STRENGTH TRAINING FOR THE WARFIGHTER
WILLIAMJ. KRAEMER1,2 ANDTUNDE K. SZIVAK1
1Human Performance Laboratory, Department of Kinesiology; and2Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut
Kraemer, WJ and Szivak, TK. Strength training for the warfighter. J Strength Cond Res 26(7): S107–S118, 2012—
Optimizing strength training for the warfighter is challenged by past training philosophies that no longer serve the modern warfighter facing the “anaerobic battlefield.” Training approaches for integration of strength with other needed physical capabilities have been shown to require a periodiza- tion model that has the flexibility for changes and is able to adapt to ever-changing circumstances affecting the quality of workouts. Additionally, sequencing of workouts to limit over- reaching 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 the negative influences of extreme exercise pro- grams 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 the warfighter is an elite athlete, it is time that training approaches that are scientifically based are updated within the military to match the functional demands of modern warfare and are given greater credence and value at the com- mand levels. A needs analysis, development of periodized training modules, and individualization of programs are needed to optimize the strength of the modern warfighter.
We now have the knowledge, professional coaches and non- profit organization certifications with continuing education units, and modern training technology to allow this to happen.
Ultimately, it only takes command decisions and implementa- tion to make this possible.
KEYWORDSstrength training, military, periodization, resistance training, tactical
Conditioning programs that address maximal strength and power are increasingly being recog- nized as potentially important components of military fitness (34). Historically, and even today, the focus of conditioning in the military has been on aerobic- type endurance training. Part of this arises out of the ease of implementation of such programs and the simplicity of the exercise prescription when training large numbers of soldiers during a physical training period. Additionally, physical train- ing has often been geared toward performance on aerobic components of annual physical fitness tests, rather than on real-world mission requirements. However, because recogniz- ing and adequately addressing the demands on the warfighter is an ever-evolving challenge due to the diversity of physical, psychological, and environmental factors faced on the battle- front, the pivotal role of well-designed total conditioning programs is clearly apparent. There is no doubt that a war- fighter’s maximal strength and power will dictate the magni- tude of force and power in submaximal high-intensity endurance performances, literally translating into better performance on the modern-day battlefield.
Progressive heavy resistance training remains the primary modality to improve an athlete’s maximal strength and power.
With this comes the need for resistance training equipment and facilities to implement properly designed programs.
Although weight rooms and conditioning facilities are found on almost every base, the size of the facilities and sophistica- tion of the equipment may not meet the requirement to train every soldier. Although soldiers in the United States assigned to specialized units (i.e., Special Operations Forces) now have access to strength and conditioning facilities under the Tactical Human Optimization, Rapid Rehabilitation, and Reconditioning (THOR3) program, these same resour- ces are not available to conventional military units, limiting the type of training that can be conducted with large num- bers (e.g., 100+) of soldiers. Furthermore, the need exists for properly educated, trained, and certified professionals within each unit to effectively implement specialized programs needed for the different military occupational skill sets and to identify the differential demands of each individual soldier that must be addressed for optimal progression and physical development. Herein have evolved the historical conflicts surrounding military physical training, as concepts such as individualization, sophisticated equipment, and training
Address Correspondence to William J. Kraemer, william.kraemer@uconn.
Journal of Strength and Conditioning Research Ó 2012 National Strength and Conditioning Association
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 the warfighter’s tough mentality and the ever-present need to cut fat and get “ripped” to meet the military’s body composition requirements (2). Furthermore, these programs are randomly administered and not individ- ualized or put into the context of other physical and psy- chological demands placed on the warfighter. However, promises of quick results cannot be ignored as a key factor in the success of these programs in attracting the warfighter’s attention, including commander and junior leaders at the company, platoon, and squad levels. Although these com- mercial programs have value, they do not incorporate work- outs within a progressive, periodized model; a method that has been well established as an effective means of training athletes for optimal performance while mitigating the risk of injury and nonfunctional overreaching or overtraining.
At present, although more hires of National Strength and Conditioning Association Certified Strength and Condition- ing Specialists are being made each year in the U.S. military, physical training programs in most typical units are designed by junior leaders at the company, platoon, and squad levels.
