Naoki Kikuchi

Nippon Sport Science University · Department of Physical Education

Objective This study explored the interaction among ACTN3 R577X polymorphism, muscle damage, and post-exercise inflammatory response by assessing changes over time in serum creatine kinase and interleukin-6 levels. Design Ninety-five active Japanese participants (50 men and 45 women: 22.2 ± 2.3 years) who did not perform daily upper limb strength...

Osteoporosis is a significant health concern for postmenopausal women, necessitating efficient screening methods for bone health. This study explores the potential of muscle function, assessed through the 30-s chair stand test (CS-30), as an indicator for low bone stiffness in this demographic, aiming to establish a practical threshold for large-sc...

The greater muscle fiber cross-sectional area (CSA) is associated with greater skeletal muscle mass and strength, whereas muscle fiber atrophy is considered a major feature of sarcopenia. Muscle fiber size is a polygenic trait influenced by both environmental and genetic factors. However , the genetic variants underlying inter-individual difference...

BACKGROUND: The evidence of response to velocity loss cut-off training with similar total repetitions are limited. OBJECTIVE: This study aimed to examine the effects of different velocity loss training protocols after 3 weeks of traditional resistance training protocols on strength and power in trained men. METHODS: Twenty highly trained men partic...

This study sought to assess how post-game creatine kinase (CK) levels correlate with the number of sprints and the impact of the ACTN3 polymorphism on this response. This research constituted a descriptive/observational, retrospective cross-sectional study. DNA was extracted from blood samples for ACTN3 polymorphism genotyping. CK was measured 48 h...

Background Recently, genetic predisposition to injury has become a popular area of research and the association between a few single nucleotide polymorphisms (SNPs) and the susceptibility to develop musculoskeletal injuries has been shown. This pilot study aimed to investigate the combined effect of common gene polymorphisms previously associated w...

Background: Sprint interval training (SIT) improves maximal aerobic and anaerobic performance, including oxygen uptake (VO2 max ), power output, and sprint performance. This study aimed to investigate the effect of SIT load on V̇O 2max in trained subjects. Methods: SIT was performed twice a week for three weeks by twenty-four trained men (aged:...

Individual differences in muscle strength recovery after eccentric exercise may be influenced by sex and genotype. A candidate genetic polymorphism associated with response during muscle recovery is the MMP3 gene rs522616 polymorphism, encoding matrix metalloproteinase (MMP-3). Here, we investigated the effect of the MMP3 gene rs522616 polymorphism...

Background. Recently, genetic predisposition to injury has become a popular area of research and the association between a few Single Nucleotide Polymorphisms (SNPs) and the susceptibility to develop musculoskeletal injuries has been shown. This pilot study aimed to investigate the combined effect of common gene polymorphisms previously associated...

Purpose This study examined whether decline in cognitive function is related to arterial stiffness and reduction in physical fitness in middle-aged and older adults. Methods A total of 1554 healthy middle-aged and older adults participated in this study. The trail making test parts-A (TMT-A) and B (TMT-B), brachial-ankle pulse wave velocity (baPWV...

The objective of this study was to investigate the effects of free weight and body mass‐based resistance training (RT) on muscle size and thigh intramuscular fat (IMF) in young and middle‐aged individuals. Healthy individuals (aged 30–64 years) were assigned to either a free weight RT group (n = 21) or a body mass‐based RT group (n = 16). Both grou...

Ginszt, M, Saito, M, Zięba, E, Majcher, P, and Kikuchi, N. Body composition, anthropometric parameters, and strength-endurance characteristics of sport climbers: a systematic review. J Strength Cond Res XX(X): 000-000, 2023-Sport climbing was selected to be part of the Summer Olympic Games in Tokyo 2021 with 3 subdisciplines: lead climbing, speed c...

The R577X polymorphism in the α-actinin-3 gene (ACTN3) is associated with muscle strength and power; there is an association between ACTN3 R577X polymorphism and range of motion (ROM). We examined the effect of the ACTN3 R577X polymorphism on ROM through meta-analysis and systematic review. Relevant studies published before April 14, 2022 were iden...

Objectives: The coronavirus disease 2019 (COVID-19) pandemic has affected people’s physical activity, sedentary behavior, and sleep. This study aimed to clarify the association between combining these factors, integrated as adherence to 24-h movement guidelines, and depressive status during the COVID-19 pandemic. Methods: At the end of October 2020...

Sports genetics research began in the late 1990s and over 200 variants have been reported as athletic performance- and sports injuries-related genetic polymorphisms. Genetic polymorphisms in the α-actinin-3 (ACTN3) and angiotensin-converting enzyme (ACE) genes are well-established for athletic performance, while collagen-, inflammation-, and estrog...

