Muscular Strength and Quality of Life in Older Adults: The Role of ACTN3 R577X Polymorphism

Role of handgrip strength in predicting the quality of life in older adults: A cross-sectional study

BACKGROUND

Quality of life (QOL) is a vital component in assessing the standard of living for seniors. Hand grip strength (HGS) is a widely used measure to diagnose muscle strength decline that often occurs due to age-related loss of skeletal muscle mass and function. This study focuses on the HGS in predicting the QOL of older adults who are referred to retirement centers in Guilan Province.

MATERIALS AND METHODS

In 2021, a cross-sectional analytical study was conducted among 115 older adults who were residing in retirement centers located in Guilan Province, Northern Iran. The participants were selected using a two-stage sampling method, where three retirement centers were randomly chosen followed by convenience sampling from each center. The selected retirement centers were situated in Langrod, Sowme'eh Sara, and Rasht cities in the east, west, and center of the province, respectively. The data were collected through a demographic information questionnaire, QOL scale (CASP-19), and HGS measurement using a dynamometer.

RESULTS

Of the participants, 57.4% were male, 51.3% had middle income, and 96.5% were categorized as young elderly. The mean overall QOL score was found to be 37.026 ± 6.123, while the mean HGS level was 31.74 ± 7.45 and 18.48 ± 5.13 among males and females, respectively. There was a significant association between the level of education and QOL (P = 0.002). Moreover, there was a positive and significant correlation between HGS and QOL (r = 0.54, P = 0.001). The results of the multiple linear regression identified HGS as a predictor of QOL (Adj R2 = 0.44, βHGS = 0.79).

CONCLUSION

Given that HGS has been identified as a predictor of QOL in older adults, improving this factor through exercise can lead to enhancement in their QOL. Therefore, regular sports exercises can be recommended as a means of improving HGS and subsequently enhancing the QOL of older adults.

Progressive strength training can reverse sarcopenia stage in middle-aged and older adults regardless of their genetic profile

The aim of this study was to verify the association of the ACTN3-R577X polymorphism with sarcopenia stage, according to the Revised European Consensus on the Definition and Diagnosis of Sarcopenia, in middle-aged and older adults, pre- and post- ST. In the 12-week longitudinal study, 71 middle-aged and older adults were evaluated; the participants were assigned to either control or intervention group. The intervention group underwent progressive ST three times a week. All participants underwent blood collection, DNA extraction, genotyping of the ACTN3-R577X polymorphism, anthropometric evaluations, and diagnostic tests for sarcopenia. The last two tests were repeated after 12 weeks. No association of the ACTN3-R577X polymorphism with sarcopenia stage was observed before and after 12 weeks. However, the intervention group remained non-sarcopenic (n = 25, p <0.05) or achieved changes in sarcopenia stage (from sarcopenic to non-sarcopenic) (n = 13, p <0.05). Our study demonstrates that progressive ST performed regularly can reverse or prevent sarcopenia regardless of genotype for the ACTN3-R577X polymorphism.

ACTN3 Genotypes and Their Relationship with Muscle Mass and Function of Kosovan Adults

Maintaining muscle mass and function is important throughout the lifestyle. While environmental factors such as physical activity and healthy nutrition are well investigated, the contribution of genetic factors is still controversial. Therefore, we aimed to investigate the impact of a common ACTN3 polymorphism (rs1815739) on body composition, handgrip strength, knee extensor peak torque, and physical performance (gait speed, 30-s arm curl, 30-s chair stand) in Kosovan adults. In total, 308 participants (160 females and 148 males, age range from 40 to 91 years) took part in this cross-sectional study. Genomic DNA was extracted from saliva and assessed for ACTN3 genotype distribution (41.5% of RR, 53.9% of RX and 4.6% of XX). Genotype allocation did not account for differences in any of the variables. Interestingly, female XX carriers were taller (p = 0.025) and had a higher isokinetic knee extension peak torque (p = 0.024) than the RX+RR group. In males, XX carriers were also taller (p = 0.049) and had a lower BMI (p = 0.026), but did not differ in any of the strength and performance parameters. These results indicate that the ACTN3 R577X polymorphism might exert a sex-specific impact on knee extensor peak torque and BMI.