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Effects of moderate intensity resistance training on bone mineral density and muscle strength of elderly women.

INTRODUCTION

The growing contingent of the elderly population, and its relation with decreased physical strength capacity and loss of bone mineral density have awakened the global scientific community to prophylactic measures of alternative experimentations (including resistance training).

Silva and colleagues (18) claim that due to the aging process there are structural and functional changes in the neuromuscular system that significantly impairs autonomy. In particular, the aging progress is linked to a significant decrease in strength in both women and men (4) that begins at 40 yrs of age in women (13).

During menopause, bone mass decreases in women. With each remodeling cycle the smaller amount of bone reabsorbed makes the bone fragile and susceptible to fractures (7,8). The incidence of osteoporosis has increased in the Brazilian population in recent years. There is an estimate that by mid-2020 osteoporosis will affect about 32 million people, and will account for more than 1.5 million fractures each year (17,20).

Exercise plays an important role in both preventing and/or treating osteoporotic problems. Yet, although Kemmler and colleagues (9) investigated the exercise effects on fitness and bone mineral density in early post-menopausal women, there are relatively few studies that seek to verify in this population the effect of moderate intensity resistance training.

We hypothesized that an increase in muscle strength and preservation of bone mineral density in elderly women occurs with 10 wks of resistance training of moderate intensity. Thus, the purpose of this study was to investigate the effects of moderate intensity resistance training on bone mineral density and muscle strength in elderly women.

METHODS

Subjects

The subjects consisted of elderly women with the ability to perform moderate intensity resistance exercises without any issues with their skeletal muscle system. Any subject who missed more than three exercise sessions, did not undergo evaluations, and/or asked for any reason to exit the program was excluded. The final sample consisted of 18 sedentary elderly women with a mean age of 64 [+ or -] 3 yrs. The subjects' body mass index (BMI) was 27.1 [+ or -] 2 kgm-2 before and 27.4 [+ or -] 2 kg x [m.sup.-2] after the exercise program.

The elderly were part of a project called UNICEUMA Without Borders where they were engaged in a computer class to stimulate memory. A total of 126 elderly participated in this project, including; active, sedentary, with and without skeletal muscle problems with and without chronic degenerative diseases.

Procedures

The evaluations were performed before and after 10 wks by students of physical education from the University Ceuma. Before starting the evaluations, the students were trained by a Professor of Physical Education at the University.

Data from the anthropometry and muscle strength evaluations were interpreted by a physical education teacher with experience in the field. The bone mineral density data were analyzed by a doctor.

Anthropometry

The following measurements were taken: (a) total body mass (kg); and (b) height (cm), using an anthropometric balance Filizola[R] for subsequent calculation of body mass index.

Evaluation of Bone Mineral Density

The Bone Mineral Density of the lumbar spine and femoral neck were performed in Maranhense Radiology Clinic, through absorptiometry by dual energy X-ray absorptiometry (DXA) of the LUNAR brand, DPX-Alpha model. The examination was performed by a medical specialist. The subject was prone on the equipment table with the legs supported at an angle of 30[degrees].

Evaluation of Muscle Strength

The test of 10 maximum repetitions was used to assess muscle strength in the upright supine and leg press of 45[degrees]. Each subject performed the maximum possible force in isotonic form, according to the assessor's signal for 10 repetitions to concentric failure of the muscles. The exercises were performed in a maximum of 5 attempts with 3 min rest intervals between each series. The noted record was the result from the average of the 2 best attempts.

Resistance Training Program

An informal and detailed lecture described and clarified the program of multi-joint resistance exercises that were performed by the subjects. As recommended by the American College of Sports Medicine (2), the program consisted of running leg press 45[degrees], seated row, leg curl, and bench press.

The exercises were performed by isotonic contraction that lasted 3 sec for the concentric phase and 3 sec for the eccentric phase (1). To establish the training intensity, maximum repetition was used (i.e., the load which enabled the attainment of a specified number of repetitions per set to concentric fatigue).

Each subject underwent 20 sessions (i.e., 2 sessions x [wk.sup.-1] for 10 wks) with a 48-hr interval of rest between each session. During the first 2 wks, the subjects performed 3 sets of 15 repetitions maximum (low intensity) in order to adapt. Then, the subjects performed 3 sets of 10 repetitions maximum for 8 wks. Control of the training load was carried out in accordance with Baechle and Earle's (3). A rest interval of 2-min between sets (13) was used.

Statistical Analyses

The stored data were analyzed using the Stata / SE 11.1 (Stata Corp, College Station, Dallas, USA). Quantitative variables were expressed as mean [+ or -] standard deviation checked for differences using ANOVA and Student's t test with the alpha set at P<0.05.