They rely on their 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 the field of exercise science. Owing to the large numbers of soldiers to be trained (e.g., 100+), limited time and facilities, the result is that most fitness programs are based on local muscular endurance, calisthenics, and running as the pri- mary forms of physical training. In addition, many commer- cial 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 cumu- lative stress of both mission demands and extensive physical training can contribute to injury and nonfunctional over- reaching concerns when a lack of individualization and periodized training needed for rest and recovery is missing from the training schedule equation.
CHALLENGES FORRESISTANCETRAINING IN THEMILITARY
The primary objective of any resistance training program is to improve physical performance and prevent injury by strengthening muscles and the associated connective tissues (25). Improvement in physical performance requires a careful examination of the demands of a sport or particular position or in this case the demands of the soldier’s given military occupational specialty. Thus, the basic goals for any resis- tance training program are to improve maximal strength and power because these are the basic hallmarks of neuro-
muscular fitness. It is upon these two fundamental pillars of neuromuscular fitness that one can then 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 the performance requirements of the particular occupational specialty and overlay it with the current capabilities of the individual warfighter (6). Additionally, once the program is designed, implementation does demand proper instruction on exercise techniques, spotting, and monitoring of the physiological demands placed on the 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 the areas of nutrition, sleep, alcohol, and smoking, which can all impact physical development and recovery. Here again, commercial shortcuts for needed equipment, supervi- sion, 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 the warfighter.
Once the basic core physical capabilities of strength and power development have been addressed, one can then develop program variations that build upon these fundamen- tals and further address performance characteristics needed for a given military occupational specialty. However, pro- grams that start with the specifics and ignore the basic core elements of strength and power limit optimal development over time and set the stage for injury. The fundamental principles of proper progressive overload, specificity, and periodization cannot be ignored in any program that seeks to optimally prepare the individual warfighter for the physical demands of their occupational specialty (25).
THEPHYSIOLOGICALBASIS OFSTRENGTH AND
To understand exercise at its most fundamental levels and how the external demands of any exercise interact with the neuromuscular system, it is important to understand the concept of “size principle.” This is paramount for understand- ing maximal strength and power development because too often exercise is not defined in careful enough terms to be effective for the intended outcome. Thus, it is important to develop a basic understanding of the underlying physiology at work when one exercises or trains the neuromuscular system.
The term was coined by Professor Elwood Henneman of Harvard University who made a series of his own initial observations in the late 1950s and by the late 1970s solidified the basic concept that governs motor unit recruitment, “the size principle (4,9).” It is the fundamental principle that is
paramount in understanding the seminal basis of exercise and even more important in understanding resistance exer- cise and training.
To produce more and more force in a muscle, there is a demand for the orderly recruitment of more and more motor units (i.e., the alpha motor neuron and its associated muscle fibers). Thus, the size principle dictates that lower amounts of force require fewer motor units than higher amounts of force. With resistance training, it is the amount of resistance used in an exercise that dictates how many motor units in that muscle are needed to move the weight in the desired pattern of a lift. In practical terms, the impor- tance of this principle is stunning and often times not appreciated! The amount of muscle that is trained by an exercise is directly related to the amount of the external resistance that is used. Strikingly, many workouts do not train all of the available motor units. Thus, the basic core concept of specificity of training is based in motor unit recruitment and thus the size principle! If proper loading of the 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 the optimization of training. There- fore, the 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 the military.
Going back to the basics, each motor unit can be composed of different numbers of muscle fibers and also different sizes of muscle fibers leading to the 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 40–60 to 60–40% type 1 or type 2 muscle fibers in their 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 the high percentage of type 1 fibers in elite marathon runners or the higher percen- tages of type 2 muscle fibers in elite sprinters’ locomotor muscles, giving them the obvious genetic advantage for ox- idative capacity and speed, respectively. Some individuals have a low number of muscle fibers that can dictate the amount of lean tissue mass they can develop (e.g., a mara- thon runner or some women’s upper body musculature).
