Secondary Logo

Journal Logo

U.S. Army Physical Demands Study

Differences in Physical Fitness and Occupational Task Performance Between Trainees and Active Duty Soldiers

Canino, Maria C.1; Foulis, Stephen A.1; Zambraski, Edward J.1; Cohen, Bruce S.1; Redmond, Jan E.1; Hauret, Keith G.2; Frykman, Peter N.1; Sharp, Marilyn A.1

The Journal of Strength & Conditioning Research: July 2019 - Volume 33 - Issue 7 - p 1864–1870
doi: 10.1519/JSC.0000000000002681
Original Research
Free

Canino, MC, Foulis, SA, Zambraski, EJ, Cohen, BS, Redmond, JE, Hauret, KG, Frykman, PN, and Sharp, MA. U.S. Army Physical Demands Study: Differences in physical fitness and occupational task performance between trainees and active duty soldiers. J Strength Cond Res 33(7): 1864–1870, 2019—U.S. Army initial entry training (IET) is designed to prepare trainees for the military environment and subsequent training, including specific programs to increase physical fitness to perform job-specific tasks to the minimal acceptable performance standard (MAPS). The aim of this study was to compare physical fitness and occupational task performance of trainees at the end of IET to that of active duty soldiers. One hundred seventy-nine male combat arms trainees at the end of IET and 337 male combat arms active duty soldiers performed a sandbag carry (SBC), casualty drag (CD), and move under direct fire (MUF). Physical fitness was assessed using Army Physical Fitness Test scores. A questionnaire was administered to determine frequency of task performance. Active duty soldiers compared with trainees were older (p < 0.01) and performed more push-ups (p < 0.01) and sit-ups (p < 0.01). Trainees performed the 2-mile run faster (p < 0.01). Ninety-four percent of trainees and 99% of active duty soldiers performed the 3 tasks to the MAPSs. Active duty soldiers performed significantly faster on both the SBC (p < 0.01) and CD (p < 0.01) and reported a higher task frequency on the SBC (p = 0.03) and CD (p < 0.01). No difference in MUF performance (p = 0.16) and task frequency (p = 0.13) was detected. Initial entry training seems to provide sufficient physical training as most trainees were able to meet the MAPSs; however, performance differences were still apparent between trainees and active duty soldiers. Additional practice performing the physically demanding tasks may help maximize performance on the physically demanding job requirements.

1Military Performance Division, U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts; and

2Injury Prevention Division, U.S. Army Public Health Center, Aberdeen Proving Ground, Aberdeen, Maryland

Address correspondence to Maria C. Canino , maria.c.canino.ctr@mail.mil.

Back to Top | Article Outline

Introduction

Optimally preparing army trainees during initial entry training (IET) for the physical demands of their military occupational specialty (MOS) is essential to ensure military readiness in both training and deployed environments. The goal of IET is to mentally and physically prepare trainees for the military environment and subsequent training (31). Individual physical capability may directly influence the combat effectiveness of a military organization (4). Physically demanding MOSs, particularly those with high strength demands, have been shown to be associated with an increased risk of musculoskeletal injury (27), which can compromise overall military readiness. Trainees and soldiers need to develop and maintain high levels of physical fitness to successfully perform occupational tasks and prevent injuries (14). Some tasks also contain skill-related components that must be developed to increase the efficiency of task performance (14).

In the past, the U.S. Army has not required any formal assessments of a trainee's ability to perform the physically demanding tasks of their intended MOS before IET graduation. Physical fitness and readiness for duty have been evaluated by administering the Army Physical Fitness Test (APFT) at the end of IET as a graduation requirement for trainees, whereas active duty soldiers perform it biannually. The APFT consists of the maximum number of push-ups and sit-ups in 2 minutes and a timed 2-mile run. These events are measurements of muscular endurance and cardiorespiratory fitness. Although the APFT is a good indicator of overall physical fitness (18), the APFT has been consistently shown to not correlate well with soldiering tasks (8,16). This raises concerns with the APFT's ability to determine an individual's ability to perform physically demanding occupational tasks (13,16) due to the lack of muscular strength and power assessments.

