The 2nd edition of the Physical Activity Guidelines for Americans 2018 was recently published, with the aim of encouraging physical activity as a means for improving cardiovascular and muscular fitness, prevent disease and promote a healthy lifestyle. This guide changes regarding the last 2008 edition; one of the most relevant is the importance of the total time of physical activity performed daily and weekly. Periods of physical activity of any length are beneficial for a healthy life. More health benefits occur at higher intensity, frequency and duration of physical activity.
Physical activity (PA) provides benefits regardless of body weight, gender and age. Immediately blood pressure and anxiety are reduced, while insulin sensitivity and sleep quality are improved (time before sleeping and getting up, increased deep sleep and less sleepiness during the day). In addition, in the long term it helps minimizing overweight or obesity, hypertension and high cholesterol, triglycerides and glucose.
Regarding overweight and obesity, PA is important to prevent and reduce excess body weight, also help maintaining the current weight or weight already lost. It is possible to need over300 minutes a week for a substantial weight loss, as well as a further reduction in caloric intake for it to be more effective. It is worth mentioning that muscular PA helps maintaining muscle mass during weight loss.
By practicing PA regularly, risk of death due to cardiovascular disease (CVD) is reduced and disease progression and complications derived are prevented with 90 minutes per week of moderate-intensity PA. This occurs as the immediate reduction of the blood pressure and consequently of hypertension. As for type 2 diabetes, its risk and progression are reduced by increasing insulin sensitivity, thus controlling blood glucose and reducing diabetes complications. In people with diabetes, it is recommended to adapt the type and level of PA with the health team to monitor blood glucose and anticipate any injury, especially in the feet.
Being sedentary represents a health risk if no physical activity is performed at all. There is no maximum time recommended to be inactive or sedentary, because the risks depend on the amount of physical activity that is performed in total. Moderate-intensity PA for at least 60 to 75 minutes a day, or 30 to 40 minutes of vigorous PA seems to protect against the risk of death from all causes. The recommendation is to spend less time sitting and more time active.
It is ideal to stay active throughout life, so different types and intensities of activities are recommended according to age:
- Children from 3 to 5 years: they must do physical activity throughout the day to have a healthy growth and development. It should include several activities of light, moderate and vigorous intensities such as riding a tricycle, jumping and free play for 3 hours a day.
- Children and adolescents (6 to 17 years): they must have enough opportunities to perform PA, appropriate for their age. At least 60 minutes a day of aerobic activities (running, jumping, cycling) are mostly recommended; also, to include activities of vigorous intensity (football, martial arts, swimming), bone strengthening (jumping rope, playing basketball or tennis) or muscular (outdoor games, pull a rope, bands or weights) each twice a week Children perform all three types during free play, while adolescents benefit from scheduled PA and sports. In Mexico, only 17% of children (10 to 14 years old) and 57% of adolescents (15 to 19 years old) meet the goal of 60 minutes of PA per day.
- Adults (18 to 64 years): an active lifestyle is recommended by performing a total of 150 to 300 minutes per week of moderate-intensity PA (walking, swimming or recreational cycling, dancing) or 75 to 150 minutes of vigorous-intensity PA (running, swimming session, jumping rope, aerobics), as well as a combination of both. Muscle strengthening exercises are also advised 2 days per week. Over 300 minutes per week involve additional benefits.
- Pregnant women: 150 minutes per week of moderate intensity PA during and after pregnancy are recommended, under constant monitoring by a health team. PA decreases excessive weight gain and the risk of developing gestational diabetes during pregnancy, as well as preventing excessive weight of the baby at birth, and by helping to recover pre-pregnancy weight. Contact sports or those with risk of falling should be avoided.
- Older adults over 65: Aerobic, balance and muscle strengthening activities are recommended at least 150 minutes per week. This prevents the appearance and /or progression of chronic diseases.
If you do not perform enough physical activity or spend a lot of time sitting, the first step is to gradually replace (in duration and intensity) sedentary time with light physical activity, for short periods of time. This must be continued throughout the week and gradually increased, so that risk of cardiovascular disease and type 2 diabetes is reduced.
Piercy K, Troiano R, Ballard RM, et al. The Physical Activity Guidelines for Americans. JAMA.2018 https://jamanetwork.com/journals/jama/fullarticle/2712935
Secretaría de Salud. Encuesta Nacional de Salud y Nutrición de Medio Camino 2016: Informe final de resultados. 2016. Instituto Nacional de Salud Pública.
US Department of Health and Human Services. Physical Activity Guidelines for Americans. 2nd ed. Washington D.C. US Department of Health and Human Services. 2018. Disponible desde: https://health.gov/paguidelines/second-edition/pdf/Physical_Activity_Guidelines_2nd_edition.pdf