Muscle size is dictated by the number and type of motor units present in a given muscle, which has implications for the magnitude of strength and power development (i.e., some women and men have fewer muscle fibers in their upper body musculature, thus limiting the magnitude of upper body strength). Thus, the 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 the physical training of soldiers is that, if one only trains with light weights, then only a small amount of the motor unit pool is recruited to meet the demands of the workout protocol. Again this means that many motor units (and their muscle fibers) are not trained despite the perception of intense exercise with rigorous high repetition resistance training or long duration endurance training. The only other way such motor units can be activated is by the depletion of metabolic substrate (i.e., glycogen) but in this type of recruitment, high force or power is not part of the 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 the other systems that are left un- trained because it is a fact that adaptations in ligaments, tendons, and bone are only realized by the translation of forces placed on muscle. Light resistances (e.g., high repeti- tion maximums [RMs] or training percentages of 20% of 1RM or lower) are less effective in training the total mass of muscle and connective tissue. Thus, this has a direct in- fluence on the 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 the hypertrophy of even the type 1 motor units that are used (3,29). This is because the high electrical impulses (hertz) needed for hypertrophy and which are seen with the neural activation and electrical discharge of the 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)!
Another staggering omission by many in their under- standing of exercise is that motor unit activation dictates the physiological demands placed on the body. Basic to exercise physiology, it must be clear that the number of motor units recruited in a specific manner will dictate the amount of involvement of various physiological systems (e.g., meta- bolic, endocrine, autocrine, immunological) needed to sup- port this specific recruitment pattern. This fact is often times missed when exercise demands are discussed. Thus, the contribution of a given system will be related to the motor unit recruitment pattern from the long-term repetitive use of type 1 motor units in long duration endurance exercise to the 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 the specific demands imposed and training adaptations will follow the coined term of the specific adaptations to imposed demands (SAID) principle. Metabolic homeostasis and dam- age and repair requirements are all dictated by the demands
placed on the body for specific patterns of motor unit recruitment and in this process both the motor units and associated physiological systems are trained with repetitive exposure to the stimuli.
Figure 1 overviews this important concept of motor unit recruitment in the translation of “size principle” to resistance exercise. Although resistance exercises should not be per- formed to failure because of joint stress and potential for injury resulting from technique failure, the figure shows that the amount of load used impacts the level of motor unit recruit- ment seen (i.e., a greater percentage of 1RM used in an exer- cise recruits a greater number of motor units), going up the recruitment order in an orderly fashion from low to high threshold motor units (4). The same process occurs even when the available motor units are small or composed of primarily type 1 endurance type fibers as seen in the abdomi- nals or hand musculature. Differences between large and small muscles are related to the amount of rate coding needed to achieve maximal voluntary contraction levels. Interestingly, even with eccentric actions such orderly recruitments con- tinue 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 their 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.
Since 1983, the acute program variables have been over- viewed many times, and each variable really represents a cluster of many different variables that were derived from
a multivariate cluster analysis of features that were reported to be part of workouts in different weight training programs over the past millennium. Nevertheless, they still provide a quantifiable profile of a given resistance training workout.
Owing to the fact that modern training technology using periodized programs uses a wide variety of different workout combinations to address the different physiological needs of the individual, such a domain paradigm is helpful in analyzing the effectiveness of a given workout (6).
Before any exercise prescription process, a “needs analysis”
has to be undertaken to determine the biomechanical specific- ity for the movement patterns to be trained, the metabolic demands, and the potential sites of injury that need to be addressed to limit injury or “prehabilitate” movement patterns that will be under the most stress (6). The functional needs of the soldier, given their particular military occupational spe- cialty, must be matched as well to create a conditioning pro- gram focused on what has been termed the “anaerobic battlefield.” This approach is likely the most important perspec- tive to have to reduce the heavy reliance upon long distance endurance training, which is ineffective in training strength and power, as the core component of military fitness programs.