In 2017, the U.S. Army instituted new physical employment standard testing (9). The U.S. Army Training and Doctrine Command now requires trainees to successfully perform common and MOS-specific physically demanding tasks to the minimal acceptable performance standard (MAPS) by the end of IET. It is unclear how well trainees perform these tasks in comparison with experienced soldiers, who have reported performing these tasks as part of their job duties (5,30). As part of the U.S. Army Physical Demands Study (8), fully trained soldiers were assessed performing the physically demanding tasks of their respective MOS. The aim of this study was to compare physical fitness and occupational task performance of U.S. Army combat arms trainees at the end of their IET to that of active duty combat arms soldiers to evaluate trainee combat readiness.

Back to Top | Article Outline

Methods

Experimental Approach to the Problem

The U.S. Army trainees at the end of IET and active duty soldiers completed 3 occupational tasks (i.e., sandbag carry [SBC], casualty drag [CD], and move under direct fire [MUF]). Physical fitness was assessed using APFT scores, which were collected from the trainees' units and were self-reported by the active duty soldiers. Physical fitness and occupational task performance measures were compared between trainees and active duty soldiers. In addition, a task frequency questionnaire was administered to see whether there were significant differences in exposure to the physically demanding MOS tasks and frequency of task performance.

Back to Top | Article Outline

Subjects

A total of 179 U.S. Army male combat arms trainees at the end of their IET and 337 active duty male combat arms soldiers performed 3 critical physically demanding tasks (CPDTs): SBC, CD, and MUF. All subjects held one of the following combat arms MOSs: infantryman (11B), infantryman-indirect fire (11C), fire support specialist (13F), or cavalry scout (19D).

The investigators adhered to the policies for protection of human subjects as prescribed in Army Regulation 70-25, and the research was conducted in adherence with the provisions of 45 Code of Federal Regulations (CFR) Part 46. All subjects were briefed on the methodology of the study. Subjects completed an informed consent document approved by the U.S. Army Research Institute of Environmental Medicine Institutional Review Board and a health risk screening questionnaire. In compliance with Department of Defense Instruction (DoDI) 3216.202, trainees who are 17 years of age are considered adults while in federal duty status and are allowed to consent without parent or guardian approval.

Back to Top | Article Outline

Procedures

Height (cm) and body mass (kg) were measured and recorded for all subjects and body mass index (BMI; kg·m−2) was calculated from these measures. Subjects also completed a task frequency questionnaire to report whether they have performed the 3 CPDTs (prevalence) and, if so, how many times they have performed each of them (frequency) throughout their career. Physical fitness was assessed using APFT data. The APFT was performed at their respective army posts after the procedures specified in U.S. Army FM 7-22 (11). This includes maximum number of push-ups and sit-ups in 2 minutes and a timed 2-mile run (minutes). Final APFT scores of the trainees were obtained from training units and administered within 2 weeks of the current study. Active duty soldiers self-reported their most recent APFT scores, which is administered every 6 months. Although the study investigators did not conduct the active duty soldiers' APFT, strong correlations (r = 0.71–0.85) have been reported when comparing unit- and self-reported APFT data (12,23).

All subjects were instructed to perform 3 CPDTs for time as previously described by Foulis et al. (7): SBC, CD, and MUF. Briefly, the SBC MAPS required moving 16 sandbags (18.1 kg each) a distance of 10 m and building a hasty fighting position in 16 minutes (Figure 1A). The CD MAPS required dragging a 123-kg simulated casualty 15 m in 60 seconds (Figure 1B). The MUF entailed a series of 15, 6.6-m combat rushes that cycled between 2 kneeling and 1 prone rest positions (Figure 1C). The MAPS for MUF was to successfully complete the task.

Figure 1

Figure 1

Back to Top | Article Outline

Statistical Analyses

Statistical analyses were performed using SPSS for Windows Version 24 (IBM Corporation, Armonk, NY, USA) and Microsoft Excel 2013 (Microsoft, Redmond, WA, USA). Descriptive statistics were calculated and reported as mean ± SD for each group. Independent sample t-tests were used to compare group differences in demographics. Univariate analysis of covariance, with age, height, and body mass as covariates, was used to compare differences in APFT scores and CPDT performance between the trainees and active duty soldiers. For any CPDT where the MAPS was not achieved by all subjects, a chi-square analysis was performed to determine whether there was a significant difference between trainees and active duty soldiers in the percentage of attaining the MAPS. The Mann-Whitney U-test was used to determine differences in CPDT performance frequency based on self-report. An alpha level of p ≤ 0.05 was used for significance testing.