RESULTS

Based on the results shown in Table 1 (P = 0.8684), the mean difference in lumbar spine bone mass density in the elderly women before and after moderate intensity resistance training was not significant. The elderly women neither gained nor lost bone mineral density in the sample investigated.

Based on the results shown in Table 2 (P = 0.8471), the mean difference in lumbar spine bone mass density (BMD) at the femoral neck in the elderly women before and after moderate intensity resistance training was not significant. The elderly women neither gained nor lost bone mineral density in the sample investigated.

The strength of the lower extremities muscles in the elderly women subjects was evaluated by the 10 RM Test (Leg Press Exercise) in two stages: before and after the activity with test application for Students samples matched, considering the decision level alpha = 0.01.

The results in Table 3 show that the difference in strength levels observed with the practice of exercise is significantly increased (P<0.0001). Also, based on the (t) Negative (-8.4604), it follows that the level of muscle strength before the activity was well below that obtained after resistance training program. Therefore, we can say that the moderate intensity resistance training promoted a significant improvement in the strength of the muscles of the lower extremities in the elderly women subjects.

The strength of the muscles of the upper limbs in the elderly women subjects was evaluated by the 10 RM bench press exercise in two stages: before and after the activity with test application for Students samples matched, considering the decision level alpha = 0.01.

The results indicate in Table 4 that the difference in the elderly women subjects' strength after resistance training is significantly (P<0.0001) increased. Therefore, once again regarding strength improvement, it is clear that the moderate intensity resistance training resulted in a significant improvement in the strength levels of the upper limbs muscles in the elderly women.

DISCUSSION

The main finding of this study was that moderate intensity resistance training performed twice a week for 10 wks resulted in a significant increase in muscle strength of the pectoral and quadriceps muscles. Moreover, it is reasonable to conclude that maintenance of bone mineral density in the elderly women in this study was achieved, especially since there was no significant loss in both the subjects' femoral neck region and lumbar spine. The results indicate that moderate intensity resistance training in elderly females is a good non-pharmacological strategy to increase muscle strength and promote bone mass maintenance.

It is important to note that the findings are in agreement with Silva et al. (18) who reported an improvement in strength, muscle mass, and functional autonomy in elderly following a resistance training program. The findings also help to support most of the earlier work by Vale et al. (19) who observed an increase in maximum strength, flexibility, and functional autonomy in their elderly subjects following strength training 2 times x [wk.sup.-1]. There are other studies, such as Buzzachera and colleagues (5), as well as the American College of Sports Medicine (2) that emphasizes the importance of resistance training in the improvement of muscle strength and cardiorespiratory fitness in elderly subjects.

Interestingly, contrary to the results obtained in the present study, Pruitt et al. (15) observed an increase of 1.6% in bone mineral density in the lumbar region after low to moderate intensity resistance training. Kerr and colleagues (10) also reported an increase in bone mineral density in after 2 yrs of moderate intensity resistance training in postmenopausal women.

Recent study by Pinheiro et al. (14), with resistance training, where 16 volunteers were submitted for a period of 12 months to two distinct groups of physical exercise. The treatment group practiced resistance training that was divided into 6 cycles with intensity of 70 to 90% of the subjects' maximum load (RM 10). The second group was the control group. The results indicated significant differences in support of the treatment the group that trained the lumbar spine L2-L1 (6.8%, P=0.001), femoral neck (4.8%, P=0.005), and trochanter (0.76%, P=0.005). The authors stated that post-menopausal women with low mineral density should engage in resistance training.

The use of exercise, especially resistance training exercise, has been demonstrated to be a relevant means to promoting and maintaining bone mass and promoting mechanical stimulation that leads to the osteogenesis (9). The lumbar spine responds best to resistance exercises, as they have higher amounts of trabecular bone and are more metabolically active (11,12,15). The femoral neck is especially a susceptible bone to increase bone mineral density since the effect of physical activity on the bone mineral density occurs at sites that support stress (12).

Corroborating the results of this study, Meireles and Nunes (11) examined the effect of a resistance training program lasting 12 months, frequency of 3 sessionswk-1 with loads ranging from 60 to 85% of 1 RM on the bone mineral density of postmenopausal women. The authors observed a 25% reduction in the column bone mineral density and 77% of bone mineral density of the femur. Thus, they concluded that there was a significant reduction in bone mineral density in postmenopausal women.

Although the practice of resistant exercise can positively influence muscle strength in relation to bone remodelling, the process responsible for this result is not entirely clear. Other factors such as genetic characteristics of the individual, nutritional status, and hormonal factors are also likely to influence the findings. Hence, there is the need for more studies designed to identify the influence of different intensities, duration, and frequency of specific resistance training exercises to realize the identified benefits.

