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.
The use of a periodized resistance training program allows for planned variation in the exercise stimuli through changes in volume and intensity (1,19,20,32–34). The 2 major models of periodization are linear and undulating (nonlinear). Linear periodization is a classic model that uses gradual increases in the training intensity while decreasing the training volume between cycles. Undulating periodization has more frequent adjustments in the intensity and volume, thus providing greater demands on the neuromuscular system and continuous changes on the stimuli (33).
An undulating periodization program can be modified based on the acute demands of the mission that may warrant rest/recovery. Increased awareness of lifting and movement technique coupled with neuromuscular adaptations may result in better task performance, reduced plateau in training, and a decrease in musculoskeletal injuries (33,40). Soldiers need to vary their daily intensity and volume to maximize strength increases and avoid stagnation. Particularly important is the ability to track unit training that may affect or be affected by PT. Many Army units have training cycles that can be physically and psychologically demanding. This information will be useful because the periodization scheme of the PT program is developed along with an understanding that acute amendments to the PT schedule may be warranted based on feedback and the daily physical status of soldiers (e.g., delayed onset muscle soreness, illness, fatigue, and so on).
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.
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