The Future of Marine Corps Fitness
The Marine Corps has a fitness problem. Nearly every day, we are learning something new about fitness, human performance, and the way our bodies operate most efficiently, but the Marine Corps has dragged its feet in implementing changes to accommodate the latest information. Today, the Officer Candidates School webpage provides 90 and 180 day fitness preparation plans for interested candidates. Neither plan, however, recommends a structured strength regimen. Rather, the published plans consist only of high repetition bodyweight exercises and a high volume of moderate-intensity running. Additionally, neither the physical fitness test (PFT) nor the combat fitness test (CFT) provide a test of strength, which means the Marine Corps does not reward Marines for being strong—a critical element of fitness. Further, most Marines fail to recognize the impact functional strength has on endurance capacity. Combat readiness suffers as a result. The Marine Corps recognizes there are deficiencies, as evidenced by recent changes in the physical and combat fitness tests, the creation of high intensity tactical training (HITT), and the new Force Fitness Instructor MOS. Although these implementations may yield positive results, the concept of increasing repetition requirements and making run times faster is both unsustainable and insufficient. We are preparing the wrong way for the wrong test. The Corps needs education, functional strength, and a more complete fitness test. Intensity must be prioritized over volume—more is not better. This article serves to address fitness education, the importance of overall strength, and to recommend the implementation of the functional strength and power test.
First, some basic definitions:
• Compound exercise: More than one joint flexes and/or extends at the same time. These exercises produce the largest hormonal response, and are best for developing functional strength and power. For example, a squat requires flexion in three places: the hips, knees, and ankles. Other examples include: deadlift, clean, press, and bench press.
• Isolation exercise: One joint flexes or extends at a time. These exercises have a lower hormonal response, require less energy, and are not as effective for functional strength. For example, a bicep curl requires flexion followed by extension at the elbow.
• Adenosine triphosphate (ATP): The molecule that is broken down and used to provide energy to the human body. The human body uses three energy systems to turn ATP into usable energy.
• Intensity: A percentage of your maximum effort in a given event, i.e. running at 80 percent of your maximum heart rate or bench pressing 70 percent of your 1 repetition maximum (RM).
• Volume: The accumulation of sets, repetitions, distance, etc. For example, 5 miles of running or 2,000 pounds of squatting (10 repetitions at 200 pounds).
• The three energy systems1 (or metabolic pathways).
• Phosphagen or phosphocreatine (PC) pathway: Responsible for short, high intensity exercise lasting around 10 seconds using ATP as its primary fuel. This is your maximal strength and power. For example, a heavy barbell back squat or 100-meter sprint.
• Glycolytic (GL) pathway: Responsible for max effort exercise lasting from 30 seconds to about 21/2 minutes using blood glucose or stored muscle glycogen to convert to ATP. The movement to contact and maneuver under fire during the CFT are good examples.
• Oxidative or aerobic (OX) pathway: Responsible for longer, slower events such as a three-mile run or a nine-mile hike using oxygen to produce ATP. Indicated by the “Mitochondrial respiration” line on Figure 1.
Our bodies use whichever energy system(s) is required for the task at hand. For example, if you are executing a combat patrol and take enemy contact, your body will switch from the OX pathway (patrolling at a walking pace) to the PC pathway (sprinting for cover) and will continue adjusting as required. Figure 1 provides a visual understanding of the metabolic pathways. Note that all three pathways are operating in some fashion at any time and will adjust to demand. The x-axis is duration of exertion in seconds and the y-axis is ATP turnover, or energy demand.
Figure 1: Energy Systems
These systems are crucial to understanding complete fitness. Imagine the three metabolic systems (PC, GL, and OX in order from top to bottom) are part of a three-tiered fountain (see Figure 2) where filling one of the upper tiers also helps fill the lower tiers. Therefore, filling the PC tier also begins filling the GL tier and then the OX tier. If a Marine fills the top tier of the fountain (strength and power), he will also fill the other two tiers (aerobic endurance). However, if a Marine attempts to fill the fountain only filling the bottom tier (basing their training on endurance), they will never be able to effectively fill the two tiers above. Strength and power can improve endurance, but only training endurance does little to improve strength and power.