Choice of Exercise
To meet the specific demands of the 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 the 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 the 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 the dominant modality in a pro- gram better influences multidi- rectional control of external resistances likely to be experi- enced in the natural environ- ment and helps develop balance under load and stabil- ity with movement. Important to the exercise choice is that equipment “fit” is appropriate so that full range of motion and optimal performance of the exercise can be achieved.
The choice of exercise will dic- tate what angles are trained and in what manner, because
Figure 1. A diagrammatic view of the 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 the different color depicting the 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).
these mediate the resistances used and the motor unit re- cruitment that results. The exercise choice dictates the pri- mary mechanical (i.e., movement) patterns that the body will experience, which are then influenced by the other acute program variables. Thus, the choices made within the acute program variable paradigm are what define the workout.
Order of Exercise
The order of exercises in a workout will dictate the resistance load that can be used and the quality of the motor unit recruitment. Typically, large muscle group exercises are placed at the beginning of a workout to allow the greatest amount of resistance to be used. One can then progress to smaller and smaller muscle group exercises where the order is not as impactful on the resistance used (30). A host of different exer- cise order combinations have been used from circuit weight training protocols (e.g., arm then leg or arm-arm then leg- leg) to complex training that endeavors to optimize recruit- ment of one set of motor units by stimulating another (e.g., heavy 5RM squats before maximal vertical plyometric jumps for power). The order of the exercises in a workout should not be random but rather should have a planned purpose, dictated by the specific goals of the training pro- gram (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.
Classic to the concept of resistance training is the amount of the 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 the particular resistance choice to be made and therefore also impacts the 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 the force component and the velocity component need to be considered when train- ing strength and power. There is an interrelationship between force and power in that as the force component of the equation is increased so is power, but this is specific to the velocity the movement is trained at. Thus, periodized programs use a variety of workouts that train the entire force velocity curve to lift the whole curve up and to the 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 the repetitions performed will be dictated by the resistance load used, the number of sets will determine the 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 the 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
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 the
“metabolic dial” for a workout that must be carefully manip- ulated. Dialing up too much metabolic glycolytic intensity too quickly in a training program progression can lead to adverse symptomatology (e.g., nausea, dizziness, and vomit- ing) that is not indicative of a “good workout.”
Although short rest workouts can be an effective compo- nent in a periodized training program, they must be gradually integrated and properly progressed. This is based upon the development of the 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 over- kill 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 sup- port the dramatically high metabolic demands of the work- out protocols (12,13).
Such short rest workouts really require a rest day after the 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
Figure 2. The goal of most training is to use a variety of resistance loads that train the whole force velocity curve from heavy loads to explosive exercises with lighter loads moving the entire force velocity curve up and to the right in the concentric force velocity domain curves depicted.
and another 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 the morning and lifting in the afternoon after about 6 hours of rest and proper nutrition (18). However, even here the price to be paid is a loss of adaptive increases in type 1 muscle fiber size and no anaer- obic power increases after 3 months of training. This might be mitigated by reducing the oxidative stress by using only one sprint interval training day. Furthermore, even when short rest workouts can be tolerated, care must be taken to check and monitor exercise technique because its disintegra- tion is more probable, resulting in excessive microtears and injury to tissue. Short rest workouts in the weight room and sprint interval training on the 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 the body, thus creating an increased potential for overreaching conditions (7,32,33).
The heavier the resistance, the longer the rest that is needed to optimally recruit motor units. Although so-called strength-endurance is an important fitness characteristic, one cannot lift the 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; therefore, if strength is the primary target for im- provement, 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.
Almost inherent in every mili- tary training program is the challenge of training both aer- obic 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 the ones that are susceptible to the diverse op- posing stimuli for physiological adaptation. High-intensity en- durance training stimulates recruited motor units to opti- mize the size of their muscle fibers to increase oxidative ca- pacity (typically type 1 slow twitch fibers) by reducing their size (i.e., cross-sectional area), what might be called exercise- induced 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
TABLE1. 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 the understanding that this produces some of the highest metabolic stress responses in the weight room.
Heavy: 4–5 min for handling the heaviest resistance loads.
Very heavy: use of$5–7 min when maximal lifts are being performed.
