By V. Hauschild, MPH Defense Centers for Public Health – Aberdeen
ABERDEEN PROVING GROUND, Md. – Some people become less physically active as they get older, which can lead to weight gain and a decline in physical fitness. The Centers for Disease Control and Prevention reports that as people age, their body composition gradually shifts, so they have less muscle and more fat.
Military public health experts have determined that these natural body changes occur even in relatively healthy and fit active-duty service members.
Dr. Joseph Pierce, an exercise physiologist who works for the Defense Center for Public Health–Aberdeen, and his co-workers have conducted several comparisons of height and weight measured as body mass index, known as BMI, and percent body fat, among Soldiers from different age groups.
In addition to health metrics, military studies have also evaluated changes in physical fitness and performance through fitness test results, such as the 2-mile run and push-ups.
“There were corresponding increases in BMI and percent body fat with increases in age,” says Pierce. “But increased fatness and higher weight are not necessarily a bad thing if fitness can be maintained.”
Pierce says his prior work has shown that although Soldiers with lower BMI and lean body weight perform well on aerobic tests such as the 2-mile run, those with higher BMIs are more successful with tests of power and strength, such as sled drags and deadlifts.
“While all the evaluated Soldiers were ‘fit’ according to Army standards, the evidence shows that being fit can be reflected by a range of BMI and body fat,” says Pierce. “The key is to maintain fitness, body weight, and fat percentage within healthy limits.”
As described on page 85 in the 2022 Health of the Force report, known as HoF, a recent study of Soldiers who completed the six-event Army Combat Fitness Test found that as these male service members’ age increased, their fitness performance decreased.
“For most fitness test events, there were improvements in test results up through the early mid-30s,” says Pierce. “Among the soldiers in their mid-30s and older, we started to see consistent declines even when there was only one age standard at the time.”
Current policies reflect the science supporting the relationship between fitness and fatness. For example, the 2022 Department of Defense policy on body composition allows individual Services to implement policies that exempt body fat standards if service members attain high scores on physical fitness tests.
In March 2023, an Army Directive was published that allows Soldiers who score 540 points or more on their ACFT, with a minimum of 80 points in each event, to be exempt from the Army body fat assessment. The new Army policy will help to avoid flagging those Soldiers who score exceptionally high on the ACFT but exceed Army weight or body fat standards.
The other scientific aspect reflected by the Army fitness testing is the adjustments that have now been made that reduce ACFT standards for older age groups.
“The take-home message is to recognize that just because your body will change as you age, you can offset some age-related deficits through maintaining your physical exercise regimen while understanding that you may have to modify some activities,” says Pierce.
The good news is that weight gain can be prevented by choosing a lifestyle that includes daily physical activity and healthy eating habits. The Military OneSource Health and Wellness Coaching Program is a helpful resource that can assess any needed exercise regimen adjustments.
This is important news for active-duty service members, who must maintain specific levels of fatness and fitness as required by DOD and military policy. Service members can find helpful information about fitness and training at https://www.hprc-online.org/physical-fitness/training-performance.
Non-military and retired personnel should also be mindful of their body’s natural changes in composition and metabolism as they age. Avoiding weight gain and staying fit are important for everyone as we age. Maintaining fitness can also reduce many chronic diseases, such as heart disease, stroke, Type 2 diabetes, high blood pressure, osteoarthritis, and some forms of cancer.
“The changes are common for most adults, so plan on life-long dedication to a regular exercise program,” says Pierce. “The types of exercise you choose may need to be modified over time to reduce risk of injury.”
For example, the CDC Physical Activity Guidelines for Adults calls for at least 150 minutes of moderate aerobic activity each week – which can be spread out during the week, such as 30 minutes a day, 5 days a week.
“Even if you can’t [exercise] 30 minutes at one time,” Pierce says, “You still get the benefits as long as you can find ways to incorporate smaller bouts of activity, so you accumulate the total time recommended.”
Aerobic exercises such as distance running can put pressure on the joints which can result in injuries, especially as we age. For example, findings on page 32 of the HoF show that injuries occur more frequently in service members over 45 years of age. So, lower-impact aerobic activities such as brisk walking, swimming or stationary cycling may replace running as we grow older.
In addition to regular aerobic exercise, the CDC calls for at least two days of muscle-strengthening activity. Lifting free weights is one option; alternative muscle-strengthening activities include using machines, bands, or even the body (squats, leg lifts, push-ups, planks).
The CDC indicates only 28 percent of men in the United States met these guidelines for aerobic and muscle-strengthening activities in 2020.
While active-duty service members can provide the time and “required motivation” to stay fit, everyone should make meeting the CDC’s physical activity guidelines a goal.
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