, it is replaced, and that workout is attempted for anor day within that same week. The key is to accomplish planned workouts for week, but for a given day, an evaluation is made if particular workout can be done with needed quality required for it to stimulate needed adaptation in body (e.g., maximal power). If not, one does not want to just waste time with ineffective training stimuli so a different workout is performed or rest is taken. For example, you have planned a plyometric training workout for power development and stability training on a Monday, but because of operational demands, soldier cannotevenjumpto90%ofhisorherbestjump.one cannot just go through motions as power training must be done in a rested condition to see improvements in maximal performance development (e.g., you do not get faster running slow). At this point, you would default to anor workout while evaluating potential overreaching as velocity of movement and power are first to go before strength in an overreaching condition. One might do a light resistance training day with low volume to allow for recovery yet still accomplish a workout for given day. Although competitive athletes and warfighters will not admit to being tired, performance will dictate actual condition, and it is up to strength and conditioning professional to make call and alter workout and its progression. One can make up power workout somewhere else when optimal in that week s cycle. Here is where planned but flexible nature of this program approach shines. To coin an old U.S. Marine saying, Improvise, adapt, and overcome. The Microcycle In a nonlinear program design, microcycle is a single training day. The workout is part of a mesocycle plan and n with flexible nonlinear programming one attempts to adhere to plan dependent upon individual s physical condition and wher circumstances surrounding day make plan untenable (e.g., power workout planned but a 10-mile roadmarchwassurpriseofmorning).thereareahost of different workouts that can be configured based on what goals of mesocycle are and what weekly cycle will allow. Sometimes, this can mean a very short mesocycle of 6 weeks because of influx and efflux of soldiers, which requires adaptability on part of strength and conditioning professional. One must work within given timeframes, even when not ideal, to optimize warfighter s physical development from a neuromuscular perspective. Thus, workouts can vary in intensity, volume, and frequency and are n furr defined by or acute program variables. Training Optimization The importance of optimal training cannot be overstated. Elite athletes do not enter a competition and do well if y are overtrained or have not tapered into an optimal phase of training. Although mission tempo is unpredictable, importance of not overshooting one s ability to recover becomes even more important to optimize mission. If one uses a program that has within a week hard runs and 6 short rest metabolic resistance training workouts, re is no way that recovery has been allowed and if a mission calls, physical fatigue and tissue damage will be less than optimal. Most likely soldiers will still be able to get job done, but this is typically because of youth or incredible toleration of pain and suffering warfighter possesses, yet as old commercial on TV about your car states, pay me now or pay me later. The body has an extraordinary capability to absorb physical training mistakes, but concern is that additive nature of stress (i.e., dramatic increases in cortisol concentrations, increases in free radicals, immune suppression, and with excessive endurance training in men, reductions in normal testosterone concentrations) results in a reduction in individual s anabolic state, slows down tissue adaptations, and ultimately impacts neuromuscular function. Thus, from a resistance training program design perspective, it is important to understand how to get most out of each training session while allowing for recovery of tissue (e.g., supercompensation), and recognizing that this is different from athlete who can plan logistics of a program with more certainty. It is vital for a warfighter s program to have recovery and restoration as hallmarks of each training week. WORKOUT STYLES A number of workout styles exist dependent upon different combinations of intensity and volume interactions. As estimated by Fleck and Kraemer, an almost infinite number of workout styles can be created as every time you change an angle of an exercise you change recruitment pattern; rest periods are variable from low rest, which places a greater metabolic challenge to long rest periods which are needed for optimal power and force production. Order effects (i.e., complex training strategies) combined with number of sets performed determine total amount of work being done in a workout or cycle. Therefore, it is important to understand that created workouts and ir sequencing into a training program dictate specific stimuli that will affect acute physiological demands, maladaptation or positive adaptation leading to performance status. With flexible nonlinear periodized approach, one has many workouts that can be incorporated into a plan for a 6- to 12-week mesocycle and n used as appropriate over that cycle of training. Thus, choices are many, and this allows variety, yet need for a clear goal for each mesocycle remains so that workouts can be optimized accordingly each day. There are several types of workouts that are frequently used and studied in literature. The multiple numbers of exercises that can be used in se workouts will dictate musculature that is activated; refore, se typical workouts are anchored by intensity that is to be used. Resistance loads exist over a continuum and finite cutoffs are VOLUME 26 SUPPLEMENT 7 JULY 2012 S115