Figure 2: Three-tiered fountain.
Functional Strength, Applied
Consider the following example: Cpl Curl strength trains regularly and focuses primarily on individual muscle groups by performing isolation exercises and rarely doing compound movements, thereby neglecting his high-end strength, power, and the PC energy system. He can squat 200 pounds for one repetition and usually does “cardio” following his workout by running 3 miles, occasionally with a flak jacket at a moderate intensity. Another Marine, Sgt Squat, does functional strength and power training with compound exercises. He squats, deadlifts, presses, and cleans regularly and with good range of motion. He can squat 350 pounds for one repetition. His cardio consists of high-intensity intervals and metabolic conditioning workouts. Both are in the same unit and have a nine-mile hike, an aerobic event, coming up. The gear list equates to a total of 100 pounds, not an uncommon load. Halfway through the hike, Cpl Curl begins to struggle and eventually falls behind while Sgt Squat handles the hike with ease. What happened?
If each step these two Marines take during the hike are like one mini-repetition, each step required Sgt Squat to exert only 29 percent of his maximum capacity (100 pounds of gear divided by a 350 pound squat) while each step Cpl Curl took required him to exert 50 percent of his capacity (100 pounds of gear divided by a 200 pound squat). Eventually, Cpl Curl’s body was unable to keep up with the energy demand required for carrying a heavy load. In Cpl Curl’s regular physical training regimen, he only filled the bottom tier of the fountain and failed to effectively fill the two above. Sgt Squat used high intensity interval training to supplement his strength training, allowing him to effectively fill all three tiers from the top-down.
Math demonstrates the efficacy of this model, but does science? As it turns out, this is a common finding in studies that examine the relationship between strength, power, and endurance. In a study conducted by Leena Paavolainen, et al., 22 elite male cross-country runners were split into 2 groups for a 9 week training program. The “experimental group” replaced 32 percent of their overall training volume with explosive strength training, and the control group replaced only 3 percent of their training volume with the explosive exercises. The results: the experimental group showed statistically significant improvements in their 5km run time, running economy, and maximal 20 meter speed. (See Figure 3.) Specifically, runners in the experimental group shaved approximately 30 seconds off their 5km run time whereas the control group showed no improvement, actually getting slightly slower. This was after only nine weeks using relatively light loads at explosive speeds.2
Figure 3. 5km run times before and after in the experimental group (E) and control group (C).
In another study, 17 well-trained male and female runners, who had not strength trained in the previous 6 months, were tested for 5km run times and were then split into a test group and a control group. For three days per week for eight weeks, the test group performed half squats with four sets of four repetitions with their 4RM. They were given three minutes of rest between sets. They used free weights and added 2.5 kilograms each time they were able to complete a set without failure—a basic progressive overload principle. The control group conducted the same tests before and after the experiment but did not include any strength training. Results yielded a 33.2 percent improvement in 1RM half squat, a 26 percent increase in rate of force development, improved running economy (efficiency) at 70 percent effort, and a 21.3 percent increase in time to exhaustion at maximum aerobic speed (participants could run for longer at maximum aerobic speed). The control group showed no improvements in any metric that was measured.3
A third study examined the effectiveness of high intensity cardio versus steady state cardio in 40 individuals divided across four groups. Group 1 performed long, slow distance running (45 minutes at 70 percent max heart rate)—a common Marine Corps PT session. Group 2 performed lactate threshold training, running for 24.25 minutes at 85 percent max heart rate. Group 3 performed 47 running intervals of 15 seconds at 90 to 95 percent max heart rate and 15 seconds of active recovery jogging at 70 percent max heart rate. Group 4 performed four intervals lasting four minutes at 90 to 95 percent max heart rate with a 3-minute active recovery (70 percent effort) time between intervals. The results showed a significant difference between Groups 1 and 2 (the steady state, lower intensity groups) and 3 and 4 (high intensity group) in improving VO2 max. VO2 (maximal oxygen uptake) is considered one of the best scientific predictors of aerobic endurance, but typical Marine Corps PT sessions lack the intensity required to improve this metric. If there is one thing to take from this study it is that intensity is key—more is not better.4
Endurance training should not be dismissed, however. It tests aerobic capacity, efficiency, and, perhaps most importantly, mental toughness. Yet, there are better more efficient ways to train. From there, we can use a high level of physical fitness to test mental toughness and improve combat readiness.
