The American College of Sports Medicine (ACSM) has maintained a position stand since 1978 ("Recommended Quantity and Quality of Exercise for Developing and Maintaining Fitness in Healthy Adults") outlining the amount of exercise shown in an extensive body of literature to be optimum for achieving and maintaining physical fitness in the general population. They differentiate between the amount of exercise needed for general health and the amount needed for improvement in fitness level, as defined by an improvement in maximum oxygen consumption (VO₂max). In the updated position stand (1990), ACSM recommended the frequency (3–5 times/wk), intensity (60–90% of maximum heart rate), duration (20–60 minutes of continuous aerobic activity depending on intensity), and mode (activity using large muscle groups that can be maintained continuously) of the exercise required for development and maintenance of a level of physical fitness similar to that required by all military troops for readiness. In this version of the position stand, resistance exercise is an added recommendation—conditioning of the major muscle groups at least 2 d/wk to ensure sufficient strength to perform normal activities of daily living, maintain fat-free mass (FFM), and control body weight.

In 1991, the U.S. Department of Health and Human Services published Healthy People 2000 (DHHS, 1991), in which it indicated one of its goals to be an increase in the activity level of the general population to improve health (Items 1.1 to 1.14). In 1995, the National Institutes of Health convened a consensus conference on physical activity and cardiovascular health at which the participants agreed that a minimum of 30 minutes each day of moderate physical activity (defined as brisk walking) would improve health, and that for most individuals, more exercise of greater intensity would further improve health. This group also agreed that resistance exercise should be incorporated into an ongoing exercise program at least 2 days each week.

In 1996, the U.S. surgeon general (DHHS, 1996) issued a report, Physical Activity and Health, outlining and evaluating the literature available, which supports exercise as an important part of an overall program of health, and recommending a minimum of 150 kcal/d of strenuous exercise to protect against the risk of heart disease, colon cancer, hypertension, and diabetes.

Clearly, some disagreement exists among these groups of individuals as to the amount of physical activity required for health. There is a consensus, however, that regular physical activity is part of a healthy lifestyle that is compatible with readiness, and that daily physical activity generally increases health and fitness. Extrapolation to the military situation suggests that a consistently ready, fit, and healthy force is one that routinely engages in at least the level of exercise recommended by the ACSM. In addition, however, military personnel must be ready to perform the maximum requirements of their job specialties at any moment.

Much evidence in the civilian literature supports the need for job-related training. Individuals who routinely practice the highest demand activities of their job description experience fewer injuries during performance of those activities while on duty (Jackson, 1994). Failure to maintain training level results in a very rapid decline in physiological function. Detraining of strength manifests in a decrease in muscle mass in as little as 1 week (Brooks et al., 1996), and endurance capacity can diminish in 2 weeks (Coyle et al., 1984) or less (Hickson et al., 1985). Firefighters, who achieve competence in specific job capabilities during training, have been shown to lose those competencies when they rely on customary day-to-day job activities (Ellam et al., 1994). Studies in both military and civilian sectors show that individuals participating in a routine strenuous activity program experience fewer stress fractures. Thus, to provide for a military

Front Matter (R1-R16)

Executive Summary (1-24)

1 Introduction (25-32)

2 Body Composition (33-60)

3 Physical Fitness Policies and Programs (61-86)

4 Weight Management (87-108)

5 Nutritional Concerns of Military Women (109-126)

6 Pregnancy and Lactation and Postpartum Return-To-Duty Fitness (127-156)

7 Conclusions and Recommendations (157-170)

Appendixes (171-172)

A Workshop Summary, Agenda, Participants, and Abstracts (173-252)

B Practices and Policies Tables (253-262)

C Military Occupational Specialty Classification Tables (263-280)

D Search Strategy for Literature Review (281-284)

E Civilian Inquiry Letter and Table of Responses (285-290)

F Abbreviations (291-294)

G Bibliography (295-334)

H Biographical Sketches (335-338)

Index (339-352)