Several studies have shown that conditioning programs consisting of resistance and cardiovascular training in female soldiers improve physical performance, including adaptations in strength, power, and endurance, and also show that resistance training reduces gender differences in physical performance (10,15,18,19,31). Kraemer et al. (18) examined several periodized resistance training programs over a 6-month period. Subjects in the study were grouped into a total or upper-body only strength/power exercise program using 3- to 8-RM loads, a total or upper-body only strength/hypertrophy exercise program using 8- to 12-RM loads, an aerobic-only group, and a field exercise group. The field exercise group was limited to body weight, partner-assisted resistance, and ballistic exercise. The results of the study demonstrated that improvements were specific to the type of training program used. Significant improvements were observed in military occupational tasks such as repetitive box lifting in both the total body and upper-body resistance training groups. The study also demonstrated improvements in 1RM squat and bench press in the field training group during the first 3 months of training, supporting the inclusion of alternate training methods into a strength training program when traditional resistance training equipment may not be available. Most importantly, because it relates to the disparity of strength between men and women, this study demonstrated that 6 months of resistance training reduced the gender gap in physical performance measures. Moreover, all female soldiers in the resistance training groups successfully attained scores in the 2-minute push-up, 2-minute sit-up, and 2-mile run events that would pass the Army Physical Fitness Test (APFT), whereas the same was not true in the aerobic or field exercise groups. To support the importance of resistance training as an effective strategy to improve the ability to perform occupational tasks, Knapik (16) also reported that progressive resistance exercise with interval training improved the manual material handling capability of female soldiers. Additional studies support a combination of various types of training that include strength, power, ballistic, and plyometric exercises to elicit the greatest performance improvements in women (11,13,29,37).
When monitoring the strength and conditioning program, it can be expected that men and women may exhibit different responses to the program, especially in new trainees. Kell (15) examined the absolute and relative strength of men and women with previous resistance training experience after a 12-week traditionally periodized resistance training program. The program was a split routine with intensity of 55–87% for 3–4 sets per exercise. An approximate 28–38% increase in strength was seen in both female and male soldiers as a result of the periodized resistance training. Although the men were stronger in absolute terms, the women were more responsive to the training program.
The APFT is comprised a 2-mile run and 2 minutes of push-ups and sit-ups. Desired outcomes of an Army PT program should not only be based on measurable improvements in the performance of the APFT events. By military standards, physical improvements should include decreased run/loaded march times for a specific distance and increasing the number of push-up and sit-up repetitions in a given time. Improving performance safely and effectively with considerations of daily mission requirements and operational tempo are necessary metrics by which to monitor workouts, performance, rest, and recovery. Resistance training provides a stimulus by which women can significantly improve strength, and thus increase the likelihood of safely and successfully performing military occupational tasks that require a strength component.
Occupational demands (e.g., load carriage, box lifting) often require multijoint functioning, and several studies have examined long-term effects of multijoint exercises on the physical performance in women. Kraemer et al. (18,19) showed that a nonlinear program focused on strength and power using multijoint exercises was capable of producing continued increases in muscle hypertrophy in untrained women beyond 6 months. In another study, Reynolds et al. (31) conducted a 24-week periodized strength- and running-based training program in 45 recreationally active women, which resulted in a 33% improvement in maximum box weight that was lifted to a height of 52 inches. When posttraining results were compared with a sample of Army men, the women's average maximum box weight lifted was 81% (117 lb) of the box weight lifted by men (144 lb). Additionally, the study found that the women's loaded marching speed was 80% (4 mph) of the men's speed (5 mph) after completion of the training program. Although female soldiers were not able to lift as much weight as their male counterparts, the average weight lifted by women at the conclusion of this study falls within the MOS Physical Demands Rating of “heavy” by the U.S. Army. This study further supports that a periodized exercise training program results in significant performance improvements in women, thus narrowing the margin of fitness outcomes between men and women (Figure 2).
Competitive athletes generally tailor their PT to a specific sport and position and periodize their exercise training so that they are at their peak physical performance during a competitive season or event. Soldiers, however, must possess a strong foundation of fitness consisting of a myriad of physical capabilities that draw on all facets of physical and psychological fitness necessary to successfully maintain a state of physical and operational readiness. Considering that women are integrating into broader military occupational roles that are often physically arduous and conducted in hostile and austere environments, appropriate PT is the conduit to unit physical and operational readiness.