Back to Top | Article Outline

Results

Group characteristics are provided in Table 1. Active duty soldiers were significantly older (p < 0.01). There were no differences in height (p = 0.29), body mass (p = 0.47), or BMIs (p = 0.77) between groups. The results from the APFT data in Table 2 show that active duty soldiers performed more push-ups (p < 0.01) and sit-ups (p < 0.01) in 2 minutes compared with the trainees. By contrast, the trainees had faster 2-mile run times than active duty soldiers (p < 0.01).

Table 1

Table 1

Table 2

Table 2

Performance on the 3 CPDTs is summarized in Table 3. Active duty soldiers performed significantly better on the SBC (p < 0.01) and CD (p < 0.01) tasks. No differences were found in MUF performance between the trainees and active duty soldiers (p = 0.16). All subjects met the MAPS for the SBC and MUF tasks. For the CD, a greater percentage of active duty soldiers attained the MAPS compared with the trainees (99.7 vs. 93.9%, respectively; p < 0.01). Active duty soldiers reported a greater frequency of task performance on the SBC (p = 0.03) and CD (p < 0.01) compared with the trainees (Table 4). No difference in task performance frequency was detected on MUF (p = 0.13) between the 2 groups.

Table 3

Table 3

Table 4

Table 4

Back to Top | Article Outline

Discussion

The current study shows that active duty soldiers compared with trainees performed significantly better in push-ups, sit-ups, the SBC, and the CD. Compared with active duty soldiers, trainees performed the 2-mile run significantly faster. Overall, IET seems to provide sufficient physical training because most trainees (>90%) were able to meet the MAPSs for the 3 CPDTs.

Recently, it was determined that U.S. Army male active duty soldiers performed significantly better on the APFT events across all age groups in comparison with male trainees in the first 3 weeks of their IET (6). It was assumed the differences on the APFT were likely due to the active duty soldiers having more experience performing the test along with more intense physical training. Because the trainees' APFT data in the current study were retrieved from the end of their IET rather than the beginning, the trainees had already become familiarized with the APFT events. The active duty soldiers performed significantly more push-ups and sit-ups, whereas trainees had faster 2-mile run times. The faster 2-mile run times by the trainees could be due to the greater emphasis placed on cardiorespiratory fitness during IET, related to the forms of running, road marching, obstacle courses, and other strenuous modes of physical activity (15,21). Although strong correlations have been previously reported between self- and unit-reported APFT data, slightly inflated performance values have been shown in self-report data (23). The potential inflation may have led to higher push-up and sit-up scores in the active duty soldiers; however, they still reported slower 2-mile run times compared with the trainees in this study.

The SBC is a repetitive lift-and-carry task that requires a combination of muscular strength and muscular endurance. It has been shown that expert and novice workers perform manual materials handling tasks differently in terms of body position during loading/unloading phases, foot movements during the transfer, and grip on the material (1). The active duty soldiers had a longer mean service time (i.e., 3 years) and reported performing the task more frequently, which may have allowed refinements in techniques to improve performance and efficiency of the task; however, the current study did not use visual aids (e.g., video recording) to analyze or evaluate technique differences between trainees and active duty soldiers. Other variables such as muscular strength levels and muscle mass may also have been responsible for performance differences in particular manual materials handling task (29).

Lean body mass and physical fitness have been shown to be modifiable factors that can improve occupational carrying performance. It has been reported that body composition, muscular strength, muscular power, and sprint time are all strong predictors of a manual carrying task performance (4,19). Beck et al. (2) reported leg lean mass as the most influential contributor for performance on 2 military carrying tasks. Unfortunately, we were unable to adjust for body composition in our subjects to determine the effect of lean body mass on SBC performance.

