Tome Ikezoe

Acute and prolonged effect of static stretching on the passive stiffness of the human gastrocnemius muscle tendon unit in vivo

Static stretching (SS) is commonly used to prevent or improve limited joint mobility. However, it is unclear whether the components of the muscle‐tendon unit (MTU) are affected by 5 min of SS. This study investigated the acute and prolonged effect of SS on the mechanical properties of the MTU. The subjects comprised 15 male participants (mean age: 21.5 ± 1.6 years). MTU stiffness, muscle stiffness, tendon stiffness, and fascicle length of the gastrocnemius muscle were measured by ultrasonography and a dynamometer while the ankle was passively dorsiflexed. The measurements were performed prior to the 5 min of SS, immediately after the SS, and 10 min after the SS. MTU stiffness and muscle stiffness significantly decreased at both immediately and 10 min after SS, whereas no significant differences in MTU stiffness and muscle stiffness were found between immediately and 10 min after SS. Tendon stiffness immediately after SS was significantly higher than prior to and 10 min after SS. No significant change in the fascicle length occurred after SS. These results suggest that 5 min of SS affects MTU and muscle stiffness both immediately and 10 min after SS, which may be associated with a change in the connective tissue properties. © 2011 Orthopaedic Research Society Published by Wiley Periodicals, Inc. J Orthop Res 29:1759–1763, 2011

Age-related muscle atrophy in the lower extremities and daily physical activity in elderly women.

This study investigated the relationship between age-related declines in muscle thickness of the lower extremities and daily physical activity in elderly women. The subjects comprised 20 young women and 17 elderly women residing in a nursing home. Lower limb muscle thickness was measured by B-mode ultrasound with the following 10 muscles; gluteus maximus, gluteus medius, gluteus minimus, psoas major, rectus femoris, vastus lateralis, vastus intermedius, biceps femoris, gastrocnemius and soleus. Daily physical activity was evaluated using life-space assessment (LSA) which assessed the life-space level, degree of independence, and frequency of attainment. Muscle thickness in the gluteus maximus, gluteus medius, gluteus minimus, psoas major, rectus femoris, vastus lateralis, vastus intermedius, biceps femoris and gastrocnemius, but not soleus, was significantly greater in the young group than the elderly group. The greatest rates of age-related loss of skeletal muscle mass in the lower limbs showed in the psoas major, while the smallest loss showed in soleus muscle. Only the gluteus medius was significantly associated with the LSA score (r = 0.528, p < 0.05) in elderly women. These results suggest that the reduction in skeletal mass with age is smaller in soleus muscle, and that the age-related decline in gluteus medius muscle is influenced by daily physical activity.

Acute effects of static stretching on muscle hardness of the medial gastrocnemius muscle belly in humans: an ultrasonic shear-wave elastography study.

This study investigated the acute effects of static stretching (SS) on shear elastic modulus as an index of muscle hardness and muscle stiffness and the relationship between change in shear elastic modulus and change in muscle stiffness after SS. The patients were 17 healthy young males. Muscle stiffness was measured during passive ankle dorsiflexion using a dynamometer and ultrasonography before (pre) and immediately after (post) 2 min of SS. In addition, shear elastic modulus was measured by a new ultrasound technique called ultrasonic shear wave elastography. The post-SS values for muscle stiffness and shear elastic modulus were significantly lower than the pre-SS values. In addition, Spearmans rank correlation coefficient indicated a significant correlation between rate of change in shear elastic modulus and rate of change in muscle stiffness. These results suggest that SS is an effective method for decreasing shear elastic modulus as well as muscle stiffness and that shear elastic modulus measurement using the shear wave elastography technique is useful in determining the effects of SS.

Atrophy of the lower limbs in elderly women: is it related to walking ability?

This study investigated the relationship between walking ability and age-related muscle atrophy of the lower limbs in elderly women. The subjects comprised 20 young women and 37 elderly women who resided in nursing homes or chronic care institutions. The elderly subjects were divided into three groups according to their walking ability. The muscle thickness of the following ten lower limb muscles were measured by B-mode ultrasound: the gluteus maximus, gluteus medius, gluteus minimus, psoas major, rectus femoris, vastus lateralis, vastus intermedius, biceps femoris, gastrocnemius and soleus. Compared to the young group, muscle thicknesses of all muscles except the soleus muscle were significantly smaller in all the elderly groups. There were no significant differences between the fast- and slow-walking groups in the thickness of any muscle. In the dependent elderly group, noticeable muscle atrophy was observed in the quadriceps femoris muscle. The results of this study suggest that the elderly who are capable of locomotion, regardless of their walking speed, show a moderate degree of age-related atrophy, while those who do not walk exhibit more severe atrophy, especially in the quadriceps femoris muscle.

Age-related changes in the thickness of the deep and superficial abdominal muscles in women

The study investigated age-related changes in the thickness of the deep and superficial abdominal muscles of 103 healthy women who could walk independently The participants were classified into five age groups: young (n=26; 20-24 years), young adult (n=26; 25-44 years), middle-aged (n=16; 45-64 years), young-old (n=16; 65-74 years), and old-old (n=19; 75-85 years). The muscle thicknesses of the right rectus abdominis, external oblique, internal oblique, and transversus abdominis were measured using ultrasound imaging. The rectus abdominis was significantly thicker in the young group compared with the young adult, middle-aged, young-old, and old-old groups (p<0.05). The external oblique and internal oblique muscles were significantly thicker in the young group compared with the middle-aged, young-old, and old-old groups (p<0.05). However, there were no significant differences in the thickness of the transversus abdominis between groups. The results suggest that age-related muscle atrophy occurs from an early age in superficial abdominal muscles, such as rectus abdominis, and that age-related atrophy is less in deep abdominal muscles such as the transversus abdominis.

