The purpose of this study was to test the endurance of the soleus muscle, and to examine the joint position at which it is most active, while simultaneously suppressing the activity of the gastrocnemius. Ten young males performed maximum isometric contraction of the triceps surae for 100 s, and the endurance and plantar flexion torque of this muscle were measured at various angles of the knee and ankle joints. The electromyogram was measured simultaneously and subsequently converted into integrated electromyogram (IEMG) values. With the knee flexed at 130 degrees, the rate of change in IEMG values for the soleus (0.454% x s(-1)) with the ankle in a neutral position was significantly higher than that for the medial and lateral gastrocnemius. Both with the ankle dorsiflexed at 10 degrees and in the neutral position, the rate of change in IEMG for the soleus was significantly higher with the knee flexed at 90 degrees and 130 degrees than with the knee fully extended. With the knee flexed at 90 degrees and 130 degrees, the IEMG activity of the soleus during the initial (5-10 s) and final 5 s tended to be higher than those for the medial and lateral gastrocnemius, regardless of the ankle joint position. We conclude that the position in which the soleus acts most selectively during a sustained maximum isometric contraction of the triceps surae is with the ankle in a neutral position and the knee flexed at 130 degrees.
Abstract.[Purpose] The purpose of this study was to compare the effects of muscle strength training and muscle endurance training on muscle deoxygenation level and endurance performance. [Subjects and Methods] Nineteen healthy young men were randomly assigned to a muscle strength training (STR: n = 6) group, muscle endurance training (END: n = 6) group, or a control (CON: n = 7) group. The training intensity for STR was 60°/sec × 10 repetitions × 5 sets/day and that for END was 240°/sec × 50% fatigue repetitions × 2 sets/day, 3 days/week, for 6 weeks. All subjects performed cardiopulmonary exercise testing (CPX) to measure maximum oxygen uptake, exercise time and muscle deoxygenation level of vastus lateralis, and underwent muscle strength and muscle endurance measurements pre-and post-training. [Results] In the STR group, muscle strength tended to increase, while muscle endurance significantly increased in the END group. Muscle deoxygenation level was significantly increased in both training groups. Maximum oxygen uptake did not change; however, in the END group alone, exercise time was significantly prolonged.[Conclusion] These results suggest that muscle endurance training is more effective at increasing endurance performance than muscle strength training.
[Purpose] Urinary incontinence is a frequent postpartum complication. Thus, this study
aimed to examine the associations of transversus abdominis muscle thicknesses at rest and
during an abdominal drawing-in maneuver with urinary incontinence in females at 2 months
postpartum. [Participants and Methods] The participants included 18 females at 2 months
postpartum with or without urinary incontinence, and 10 nulliparous females as controls.
Transversus abdominis thickness was measured at rest and during the abdominal drawing-in
maneuver using diagnostic ultrasonography. The Japanese version of the International
Consultation on Incontinence Questionnaire-Short Form was used to evaluate urinary
incontinence. [Results] Females at 2 months postpartum were divided into groups with and
without urinary incontinence according to questionnaire scores. The muscle thickness
during the abdominal drawing-in maneuver contraction was significantly lower in those with
urinary incontinence than in those without urinary incontinence and controls. [Conclusion]
The results showed significantly reduced transversus abdominis thickness during
contraction, which suggested reduced transversus abdominis strength in females with
postpartum urinary incontinence. Thus, promoting synergistic contraction of the inner
unit, including the transversus abdominis, in exercise therapy may be more effective for
postpartum urinary incontinence.
We evaluated the trunk abdominal muscle thickness while performing different exercises to identify the most effective training and to investigate the subjective difficulty associated with exercising. Twenty-eight men (mean age: 21.6 ± 0.9 years) without orthopedic diseases were enrolled. Ultrasonic imaging was used to measure the thickness of the transversus abdominis (TA), internal oblique, and external oblique muscles while at rest and while performing the abdominal draw-in maneuver and abdominal bracing. Measurements were made in the supine and sitting positions, and the subjective difficulty in performing each exercise was examined using a 5-level evaluation scale. The TA and internal oblique muscle thicknesses were significantly greater during the abdominal draw-in maneuver (ADIM) than during bracing or resting, in the supine and sitting positions. The subjective difficulty of abdominal bracing (AB) was graded significantly higher than that of ADIM. Additionally, a correlation between subjective difficulty and muscle thickness was found for the TA and IO. Our results may contribute to the choice of more effective exercises for spinal stability.
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