Discussion
muscle mass, muscle atrophy, pre-hypertension, sarcopenia, muscle wasting
INFILTRATION, MUSCLE ATROPHY, HYPERTENSION, HYPERLIPIDEMIA, SARCOPENIA, ADHESION, INSULIN RESISTANCE, METABOLIC SYNDROME, TYPE 2 DIABETES, HIGH BLOOD PRESSURE, INSULIN SENSITIVITY, MUSCLE WASTING
The main finding of the current study is that a 12-week folk-dance training performed by older adults significantly improved insulin sensitivity indicators with a significant drop in BDNF and the rise of irisin concentrations. Additionally, CAF, a potential marker for muscle atrophy, resulted in a reduced association with improved physical performance. It is worth to note that such beneficial effects in insulin sensitivity were pronounced, especially among those subjects who presented the worse condition (i.e., frank insulin resistance) at baseline.The improvement in insulin sensitivity and resistance indicators was visible mainly in HOMA-IR, HOMA-%S, and QUICKI. The positive effects were more pronounced in the folk-dance training group compared to the balance training group, among whom only a tendency to improve insulin sensitivity indicators was observed. The discrepancies between groups may result from slight, although not significant, differences in baseline values of these parameters. These results reflect the findings of previously published research, where the positive effect of physical training was more pronounced among people with type 2 diabetes, hypertension, hyperlipidemia, or metabolic syndrome. Indeed, the recorded reductions in total cholesterol, LDL, fasting insulin, and HOMA-IR were not as pronounced in healthy subjectsTogether with beneficial changes in insulin sensitivity registered in our trained groups, we noted the reduction of blood pressure. Although the awareness of the need for physical activity is growing, the elderly may be afraid of undertaking regular physical activity. Both resistance and long-term aerobic training have been commonly suggested to reduce blood pressure in middle-aged individuals with pre-hypertension and frank hypertensionAdditionally, we hypothesize that the amelioration in insulin resistance was associated with a reduction in BDNF concentrations.The primary function of BDNF is to regulate neurogenesis in the brain; however, it has also been shown to have a pivotal role in the regulation of peripheral metabolism, especially energy balance and insulin sensitivityThe results from studies conducted on humans are ambiguous regarding the relationship between BDNF and long-term exercise protocols. No effectsAnother exerkine that may regulate insulin resistance in response to physical training is irisin. Irisin is expressed in skeletal muscle and other tissues and seems to induce a brown-like phenotype in some white adipocytes, which improves multiple metabolic parameters by increasing energy expenditureAlong with insulin sensitivity improvement, the reduction of the systemic immune-inflammation index was evidenced in the balance group and a trend to reduction in the folk-dance group. In the last published review, authors pointed out that irisin-mediated alterations in cytokine production results in reduced macrophage migration and infiltration, vascular leukocyte adhesion and migration, and acute phase inflammatory responseAlthough we did not determine muscle mass, our study focused on motor and functional balance test results (TUG and 6MWT). In both training groups, together with shifts of BDNF and irisin, the amelioration of these muscle functions was recorded. As irisin has been suggested as muscle wasting and muscular performance biomarkerAmong the proteins considered as biomarkers of muscle atrophy and sarcopenia analyzed in this study—myostatin and CAF, only the latter substantially changed. Although previous studies showed a reduction in myostatin concentration, we did not observe such an effect. However, different results have been reported depending on sex, age, and exercise type (aerobic or resistance)This study presents some limitations that should be highlighted. Future studies should include assessing cognitive functions to evaluate if the changes in exerkines are related to cognition improvement. However, for this purpose, previous studies, including ours, indicated that dance training is an effective method to improve cognitive abilitiesOverall obtained data indicated that both training programs effectively improve physical performance, dynamic balance, and inflammatory status and reduce high blood pressure. However, folk dance appears to be more beneficial in ameliorating insulin resistance. The changes in response to training interventions are connected with shifts in BDNF, irisin, and CAF concentrations. Since there is limited data regarding the direct connection between BDNF, irisin, and CAF in humans, obtained results have particular meaning and fill the gaps in this research area.