As the PT program is developed, the unique set of skills and physical capabilities (e.g., baseline fitness measures, military task requirements, and rate of physical progression) of all soldiers in a unit need to be assessed, along with an understanding that acute or daily adjustments may be needed based on operational tempo and soldier feedback. Additionally, disparities exist between men and women in baseline fitness measures of power, muscular strength, and endurance, which are important considerations when developing and implementing a PT program. A concurrent PT program consisting of both cardiovascular and resistance exercises that physically tax all muscle groups and develops all fitness parameters is a requisite to successfully perform military occupational tasks and mitigate injuries. Additionally, an undulating periodized fitness program will optimally prepare the female soldier for future endeavors that require a high level of physical preparedness while also reducing the potential for injury. It is the responsibility of the strength and conditioning professional to design PT programs that increase the physical work capacity of women by enabling them to attain their maximal physiological potential.
The authors would like to thank Dr Edward J. Zambraski, Dr Jan E. Redmond, Marilyn Sharp, and Kristen Heavens for their valuable input and guidance in the development of this article.
1. Baechle TR, Earle RW; National Strength & Conditioning Association (U.S.). Essentials of Strength Training and Conditioning. Champaign, IL: Human Kinetics, 2008.
2. Bien DP. Rationale and implementation of anterior cruciate ligament injury prevention warm-up programs in female
athletes. J Strength Cond Res 25: 271–285, 2011.
3. Bullock SH, Jones BH, Gilchrist J, Marshall SW. Prevention of physical training-related injuries recommendations for the military
and other active populations based on expedited systematic reviews. Am J Prev Med 38: S156–S181, 2010.
4. Cline AD, Jansen GR, Melby CL. Stress fractures in female
army recruits: Implications of bone density, calcium intake, and exercise. J Am Coll Nutr 17: 128–135, 1998.
7. Evans RK, Antczak AJ, Lester M, Yanovich R, Israeli E, Moran DS. Effects of a 4-month recruit training program on markers of bone metabolism. Med Sci Sports Exerc 40: S660–S670, 2008.
8. Evans RK, Negus CH, Centi AJ, Spiering BA, Kraemer WJ, Nindl BC. Peripheral QCT sector analysis reveals early exercise-induced increases in tibial bone mineral density. J Musculoskelet Neuronal Interact 12: 155–164, 2012.
9. Finestone A, Milgrom C, Evans R, Yanovich R, Constantini N, Moran DS. Overuse injuries in female
infantry recruits during low-intensity basic training. Med Sci Sports Exerc 40: S630–S635, 2008.
10. Gravelle BL, Blessing DL. Physiological adaptation in women concurrently training for strength and endurance. J Strength Cond Res 14: 5–13, 2000.
11. Grieco CR, Cortes N, Greska EK, Lucci S, Onate JA. Effects of a combined resistance-plyometric training program on muscular strength, running economy, and Vo2
peak in division I female
soccer players. J Strength Cond Res 26: 2570–2576, 2012.
12. Heir T, Eide G. Injury proneness in infantry conscripts undergoing a physical training programme: Smokeless tobacco use, higher age, and low levels of physical fitness are risk factors. Scand J Med Sci Sports 7: 304–311, 1997.
13. Hendrickson NR, Sharp MA, Alemany JA, Walker LA, Harman EA, Spiering BA, Hatfield DL, Yamamoto LM, Maresh CM, Kraemer WJ, Nindl BC. Combined resistance and endurance training improves physical capacity and performance on tactical occupational tasks. Eur J Appl Physiol 109: 1197–1208, 2010.
14. Jones BH, Cowan DN, Tomlinson JP, Robinson JR, Polly DW, Frykman PN. Epidemiology of injuries associated with physical training among young men in the army. Med Sci Sports Exerc 25: 197–203, 1993.
15. Kell RT. The influence of periodized resistance training
on strength changes in men and women. J Strength Cond Res 25: 735–744, 2011.
16. Knapik JJ. The influence of physical fitness training on the manual material handling capability of women. Appl Ergon 28: 339–345, 1997.
17. Knapik JJ, Sharp MA, Canham-Chervak M, Hauret K, Patton JF, Jones BH. Risk factors for training-related injuries among men and women in basic combat training. Med Sci Sports Exerc 33: 946–954, 2001.
18. Kraemer WJ, Mazzetti SA, Nindl BC, Gotshalk LA, Volek JS, Bush JA, Marx JO, Dohi K, Gomez AL, Miles M, Fleck SJ, Newton RU, Hakkinen K. Effect of resistance training
on women's strength/power and occupational performances. Med Sci Sports Exerc 33: 1011–1025, 2001.
19. Kraemer WJ, Nindl BC, Ratamess NA, Gotshalk LA, Volek JS, Fleck SJ, Newton RU, Hakkinen K. Changes in muscle hypertrophy in women with periodized resistance training
. Med Sci Sports Exerc 36: 697–708, 2004.
