Publications by authors named "Hayao Ozaki"

Objectives: This study aimed to determine the effects of high-intensity isokinetic training with blood flow restriction during rest interval between set (rBFR) versus during exercise (eBFR) on muscle hypertrophy and increasing muscle strength and determine whether BFR-induced exercise pain is suppressed by rBFR.

Materials And Methods: Fourteen arms (7 participants) were recruited for the study. We conducted the following interventions for each arm: eBFR (n=4), rBFR (n=5), and exercise only (CON, n=5).

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Purpose: Physical activity (PA) is likely to be the most important modifiable factor in skeletal muscle development. However, the influence of PA on the skeletal muscle of preschool children has not been thoroughly investigated. The main objective of this study was to quantitatively measure PA, and then, to assess whether associations exist between site-specific muscle changes and PA in relation to sex and weight statuses in preschool children aged 3 to 4 years.

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Background: Grip strength is a marker of future health conditions and is mainly generated by the extrinsic flexor muscles of the fingers. Therefore, whether or not there is a relationship between grip strength and forearm muscle size is vital in considering strategies for grip strength development during growth. Thus, this study aimed to examine the association between changes in grip strength and forearm muscle thickness in young children.

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Purpose: Physical activity (PA) is widely recognized as a key factor in promoting skeletal muscle growth, though little is known about the specific impact of PA on the skeletal muscle development of preschool children. The purpose of this study is to investigate whether there is a relationship between PA levels and skeletal muscle thickness in preschoolers. By exploring this relationship, we hope to gain a better understanding of how PA can be used to promote healthy skeletal muscle development in preschoolers.

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  • The study investigated how changing gear ratio and cadence affect gross efficiency (GE) and the index of pedal force effectiveness (IFE) in male cyclists using a road racing bicycle.
  • Nine male cyclists performed graded cycling tests, measuring GE and IFE based on respiratory and pedal force data while varying gear ratios and cadence.
  • Results showed that increasing the gear ratio positively impacted GE and IFE, while changes in cadence had minor effects on GE and a stable IFE, indicating that gear ratio is more influential than cadence on performance.
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  • Handgrip strength (HGS) is an important indicator of health in children and adults, and low HGS in childhood may persist into adulthood without intervention.
  • The review explored whether physical exercise interventions can effectively improve HGS in children, revealing traditional exercise programs may not significantly enhance HGS beyond normal developmental changes.
  • It suggests that targeted grip exercises could lead to greater improvements in HGS, highlighting the need for incorporating these exercises into physical activity programs for children to potentially enhance long-term health.
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  • * Participants were assessed using various tests to categorize them based on LS, and daily PA was measured with wrist accelerometers.
  • * Findings revealed that women engaging in more than 28 minutes of moderate to vigorous physical activity daily had significantly lower odds of LS compared to those who were less active, while this association was not found in men, highlighting potential sex differences in the relationship between PA and LS.
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Purpose: We assessed the effects of low-intensity exercise with blood flow restriction (BFR) during rest intervals on recovery of muscle function and pain during exercise and rest intervals.

Methods: Participants were 10 males and study arms of the participants were randomly assigned into three conditions; low-intensity exercise with BFR during rest intervals (rBFR), low-intensity exercise with BFR during exercise (eBFR) and low-intensity exercise only (EO). The exercise task was elbow flexion until repetition failure at 30% of 1 RM and cuff pressure was 120 mmHg.

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  • The study investigates site-specific muscle loss in elderly males (ages 65-74) with locomotive syndrome (LS), a condition characterized by reduced mobility.
  • Researchers compared 100 men using risk tests for LS and found that those with LS had lower muscle mass, particularly in the rectus abdominis and anterior thigh, and exhibited poorer physical performance in tests like sit-ups and walking times.
  • The findings suggest that specific muscle loss may be linked to age-related physical functions, highlighting the impact of LS on mobility and muscle health in older adults.
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Objective: The previous results from cross-sectional studies indicate that there could be alterations across time in handgrip strength (HGS) asymmetry. One way to investigate this is to test the same children multiple times. Therefore, we aimed to evaluate the laterality of HGS in healthy young children at two different time points separated by a year.

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  • Resistance training helps combat age-related muscle loss in older adults, but its effectiveness can vary by individual.
  • A study with 69 Japanese elderly participants found that low-load resistance training significantly improved muscle thickness, especially in those with normal serum albumin levels.
  • Low serum albumin may indicate a reduced response to resistance training, suggesting it could be a biomarker for predicting training outcomes in elderly individuals.
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  • * Involving 678 participants, it compared the CS-30 results with established sarcopenia criteria and other muscle strength tests, using ROC analysis to determine optimal CS-30 scores for diagnosing the condition.
  • * Findings revealed a positive correlation between CS-30 scores and sarcopenia, identifying 15 stands for women and 17 for men as optimal cut-off points for screening.
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It is unclear whether the measurement of maximum muscle strength in younger children can be performed accurately due to factors such as motivation and maturity (i.e., the ability to receive instruction).

