Japanese Journal of Physical Fitness and Sports Medicine
Online ISSN : 1881-4751
Print ISSN : 0039-906X
ISSN-L : 0039-906X
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Volume 55, Issue 4
Displaying 1-9 of 9 articles from this issue
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Review
  • NOVEL POSSIBILITIES OF SKELETAL MUSCLE HYPERTROPHY MECHANISM
    CONTRIBUTION OF STEM CELLS AND RELATIONSHIP OF OTHER SIGNALING PATHWAYS
    JUN KOMAZAWA, SHIGERU YAMADA
    2006 Volume 55 Issue 4 Pages 367-384
    Published: August 01, 2006
    Released on J-STAGE: May 15, 2007
    DOIhttps://doi.org/10.7600/jspfsm.55.367
    JOURNAL FREE ACCESS
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    This review explores novel possibilities of skeletal muscle hypertrophy mechanism based on previous studies. Hypertrophy and/or regeneration of skeletal muscles are caused by activation of satellite cells, induced by mechanisms such as growth factors and cytokines. Many unsolved problems, however, yet remain concerning signaling pathways, activated by such substances, and regulation of transcriptional factors and cell cycles.
    In recent years, possible involvement of not only satellite cells but also tissue-specific stem cells in skeletal muscle hypertrophy has been reported from studies made on stem cell transplantation in muscle regeneration.
    It has been elucidated that differentiation plasticity of tissue-specific stem cells contributes to hypertrophy and/or regeneration of skeletal muscles. Moreover, satellite cells have come to be regarded as one kind of tissue-specific stem cells, since they have been known to exhibit diversity, by their differentiating into not only skeletal muscle cells but also other tissue cells, as well as self renewal capacity.
    This review also summarizes findings on signaling pathways based on ligand receptor characterization. Among the various signaling pathways, focus was especially placed on the possibilities of Wnt signaling pathway and Notch signaling pathway on skeletal muscle hypertrophy, indicating that Wnt expression in adult muscle stem cells leads to regulation of skeletal muscle hypertrophy.
    It has also become evident that Notch signaling pathway is associated with the activation of satellites cells, and that functional decline of such signaling pathway causes a decline in the activation of satellite cells. Such functional decline of Notch signaling pathway has also been revealed as the reason for the decline of regenerative capacity of skeletal muscles due to advancing age. Further discussion on the involvement of Notch signaling pathway in skeletal muscle hypertrophy is made based on these results. As indicated above, the roles of ligands and/or receptors of canonical growth factors, signaling pathways, and transcriptional factors contributing to skeletal muscle hypertrophy were reexamined in this review, after which the contribution of tissue-specific cells to skeletal muscle hypertrophy was discussed based on the results of muscle regeneration studies. Furthermore, focus was centered on Wnt and Notch signaling pathways, both of which are attracting renewed attention, and study was made on the possibility of the involvement of these pathways in skeletal muscle hypertrophy process.
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  • THE RELATIONSHIP BETWEEN BODY WEIGHT REDUCTION AND INTENSITY OF DAILY PHYSICAL ACTIVITIES ASSESSED WITH 3-DIMENSION ACCELEROMETER
    TAKETAKA HARA, YOSHIHIRO MATSUMURA, MATSUKI YAMAMOTO, TADAHARU KITADO, ...
    2006 Volume 55 Issue 4 Pages 385-392
    Published: August 01, 2006
    Released on J-STAGE: May 15, 2007
    DOIhttps://doi.org/10.7600/jspfsm.55.385
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    We investigated the relationship between body weight reduction and intensity of daily physical activities assessed with 3-dimensional accelerometer during a 3-month exercise program. Twenty-six middle-aged women (58.1±7.4 yrs.) participated in this study. Participants underwent a 90-min endurance exercise intervention once a week, and a 3-dimensionsal accelerometer was attached through the program. Body weight (BW), body mass index, fat mass and percent body fat were reduced significantly (p<0.001), while diastolic blood pressure (p<0.01) and shuttle stamina walking test (p<0.05) improved significantly after the exercise intervention. Moreover, a significant negative correlation was observed between the changes in BW and total activity time (TAT) per day of more than 3METs (TAT≥3METs)(r=−0.580, p<0.01) and TAT≥4METs (r=−0.627, p<0.001). To the contrary, the daily steps and the TAT≥2METs were not related to the changes in BW. After adjusting daily steps, TAT≥3METs (β=−0.630, p<0.01) and TAT≥4METs (β=−0.659, p<0.01) were still significantly related to the changes in BW. These results indicate that weight reduction has a much closer relationship with exercise intensity than daily steps. It is important to keep both quantity and intensity of exercise in the unsupervised exercise program aimed at weight reduction.