CONCLUSIONS

While the findings indicate that there was no significant difference in the changes of bone mineral density in the lumbar spine and femoral neck, the 10-wk moderate intensity resistance exercise resulted in a significant increase in muscle strength in the upper and the lower limbs of elderly women. We suggest that further research is carried out to help ensure a better understanding of the physical mechanisms that influence strength development and bone mass in conjunction with resistance training.

ACKNOWLEDGMENTS

The authors thank the generous cooperation of the volunteers who participated in this study.

Address for correspondence: Professor Janaina Oliveira Bentivi Pulcherio, Universidade Ceuma, Rua Josue Montello, S/N, Sao Luis--MA, Brazil, 65080-805, Brazil, Phone: (55) (98) 991112624, Email: janabentivi.orl@gmail.com

REFERENCES

(1.) American College of Sports Medicine. Diretrizes do ACSM para os Testes de Esforco e sua Prescricao. (7nd Edition). Editora Guanabara Koogan, 2007.

(2.) American College of Sports Medicine. Progression models in resistance training for healthy adults. Med Sci Sports Exerc. 2002;34:364-380.

(3.) Baechle TR, Earle RW. Fundamentos do Treinamento de Forca e do Condicionamento. (2nd Edition). Editora Manole, 2010.

(4.) Binder EF, Yarasheski KE, Steger-May K, Sinacore DR, Brown M, Schechtman KB, et al. Effects of progressive resistance training on body composition in frail older adults: results of a randomized, controlled trial. Journal of Gerontology: Medical Sciences. 2005;60A(11):1425-1431.

(5.) Buzzachera CF, Elsangedy HM, Krinski K, Colombo H, Campos W, Silva SG. Efeitos do treinamento de forca com pesos livres sobre componentes da aptidao funcional em mulheres idosas. Rev da Educacao Fisica/UEM. 2008;19(2):195-203.

(6.) Coelho Filho JM, RAMOS, l. Epidemiologia do envelhecimento no Nordeste do Brasil: resultados de inquerito domiciliar. Revista de Saude Publica. 1999;33(5):445-453.

(7.) Guarniero R, Oliveira LG. Osteoporose: atualizacao no diagnostico e principios basicos para o tratamento. Rev Bras Ortop. 2004;39(9):477-485.

(8.) Ishiday Y, Tertiness I, Heersche JNM. Progesterone and dexamethasone stimulate proliferation and differentiation of osteoprogenitors for adipocytes and macrophages in call populations derived from adult rat vertebral. J Bone Miner Res. 1996; 11:921 -930.

(9.) Kemmler W, Engelke K, Lauber D, Weineck J, Hensen J, Kalender WA. Exercise effects on fitness and bone mineral density in early post menopausal women: 1-year EFOPS results. Med Sci Sports Exerc. 2002;34:2115-2123.

(10.) Kerr D, Ackland T, Maslen B, Morton A, Prince R. Resistance training over 2 years increase bone mass in calcium-replete in postmenopausal women. J Bone Miner Res. 2001;16:170-181.

(11.) Meireles G, Nunes V. Treinamento fisico resistido para mulheres na pos-menopausa com osteopenia e osteoporose. Saude e Pesquisa. 2012;5(1):67-74.

(12.) Menkes A, Mazel S, Redmond RA, Koffler K, Libanati CR, Gundemberg CM, et al. Strength training increases regional bone mineral density and bone remodeling in middle-aged and older men. J Appl Physiol. 1993;74:2478-2484.

(13.) Paasuke M, Ereline J, Gapeyeva H, Sirkel S, Sander P. Age-Related differences in twitch contractile properties of plantarflexor muscles in Women. Acta Physiologica Scand. 2000;170:51-57.

(14.) Pinheiro CJB, Carvalho MCGA, Silva NSL, Bezerra JCP, Drigo AJ, Dantas, EHM. Efeitos do treinamento resistido sobre variaveis relacionadas com a baixa densidade ossea de mulheres menopausadas tratadas com alendronato. Rev Bras Med Esporte. 2010:16(2):121-125.

(15.) Pruitt LA, Jackson RD, Bartels RL, Lehnhard HJ. Weight training effects on bone mineral density in early postmenopausal women. J Bone Miner Res. 1992;7:179-185.

(16.) Ramos JM, Mansoldo AC. Efeito de 8 meses de hidroginastica em idosas com osteoporose. Motriz. 2007;13(2):123-128.

(17.) Raso V, Matsudo SMS, Matsudo VKR. A forca muscular de mulhres idosas decresce, principalmente apos oito semanas de interrupgao de um programa de exercicios com pesos livres. Rev Bras Med Esporte. 2001;7(6):186.

(18.) Silva CM, Gurjao ALD, Ferreira L, Gobbi LTB, Gobbi S. Efeito do treinamento com pesos, prescrito por zona de repetigoes maximas, na forca muscular e composicao corporal em idosas. Revista Brasileira de Cineantropometria & Desempenho Humano. 2006;8(4):39-45.