Heavy physically demanding military tasks, such as the CD, require high levels of muscular strength (22). Heavier (34) and taller (25) individuals are able to complete a CD task faster. Dragging a casualty can be separated into 2 parts: the vertical lifting and the horizontal pulling of the casualty (25). In addition, the friction of the pulling surface (i.e., smooth vs. rough) contributes to overall performance. For example, on rough surfaces (e.g., grass or gravel), it is optimal to lift the casualty higher off the ground to reduce the amount friction. This, however, requires greater levels of muscular strength to lift the casualty, which puts shorter and weaker individuals at a disadvantage (32). The statistical analyses were adjusted for both height and body mass, but performance differences were still observed between trainees and active duty soldiers.

Foulis et al. (7) reported that CD performance did not improve across 4 trials in active duty soldiers, indicating that neither learning nor training effects were experienced. Both upper- (20) and lower-body (24) muscular power have been reported to be strong predictors of CD performance. In addition, the skill-related components required for heavy drag tasks can only be attained from practice (28). It is speculated that greater levels of muscular strength and power, self-reported higher task frequency, and the development of skill components from increased task exposure may have contributed to superior performance in the active duty soldiers in this study.

There were no differences in MUF performance between trainees and active duty soldiers. Foulis et al. (7) reported performance improvements in MUF from only the first to second trial. This indicates that an additional trial may have been necessary to familiarize subjects to the task simulation compared with how they would normally perform it during training. Furthermore, our results showed a 1.8-second (0.03 minutes) difference, which is less than the 3.6-second detectable difference reported in the reliability study (7). The 2-second or approximately a 1% difference between the trainees and active duty soldiers in the current study may not seem very substantial; however, one could contend this difference could mean life or death in a combat environment.

Performing combat rushes (e.g., MUF) while carrying an external load (extra weight to move) and holding a weapon (upper-body restriction for sprinting) require specific physical conditioning in order for significant improvements in performance (33). Billing et al. (3) found that maximal velocity did not change in repeated 6-meter sprint repetitions with varying external loads in experienced soldiers. Although a slower sprint time would be expected when wearing an external load, 51.7% of total performance loss during a prone start sprint with an external load occurred in the first 5 meters (33). The requirement of rising from a prone position with an external load into a sprint slows the momentum of performance at the start. The current study required the subjects to assume a prone position at every third marker. Rising from a prone position under a heavy load multiple times and the difficulty to improve sprint performance in a short distance (6.6 meters) are 2 possible explanations for the lack of performance differences between trainees and active duty soldiers. The 2 groups likely had equivalent skills performing this task because there were no differences in the reported performance frequency of task. Further research should investigate training modalities to improve performance on repeated sprint ability with an external load.

Finally, an important factor must be addressed regarding the task frequency questionnaire because there was not an equivalent timeframe between the trainees and active duty soldiers. The active duty soldiers based their answers on their entire military career (mean time in service of 3 years), whereas the trainees' careers consisted of only their time in IET (12–14 weeks). Harman et al. (10) state that short training periods (such as 8–10 weeks in basic combat training) may not elicit large improvements in physical performance of military tasks. Others have suggested task-specific physical training, and more exposure to the task is effective in improving performance of a single task (17,26). It is speculated that one of the explanations for better SBC and CD performance by the active duty soldiers is that they had more experience performing the tasks due to a longer time in service. This factor highlights the importance of having sufficient time to practice the tasks to improve performance.

Back to Top | Article Outline

Practical Applications

This study highlights physical fitness and occupational task performance differences between trainees and experienced active duty soldiers. Most trainees met the MAPSs at the end of their IET, indicating that IET was successful in preparing the trainees to perform the physically demanding tasks of their MOS. Although the trainees may have met the minimal physical requirements at the end of their IET, performance differences were still apparent between the trainees and active duty soldiers, possibly in part to physical fitness and experience differences. Refinements should be continuously made to ensure that IET is optimizing performance in soldiers and other tactical athletes. This may include more task-specific practice of physically demanding tasks and the development of conditioning programs to enhance muscular strength and power.

Back to Top | Article Outline

Acknowledgments

The authors thank all the researchers and soldiers who participated in the data collection. The research team adhered to the policies for protection of human subjects as prescribed in Army Regulation 70-25, and the research was conducted in adherence with the provisions of 45 Code of Federal Regulations (CFR) Part 46. This research was supported in part by appointments to the Postgraduate Research Participation Program at the U.S. Army Research Institute of Environmental Medicine administered by the Oak Ridge Institute for Science and Education. The opinions or assertions contained herein are the private views of the author(s) and are not to be construed as official or as reflecting the views of the Army or the Department of Defense. Any citations of commercial organizations and trade names in this report do not constitute an official Department of the Army endorsement or approval of the products or services thereof.