20. Kraemer WJ, Szivak TK. Strength training for the warfighter. J Strength Cond Res 26(Suppl 2): S107–S118, 2012.
21. Lester ME, Urso ML, Evans RK, Pierce JR, Spiering BA, Maresh CM, Hatfield DL, Kraemer WJ, Nindl BC. Influence of exercise mode and osteogenic index on bone biomarker responses during short-term physical training. Bone 45: 768–776, 2009.
22. Maxfield BD. Army Demographics FY12 Army Profile. Washington, DC: Department of the Army, 2012.
23. Myers DC, Gephardt DL, Crump CE. Validation of the military
entrance physical strength capacity test. In: U.S. Army Research Institute for the Behavioral and Social Sciences Technical Report 610. Dot Army, ed, Washington, DC: Department of the Army, 1984.
24. Nindl BC, Harman EA, Marx JO, Gotshalk LA, Frykman PN, Lammi E, Palmer C, Kraemer WJ. Regional body composition changes in women after 6 months of periodized physical training. J Appl Physiol 88: 2251–2259, 2000.
25. Noyes FR, Barber Westin SD. Anterior cruciate ligament injury prevention training in female
athletes: A systematic review of injury reduction and results of athletic performance tests. Sports Health 4: 36–46, 2012.
26. O'Donnell FM. Physical Training Programs in Light Infantry Units: Are They Preparing Soldiers for the Rigors of Combat? US Army Command and General Staff College, Ft. Leavenworth, KS, 2001. pp. 1–115.
27. O'Driscoll J, Kerin F, Delahunt E. Effect of a 6-week dynamic neuromuscular training programme on ankle joint function: A case report. Sports Med Arthrosc Rehabil Ther Technol 3: 13, 2011.
28. O'Hara RB, Serres J, Traver KL, Wright B, Vojta C, Eveland E. The influence of nontraditional training modalities on physical performance: Review of the literature. Aviat Space Environ Med 83: 985–990, 2012.
29. Pienaar C, Coetzee B. Changes in selected physical, motor performance and anthropometric components of university-level rugby players after one microcycle of a combined rugby conditioning and plyometric training program. J Strength Cond Res 27: 398–415, 2013.
30. Protzman RR, Griffis CG. Stress fractures in men and women undergoing military
training. J Bone Joint Surg Am 59: 825, 1977.
31. Reynolds KL, Harman EA, Worsham RE, Sykes MB, Frykman PN, Backus VL. Injuries in women associated with a periodized strength training and running program. J Strength Cond Res 15: 136–143, 2001.
32. Rhea MR, Alderman BL. A meta-analysis of periodized versus nonperiodized strength and power training programs. Res Q Exerc Sport 75: 413–422, 2004.
33. Rhea MR, Ball SD, Phillips WT, Burkett LN. A comparison of linear and daily undulating periodized programs with equated volume and intensity for strength. J Strength Cond Res 16: 250–255, 2002.
34. Rhea MR, Phillips WT, Burkett LN, Stone WJ, Ball SD, Alvar BA, Thomas AB. A comparison of linear and daily undulating periodized programs with equated volume and intensity for local muscular endurance. J Strength Cond Res 17: 82–87, 2003.
35. 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.
36. Roy TC, Ritland BM, Knapik JJ, Sharp MA. Lifting tasks are associated with injuries during the early portion of a deployment to Afghanistan. Mil Med 177: 716–722, 2012.
37. Saez de Villarreal E, Requena B, Izquierdo M, Gonzalez-Badillo JJ. Enhancing sprint and strength performance: Combined versus maximal power, traditional heavy-resistance and plyometric training. J Sci Med Sport 16: 146–150, 2013.
38. Smith MM, Sommer AJ, Starkoff BE, Devor ST. Crossfit-based high intensity power training improves maximal aerobic fitness and body composition. J Strength Cond Res 11: 3159–3172, 2013.
39. Strohbach CA, Scofield DE, Nindl BC, Centi AJ, Yanovich R, Evans RK, Moran DS. Female
recruits sustaining stress fractures during military
basic training demonstrate differential concentrations of circulating IGF-I system components: a preliminary study. Growth Horm IGF Res 22: 151–157, 2012.
40. Szivak TK, Kraemer WJ, Nindl BC, Gotshalk LA, Volek JS, Gomez AL, Dunn-Lewis C, Looney DP, Comstock BA, Hooper DR, Flanagan SD, Maresh CM. Relationships of physical performance tests to military
-relevant tasks in women. US Army Med Dep J 1–7, 2013.
41. Yanovich R, Merkel D, Israeli E, Evans RK, Erlich T, Moran DS. Anemia, iron deficiency, and stress fractures in female
combatants during 16 months. J Strength Cond Res 25: 3412–3421, 2011.