10 Strength Training really related to broad spectrum of effects documented in various zones. It is also important to understand that RM zones and percentage of 1RM will lose ir equity as size of muscle group changes, with larger muscle groups capable of more repetitions at a given percentage load and smaller muscle groups performing fewer repetitions with a given intensity. In addition, machines with fixed paths allow more repetitions to be performed compared with free weights (e.g., 80% of 1RM in leg press ;22 reps, vs. squat ;10 reps). Thus RM zones of typically 3 repetitions are used for many exercises and n percentage of 1RM in many ors (e.g., power cleans, pulls), derived eir from testing or from prediction equations. Very Very Light Workouts This type of workout uses higher repetitions of.20rm up to 150RM and typically uses only 1 set in a few muscle group exercises. The goal of this type of workout as verified by research is to increase local muscular endurance. It primarily trains type 1 slow twitch motor units and if more than one set is used places demands on se motor units for metabolic substrate as with any high volume workout. If done as a single set of 20 30RM with.1 minute rest between exercises, it can also be used a recovery workout allowing high threshold motor units to recover and repair. The key to this is that workout does not produce high amounts of oxygen reactive species and free radicals in circulation as can happen if metabolic intensity is ramped up with short rest periods and high volumes of work. So essentially re are a host of workouts within this very, very light intensity domain, and effect will be based on rest periods used that dictate metabolic demand and number of sets that will impact volume of work. Exercise technique can be seen to fail when such high repetition numbers are used in a set, and this can lead to increased microtears in tissue and injury. Therefore, monitoring of technique and proper exercise choices are vital in se workout styles. Thus, a recovery very, very light workout differs from high volume short rest workouts by rest period length and number of sets. Very-Light Workouts This is next in line of intensities ranging from 12 to 20RM. The intensity is increased, which indicates more motor units will be used to perform set. Again, this type of workout is directed toward again enhancing local muscular endurance but with heavier weights used at lower end of continuum, strength development can also be observed albeit much less than with heavier resistances. Similar to very very light workouts, se workouts are physiologically put in context of number of exercises and sets that determine total work and rest period lengths that determine metabolic demands. Also, we see here that because of fatigue that occurs with higher repetition number, choice of exercise and technique monitoring are vital concerns to limit potential for injury. Here again, a wide continuum of workouts are possible, but one has to determine wher goal is to use it for a recovery workout vs. as an intense local muscular endurance workout with elevated metabolic and recovery demands, as seen with very very light workouts. Moderate Workouts These workouts dominate field of resistance training as y range in intensity from 8 to 12RM and have been widely used because of ir ability to promote both strength and muscle size improvements in untrained individuals. These workouts are again differentiated by number of sets and exercises and rest period lengths that dictate metabolic demands. This resistance intensity range has been shown to produce highest level of stress of any of workouts when rest period length is shortened to 1 2 minutes between sets and exercises. This methodology grew out of cut phase training approach typically seen in bodybuilders. When combined with longer rest and 8 10 exercises, it has typically been standard workout for most individuals starting a resistance training program. However, when used within context of short rest training, it creates a dramatic combination of muscle tissue damage, free radical production, and highest elevations in both anabolic and catabolic hormones and cytokines. Thus, sequencing of this workout with a rest day to allow for recovery is a vital aspect in avoiding overreaching implications. This is especially important for warfighter so as not to compromise immediate mission readiness or cause loss of duty time because of excessive soreness or injury. Heavy Workouts These workouts use typically 3 6RM loads and are directed toward increasing muscular strength or maximal force production capabilities in a given exercise movement. Outside of individuals or muscles with predominately type 1 slow twitch muscle fibers, se loads will recruit a predominant majority of motor units available. Typically, large muscle group exercises (e.g., squats, leg presses, rows, pulls, cleans, bench press) are used for se types of loading. Because fatigue will reduce number of repetitions that can be performed in a set with a heavy load, longer rest periods of.3 minutes are used. Because of higher eccentric loading, a greater potential for muscle tissue damage exists; however, this type of training also provides a protective mechanism reducing muscle damage from eccentric mechanical stress exposure when musculature is trained. This is an important protective feature for warfighter because this enhances repair and recovery. Very Heavy Workouts These loads are skilled based in that y range in 1 2RM range and are used for direct determination of maximal strength and recruit all available motor units in muscle groups used to perform given exercise. Exercise technique is vital within any workout and is important here as well. In S116

