The effects of stretching on the flexibility, muscle performance and functionality of institutionalized older women

Stretching has been widely used to increase the range of motion. We assessed the effects of a stretching program on muscle-tendon length, flexibility, torque, and activities of daily living of institutionalized older women. Inclusion/exclusion criteria were according to Mini-Mental State Examination (MMSE) (>13), Barthel Index (>13) and Lysholm Scoring Scale (>84). Seventeen 67 ± 9 year-old elderly women from a nursing home were divided into 2 groups at random: the control group (CG, N = 9) participated in enjoyable cultural activities; the stretching group (SG, N = 8) performed active stretching of hamstrings, 4 bouts of 1 min each. Both groups were supervised three times per week over a period of 8 weeks. Peak torque was assessed by an isokinetic method. Both groups were evaluated by a photogrammetric method to assess muscle-tendon length of uni- and biarticular hip flexors and hamstring flexibility. All measurements were analyzed before and after 8 weeks by two-way ANOVA with the level of significance set at 5 percent. Hamstring flexibility increased by 30 percent in the SG group compared to pre-training (76.5 ± 13.0° vs 59.5 ± 9.0°, P = 0.0002) and by 9.2 percent compared to the CG group (76.5 ± 13.0° vs 64.0 ± 12.0°, P = 0.0018). Muscle-tendon lengths of hip biarticular flexor muscles (124 ± 6.8° vs 118.3 ± 7.6°, 5.0 ± 7.0 percent, P = 0.031) and eccentric knee extensor peak torque were decreased in the CG group compared to pre-test values (-49.4 ± 16.8 vs -60.5 ± 18.9 Nm, -15.7 ± 20 percent, P = 0.048). The stretching program was sufficient to increase hamstring flexibility and a lack of stretching can cause reduction of muscle performance.

Efeito do alongamento e do exercício contra-resistido no músculo esquelético de rato / Effect of stretching and resistive exercise on skeletal muscles in rats

OBJETIVO: Analisar o efeito do alongamento e do exercício resistido no músculo sóleo de rato. MATERIAIS E MÉTODOS: Foram avaliados 24 ratos Wistar (380±50g) divididos em quatro grupos (n=6): C, controle-intacto; Along, alongamento do músculo sóleo esquerdo durante 40 minutos; ER, exercício resistido, quatro séries de dez saltos; ER+Along, exercício resistido e alongamento. Após oito semanas, foi realizada a eutanásia dos animais e os músculos sóleos foram avaliados quanto ao peso muscular, área de secção transversa das fibras musculares (ASTFM), comprimento muscular, número de sarcômeros em série, comprimento dos sarcômeros e porcentagem de tecido conjuntivo. A análise estatística foi realizada pela comparação entre grupos, por meio do teste de análise de variância (ANOVA) post hoc Tukey, com significância <0,05. RESULTADOS: As ASTFM dos grupos ER e Along aumentaram quando comparadas ao grupo C. O comprimento muscular e o número de sarcômeros em série do ER+Along foram inferiores aos dos grupos Along e ER. O número de sarcômeros em série do Along foi superior ao C. Não foram encontradas alterações no comprimento dos sarcômeros e na porcentagem de tecido conjuntivo. CONCLUSÕES: O exercício resistido associado ao alongamento causou diminuição no comprimento muscular e no número de sarcômeros em série, provavelmente devido à freqüência diária de exercícios. A realização isolada do alongamento, duas vezes por semana, ou do exercício resistido, três vezes por semana, foi suficiente para induzir hipertrofia muscular.

OBJECTIVE: To analyze the effect of stretching and resistive exercise on the soleus muscle in rats. METHODS: Twenty-four Wistar rats (380±50g) were evaluated, divided into four groups (n=6): C, intact controls; S, left soleus muscle stretched for 40 minutes twice a week; RE, resistive exercise consisting of four series of ten jumps three times a week; and RE+S, resistive exercise plus stretching. After eight weeks, the animals were sacrificed and their soleus muscles were evaluated regarding muscle weight, muscle fiber cross-sectional area (MFCSA), muscle length, number of sarcomeres in series, sarcomere length and percentage of connective tissue. The statistical analysis consisted of comparisons between the groups using the analysis of variance (ANOVA) post-hoc Tukey tests, with a significance level set at <0.05. RESULTS: The MFCSA in RE and S were greater than in C. Muscle length and the number of sarcomeres in series in RE+S were less than in S and RE. The number of sarcomeres in series in S was greater than in C. No changes were found in sarcomere length or percentage of connective tissue. CONCLUSIONS: Resistive exercise associated with stretching caused a decrease in muscle length and in the number of sarcomeres in series, probably due to the daily frequency of exercises. Stretching alone, performed twice a week, or resistive exercise performed three times a week, was sufficient to induce muscle hypertrophy.