(19.) Vale RGS, Barreto ACG, Novaes JS, Dantas EHM. Efeitos do Treinamento Resistido na Forga Maxima, na Flexibilidade e na Autonomia Funcional de Mulheres Idosas. Revista Brasileira de Cineantropometria & Desempenho Humano. 2006;8(4):52-58.

(20.) Volkmann F, Castro JAS. Incidencias das fraturas proximais de femur em Porto Alegre no ano de 1992. Arq Bras Endocrinol Metabol. 1998;42(5):S138.

Solange N.A. Bacelar [1], Fabiano J.F. Almeida [1], Bismarck A. Sauaia [1], Tania M.G. Novais [1], Ana E. A. Furtado [1], Laura M. Quintanilha [1], Janafna O.B. Pulcherio [1], Jose F. Filho [2], Bruno B. Gambassi [1]

[1] Ceuma University, Physical Education Department, Sao Luis, MA, Brazil, [2] Federal University of Rio de Janeiro, Physical Education Department, Rio de Janeiro, RJ, Brazil
Table 1. Bone Mineral Density (BMD) at the Lumbar Spine in
Elderly Women Who Underwent Moderate Intensity Resistance
Exercises.

Subjects       Bone Mineral Density at Lumbar Spine
                        (g x [cm.sup.-2])

            BRE    Mean     ARE    Mean    (P value)

01         1.084           1.100
02         0.975           0.959
03         0.814           0.847
04         0.953           0.943
05         1.008           1.032
06         1.043           0.986
07         0.932           0.886
08         0.923           0.959
09         0.898           0.856
10         0.885   0.940   0.893   0.935    0.8684
11         0.723           0.736
12         0.855           0.870
13         0.988           0.955
14         0.965           0.990
15         1.071           1.084
16         0.755           0.819
17         1.004           0.934
18         1.049           0.982

Legend: BRE = before resistance exercises;
ARE = after resistance exercises

Table 2. Bone Mineral Density (BMD) at the Femoral Neck in
Elderly Women Who Underwent Moderate Intensity Resistance
Exercises.

Subjects       Bone Mineral Density at Femoral Neck
                         (g x [cm.sup.-2])

            BRE    Mean     ARE    Mean    (P value)

01         1.003           0.999
02         0.836           0.829
03         0.861           0.867
04         0.943           0.928
05         1.028           1.033
06         1.091           1.083
07         1.038           1.017
08         1.006           1.000
09         0.819           0.805
10         0.754   0.916   0.763   0.909    0.8471
11         0.815           0.816
12         0.742           0.738
13         0.986           0.993
14         0.821           0.814
15         1.072           1.065
16         0.817           0.765
17         0.830           0.828
18         1.023           1.012

Legend: BRE = before resistance exercises; ARE = after resistance
exercises

Table 3. Strength Levels of the Muscles of the Lower Limbs in
Elderly Women Who Underwent Moderate Intensity Resistance
Exercise (Evaluated by 10 RM Test--Leg Press Exercise).

Subjects   Strength Levels of the Muscles of the Lower Limbs (kg)

           BRE   Mean     SD    ARE   Mean     SD        t

01         60                   80
02         50                   76
03         62                   80
04         66                   80
05         54                   90
06         60                   80
07         50                   84
08         50    52.56   6.92   60    74.78   10.22   -8.4604
09         60                   70
10         40                   90
11         50                   60
12         50                   70
13         50                   60
14         54                   70
15         50                   86
16         40                   60
17         50                   70
18         50                   80

P value (bilateral) < 0.0001; Legend: BRE = before resistance
exercises; ARE = after resistance exercises; SD = standard
deviation.

Table 4. Strength Levels of the Muscles of the Anterior Chest in
Elderly Women Who Underwent Moderate Intensity Resistance
Exercise (Evaluated by 10 RM Test--Bench Press Exercise).

Subjects          Strength Levels of the Muscles of the Anterior
                             Chest (Pectoral) (kg)

           BRE   Mean    SD    ARE   Mean     SD       t

01          8                  12
02          8                  12
03          8                  12
04          6                  10
05          8                  14
06          6                  10
07          6                  10
08          6    6.67   0.97    8    10.78   1.69   -12.0230
09          6                   8
10          6                  12
11          6                   8
12          6                  10
13          6                  10
14          6                  12
15          8                  12
16          6                  12
17          6                  12
18          8                  10

P value (bilateral) < 0.0001; Legend: BRE = before resistance
exercises; ARE = after resistance exercises; SD = standard deviation.
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Author:Bacelar, Solange N.A.; Almeida, Fabiano J.F.; Sauaia, Bismarck A.; Novais, Tania M.G.; Furtado, Ana
Publication:Journal of Exercise Physiology Online
Article Type:Report
Date:Dec 1, 2015
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