Science demonstrates why Sgt Squat was able to out-perform Cpl Curl, and their situation is both common and universally applicable. Marines who squat frequently can exert more force on the ground and move faster when sprinting for cover. Marines who deadlift properly will use the same technique when lifting sandbags, water jugs, and carrying ammo cans. Marines who clean and press will have no problem lifting main packs from the ground and loading them onto the bed of an MTVR, all with less risk of injury and greater efficiency. These examples, and many more, demonstrate the potential improvements to combat effectiveness.
If these concepts were understood and applied, the overall physical performance of Marines in garrison and combat would increase dramatically. Marines would cover more ground faster, be less reliant on vehicles, fatigue slower, and would be more durable. Casualty evacuation would be faster and those remaining would have the endurance to continue fighting. Confidence would be higher. Our continued lethality as a warfighting organization necessitates a reassessment of our fitness programs, and it begins with our fitness tests. If we change the test, we change the way Marines prepare for the test, and that is the ultimate goal.
Functional Strength and Power Tests (FSPTs)
Our fitness tests must validate the capacity and efficiency of our energy systems. The smallest Marine must be able to evacuate the largest casualty; therefore, the test must require a high level of strength. The test must be easy to conduct, measure, and repeat by Marines in any location. Finally, and most importantly, the test would change the way Marines prepare for combat.
The PFT and CFT are one dimensional. They reward thin, aerobically- superior Marines and do not demand a significant level of strength in any particular modality. Currently, Marines can lack functional strength and appear fit, but this comes with reduced capability on the battlefield. Below are options as part of the functional strength and power test (FSPT), a test that addresses these concerns. Some events appear similar to current metrics with an added dimension while other elements are new. These are not meant to be definitive but to start a conversation about potential options. These events require that Marines become proficient in fundamental barbell strength and power exercises and require a high degree of conditioning, translating into a greater capacity to move large loads, long distances, quickly. (See Figure 4.)
Potential for Injury
A common concern with compound strength training is the potential for injury. Injury rates among elite and recreational trainees from both strength and endurance backgrounds have been widely researched. In multiple studies analyzed by StrengthandConditioningResearch.com,6 runners and endurance athletes experience between 2.5–12.1 injuries per 1,000 hours of training, whereas strength sports such as powerlifting and Olympic weightlifting only experience between 0.24 and 5.1 injuries per 1,000 hours of training.
In an interview the 1st Bn, 1st Marines Battalion Surgeon, LT Justin Beck, indicated that knee and lower back pain account for the preponderance of chronic injuries among Marines.7 Knee pain is usually expressed as patellar tendonitis and is the result of excessive running and hiking (overuse injury) as well as a lack of lower body development. Lower back pain is typically reported as the result of hiking or lifting weights. LT Beck stated that when a Marine reports an injury due to lifting weights, it is the result of poor form and a lack of proper technique. When questioned on the consistency of their physical training (specifically weight lifting), Marines typically reveal they either do not follow a structured strength plan, tried to lift more than they should have, or both.
In addition to warming up properly, LT Beck agreed that the best method for combating these injuries is the use of a structured, supervised strength plan. Strengthening the hips and posterior chain (lower back, glutes, and hamstrings) helps prevent common knee and lower back injuries by creating a balanced, stable base of support. This training also teaches Marines to use their musculature correctly when carrying heavy loads. Success in the FSPTs requires these recommendations are adhered to and requires unit leader’s investment in preparing their Marines properly.
The fiscal benefit to this approach is an additional benefit. For example, a common piece of gym equipment8 within the Marine Corps, such as the Nautilus Nitro-Nove Leg Extension/Curl machine, costs $3,799.99. For less, the Marine Corps could purchase three new barbell stands, each with a 365-pound barbell/plate combination. The same dollar amount could purchase forty 70-pound kettlebells, sixty 53-pound kettlebells, or seventy-nine 35-pound kettlebells. The Nautilus services one person and trains one muscle group. Common functional strength and fitness equipment costs considerably less and trains entire units—all requiring far less maintenance and producing superior results. To create functionally fit, confident, combat-ready Marines, the Marine Corps must reconsider this as a viable equipment investment strategy.
