Hard manual labor – construction of buildings, house repairs, plowing fields, factory work -- may result in stronger muscles and a good physique. But it may also lead to joint and muscle pains. And, more disturbingly, manual labor may increase the risk of developing dementia later in life.

A new study from the University of Copenhagen suggested hard physical work may have a connection to dementia -- a loss of memory and thinking skills, most often related to age. Researchers investigated what job-related physical activity may do to the brain. They began with data from the Copenhagen Male Study, done in 1970 and 1971, in which 4,721 male workers aged 40 to 59 years self-reported on the work they did daily.

Researchers then followed them from age 60 until the year 2016, compiling health data, including the development of dementia. They made a distinction between leisure-time physical activity and long-term occupational physical activity. They adjusted for factors like age, socioeconomic status, marital status and mental stress.

The study identified 697 cases of dementia among all participants. They found that men who completed more long-term, hard physical work had a 55% higher risk of dementia than men doing sedentary jobs.

On the other hand, the study also found that men who engaged in more leisure-time physical activity had a lower rate of dementia than men with more sedentary leisure time – the difference between going to the gym daily and watching TV from the couch.

"Before the study, we assumed that hard physical work was associated with a higher risk of dementia. It is something other studies have tried to prove, but ours is the first to connect the two things convincingly," said lead author Kirsten Nabe-Nielsen, PhD, in a press release.

Dr. Nabe-Nielsen added that older studies indicated a likely negative effect of hard physical work on blood circulation. This may increase the chances of cardiovascular diseases, such as hypertension, or high blood pressure, and heart failure.

The study had some limitations, including the sole focus on Denmark, the lack of female participants and the use of self-reported data. Further research would be needed to learn more about the connection between hard physical work and dementia risk, especially among people who are working at a young age.

Positive physical activity

As for positive physical activity, The World Health Organization (WHO) recommends that we get at least 150 minutes of moderate-intensity aerobic physical activity per week to improve overall health and reduce the risk of many diseases.

If you're aged 18 to 64 years, do some exercises or other activities like dancing, gardening, hiking and swimming for 2.5 hours each week. You may split that 2.5 hours into different activities. For example, you may garden for 20 minutes in the morning and do some dancing for 15 minutes in the afternoon.

If you're feeling bold, try more vigorous activities. But the recommended total minutes per week is 75. If you have a chronic health condition, consult with your doctor on what exercise routine you may do. Do not start a routine without your doctor's advice.

For children younger than 18 years, ask a pediatrician which activities can promote physical and mental development.

Remember, house chores count as physical activity, so if housework is cramping your schedule, monitor how many minutes you've spent on it. And ask your doctor which house chores are beneficial to your body.

Engage the Brain

The brain may benefit from physical activities. An article from the US National Institute on Aging suggests activities that engage the mind. Pursuing a new hobby or volunteering may make you feel happier and healthier. One study explored that angle. Researchers found that older adults who focused on learning quilting or digital photography for an average of about 16 hours a week for three months had better memory and reasoning ability than those who only socialized and did less mentally demanding tasks.

The bottom line is, moving more is better than moving less, and learning new things helps your brain stay active.