Effect of passive stretching on the immobilized soleus muscle fiber morphology

The aim of the present study was to determine the effect of stretching applied every 3 days to the soleus muscle immobilized in the shortened position on muscle fiber morphology. Eighteen 16-week-old Wistar rats were used and divided into three groups of 6 animals each: a) the left soleus muscle was immobilized in the shortened position for 3 weeks; b) during immobilization, the soleus was stretched for 40 min every 3 days; c) the non-immobilized soleus was only stretched. Left and right soleus muscles were examined. One portion of the soleus was frozen for histology and muscle fiber area evaluation, while the other portion was used to identify the number and length of serial sarcomeres. Immobilized muscles (group A) showed a significant decrease in weight (44 ± 6 percent), length (19 ± 7 percent), serial sarcomere number (23 ± 15 percent), and fiber area (37 ± 31 percent) compared to the contralateral muscles (P < 0.05, paired Student t-test). The immobilized and stretched soleus (group B) showed a similar reduction but milder muscle fiber atrophy compared to the only immobilized group (22 ± 40 vs 37 ± 31 percent, respectively; P < 0.001, ANOVA test). Muscles submitted only to stretching (group C) significantly increased the length (5 ± 2 percent), serial sarcomere number (4 ± 4 percent), and fiber area (16 ± 44 percent) compared to the contralateral muscles (P < 0.05, paired Student t-test). In conclusion, stretching applied every 3 days to immobilized muscles did not prevent the muscle shortening, but reduced muscle atrophy. Stretching sessions induced hypertrophic effects in the control muscles. These results support the use of muscle stretching in sports and rehabilitation.

Effect of one stretch a week applied to the immobilized soleus muscle on rat muscle fiber morphology

We determined the effect of stretching applied once a week to the soleus muscle immobilized in the shortened position on muscle fiber morphology. Twenty-six male Wistar rats weighing 269 ± 26 g were divided into three groups. Group I, the left soleus was immobilized in the shortened position for 3 weeks; group II, the soleus was immobilized in the shortened position and stretched once a week for 3 weeks; group III, the soleus was submitted only to stretching once a week for 3 weeks. The medial part of the soleus muscle was frozen for histology and muscle fiber area evaluation and the lateral part was used for the determination of number and length of serial sarcomeres. Soleus muscle submitted only to immobilization showed a reduction in weight (44 ± 6 percent, P = 0.002), in serial sarcomere number (23 ± 15 percent) and in cross-sectional area of the fibers (37 ± 31 percent, P < 0.001) compared to the contralateral muscles. The muscle that was immobilized and stretched showed less muscle fiber atrophy than the muscles only immobilized (P < 0.05). Surprisingly, in the muscles submitted only to stretching, fiber area was decreased compared to the contralateral muscle (2548 ± 659 vs 2961 ± 806 µm², respectively, P < 0.05). In conclusion, stretching applied once a week for 40 min to the soleus muscle immobilized in the shortened position was not sufficient to prevent the reduction of muscle weight and of serial sarcomere number, but provided significant protection against muscle fiber atrophy. In contrast, stretching normal muscles once a week caused a reduction in muscle fiber area.

A new model for the immobilization of the rat hind limb

An alternative device for the immobilization of the hind limb of the rat was developed to study the effects of chronic disuse on the soleus and tibialis anterior muscles, maintained for 3 weeks in the shortening and the stretching positions, respectively. The proposed device is made of steel mesh and cotton materials, and has some advantages when compared to cast or plaster cast: it is cheaper, lighter (12 g or 4 percent of the body weight of the rat) and the same unit can be easily adjusted and used several times in the same animal or in animals of similar size. Immobilization is also useful to restrain the movements of the hip, knee, and ankle joints. Male rats (291 ± 35 g and aged 14 ± 2 weeks) were used to develop and test the model. The soleus muscle of 18 rats was maintained in a shortened position for 21 consecutive days and lost 19 ± 7 percent of its length (P = 0.008) and 44 ± 6 percent of its weight (P = 0.002) compared to the contralateral intact muscle. No difference (P = 0.67) was found in the stretched tibialis anterior of the same hind limb when compared to the contralateral muscle. No ulcer, sore or foot swelling was observed in the animals. Immobilization was effective in producing chronic muscle disuse in the hind limbs of rats and is an acceptable alternative to the traditional methods of immobilization such as cast or plaster cast