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  • - This study investigated the effects of low-load resistance training done twice a week on muscle size, strength, and physical functions in untrained older adults, comparing supervised training to a mix of supervised and unsupervised sessions.
  • - A total of 51 participants aged 57-75 were divided into two groups: one receiving full supervision and another receiving partial supervision with some home workouts.
  • - Results showed that while both groups experienced improvements in muscle strength and physical functions, the supervised group had greater muscle growth, highlighting the benefits of consistent supervision during training.
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An increased ability to supply energy to skeletal muscle is expected to contribute to greater athletic performance, and therefore, a variety of training methods are used for improving these energy supply systems. These methods are classified into two broad categories: a bout of continuous exercise at a given load/intensity and intermittent bouts of exercise at a given load/intensity with recovery intervals. Interestingly, recent work suggests that a training method which starts at a high load/intensity and gradually decreases the exercise load/intensity within a given training set (stepwise load reduction training) may provide a range of adaptations.

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The purpose of the present study was to investigate the effect of the progressive walking program on lower limb muscle size and strength and evaluated whether the stair-climbing exercise provided additional training effects when combined with the walking program. Fifteen elderly subjects (age 69 ± 1 years, height 1.63 ± 0.

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Background: Locomotive syndrome (LS) is associated with weakness and loss of function in the musculoskeletal organs. We aimed to determine the association between LS components and blood parameters in middle-aged and elderly individuals.

Methods: We included 223 middle-aged and elderly individuals in this study (104 men and 119 women; age: 40-85 years).

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  • - The study investigated the impact of a 17-week progressive walking program on reducing the risk of locomotive syndrome in 24 untrained elderly Japanese individuals, averaging 68 years old.
  • - Participants underwent various tests to measure their locomotive function and muscle strength at the beginning, midway, and end of the program.
  • - Results showed significant improvements in both the two-step test and geriatric locomotive function scale scores, linked to increased knee flexor strength and better overall physical function.
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Purpose: High-intensity neuromuscular electrical stimulation (NMES) training can induce muscle hypertrophy at the whole muscle and muscle fiber levels. However, whether low-intensity NMES training has a similar result is unknown. This study aimed to investigate whether low-intensity NMES training could elicit muscle hypertrophy at the whole muscle and muscle fiber levels in the human skeletal muscle.

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The present study examined the effects of exercise utilising traditional resistance training (leg press) or 'cardio' exercise (recumbent cycle ergometry) modalities upon acute physiological responses. Nine healthy males underwent a within session randomised crossover design where they completed both the leg press and recumbent cycle ergometer conditions. Conditions were approximately matched for effort and duration (leg press: 4 × 12RM using a 2 s concentric and 3 s eccentric repetition duration controlled with a metronome, thus each set lasted  60 s; recumbent cycle ergometer: 4 × 60 s bouts using a resistance level permitting 80-100 rpm but culminating with being unable to sustain the minimum cadence for the final 5-10 s).

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To investigate the effects of a single high-load (80% of one repetition maximum [1RM]) set with additional drop sets descending to a low-load (30% 1RM) without recovery intervals on muscle strength, endurance, and size in untrained young men. Nine untrained young men performed dumbbell curls to concentric failure 2-3 days per week for 8 weeks. Each arm was randomly assigned to one of the following three conditions: 3 sets of high-load (HL, 80% 1RM) resistance exercise, 3 sets of low-load [LL, 30% 1RM] resistance exercise, and a single high-load (SDS) set with additional drop sets descending to a low-load.

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Aim: Here, we aimed to compare the effect of a combination of body mass-based resistance exercise and moderate-intensity (55% peak oxygen uptake [ V˙O peak]) walking or high-intensity (75% V˙O peak) walking on muscle size and V˙O peak in untrained older women.

Methods: A total of 12 untrained older women (mean age 60 ± 2 years) were randomly assigned to either a moderate-intensity aerobic training group (n = 6) or high-intensity aerobic training group (n = 6). Both groups carried out body-mass based (lower body) resistance exercises (2 sets of 10 repetitions) on 3 days/week for 8 weeks.

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This paper reviews the existing evidence for the potential contribution of metabolic and mechanical stimuli to muscle growth in response to a variety of exercise modalities and intensities. Recent research has demonstrated that low-load resistance training can elicit comparable hypertrophy to that of high-load resistance training when each set is performed until failure. The degree of metabolic fatigue would be greater for resistance training with lower loads compared to higher loads at the point of muscle failure, which may compensate for the lower mechanical stress.

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