COVID-19 pandemic and home-based physical activity.

To the Editor:

The article by Nyenhuis et al is very interesting and adds important information about exercise and social distancing during the coronavirus disease 2019 pandemic. Social isolation/distancing (“stay home”) can increase sedentary behavior and decrease the level of physical activity, which has already been linked to poor survival rates.

Conceptually, exercise training is a structured physical activity for a specific purpose, such as a training to gain lower limbs strength and decrease the risk of falls in old people. Thus, although exercise training provides important benefits, as shown by Nyenhuis et al, it needs a proper prescription to be safely and efficiently performed, even at home. Physical activity, on the other hand, is “any bodily movement produced by skeletal muscles that results in energy expenditure” above 1.5 metabolic equivalent (MET), such as walking to work or performing household chores. It is known that 1 MET is equivalent to resting metabolism, or 1 kcal/kg/h or 3.5 mL/kg/min of oxygen consumption (general numbers).

In this sense, understanding home-based physical activity, and not just exercise training, is relevant to keep ourselves healthy. This text also shows that adults may be already in accordance with Word Health Organization (WHO) recommendations for physical activity (150 minutes of moderate-intensity physical activity, 75 minutes of vigorous-intensity physical activity, or an equivalent combination of them per week).

Let us consider 3 major variables (Table I ): type of activity (cleaning the floor, for example), intensity (how much this activity tires and expends energy), and duration (for how long this activity is carried out). In general, the intensity of physical activity can be classified as light (<3 METs), moderate (3-5.9 METs), or vigorous (>6 METs). Example 1: John (random name), 30 years old, 60 kg, has 2 children. During his morning activities, he gets up early and prepares breakfast (3.5 METs) for approximately 20 minutes. Then, he cleans the floor (3.8 METs) for 10 minutes, and then takes 15 minutes to bathe the children (3 METs). Thus, taking into account that cooking, cleaning the floor, and bathing the children are moderate-intensity physical activities (>3 METs), John, that morning, reached more than 30 minutes of moderate-intensity physical activity and he is in agreement with WHO recommendations. Example 2: John, the next day, bathed the dog (3.5 METs) for 15 minutes, then danced (7.8 METs) and sang with his children for 20 minutes the songs they liked most, and after a break decided to paint (4.5 METs) the walls of the room for about 20 minutes. Thus, we observed that John made a moderate-intensity (>3 METs) to vigorous-intensity (>5.9 METs) effort in just 55 minutes. Thus, it complied with WHO recommendations.

Table I

Suggestions for home-based physical activity and respective intensities

Daily activities	METs	Estimated VO2 (mL/kg/min)	Avarage time (min)
Resting	1	3.5	1
Home activity
Sweep the floor	3.8	13.3	10
Wash dishes	2.5	8.75	8
Washing clothes by hand	4	14	15
Ironing	1.8	6.3	10
Cooking or food preparation	3.5	12.25	20
Child care, standing	3	10.5	15
Standing, bathing dog	3.5	12.25	15
Playing with child(ren)	5.8	20.3	15
Playing with animals	2.8	9.8	15
Shaving, brushing teeth	2	7	5
Bathing	1.5	5.25	10
Increase self-care
Hairstyling, standing	2.5	8.75	5
Putting on make-up	2	7	5
Dance and sing songs you like
General dancing	7.8	27.3	15
Playing musical instruments	2	7	20
Using or climbing up ladder	8	28	15

VO, Oxygen uptake.

In conclusion, when staying home is a necessity during the coronavirus disease 2019 pandemic, it is still possible to meet the WHO recommendations for physical activity. We should avoid high sedentary behavior and look at domestic activities as an opportunity to stay healthy.