Purpose: This study investigated the effect of online home-based resistance exercise training on fitness, depression, stress, and well-being. A total of 67 individuals participated. Of them, 28 participants (13 men and 15 women, average age: 45.1 ± 12.2 years) performed the same exercise training online (n = 17), using Zoom, or in person (n = 11) i...

In recent years, people tend to be more health-conscious. Due to this, strength training has been attracting attention as an effective way to maintain and improve muscle strength which affects QoL. In this study, we developed a resistance training device for multi kinds of muscle trainings, which is able to set an arbitrary load by motor control. T...

This study aimed to investigate the relationship between power-oriented genetic polymorphisms and weightlifting status, create a total genotype score (TGS), and validate the association between TGS models and power-oriented athletes. First, 192 weightlifters and 416 controls were studied, and 12 polymorphisms that have previously been associated wi...

Purpose The aldehyde dehydrogenase 2 (ALDH2) rs671 polymorphism, which is exclusive to the Asian population, is related to many diseases. A high reactive oxygen species production in mitochondria, and low muscle strength in athletes and non-athletes, has been observed, as our previous study demonstrated. The purpose of this research was to investig...

Muscle injuries are among the main reasons for medical leavings of soccer athletes, being a major concern within professional teams and their prevention associated with sport success. Several factors are associated with a greater predisposition to injury, and genetic background is increasingly being investigated. The aim of this study was to analyz...

The rs671 polymorphism is associated with the enzymatic activity of aldehyde dehydrogenase 2 (ALDH2), which is weakened by the A allele in East Asians. We recently reported the association of this polymorphism with the athletic status in athletic cohorts and the muscle strength of non-athletic cohorts. Therefore, we hypothesized the association of...

Background: In this study, we examined the Sex difference of the effect of rest intervals on lifting velocity during resistance exercise. Methods: Twenty-two trained subjects (11 men and 11 women) were included. Each protocol consisted of 3 sets of 10 repetitions at 70% of 1- repetition maximum (1RM) with rest intervals of 90 s (R90), 150 s (R15...

Physical fitness comprises motor ability and health-related factors. The concept of health-related physical fitness is well-known and established through abundant evidence, such as the Tokyo Gas study and Hisayama study. Although the Active Guide - Japanese Official Physical Activity Guidelines for Health Promotion were published in 2013, there are...

This study aimed to examine how genetic polymorphisms related to muscular strength and flexibility influence artistic gymnastic performance in an attempt to identify a novel polymorphism associated with flexibility. In study 1, the passive straight-leg-raise (PSLR) score and aromatase gene CYP19A1 rs936306 polymorphism, a key enzyme for estrogen bi...

Aldehyde dehydrogenase 2 (ALDH2) catalyses aldehyde species, including alcohol metabolites, mainly in the liver. We recently observed that ALDH2 is also expressed in skeletal muscle mitochondria; thus, we hypothesize that rs671 polymorphism-promoted functional loss of ALDH2 may induce deleterious effects in human skeletal muscle. We aimed to clarif...

The purpose of this study was to compare the frequency of COL1A1 rs1107946 polymorphism between sport climbers and controls from three ethnic groups (Japanese, Polish, and Russian) and investigate the effect of the COL1A1 rs1107946 polymorphism on the age-related decrease in flexibility in the general population. Study I consisted of 1929 healthy p...

Purpose: In this study, we examined sex differences in lifting velocity and blood lactate concentration during resistance exercise using different rest intervals (RIs). Methods: Twenty-two trained men (n = 11) and women (n = 11) completed different RIs resistance exercise sessions (90s (R90), 150s (R150), and 240s (R240)). All sessions consisted of...

A specialized training machine, known as a rowing machine or kayak ergometer is used for kayak paddler's indoor training. However, conventional ergometers do not focus on accurately reproducing the feeling of paddling resistance experienced in kayaking on the water, hence kayak paddlers have a risk of learning a paddling form specific to the ergome...

The aim of this study is to develop an inexpensive and easy-to-use motion measurement system which can assess complex motions, e.g. squat exercise, in non-contact manner. To measure 3D posture of a human being, a compact RGB-D camera is used. Here, 2D human-pose is estimated by a skeleton tracking algorithm using RGB image, and 3D human-pose is rec...

A recent case-control study identified 28 DNA polymorphisms associated with strength athlete status. However, studies of genotype-phenotype design are required to support those findings. The aim of the present study was to investigate both individually and in combination the association of 28 genetic markers with weightlifting performance in Russia...

PurposeThe aim of this study is to investigate the influence of the MCT1 T1470A polymorphism (rs1049434) on repeated sprint ability (RSA) and lactate accumulation after RSA testing.Methods Twenty-six elite Italian male football players (age: 17.7 ± 0.78 years; height: 179.2 ± 7.40 cm; weight: 72.1 ± 5.38 kg) performed RSA testing (6 × 30-m sprints...

