Lifelong Exercise Prevents “Inflammaging”

Image source: runnersworld.com

There are many theories to why we age, why our bodies seem to decline inevitably with the passage of time.

One of the theories suggests that inflammation caused by aging leads to a progressive downward spiral into disease, frailty, and reduced quality of life.

Inflammation is a beneficial process, despite receiving generally negative publicity in the health and wellness sphere. Name any disease or ailment, and inflammation has likely been cited as the cause. Drugs, foods, and detoxes designed to abolish inflammation are marketed far and wide.

But we need inflammation — it’s our body’s response to infection, injury, or some sort of foreign virus that we need to fight off. The inflammatory response is a protective mechanism…in the short term.

However, chronic low-grade inflammation is the source of problems. In contrast to an acute inflammatory response, persistent levels of inflammation are known to cause damage to cells, tissues, and DNA within the body. If inflammation fails to resolve, damage accumulates over time. This leads to processes associated with aging and disease.

A critical driver of the age-associated increase in inflammation could be related to exercise (or a lack thereof). With aging and a lack of physical activity, muscle mass declines and fat mass increases. The effects on inflammation here are two-fold.

For one, adipose (fat) tissue is actually a source of pro-inflammatory cytokines. More fat tissue means more inflammation. Additionally, skeletal muscle can be a source of pro, but also anti-inflammatory cytokines. As lean mass goes down with age, we lose the beneficial anti-inflammatory effects of muscle.

Source: de Lemos Muller et al.

For this reason, exercise is important…especially for aging individuals. It’s necessary to build (or at least maintain) muscle mass and prevent sarcopenia — the age-related decline in muscle mass.

The data are pretty conclusive: people who are considered “lifelong exercisers” have better cardiovascular and skeletal muscle health than couch potatoes of the same age. They also have lower levels of inflammation. Lower inflammation is likely both a cause and a consequence of the superior health and functional abilities observed in these individuals.

It’s pretty cut-and-dry — exercise staves off the inflammation associated with aging. It also may reduce inflammation in response to increased “stressors” like exercise, which would also be beneficial. Inflammation can actually interrupt adaptations to exercise. Thus, in older people who start to exercise, they might not get the most bang for their buck if high-levels of inflammation follow the exercise bout.

A new study published in the Journal of Applied Physiology took an interesting approach to study how aging, exercise, and inflammation interact.

Titled “Effects of Aging and Lifelong Aerobic Exercise on Basal and Exercise-Induced Inflammation”, the study investigated how levels of inflammation at rest and after exercise were different among groups of different ages and fitness levels.

They recruited groups of young healthy exercisers, old lifelong exercisers, and old sedentary people (all men).

Of particular interest in this study is the lifelong exercise (LLE) group. These men had been exercising for an average of 50 years, and reported doing 5 days (~7 hours) per week of exercise. This is pretty remarkable given the fact that they were 75 years old. Within this group, researchers created two subgroups — a lifelong exercise “performance” group and a “fitness” group. The performance group reported participating in “vigorous” training while the fitness group exercised for overall health (i.e. at a lower intensity).

In these groups, blood draws and muscle biopsies (from the thigh) were taken at two time points; once at rest and another 4 hours after the participants completed a bout of resistance training exercise (knee extensions). This exercise was designed to elicit a “stress” response in the muscle.

Blood and muscle samples were analyzed for a variety of pro- and anti-inflammatory factors. Of note: C-reactive protein (CRP), IL-6, TNF-alpha, insulin-like growth factor (IGF-1), and several components of the prostaglandin pathway.

Results: Basal Inflammation

One of the main findings for basal (resting) inflammation was that levels of IL-6, a pro-inflammatory cytokine, were significantly higher in the older sedentary men compared to young and old exercising groups.

In terms of anti-inflammatory factors, the lifelong exercisers were found to have 43% more IL-10 and 66% more TGF-beta compared to the young and old groups, respectively.

Both of these results support the fact that aging increases inflammation, and exercise reduces it.

Results: Exercise-Induced Inflammation

The theme of inflammation held consistent after exercise. The pro-inflammatory marker TNF-alpha increased in the older sedentary group after exercise, while remaining unchanged in the young and older exercising groups.

The authors note that TNF-alpha is involved in proteolytic (protein degrading) pathways within cells, and thus, could contribute to pathological responses in older muscle. An increase in inflammation after exercise could indicate an inability to “resolve” inflammation in this group, and perhaps a reduced adaptive response to exercise.

Overall, this study provides some obvious but also some novel conclusions.

For one, the idea that aging is pro-inflammatory in both the blood and muscle environment is strengthened by these findings. Furthermore, the beneficial “anti-aging” effects of exercise on inflammation were well-supported.

The authors place the findings in context by explaining that a failure to reduce inflammation after exercise could perhaps be detrimental; limiting older individuals’ ability to adapt to training.

I find small issue with this for one reason. This was an acute study, and it could well be expected that older individuals with zero exercise history would experience some sort of “negative” response to exercise. Exercise is a stress, and someone unaccustomed to it will, initially, have some side effects. In this case, the side effects were inflammation-related.

Train these people for a few weeks, and I’d bet the inflammatory response to exercise goes down.

I also wouldn’t expect young and old exercising individuals to mount an inflammatory response to the exercise in this study — it wasn’t that vigorous. A 3 x 10 set of knee extensions isn’t much of a stress for someone who has been training consistently for 50+ years.

I think the more important aspect of the exercise story here is that our ability to reduce inflammation at rest and with exercise is preserved with aging. Even more important may be the fact that starting exercise earlier is better. These people had been exercising since they were 30 years old. The benefits likely starting mounting early.

This might seem like just another study telling us that “exercise is good for you.” While true, I think the novelty lies in finding a potential mechanism by which exercise keeps us young.

Run for your life, literally.

A muscle stain from one of the lifelong exercisers

References

Lavin KM, Perkins RK, Jemiolo B, Raue U, Trappe SW, Trappe TA. Effects of Aging and Lifelong Aerobic Exercise on Basal and Exercise-Induced Inflammation. J Appl Physiol. 2019

de Lemos Muller, C.H., de Matos, J.R., Grigolo, G.B. et al. J. of SCI. IN SPORT AND EXERCISE (2019) 1: 97.

PhD candidate at the University of Florida — Science writing with a particular focus on exercise and nutrition interventions, aging, health, and disease.