The Marine Corps has made efforts to address the abovementioned shortfalls. Next year promises changes in Marine Corps fitness: Marines must run faster and force fitness instructors will provide guidance and structure to commanders. However, compelling scientific evidence shows that the effort falls short of our true potential. Adding three pull-ups to the maximum PFT score and cutting a few seconds off the maximum movement to contact score fails to address the core deficiencies. Although many HITT modules include barbell strength training, the programs are unstructured and adhered to by only a small fraction of Marines. Further, the recommended PFT preparation program does not include any strength training. More drastic changes are needed.
In the Commandant’s most recent white letter,9 Gen Neller addresses the need to optimize physical performance and “make all Marines more lethal, resilient, and more capable on the battlefield.” Force fitness instructors are expected to be at the forefront of this mission, and I believe that implementing the FSPT best achieves the commander’s intent.
Fitness must be one of the Corps’ highest priorities. Gen Neller routinely emphasizes the importance of physical fitness, mandating the creation of a new MOS to meet his vision. We have the tools, we have the science, we have the information, and we have the intent. With the FSPT, we now have the method. I am proposing the Marine Corps revamp its physical fitness program again; only this time, it will be comprehensive and driven by modern science. Implement the FSPT—a well-rounded test that demands a high, but achievable, level of strength, power, and aerobic capacity. It is a test that will change the way physical training is conducted, shifting from archaic endurance-based training to a scientifically supported strength, power, and high-intensity regimen. Let’s achieve the Commandant’s intent and make all Marines more lethal, resilient, and more capable on the battlefield.
1. Jeremy DuVall, MS, CPT, Energy System Training for Athletes, (Colorado Springs, CO: National Strength and Conditioning Association, 2013), accessed at https://www.nsca.com.
2. Leena Paavolainen, Keijo Häkkinen, Ismo Hämäläinen, Ari Nummela, Heikki Rusko, “Explosive-strength Training Improves 5-km Running Time by Improving Running Economy and Muscle Power,” Journal of Applied Physiology, (Bethesda, MD: American Physiology Society, May 1999), 1527–1533. Citation includes the first of the three studies in the “Functional Strength Applied” paragraph as well as Figure 3.
3. Oyvind Storen, Jan Helgerud, Eva Maria Stoa, and Jan Hoff, “Maximal Strength Training Improves Running Economy in Distance Runners,” Medicine and Science in Sports and Exercise, (Indianapolis, IN: 2008), 1087.
4. Jan Helgerud, Kjetill Hoydal, Eivind Wang, Trine Karlsen, Pålr Berg, Marius Bjerkaas, Thomas Simonsen, et al., “Aerobic High-Intensity Intervals Improve VO2Max More Than Moderate Training,” Medicine and Science in Sports and Exercise, (Indianapolis, IN: 2007), 665.
5. Functional Strength and Power Test 2: Men use a 32kg or 70-pound kettlebell, women use a 24kg or 55-pound kettlebell swung to eye level. Specific standards for all FSPTs will be established and introduced with enough time for Marines to learn and practice those standards prior to implementation.
6. Strength and Conditioning Research, “Which Strength Sport is Most Likely to Cause an Injury?” (8 July 2014), accessed at https://www.strengthandconditioningresearch.com.
7. LT Justin L. Beck, USN, Battalion Surgeon, 1st Bn, 1st Marines, interview by author, (26 September 2016). This interview was conducted by the author with LT Beck. In order to ensure unbiassed responses, LT Beck had not read nor was he aware of the contents of this article prior to the interview.
8. Pricing for the Nautilus Nitro-Nove Leg Extension/Curl machine is from Amazon.com. Pricing for the stand, bar/plate, and kettlebells are from Rogue Fitness and are as follows: Rogue ES-1 Squat Stand, Alpha Bar and Bumper Set, and Rogue Kettlebells.
9. Commandant of the Marine Corps, “White Letter 2-16, Marine Corps Physical Fitness Program,” (Washington, DC: 1 September 2016).