Strong muscles = strong immune system

The riper the age you reach, the worse your immune system functions, and it declines more each year. At a certain point it becomes so weak that a simple cold can mean the end. In 1999 researchers at the University of Bologna in Italy published an epidemiological study that suggests you can halt the decline of the immune system by doing resistance training. And by taking extra vitamin D.

The researchers took blood samples from 62 men and women aged between 90 and 106. They put cancer cells in the blood. And then the researchers measured how long it took the immune cells to eliminate of the cancer cells.

The older the participants in the study were, the fewer immune cells [CD16] they had in their blood. But, the more muscle mass the participants had in their upper arms, the more immune cells they had in their blood. So muscles, it would seem, counteract the negative effect that aging has on the immune system.

Black circles, solid line: relationship between muscle mass and immune cells.
White circles, dotted line: relationship between age and immune cells.


Another factor was the vitamin D level. The more vitamin D there was in the participants’ blood, the more immune cells the researchers found. The figure above shows this.

Although more muscle mass did indeed mean more immune cells, muscle mass did not influence the effectiveness with which the immune cells killed the cancer cells [E/T100]. The researchers did observe a relationship with vitamin D: the higher the vitamin level, the more cancer cells the immune cells were able to kill.


Recent research has shown that the hormone irisin, which is produced by muscles, offers protection against cancer, and that healthy but extremely old men and women have unusually large amounts of irisin in their blood. We’re willing to bet that muscle mass helps maintain a good immune system.

Resistance training = longevity.

Vitamin D, thyroid hormones and muscle mass influence natural killer (NK) innate immunity in healthy nonagenarians and centenarians.


Increasing evidence has demonstrated that the immune system closely interacts with other physiological systems, whose communications are mediated by circulating cytokines and hormones. The aim of our study was to test whether the number and cytolytic activity of NK cells in a group of relatively healthy Italian nonagenarians and centenarians were affected by the modifications of endocrine, metabolic and functional parameters that occur during ageing. Because of the extreme age of the study population, a cross-sectional analysis was performed. This study revealed that the group of oldest subjects with the highest number of NK cells and the best preserved cytolytic function also presented a preserved metabolism of thyroid hormones and vitamin D and integrity of muscle mass. In fact, the NK cell number and/or cytolytic activity of healthy subjects > 90 years old was positively associated with serum levels of vitamin D, while T3, FT4, i-PTH hormones and lean body mass were associated only with NK cell number. In conclusion, our results stress the paramount importance of nutritional evaluation in the clinical assessment of elderly people.

PMID: 10209500 PMCID: PMC1905230 [PubMed – indexed for MEDLINE]