Back to Top | Article Outline

References

1. Authier M, Lortie M, Gagnon M. Manual handling techniques: Comparing novices and experts. Int J Indust Ergon 17: 419–429, 1996.
2. Beck B, Carstairs GL, Billing DC, Caldwell JN, Middleton KJ. Modifiable anthropometric characteristics are associated with unilateral and bilateral carry performance. J Strength Cond Res 31: 489–494, 2017.
3. Billing DC, Silk AJ, Tofari PJ, Hunt AP. Effects of military load carriage on susceptibility to enemy fire during tactical combat movements. J Strength Cond Res 29: S134–S138, 2015.
4. Bilzon JL, Scarpello EG, Bilzon E, Allsopp AJ. Generic task-related occupational requirements for Royal Naval personnel. Occup Med (Lond) 52: 503–510, 2002.
5. Boye MW, Cohen BS, Sharp MA, Canino MC, Foulis SA, Larcom K, et al. U.S. Army Physical Demands Study: Prevalence and frequency of performing physically demanding tasks in deployed and non-deployed settings. J Sci Med Sport 20: S57–S61, 2017.
6. Dada EO, Anderson MK, Grier T, Alemany JA, Jones BH. Sex and age differences in physical performance: A comparison of Army basic training and operational populations. J Sci Med Sport 20: S68–S73, 2017.
7. Foulis SA, Redmond JE, Frykman PN, Warr BJ, Zambraski EJ, Sharp MA. U.S. Army Physical Demands Study: Reliability of simulations of physically demanding tasks performed by combat arms soldiers. J Strength Cond Res 31: 3245–3252, 2017.
8. Foulis SA, Sharp MA, Redmond JE, Frykman PN, Warr BJ, Gebhardt DL, et al. U.S. Army Physical Demands Study: Development of the occupational physical assessment test for combat arms soldiers. J Sci Med Sport 20: S74–S78, 2017.
9. Funkhouser AC. Commentary: Why the OPAT will improve new soldier readiness and how the Army is doing it right, 2016. Available at: https://www.armytimes.com/news/your-army/2016/12/30/commentary-why-the-opat-will-improve-new-soldier-readiness-and-how-the-army-is-doing-it-right/. Accessed November 1, 2017.
10. Harman EA, Gutekunst DJ, Frykman PN, Nindl BC, Alemany JA, Mello RP, et al. Effects of two different eight-week training programs on military physical performance. J Strength Cond Res 22: 524–534, 2008.
11. Headquarters. FM 7–22 Army Physical Readiness Training. Washington, DC: Department of the Army, 2012. Available at: http://www.apd.army.mil/epubs/DR_pubs/DR_a/pdf/web/fm7_22.pdf. Accessed November 16, 2017.
12. Jones SB, Knapik JJ, Sharp MA, Darakjy S, Jones BH. The validity of self-reported physical fitness test scores. Mil Med 172: 115–120, 2007.
13. Knapik J, Staab J, Bahrke M, O'Connor J, Sharp M, Frykman P, et al. Relationship of Soldier Load Carriage to Physiological Factors, Military Experience and Mood States. Technical Report T17-90. Natick, MA: U.S. Army Research Institute of Environmental Medicine, 1990. Available at: http://www.dtic.mil/dtic/tr/fulltext/u2/a227007.pdf. Accessed November 15, 2017.
14. Knapik JJ. The importance of physical fitness for injury prevention: Part 1. J Spec Oper Med 15: 123–127, 2015.
15. Knapik JJ, Graham BS, Rieger J, Steelman R, Pendergrass T. Activities associated with injuries in initial entry training. Mil Med 178: 500–506, 2013.
16. Knapik JJ, Hauret KG, Arnold S, Canham-Chervak M, Mansfield AJ, Hoedebecke EL, et al. Injury and fitness outcomes during implementation of physical readiness training. Int J Sports Med 24: 372–381, 2003.
17. Knapik JJ, Sharp MA. Task-specific and generalized physical training for improving manual-material handling capability. Int J Indust Ergon 22: 149–160, 1998.