Effects of balance training using wobble boards in the elderly.

Ogaya, S, Ikezoe, T, Soda, N, and Ichihashi, N. Effects of balance training using wobble boards in the elderly. J Strength Cond Res 25(9): 2616-2622, 2011—Few studies have examined balance training of elderly people using wobble boards. This study assessed the effects of wobble board balance training on physical function in institutionalized elderly people. This study examined 23 subjects (age 84.2 ± 5.9 years) who lived in a nursing home. The exercise program for the training group comprised balance training standing on a wobble board for 9 weeks, twice a week. In all, 11 training group subjects and 11 control group subjects completed this study. After 9 weeks, standing time on a wobble board, standing time on a balance mat, and maximum displacement distance of anterior-posterior center of pressure in the training group were significantly greater than those of the control group. Frequency analysis revealed that the power spectrum in 0.1-0.2 Hz significantly increased in the training group. These results suggest that wobble board training is effective for elderly people to improve their standing balance, by which they frequently control their center of gravity and maintain a standing posture on unstable surface conditions.

Time course of changes in passive properties of the gastrocnemius muscle-tendon unit during 5 min of static stretching.

The minimum time required for Static stretching (SS) to change the passive properties of the muscle-tendon unit (MTU), as well as the association between these passive properties, remains unclear. This study investigated the time course of changes in the passive properties of gastrocnemius MTU during 5 min of SS. The subjects comprised 20 healthy males (22.0 ± 1.8 years). Passive torque as an index of MTU resistance and myotendinous junction (MTJ) displacement as an index of muscle extensibility were assessed using ultrasonography and dynamometer during 5 min of SS. Significant differences before and every 1 min during SS were determined using Scheffés post hoc test. Relationships between passive torque and MTJ displacement for each subject were determined using Pearsons product-moment correlation coefficient. Although gradual changes in both passive torque and MTJ displacement were demonstrated over every minute, these changes became statistically significant after 2, 3, 4, and 5 min of SS compared with the values before SS. In addition, passive torque after 5 min SS was significantly lower than that after 2 min SS. Similarly, MTJ displacement after 5 min SS was significantly higher than that after 2 min SS. A strong correlation was observed between passive torque and MTJ displacement for each subject (r = -0.886 to -0.991). These results suggest that SS for more than 2 min effectively increases muscle extensibility, which in turn decreases MTU resistance.

Associations of muscle stiffness and thickness with muscle strength and muscle power in elderly women

Aim:  The aims of this study were to investigate the influence of age on muscle stiffness and to examine the relationships among muscle stiffness, muscle thickness, subcutaneous fat thickness, muscle strength and muscle power in elderly women.

Acute effects of static stretching on the hamstrings using shear elastic modulus determined by ultrasound shear wave elastography: Differences in flexibility between hamstring muscle components

BACKGROUND Static stretching (SS) with hip flexion and knee extension is often used to stretch the hamstrings. However, it is unclear whether there are the differences in the acute effect of this SS maneuver on flexibility between each component of the hamstrings, namely the semitendinosus (ST), semimembranosus (SM), and biceps femoris (BF) muscles. OBJECTIVES The aims of this study were to investigate the acute effects of SS on the flexibility of the individual muscle components of the hamstrings, and to examine the difference in the acute effect of SS between these components using shear elastic modulus as the index of muscle flexibility. METHOD Twenty healthy men (age, 23.4 ± 2.3 years) volunteered for this study. The shear elastic modulus of the ST, SM and BF muscles were measured using ultrasound shear wave elastography before (PRE) and immediately after (POST) 5 min of SS. Measurements of shear elastic modulus were taken with the knee at 90° (slack position) and 45° (extension position) of flexion. RESULTS In all muscles, the shear elastic modulus at both knee angles decreased significantly after SS. The percentage change in the shear elastic modulus from PRE to POST in the muscles at 45° of knee flexion was greatest in the SM. CONCLUSIONS These results suggest that SS with hip flexion and knee extension has acute effects on increasing flexibility of the hamstring muscle components, especially the SM muscle.

Effects of high-velocity resistance training on muscle function, muscle properties, and physical performance in individuals with hip osteoarthritis: a randomized controlled trial

Objective: To investigate the effects of high-velocity resistance training on muscle function, muscle properties, and physical performance in patients with hip osteoarthritis by comparison with those of low-velocity resistance training. Design: Single-blind randomized controlled trial. Setting: Home-based exercise programmes. Subjects: A total of 46 women with hip osteoarthritis were randomly assigned to the high-velocity (n = 23) or low-velocity (n = 23) training group. Interventions: Both groups underwent an eight-week daily home-based resistance training programme using an elastic band. Exercises involved hip abduction, extension, and flexion and knee extension. Participants in the high-velocity group performed the concentric phase of each repetition as rapidly as possible and returned to the initial position eccentrically in 3 s. Participants in the low-velocity group performed both the concentric and eccentric phases in 3 s. Main measures: The following outcome measures were evaluated: isometric muscle strength, muscle power, muscle thickness, muscle echo intensity, maximum walking speed, Timed Up and Go test, 3-minute walking test, Harris Hip Score, and hip pain. Results: Decreases in the time for performing the Timed Up and Go test (mean changes: high-velocity group −0.46 s, low-velocity group −0.23 s) and echo intensity of the gluteus maximus (mean changes: high-velocity group −6.8, low-velocity group −1.0) were significantly greater in the high-velocity group than in the low-velocity group. No significant difference was observed in changes of other outcome measures between the groups. Conclusion: This study revealed that high-velocity training for patients with hip osteoarthritis has partially a greater effect on muscle properties and physical performance than low-velocity training.