Previous small-scale studies have shown an association between the COL5A1 gene and anterior cruciate ligament (ACL) injury risk. In this larger study, the genotype and allele frequency distributions of the COL5A1 rs12722 C/T and rs10628678 AGGG/deletion (AGGG/-) indel variants were compared between participants: (i) with ACL injury in independent a...

This study aimed to investigate the ACTN3 R577X, ACE I/D, CKM rs8111989, and TRHR rs7832552 genotypes in climbers and controls in three ethnicities. The study consisted of 258 climbers (Japanese, n = 100; Polish, n = 128; Russian, n = 30) and 1151 controls (Japanese: n = 332, Polish: n = 635, Russian: n = 184). Genotyping results were analyzed usin...

Online exercise is undoubtedly useful and important; however, chronic adaptations to online exercise, particularly strength gain, muscle hypertrophy, and cardiovascular parameters, remain unclear. We investigated the effect of online exercise training using Zoom on fitness parameters compared with the same exercises supervised directly. In the pres...

Sport climbing will become an official event at the 2020 Tokyo Olympics; it is a popular wilderness sport among athletes and amateurs. Our previous study suggested that the T1470A polymorphism (rs1049434) of the monocarboxylate transporter 1 (MCT1) gene is associated with athletic performance and physiological phenotypes. The purpose of this study...

Purpose: We aimed to investigate the hypothesis that type I collagen plays a role in increasing bone mineral density (BMD) and muscle stiffness, leading to low and high risks of fatigue fracture and muscle injury, respectively, in athletes. As a potential mechanism, we focused on the effect of the type I collagen alpha 1 chain gene (COL1A1) varian...

Background Maximal aerobic capacity, e.g. maximal oxygen uptake (V̇O 2 max), is not constant, and it has a time-dependent variation based on the condition of individual. On the other hand, arterial properties play an important role in determining aerobic performance, and lower arterial stiffness is associated with higher cardiorespiratory fitness l...

The purpose of this study is to develop a video-based motion analysis method using OpenPose for evaluating the performance of sport climber. To evaluate the skills of sport climber quantitatively, we proposed three kinds of evaluation indices concerning the smoothness and stability of motion as well as the effort of arm. The result of experiment sh...

The myotendinous junction (MTJ) is at high risk of muscle injury, and the collagen XXII is strictly expressed at tissue junctions, specifically at the MTJ. We investigated the hypothesis that single nucleotide polymorphisms (SNPs) related to collagen type XXII alpha 1 chain gene (COL22A1) mRNA expression are associated with susceptibility to muscle...

Kumagai, H, Miyamoto-Mikami, E, Kikuchi, N, Kamiya, N, Zempo, H, and Fuku, N. A rs936306 C/T polymorphism in the CYP19A1 is associated with stress fractures. J Strength Cond Res XX(X): 000-000, 2020-A stress fracture (SF) is an overuse injury, and low bone mineral density (BMD) is the risk factor for the SF. Estrogen is suggested to have a crucial...

Homma, H, Kobatake, N, Sekimoto, Y, Saito, M, Mochizuki, Y, Okamoto, T, Nakazato, K, Nishiyama, T, and Kikuchi, N. Ciliary neurotrophic factor receptor rs41274853 polymorphism is associated with weightlifting performance in Japanese weightlifters. J Strength Cond Res XX(X): 000-000, 2020-At least 69 genetic markers are associated with power athlete...

ACE I/D polymorphism has been recently associated with the susceptibility to inflammation and muscle damage after exercise. The aim of this study was to understand the association between the ACE I/D polymorphism and muscle injuries in a large cohort of elite football players from two different countries. Seven hundred and ten male elite football p...

Terada, K, Kikuchi, N, Burt, D, Voisin, S, and Nakazato, K. Full title: Low-load resistance training to volitional failure induces muscle hypertrophy similar to volume-matched, velocity fatigue. J Strength Cond Res 36(6): 1576-1581, 2022-We investigated how resistance training (RT) to failure at low load affects acute responses and chronic muscle a...

Acetaldehyde dehydrogenase 2 (ALDH2) is an enzyme involved in redox homeostasis, as well as the detoxification process in alcohol metabolism. Nearly 8% of the world's population have an inactivating mutation in the ALDH2 gene. However, the expression patterns and specific functions of ALDH2 in skeletal muscles are still unclear. Herein, we report t...

The purpose of this study is to develop a motion sensor system which can measure 3D posture of a paddle, propulsive paddle force, and boat velocity for kayak paddlers in flat water canoeing. The system has an inertial sensor to calculate paddle kinematics, and strain gauges are used to measure the force applied to the paddle. In addition, GPS senso...

