Teenage fitness level and adult depression linked

A recently released study suggests better cardiovascular fitness at age 18 is associated with lower depression rates in adulthood.  Dr. Maria  Åberg, MD, PhD, Sahlgrenska Academy, University of Gothenburg, in Sweden, said the correlation can be seen for up to the next 40 years of a person’s life.

This is how Medscape Today reports on the study:

“A proposed mechanism is that physical exercise could reverse the reduced neuronal plasticity that is observed in both depression and bipolar disorders. Previous human studies have shown that a sedentary lifestyle increases the risk of depression, but most of these have been based on interviews with adults and the results have been inconclusive, and we felt that there was a real need for a large study with long follow-up times and objective measures of physical performance,” Dr. Åberg explained.

The researchers carried out a prospective cohort study of all Swedish men born between 1950 and 1987 with no history of mental illness who were enlisted for mandatory military service at the age of 18 years.

When enlisting, all 1,117,292 men were given extensive physical and psychological examinations, including tests of their cardiovascular and muscle fitness.

The men were followed between 1969 and 2008. The researchers used data from the Swedish National Hospital Discharge Register to see how may had received inpatient treatment for depression.

The study showed that the men who performed poorly on the cardiovascular fitness tests at age 18 years were at greater risk of being hospitalized with depression in later life.

After controlling for factors that included body mass index, conscription test center, and familial factors, the hazard ratio (HR) associated with lower cardiovascular fitness at age 18 for serious depression in adulthood was 1.96 (95% confidence interval [CI], 1.71 – 2.23).

There was no such association found for bipolar disorder (HR, 1.11; 95% CI, 0.84 – 1.47).

“Doctors can tell their teenage patients and their parents that the brain needs two types of training, both cognitive challenges and physical exercise,” Dr. Åberg said.

Another warning about endurance training

It’s not clear what defines “vigorous” when it comes to endurance training, but another team of researchers is putting the brakes to working out more than 60 minutes at a time.

On its website, the CBC reports on a scientific review published in the Mayo Clinic Proceedings, which suggests that benefits of vigorous exercise diminish after an hour, and may even cause cardiovascular events. The piece, which quotes author Dr. James O’Keefe from Missouri,  suggests that some endurance athletes could be doing damage to their hearts:

“When people come to me as a cardiologist and say they want to run a marathon I say, ‘OK, do one and cross it off your bucket list and then let’s focus on an exercise pattern that’s more ideal to producing long-term health benefits and improving your longevity,'” O’Keefe said.

People who exercise regularly have lower rates of disability and a life expectancy seven years longer on average than couch potatoes, the researchers noted.

O’Keefe wants people to understand that the lion’s share of benefits come at a relatively modest level. No further benefits are obtained beyond 30 to 60 minutes a day of vigorous activity.

The researchers said elite-level athletes commonly develop abnormal electrocardiograms and their hearts adapt in ways that traditionally weren’t thought to be harmful. Now it seems the cardiac remodelling from excessive exercise can increase their risk of heart rhythm problems like atrial fibrillation.

After people reach their mid-40s, long and intense exercise can cause scarring and fibrosis in the heart, O’Keefe said.”

The ultra running world took notice this winter when Micah True died while running a 12-miler.  The author of Born to Run , known as the Caballo Blanco, died when the rhythm of his heart went of control. He would sometimes run a 100-miles a day,  and some people blame running for his death at age 58.

His is an extreme case, but combined with the perception of increasing number of deaths at marathons, people want to know more about what could be “excessive” when it comes to endurance training and the heart.

Could exercise be bad for you?

A bit of a disturbing study – and it’s just one study- from the States, suggesting that for some healthy people exercise could be bad for the heart.  Gina Kolata writes about it on the NY Times Health blog. Here’s a portion:

“Could exercise actually be bad for some healthy people? A well-known group of researchers, including one who helped write the scientific paper justifying national guidelines that promote exercise for all, say the answer may be a qualified yes.

By analyzing data from six rigorous exercise studies involving 1,687 people, the group found that about 10 percent actually got worse on at least one of the measures related to heart disease:blood pressure and levels of insulin, HDL cholesterol or triglycerides. About 7 percent got worse on at least two measures. And the researchers say they do not know why.”

The study suggests that an equal percentage of people showed very good changes to those key measures.  One of the mysteries is that there doesn’t seem to be a significant correlate to age, gender, race, or previous level of fitness.  The study was not long-term, so failed to measure the actual impact on heart disease and mortality.

In contrast to this study, shows like the Biggest Loser are showing that exercise is a significant part of the treatment for unhealthy people with conditions like diabetes and cardiovascular disease. See this Medscape article.

So what is a jogger to do? Or a swimmer? Or cyclist? I would never suggest anyone ignore the results of good science, but in this case there is so much data supporting regular exercise — from weight loss to improved psychological outlook – that I would file this study under “lets check again about this later, when more research backs it up and spells out the significance.”

My suspicion is that many who start a new exercise program do so too vigorously, and that might have a negative impact on parts of the body.