18. Knapik JJ, Sharp MA, Steelman RA. Secular trends in the physical fitness of United States Army recruits on entry to service, 1975–2013. J Strength Cond Res 31: 2030–2052, 2017.
19. Leyk D, Rohde U, Erley O, Gorges W, Essfeld D, Erren TC, et al. Maximal manual stretcher carriage: Performance and recovery of male and female ambulance workers. Ergonomics 50: 752–762, 2007.
20. Lindberg AS, Oksa J, Antti H, Malm C. Multivariate statistical assessment of predictors of firefighters' muscular and aerobic work capacity. PLoS One 10: e0118945, 2015.
21. Lisman PJ, de la Motte SJ, Gribbin TC, Jaffin DP, Murphy K, Deuster PA. A systematic review of the association between physical fitness and musculoskeletal injury risk: Part 1-cardiorespiratory endurance. J Strength Cond Res 31: 1744–1757, 2017.
22. Mala J, Szivak TK, Flanagan S, Comstock BA, Laferrier JZ, Maresh CM, et al. The role of strength and power during performance of high intensity military tasks under heavy load carriage. US Army Med Dep J Apr-Jun: 3–11, 2015.
23. Martin RC, Grier T, Canham-Chervak M, Anderson MK, Bushman TT, DeGroot DW, et al. Validity of self-reported physical fitness and body mass index in a military population. J Strength Cond Res 30: 26–32, 2016.
24. Pihlainen K, Santtila M, Häkkinen K, Kyröläinen H. Associations of physical fitness and body composition characteristics with simulated military task performance. J Strength Cond Res 32: 1089–1098, 2018.
25. Reilly T, Olinek S. Predicting casualty evacuation performance for the Canadian land forces command. Occup Ergon 11: 1–9, 2013.
26. Roberts D, Gebhardt DL, Gaskill SE, Roy TC, Sharp MA. Current considerations related to physiological differences between the sexes and physical employment standards. Appl Physiol Nutr Metab 41: S108–S120, 2016.
27. Roy TC, Knapik JJ, Ritland BM, Murphy N, Sharp MA. Risk factors for musculoskeletal injuries for soldiers deployed to Afghanistan. Aviat Space Environ Med 83: 1060–1066, 2012.
28. Schonfeld BR, Doerr DF, Convertino VA. An occupational performance test validation program for fire fighters at the Kennedy Space Center. J Occup Med 32: 638–643, 1990.
29. Sharp M, Rosenberger M, Knapik J. Chapter 5-Common Military Task: Materials Handling. Technical Report TR-HFM-080. NATO Research and Technology Organisation, 2009. Available at: http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.215.71&rep=rep1&type=pdf. Accessed December 5, 2017.
30. Sharp MA, Cohen BS, Boye MW, Foulis SA, Redmond JE, Larcom K, et al. U.S. Army Physical Demands Study: Identification and validation of the physically demanding tasks of combat arms occupations. J Sci Med Sport 20: S62–S67, 2017.
31. Sharp MA, Knapik JJ, Patton JF, Smutok MA, Hauret K, Canham-Chervak M, et al. Physical Fitness of Soldiers Entering and Leaving Basic Combat Training. Technical Report T00-13. Natick, MA: U.S. Army Research Institute of Environmental Medicine, 2000. Available at: http://www.dtic.mil/get-tr-doc/pdf?AD=ADA374356. Accessed December 13, 2017.
32. Shephard RU. Exercise and training in women, part I: Influence of gender on exercise and training responses. Can J Appl Physiol 25: 19–34, 2000.
33. Treloar AK, Billing DC. Effect of load carriage on performance of an explosive anaerobic military task. Mil Med 176: 1027–1031, 2011.
34. von Heimburg ED, Rasmussen AK, Medbø JI. Physiological responses of fire fighters and performance predictors during a simulated rescue of hospital patients. Ergonomics 49: 111–126, 2006.
Keywords:

military; occupational performance; training

Copyright © 2019 by the National Strength & Conditioning Association.