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  • ELECTROMYOGRAM PATTERNS DURING SUSTAINED LOW-LEVEL PLANTAR FLEXIONS AND CHANGES IN BLOOD FLOW FOR "ALTERNATE ACTIVITY" AMONG THE TRICEPS SURAE MUSCLES
    HIKARI KIRIMOTO, YOSHINOBU GOTOH, NAOKI KOTAKE, KOHJI KITADA, FUTOSHI ...
    2006 Volume 55 Issue 4 Pages 393-402
    Published: August 01, 2006
    Released on J-STAGE: May 15, 2007
    DOIhttps://doi.org/10.7600/jspfsm.55.393
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    Several studies have described "Alternate activity", in which individual muscles of the synergistic muscle group alternate between high activity and silent periods, and rotate in a complementary pattern to maintain constant torque, during sustained low-level contractions. The purpose of this study was to investigate the physiological property of alternate activity among the synergists. Eight human subjects performed static contractions at an ankle joint angle of 110° plantar flexion at 10% maximal voluntary contraction (MVC) for 120 min. Simultaneously, a surface electromyogram (EMG) was recorded of the triceps surae muscles. Doppler ultrasound techniques were used to measure blood velocity and the arterial diameter of the popliteal artery during exercise. Maximal torque at MVC and mean EMG (mEMG) level decreased significantly after sustained isometric low-level contractions, but there was no significant difference in the mEMG/maximal force ratio of triceps surae muscles, which is thought to indicate peripheral fatigue between pre- and post-exercise. Throughout the "Alternate activity", arterial diameter and pulse rate did not change, but blood flow significantly increased (p<0.001) depending on an increase in blood velocity. These results suggest that "Alternate activity" among the triceps surae muscles may be one mechanism that functions either to decrease or to postpone peripheral fatigue during sustained low-level contraction.
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  • GENDER DIFFERENCES OF LOWER EXTREMITY KINEMATICS DURING SINGLE LEG LANDING
    ISSEI OGASAWARA, YUTAKA MIYANAGA, HITOSHI SHIRAKI, NAOKI MUKAI, MASAHI ...
    2006 Volume 55 Issue 4 Pages 403-412
    Published: August 01, 2006
    Released on J-STAGE: May 15, 2007
    DOIhttps://doi.org/10.7600/jspfsm.55.403
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    The higher anterior cruciate ligament (ACL) injury rate of females is one of the most sever athletic-related problems today. The purpose of this study is to compare the lower extremity kinematics between male and female during single leg landing.
    Six male and four female healthy subjects participated in this study. They jumped from a 32 cm high box and landed with the dominant leg. The landing action was filmed with three video cameras. The knee flexion, knee valgus/varus, and hip adduction/abduction angle and angle velocity were calculated.
    In female subjects, the knee flexion angle and hip adduction angle were greater compared to males. Also, the knee valgus velocity and hip adduction velocity were higher in females.
    Our results suggest that knee valgus kinematics may be related to hip adduction. It is important to evaluate hip kinematics when considering knee kinematics to prevent knee ligament injuries.
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  • INFLUENCE OF THE EXERCISE INTERVENTION ON PHYSICAL FUNCTION IN THE COMMUNITY-DWELLING INDEPENDENT ELDERLY WITH KNEE JOINT PAIN
    SHINICHIRO SATO, NOBUYOSHI NAKAMURA, SHINICHIRO SHIOZAWA, KAZUNORI MOR ...
    2006 Volume 55 Issue 4 Pages 413-420
    Published: August 01, 2006
    Released on J-STAGE: May 15, 2007
    DOIhttps://doi.org/10.7600/jspfsm.55.413
    JOURNAL FREE ACCESS
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    Purpose: The purpose of this study was to examine the influence of the exercise program for Osteoarthritis of the knee (knee OA) which American Geriatrics Society Panel on Exercise and Osteoarthritis (AGS) recommends on physical function in Japanese independent elderly with knee joint pain.