Power assist devices are attracting remarkable attention as they can reduce the burden of workers engaged in heavy labor: nursing care, manufacturing, logistics, and farming. However, the effect of power assist devices in reducing labor’s fatigue has not been sufficiently evaluated. The purpose of this study is to quantitatively evaluate the assist...

Background: Poor joint flexibility has been repeatedly proposed as a risk factor for muscle injury. The C-to-T polymorphism (rs12722) in the 3'-untranslated region of the collagen type V α1 chain gene (COL5A1) is reportedly associated with joint flexibility. Flexibility of a normal joint is largely determined by passive muscle stiffness, which is...

Background: Poor joint flexibility has been repeatedly proposed as a risk factor for muscle injury. The C-to-T polymorphism (rs12722) in the 3′-untranslated region of the collagen type V α1 chain gene ( COL5A1 ) is reportedly associated with joint flexibility. Flexibility of a normal joint is largely determined by passive muscle stiffness, which is...

Background: Poor joint flexibility has been repeatedly proposed as a risk factor for muscle injury. The C-to-T polymorphism (rs12722) in the 3′-untranslated region of the collagen type V α1 chain gene ( COL5A1 ) is reportedly associated with joint flexibility. Flexibility of a normal joint is largely determined by passive muscle stiffness, which is...

Background Poor joint flexibility has been repeatedly proposed as a risk factor for muscle injury. The C-to-T polymorphism (rs12722) in the 3′-untranslated region of the collagen type V α1 chain gene (COL5A1) is reportedly associated with joint flexibility. Joint flexibility is largely determined by muscle stiffness, which is influenced by intramus...

PURPOSE: The aim of this investigation was to determine the influence of water intake (WI) during resistance training (RT) on pulse wave velocity (PWV). METHODS: Young male adults (n= 17, 23.1±6.3 years old; 174.0±5.4 cm height; 76.4±13.3 kg weight) with at least 1 year of previous experience in RT and previously hydrated performed in two different...

Compared to sprint/power and endurance sports, the genetic contribution to success in sports that require a mixture of anaerobic and aerobic qualities has received relatively limited attention. This chapter evaluates research findings on the potential genetic variants influencing the team sports athletic status and the key factors for team sports p...

The purpose of this study is to develop a motion sensor system which can measure 3D posture of a paddle as well as propulsive paddle force for kayak paddlers. The system has an inertial sensor to calculate paddle kinematics, and strain gauges are used to measure the force applied to the paddle. In an experiment, a customized paddle equipped with th...

The aim of this study is to develop a prototype of kayak ergometer which has a potential to emulate actual on-water paddling resistance. The proposed ergometer equips a powder brake as a source of resistance and the resistance can be controlled according to the voltage signal. Moreover, the developed ergometer has a function of detecting the paddle...

Purpose: Muscle injury is the most common sports injury. Muscle stiffness, a risk factor for muscle injury, is lower in females than in males, implying that sex-related genetic polymorphisms influence muscle injury associated with muscle stiffness. The present study aimed to clarify the associations between two genetic polymorphisms (rs2234693 and...

We aimed to replicate, in a specific athletic event cohort (only track and field) and in two different ethnicities (Japanese and East European, i.e. Russian and Polish), original findings showing the association of the angiotensin-II receptor type-2 gene (AGTR2) rs11091046 A>C polymorphism with athlete status. We compared genotypic frequencies of t...

Mitochondrial aldehyde dehydrogenase‐2 (ALDH2) scavenges reactive aldehyde products, such as 4‐hydroxy‐2‐nonenal. Previous studies confirmed that the ALDH2 rs671 polymorphism is associated with hypertension and cancer, probably because of increased oxidative stress. Undesirable effects of ALDH2 rs671 might also be expected in skeletal muscles. The...

We investigated the effects of low load resistance training to failure performed with different rest intervals on acute hormonal responses and long-term muscle and strength gains. In the acute study, 14 participants were assigned to either a short rest (S, 30 s) or long rest (L, 150 s) protocol at 40% one-repetition maximum. Blood samples were take...

The purpose of present study was to examine the association between ACTN3 R577X genotype and functional characteristics of elbow flexors before and after isokinetic eccentric contractions (ECCs). Fifty-two men (age: 20.8±3.8 years, height: 172.5±5.9 cm, body mass: 64.7±6.5 kg, BMI: 21.7±1.7) who had not participated in any regular resistance traini...

Background: The authors previously identified that COL11A1 gene polymorphism is not a susceptibility factor for lumbar disc degeneration (LDD) in athletes. However, the relationship between COL11A1 gene polymorphism and cervica