Effects of resistance training in elderly women with cognitive decline

Introduction: With aging, it is common for some changes to occur in different areas of cognition, such as memory, executive function, language and psychomotor speed. However, regular physical activity has been described as an excellent way to alleviate the degeneration caused by aging within the various physical, psychological and social domains. Objective: To evaluate the effects of resistance training in elderly women with mild cognitive impairment. Methods: Experimental study with 31 sedentary elderly women divided into control (CG; n=15) and resistance training (RTG; n=16) groups who underwent assessment of anthropometric measures, body composition, maximum strength, heart rate and blood pressure and questionnaire application (Mini-Mental State Examination). Results: Cognitive ability increased in RTG (post 26.00 ± 2.13 vs. CG 22.24 ± 3.82 vs. pre 24.06 ± 2.38 RTG). In RTG, there was a reduction in systolic blood pressure (post 107.50 ± 11.97 vs. CG 126.00 ± 9.72 vs. pre 124.13 ± 12.55 mmHg RTG), diastolic blood pressure (post 68.50 ± 8.15 vs. CG 81.73 ± 4.59 vs. pre 74.69 ± 6.87 mmHg RTG) and double product (post 7746 ± 1244 vs. CG 9336 ± 1595 vs. pre 9286 ± 1309 mmHg x bpm RTG), but not in heart rate (post 72.00 ± 7.40 vs. CG 74.00 ± 10.50 vs. pre 74.94 ± 8.42 bpm RTG). Regarding muscle strength, an increase was evident in all exercises. Conclusion: The present study showed that resistance training in elderly women increased muscle strength and reduced hemodynamic variables. But the most important finding was that there was an increase in cognitive capacity.


Introduction
The elderly population represents 12% of the world population, with this number expected to double by 2050 and triple in 2100. 1 In Brazil, the growth of this population does not differ from the rest of the world, where in 2060, older people are predicted to make up 25.5% of the population (58.2 million). 2 Aging is characterized as a natural process marked by important changes, both biological and physiological, which vary from individual to individual and depend on several factors, including lifestyle, 3 and can be accompanied by a decline in physical and cognitive abilities. 4 With aging, changes in different areas of cognition are common, such as memory, executive function, language, psychomotor development and visuospatial function. 5 Mild cognitive impairment (MCI) refers to cognitive decline greater than expected for the individual's age and schooling but which does not significantly interfere with daily living activities, where it is related to difficulty in learning new information or retrieving stored information. 6 However, regular physical activity has been described as an excellent means of mitigating the degenerations caused by aging within the physical, psychological and social domains, 7 and the effects of regular physical activity include preventing or delaying the decline of cognitive functions and decreasing the risk of depression, stress, anxiety and drug use. 8 Accordingly, strength training has been considered a promising intervention to prevent or reverse, at least in part, the losses resulting from aging. 9 For elderly people, the loads used generally range from 50 to 85% of onerepetition maximum (1RM) and one to three sets are used, with eight to twelve repetitions and 2 to 3 minutes of rest between sets and exercises. refusal to participate in assessments and the training program; started using medication to treat depression and/or anxiety during the intervention period; and attendance of less than 75% of total sessions.

Anamnesis
The study participants were presented with the informed consent form, and a physical evaluation was then scheduled, for which they were instructed not to consume alcoholic and/or caffeinated beverages and not to perform vigorous physical activity in the 24 hours preceding the physical evaluation. An anamnesis questionnaire was then applied, containing personal data, medications used, eating habits, past and/or current professional activities, clinical history, pathologies, past and/or current physical activities and clinical examinations.

Anthropometric assessment and body composition
Anthropometric measurements were performed according to the International Society for the Advancement of Kinetropometry. 17 The following anthropometric variables were determined: weight, height and ten skinfolds (pectoral, medial axillary, suprailiac, supraspinale, abdominal, subscapular, triceps, biceps, medial thigh and medial calf). 17 These measurements were performed in the preand post-intervention period by the same evaluator.

Statistical analysis
The GraphPad Prism 5® program was used to statistically evaluate the data, presented as mean and standard deviation. Data normality was checked with the Shapiro-Wilk test, followed by the independent t-test, adopting p < 0.05 for a statistically significant difference.

Results
At the end of the study, 31 elderly women (64.58 ± 5.04 years) completed all experimental procedures.
The sample characteristics are presented in Table 1 and demonstrated that there were no significant differences between the groups for any of the characteristics.
Muscle strength assessment  Note: Values expressed as mean ± standard deviation. *p < 0.05 vs pre-resistance trianing group; #p < 0.05 vs post-control group.

Cognitive capacity
Regarding cognitive ability (Table 4), there was a significant difference between pre-and post-intervention RTG (p < 0.0012) and between the GC and RTG after an eight-week intervention (p < 0 .0021), demonstrating that resistance training increased the cognitive performance of the elderly.

Discussion
This study aimed to evaluate the effects of resistance training in elderly women with cognitive impairment.

Muscle strength, hemodynamic variables and MMSE
showed statistically significant differences after eight weeks of a resistance training program. Therefore, this proved to be effective in increasing muscle strength, reducing blood pressure and improving cognitive function.

Muscle strength assessment
After age 50, muscle mass decreases approximately 2% each year. 28 Similarly, there is an approximate decrease in muscle strength, which varies between 20 and 40% in elderly people aged between 70 and 80 years. 28 However, a decline in strength occurs slowly between 50 and 60 years of age, with a much faster decrease after 60. 28 The results of this research revealed that the and co-activation of agonist and antagonist muscles. 32 From a structural point of view, hypertrophied fibers provide more cross-bridges for the production of force in a maximum contraction, thus increasing the capacity to generate force when compared to normal fibers. 31

Assessment of hemodynamic variables
In the present study, a reduction in SBP, DBP and DP was observed after eight weeks of resistance training, but no changes were found in HR. Locks   Therefore, this study is clinically relevant because it proposes an intervention capable of reproducibility in a non-laboratory environment, with the easy applicability of resistance training in elderly women, helping to reduce or prevent MCI, in addition to increasing muscle strength and reducing blood pressure.
It is worth noting that more studies are needed to clarify the mechanisms involved and the most appropriate in the relationship between strength training and positive cognitive responses in the elderly.

Conclusion
Resistance training for only eight weeks with moderate to vigorous intensity improved muscle strength, hemodynamic variables and cognitive aspects in elderly women. Therefore, programs with this type of training can be recommended for this population to improve strength and cognition.