    Methods: Subjects of this study were 36 (7 males : aged 74.7±5.1 years, 29 females : aged 72.3±4.6 years) community-dwelling independent elderly with knee joint pain who voluntary participated in our exercise program. The program consisted of massage around knee, flexibility exercises in knee and ankle joints, and leg muscle development exercises. They performed these exercises twelve times for a month at regular intervals. Physical function were evaluated by the muscle strength during knee extension and flexion, the range of motion of knee joint and the center of pressure during upright standing. There were three times measurements at one month before starting of the program (the 1 st), immediately before beginning of the program (the 2 nd), and just after ending of the program (the 3 rd). Difference between change in measurement values during the observation period (subtract the 1 st from the 2 nd ; Δ1) and that during intervention period (subtract the 2 nd from the 3 rd ; Δ2) were analyzed by Students't-test.
    Results and Conclusion: There was significant difference between Δ1 (0.01±0.05 kg/wt) and Δ2 (0.04±0.05 kg/wt) on maximal muscle strength during knee extension. This result suggested that the exercise program recommended by AGS was improved the leg muscle strength in Japanese elderly with knee joint pain. However the effects of the exercise intervention were not clarified on the other physical function. As for the reasons it seems to affect the initial level of joint pain and physical function in the subjects. Therefore, reexamination of this point with a greater number of samples which the worse level of knee joint pain is needed in the future.
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  • THE HIGHER CALF PRESSURE INDUCED BY WEARING GRADUATED ELASTIC COMPRESSION STOCKING INCREASES CALF VENOUS COMPLIANCE
    GOU HAYATA, TAKASHI MIURA, TETSUJI IWASAKI, MOTOHIKO MIYACHI
    2006 Volume 55 Issue 4 Pages 421-428
    Published: August 01, 2006
    Released on J-STAGE: May 15, 2007
    DOIhttps://doi.org/10.7600/jspfsm.55.421
    JOURNAL FREE ACCESS
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    The purpose of the present study was to clarify effect of increase in calf pressure on calf venous compliance. The calf pressures were increased by wearing elastic compression stockings with different pressures (Calf pressure 0, 12, 17, 21 mmHg). Healthy twelve people (six men and six women, 43.3±15.3 years) volunteered to participate in this study. Changes in calf venous volume during spine rest were measured by mercury plethysmography. We analyzed the calf venous compliance by inflating the venous collecting cuff to 60 mmHg for 7 min, then decreasing cuff pressure at 1 mmHg/sec (over 1 min) to 0 mmHg, using cuff pressure as an estimate of venous pressure. This method produced pressure-volume curves fitting the quadratic regression (Δlimb volume)=β0+β1·(cuff pressure)+β2·(cuff pressure)2, where Δ is change. The higher calf venous compliance and volume were observed in with the higher pressure stocking. These results suggest that higher calf pressure induced by wearing elastic compression stocking increases calf venous compliance and maximum venous outflow.
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Short Communication
  • GENDER DIFFERENCES IN MUSCLE FORCE AND OXYGENATION RECOVERY FROM INTERMITTENT HANDGRIP EXERCISE
    YOKO SAITO, TAKESHI OTSUKI, MOTOYUKI IEMITSU, SEIJI MAEDA, RYUICHI AJI ...
    2006 Volume 55 Issue 4 Pages 433-442
    Published: August 01, 2006
    Released on J-STAGE: May 15, 2007
    DOIhttps://doi.org/10.7600/jspfsm.55.433
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    To investigate a relationship between gender differences in recovery from skeletal muscle fatigue and muscle oxygenation, we examined whether there is a difference in oxygen supply and consumption of the working muscles after intermittent handgrip exercise between young males and females using near-infrared spectroscopy (NIRS). Healthy young subjects (25.8±3.9 years ; males, n=10 ; females, n=10) repeated static maximal voluntary contractions (MVC) with a handgrip for 5 seconds followed by 5 seconds rest for a period of 4 minutes in Study 1. The MVC force was measured before, each minute during the handgrip exercise, and 2, 5, and 10 minutes following the exercise. In Study 2, the selected 10 subjects (males, n=5 ; females, n=5) performed the same exercise and their total- and deoxy- hemoglobin/myoglobin level was measured using the venous occlusion NIRS method; and O2 supply index (OSI) and O2 consumption index (OCI) calculated before and after the exercise. In Study 1, females exhibited higher %MVC force at the end of the exercise and during the recovery period than males (p<0.05). In Study 2, the %OSI was significantly lower in females than in males at 5 and 10 minutes in the recovery period (p<0.05), but no significant differences were detected in %OCI. Furthermore, %MVC of the recovery period correlated with %OCI of the recovery period in females (r=0.724, p=0.015), but not in males. These findings suggest that female working muscles can convert consumed oxygen more effectively after an intermittent handgrip exercise, and therefore, be able to recover muscle force faster.
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