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 the workout (18). Increases at 5 minutes after the workout, catecholamines were significantly higher by magnitudes compared with maximal treadmill exercise test results immediately after. With the exponential decay of catecholamines after the exercise, the magnitude of immediately postexercise concentrations were apparently dramatically higher. This workout protocol produced some of the highest lactate and catecholamine concentrations after exercise that have been reported in the literature. Thus, care must be taken when prescribing such exercise protocols and recovery allowed in subsequent workouts.
to happen is that type 1 fibers make no changes in their 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 the soldier athlete and compromises anaerobic capabilities, which are vitally important for the anaerobic battlefield of the present. Examining the impact of different aerobic training programs, it was shown that when soldiers only ran and even with the use of interval training, no improvements in loaded rucksack carriage over 2 miles were observed (19). Thus, the addition of a periodized heavy re- sistance training program is vital to overall physical perfor- mance. Various low volume sprint interval type workouts are a better choice to enhance maximal oxygen consump- tion or aerobic capacity while limiting the effects on anaer- obic 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 the training effects of different program combinations.
Ordering of Workouts
Although a topic of much research, the order of workouts may turn out to be a vital consideration in the subsequent adaptations to exercise training. The basis of a workout sequence appears to be related to the time course of genetic and cell signaling. Preliminary research points to the concept that those motor units that are stimulated by resistance exercise have their anabolic signaling blunted in some manner when immediately or shortly thereafter 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 environ- ment during the repair process. Alternatively, as noted before, one might separate the workouts by 6 hours, with, for example, a running workout being done in the morning and the lifting done in the afternoon. The underlying mediating mechanisms and definitive proof for the benefit of such ordering of workout modes remain experimental but
intuitively have some merit in the 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 the more prudent order of performing a workout with less oxidative and free radical stress (i.e., other forms of conditioning focusing on continuous short rest sequences, rather 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 the years. More important to the military is one corollary of periodization that is needed because of the dramatic challenges posed by competing mission schedules and differences in individual readiness to train (26). A number of features make the concept of “flexible nonlinear” periodization attractive not only to sport teams but to the military because of its rapid ability to alter a given workout on a given day (11). Flexible nonlinear periodiza- tion allows for a host of sequence orders while at times mimicking other periodization formats if the conditions allow (22,24). Thus, blocks or traditional linear sequences can be used in different mesocycles if the warfighter is ready to train and the situation is appropriate. The basis for the adaptability and therefore success of flexible nonlinear pro- gramming lies in the concept that quality of training is more important than going through the motions. Planned nonlin- ear periodization, although effective, may take longer to stimulate change because of the potentially longer cycling required to get enough heavy resistance training days. Thus, the use of the flexible nonlinear approach allows more free- dom to sequence workout days as needed in a mesocycle and defines the mesocycle dependent upon conditional needs, allowing for adaptability if the warfighter is not capa- ble of the 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 the range of mo- tion. Furthermore, the dif- ferent types of workouts allow for variety without the noncalculated mix of exercises seen in extreme commercial programs. Fi- nally, if one misses a work- out because of mission requirements or illness, one can pick up the next TABLE2. The effects of different training programs on muscle fiber cross-sectional area
in the thigh’s vastus lateralis and other performance variables (18,19).*
Type 1 Type 2 WG V_O2max 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.
workout sequence easily, modify it and continue on. One is not anchored to a set pattern outside of the desired goal for that mesocycle of 6–12 weeks. If the necessary workouts can- not be accomplished to meet the goals of a specific meso- cycle, a new one is created to allow for continuation of training.