11 competitive lifting world, one often hears term singles and doubles, which is indicative of maximal nature of such sets. Obviously, if more than one attempt is being made, rest period length used is long. This type of loading has been used with many types of pyramid loading schemes and also in strongman and strongwoman event training. Power Workouts Power workouts are designed to increase maximal power and functional capabilities. Essentially, power is part of every movement wher it is zero for isometric actions or very small for a 1RM or higher as force decreases with its peak dependent upon repetition range. The key has been to train entire force velocity curve and that means performing workouts where maximal power can be produced at different intensities. It is important to understand that only gravity creates any deceleration on movement; thus, exercise choices are vital. Hanging on to bar in a bench press and moving a light weight up and down will not help power development because only deceleration is accentuated including neural inhibition to prime movers. This is why Olympic type lifts, plyometrics, and medicine ball exercises have dominated se types of workouts. As noted in plyometric recommendations for years, an athlete must be rested and re is a need for maximal effort in each set with adequate recovery between sets to optimize one s maximal power training. In addition, strength must be maintained. If power endurance is goal, technique must be carefully monitored, and it must be realized that few if any changes will take place in maximal power development. Sex-Specific Implications Although a great deal of interest is now focused on sexneutral testing, it is apparent that women can achieve gains in physical development and physical performance as do men. The specific group of men and women who are being compared will dictate comparative results (e.g., women who are highly weight trained athletes vs. average men). Research has established that resistance training and endurance training programs can be applied successfully for both men and women (8,14,16). Thus, from untrained to trained, identical training adaptations can be observed among our female warfighters in terms of neuromuscular adaptations and performance. WORKOUT INTERACTIONS Obviously, each workout, regardless of type, exists within context of daily physical training. In addition, high mileage running is still a staple in military despite much research on compatibility and potential overtraining syndromes related to excessive long distance endurance training. Long runs of 7 10 miles are still considered norm, even though this type of training contradicts actual physical demands placed on warfighter. In recent years, increasingly anaerobic demands of military profession have led to ideal body type for male soldiers to favor that of a rugby player or American football linebacker, and for female soldiers, that of a volleyball or basketball player. This is a reflection of training adaptations which emphasize muscle size, strength, and power, with only needed cardiovascular support profiled. In modern era of anaerobic battlefield, one does not run into battle; rar, strength, power, and functional capabilities play vital roles in warfighter s success. Until this paradigm switch from aerobic athlete to anaerobic athlete is made, resolving conflicts in optimizing training programs, mission readiness and recovery capabilities for strength of warfighter will continue to be a struggle. PRACTICAL APPLICATIONS The challenges for development of an optimal strength training program for warfighter have continued to evolve over past 25 years. Although valiant attempts are being made within military to move to a more modern approach to physical training, much of what is ingrained arises from a long history that is grounded in old boxing concepts of training for roadwork, later solidified during aerobics craze of 1960s. A fast 10-mile run or completing a marathon is still viewed as a benchmark of military fitness as opposed to a 40-inch. vertical jump or a squat at 2.5 times body mass. The ultimate paradox is that se performances are not compatible within same training program and so one must choose what modern warfighter will look like physically. The influence of lay press and various commercial entities have also furr exacerbated fundamentals of workout design and training. Finally, need for individualization of training and developing facilities and programs reflective of elite athlete in strength and power sports befitting of modern warfighter is both a financial and logistical challenge but worthy of effort. Wading though myths of past and present with goal of creating an ideal training program that enhances strength, power, and functional capabilities using training technologies and methods that allow for flexibility needed in a high operational tempo environment is a harrowing process. We have technology and now certified professional strength and conditioning specialists to accomplish this mission, and with time, physical training program of modern warfighter will accurately reflect mission requirements of each military occupational specialty, while maintaining resilience and long-term health and wellness for individual. ACKNOWLEDGMENTS The authors thank our U.S. warfighters around world and ir families for ir service and sacrifices. The views, opinions, and findings contained in this report are those of authors and should not be construed as an official U.S. Department of Defense position, policy, or decision unless so designated by or official documentation. 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