The Flexible Nonlinear Program Approach
For consistency, the terminology of the flexible nonlinear approach is similar to that of classic periodization. The biggest period of time being dealt with is a “macrocycle,”
typically 12 months, the next phase is the “mesocycle,” which can range between 6 and 12 weeks and is mutable based on schedule. The smallest period of time is the “microcycle,”
which is the unique aspect of nonlinear programs and this is 1 day! Over a given mesocycle, a combination of workouts are planned to reflect the primary goal of the 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 depen- dent upon the individual’s readiness to train and this is determined with simple tests before the workout or by comparing workout logs and prior workout performances (11). Again, the goal is to promote quality and also allow for recovery to reduce the potential for overreaching (lead- ing to overtraining syndromes), which compromises the 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 the construct of the flexible nonlinear approach, but this will depend upon the goal of a particular workout design with its combination of workout variables, how that particular
workout fits into the goal for the mesocycle and how it then fits into the yearly or macrocycle training profile. In this process, not all soldiers will progress at the same rate, but general workout styles may be similar, unless a decrement is noticed in the 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 combina- tions of workouts that can be chosen which create a contin- uum of intensity, volume and rest period length interactions within the range of chosen exercises. Within the mesocycle, the guiding principle is to address the overall goal for that mesocycle. One can alter it based on the capability of the warfighter to perform the workout schedule. In some cases, the 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 the level needed, it can be switched out to a low volume recovery light workout or complete rest to avoid nonfunctional overreaching. Remem- ber this is a training program approach to conditioning and the implementation is related to the situations that exist and the needed individualization for the warfighter, the military occupational specialty, and the unit demands.
Using the unit’s yearly training plan or modular scenarios for Special Operations Forces (based around deployment cycles), one can create a basic plan based on the best avail- able knowledge. Next the goal of the mesocycle for a given period of time is developed based on the types of individuals who will use the 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 over- shooting them with program workouts that cannot be per- formed because of low fitness levels, lack of knowledge of exercise techniques, or more often, time constraints and competing unit training demands. By modifying work- outs within a given mesocycle to adapt to these training limi- tations, injuries typically seen even with functional exercises (when performed inappropri- ately) can be avoided.
Once a planned cycle is created, it is then challenged by the situational demands as to whether it can be accom- plished. If it can be done, the TABLE3. 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 the readiness for training for a particular workout.
This protocol uses a 5-day rotation (a 7-day rotation, etc. can also be used).
Light 1 set 12–15RM Very heavy for major exercises: 6 sets of 1–2RM
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 the program in proper sequence order and with adequate rest.
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 another day within that same week. The key is to accomplish the planned workouts for the week, but for a given day, an evaluation is made if the particular workout can be done with the needed quality required for it to stimulate the needed adaptation in the 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 Mon- day, but because of operational demands, the soldier cannot even jump to 90% of his or her best jump. One cannot just go through the 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 another workout while evaluating potential overreaching as velocity of movement and power are the 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 the given day. Although competitive athletes and warfighters will not admit to being tired, the performance will dictate the actual condition, and it is up to the strength and conditioning professional to make the call and alter the workout and its progression. One can make up the power workout somewhere else when optimal in that week’s cycle. Here is where the planned but flexible nature of this program approach shines. To coin an old U.S. Marine saying, “Improvise, adapt, and overcome.”
In a nonlinear program design, the microcycle is a single training day. The workout is part of a mesocycle plan and then with flexible nonlinear programming one attempts to adhere to the plan dependent upon the individual’s physical condition and whether the circumstances surrounding the day make the plan untenable (e.g., power workout planned but a 10-mile road march was the surprise of the morning). There are a host of different workouts that can be configured based on what the goals of the mesocycle are and what the 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 the part of the strength and conditioning pro- fessional. One must work within the given timeframes, even when not ideal, to optimize the warfighter’s physical develop- ment from a neuromuscular perspective. Thus, workouts can vary in intensity, volume, and frequency and are then further defined by the other acute program variables.
The importance of optimal training cannot be overstated.
Elite athletes do not enter a competition and do well if they are “overtrained” or have not tapered into an optimal phase
of training. Although mission tempo is unpredictable, the importance of not overshooting one’s ability to recover becomes even more important to optimize the mission. If one uses a program that has within a week hard runs and 6 short rest metabolic resistance training workouts, there 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 the job done, but this is typically because of youth or the incredible toleration of pain and suffering the warfighter possesses, yet as the 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 the concern is that the 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 the 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 the most out of each training session while allowing for recovery of tissue (e.g., supercompensation), and recognizing that this is different from the athlete who can plan the 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.
A number of workout styles exist dependent upon different combinations of the 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 the 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 the number of sets performed determine the total amount of work being done in a workout or cycle. Therefore, it is important to understand that the created workouts and their sequencing into a training program dictate the specific stimuli that will affect acute physiological demands, maladaptation or posi- tive adaptation leading to the performance status.
With the flexible nonlinear periodized approach, one has many workouts that can be incorporated into a plan for a 6- to 12-week mesocycle and then used as appropriate over that cycle of training. Thus, choices are many, and this allows variety, yet the 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 the literature. The multiple numbers of exercises that can be used in these workouts will dictate the musculature that is activated; therefore, these typical workouts are anchored by the intensity that is to be used.
Resistance loads exist over a continuum and finite cutoffs are
really related to the broad spectrum of effects documented in various zones. It is also important to understand that RM zones and percentage of 1RM will lose their equity as the size of the 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 then percentage of 1RM in many others (e.g., power cleans, pulls), derived either 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 the type 1 slow twitch motor units and if more than one set is used places demands on these motor units for metabolic substrate as with any high volume workout. If done as a single set of 20–30RM with.1 minute rest be- tween exercises, it can also be used a recovery workout allowing high threshold motor units to recover and repair.
The key to this is that the workout does not produce high amounts of oxygen reactive species and free radicals in the circulation as can happen if the metabolic intensity is ramped up with short rest periods and high volumes of work. So essentially there are a host of workouts within this very, very light intensity domain, and the effect will be based on the rest periods used that dictate the metabolic demand and the number of sets that will impact the volume of work.
Exercise technique can be seen to fail when such high rep- etition numbers are used in a set, and this can lead to in- creased microtears in tissue and injury. Therefore, monitoring of technique and proper exercise choices are vital in these workout styles. Thus, a recovery very, very light workout differs from high volume short rest workouts by rest period length and number of sets.
This is next in the line of intensities ranging from 12 to 20RM. The intensity is increased, which indicates more motor units will be used to perform the set. Again, this type of workout is directed toward again enhancing local muscular endurance but with heavier weights used at the lower end of the continuum, strength development can also be observed albeit much less than with heavier resistances.
Similar to the very very light workouts, these workouts are physiologically put in the context of the number of exercises and sets that determine total work and rest period lengths that determine the 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 the potential for injury. Here again,
a wide continuum of workouts are possible, but one has to determine whether the 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 the very very light workouts.
These workouts dominate the field of resistance training as they range in intensity from 8 to 12RM and have been widely used because of their ability to promote both strength and muscle size improvements in untrained individuals.
These workouts are again differentiated by the number of sets and exercises and the rest period lengths that dictate the metabolic demands. This resistance intensity range has been shown to produce the highest level of stress of any of the workouts when rest period length is shortened to 1–2 minutes between sets and exercises. This methodology grew out of the “cut phase” training approach typically seen in bodybuilders. When combined with longer rest and 8–10 exercises, it has typically been the standard workout for most individuals starting a resistance training program. However, when used within the context of short rest training, it creates a dramatic combination of muscle tissue damage, free radical production, and the 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 the warfighter so as not to compromise immediate mission readiness or cause loss of duty time because of excessive soreness or injury.
These workouts use typically 3–6RM loads and are directed toward increasing muscular strength or maximal force pro- duction capabilities in a given exercise movement. Outside of individuals or muscles with predominately type 1 slow twitch muscle fibers, these loads will recruit a predominant majority of the motor units available. Typically, large muscle group exercises (e.g., squats, leg presses, rows, pulls, cleans, bench press) are used for these types of loading. Because fatigue will reduce the number of repetitions that can be performed in a set with a heavy load, longer rest periods of .3 minutes are used. Because of the 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 the musculature is trained.
This is an important protective feature for the warfighter because this enhances repair and recovery.
Very Heavy Workouts
These loads are skilled based in that they range in the 1–2RM range and are used for direct determination of maximal strength and recruit all available motor units in muscle groups used to perform the given exercise. Exercise technique is vital within any workout and is important here as well. In the