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  • 1.
    Alm, Petter
    et al.
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Sports Medicine.
    Yu, Ji-Guo
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Sports Medicine.
    Physiological characters in mixed martial arts2013In: American Journal of Sports Science, ISSN 2330-8540, Vol. 1, no 2, p. 12-17Article in journal (Refereed)
    Abstract [en]

    Mixed martial arts (MMA) is a relatively new sport and is a mixture of many different martial arts. Currently, study on the physiological characters in the sport is very limited. The present study evaluated the physiological characters in 5 active male MMA athletes at two occasions with one year between. Aerobic- and anaerobic capacity were estimated through measurement of VO2max and anaerobic threshold using both treadmill running and arm cycling. Muscle strength was evaluated through series measurements. Body composition and personal competition records were also examined. The subjects presented above average aerobic capacity, but rather high anaerobic capacity and threshold levels compared with other similar sports. No significant difference in VO2max, anaerobic threshold or body composition was observed between the two test occasions, despite a decreased tendency in muscle strength/power in the second test compared to the first. The results were interpreted to indicate either the MMA athletes had reached the physiological requirements for MMA or the one year physical training was inefficient in further improving the parameters.                                              

  • 2. Baoren, Che
    et al.
    Ji-Guo, Yu
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Sports Medicine.
    Aging effects of exercise training on erythrocyte1995In: Journal of Shanghai Physical Education Institute, ISSN 1000-5498, Vol. 19, no S1, p. 102-104Article in journal (Refereed)
    Abstract [zh]

    长时间剧烈运动能引起循环中的红细胞损伤和老化;而长期运动训练有可能导致运动性贫血的发生,据最近的一些研究表明,尽管一次长时间剧烈运动可引起红细胞被破坏增多,但长期运动训练引起的运动性贫血,在很多情况下属于血液稀释作用造成的。本文设计6周身体训练并在训练的不同阶段进行剧烈运动,测定反映红细咆老化状态的几个敏感指标:2,3—DPG、红细胞肌酸含量及红细胞生成素等,旨在确认不同强度的训练及剧烈运动对红细胞生成和老化的影响,为进一步完善运动性贫血理论提供依据。

  • 3.
    Bengtsson, Victor
    et al.
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Sports medicine.
    Yu, Ji-Guo
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Sports medicine.
    Gilenstam, Kajsa
    Could the negative effects of static stretching in warm-up be restored by sport specific exercise?2018In: Journal of Sports Medicine and Physical Fitness, ISSN 0022-4707, E-ISSN 1827-1928, ISSN 0022-4707, Vol. 58, no 9, p. 1185-1189Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: Static stretching (SS) is widely used in warm-up as it is generally believed to increase mobility and reduce the risk of injury; however, SS has been shown to induce transient negative effects on subsequent muscle performance. Interestingly, recent studies have shown that sport specific exercise could restore SS-induced negative effects on certain sports, especially of explosive muscular performance. Whether sport specific exercise could restore SS-induced negative effects on isokinetic muscle performance remains unclear.

    METHODS: The present study conducted two different warm-ups: 2-component warm-up and 3-component warm-up on 15 university students. Both protocols contained low intensity aerobic exercise and sport specific exercise, whereas the 3-component warm-up also contained SS which has been previously proven to induce negative effects on subsequent muscle performance. After the warm-ups, the subjects performed an isokinetic test on a Biodex. To make the sport specific exercise mimic the subsequent test, both included concentric isokinetic knee extension. During the tests, muscle performance of peak torque, mean power, and total work was recorded. Comparison of the measurements on each parameter between the two warm-ups was performed using paired t test.

    RESULTS: The comparisons did not reveal any significant difference in the measurement of any parameter between the two different warm-up protocols, and calculation of Cohen's revealed small effect sizes on all of the three variables.

    CONCLUSIONS: On basis of the present results and that the SS could induce transient negative effects on subsequent muscle performance, we concluded that the negative effects of the SS on the variables were restored by the isokinetic contractions.

  • 4.
    Brännström, André
    et al.
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Sports Medicine.
    Rova, Anton
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Sports Medicine.
    Yu, Jiguo
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Sports Medicine.
    Effects and mechanisms of tapering in maximizing muscular power2013In: Sport and Art, ISSN 2331-6233, Vol. 1, no 1, p. 18-23Article, review/survey (Refereed)
    Abstract [en]

    Muscle power is of great importance in most sports, and its development is one of the most fundamental physiological adaptations for improving physical performance. In order to optimize competition performance, athletes usually decrease training load before competition, the so-called tapering, to allow physiological and psychological recovery from accumulated training stress. Tapering could be conducted through changes in training volume, intensity and/or frequency, but training volume seems to be most effective in optimizing muscular power. There are two main types of tapering: progressive tapering and one-step tapering. Currently, there is no general conclusion on tapering duration. The physiological mechanisms regarding tapering effects on neuromuscular system are largely unknown. Generally, it is believed that sustained maximal muscular power after tapering is obtained through maintaining adaptations in muscle fiber size, fiber type and neural adaptations whereas increased maximal muscular power after tapering is assumed mainly through both physiological and psychological recovery. We believe that increased maximal muscular power after tapering may also rely on higher neural drive and increased muscle fiber cross sectional area (CSA), especially in type IIA muscle fibers. Complete rest is a special form of tapering and it usually only leads to sustained maximal power. This effect is believed to be associated with decreased muscle CSA and a transformation of muscle fibers from type IIA to type IIX.

  • 5.
    Brännström, André
    et al.
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Sports medicine.
    Yu, Ji-Guo
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Sports medicine.
    Jonsson, Per
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Orthopaedics.
    Åkerfeldt, Torbjörn
    Stridsberg, Mats
    Svensson, Michael
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Sports medicine.
    Vitamin D in relation to bone health and muscle function in young female soccer players2017In: European Journal of Sport Science, ISSN 1746-1391, E-ISSN 1536-7290, Vol. 17, no 2, p. 249-256Article in journal (Refereed)
    Abstract [en]

    The present work investigated serum vitamin D (25(OH)D) status in relation to bone and muscle qualities and functions in 19 female soccer players (13–16 years) resident at northern latitude with very low sun exposure (∼32–36 h/month) during winter season (late January to early March). Serum 25(OH)D, parathyroid hormone and bone turnover markers osteocalcin (OC) and beta carboxy-terminal collagen cross-links (β-Ctx), as well as body composition and muscle performance were examined. Hormones were tested using routine laboratory methods. Fat mass, lean mass, and bone mineral density in whole body, as well as femur and lumbar spine were evaluated with dual-energy X-ray absorptiometry. Muscle performance was assessed through isokinetic knee extension and flexion, countermovement jump, and sprint running. 25(OH)D was low (50.5 ± 12.8 nmol l−1), whereas the values of bone turnover markers were markedly high (OC: 59.4 ± 18.6 μg l−1; β-Ctx: 1075 ± 408 ng l−1). All bone and muscle measurements were normal or above normal. 25(OH) D was not significantly correlated with most of the parameters of bone and muscle quality or function, except the knee extension time to peak torque (r = −0.50, p = .03). In conclusion, the level of vitamin D is markedly low in adolescent female soccer players during the winter in Sweden. However, vitamin D levels did not significantly correlate with measures of bone and muscle except a moderate correlation in time to peak torque in the knee extensors. The practical implication of low vitamin D levels in young growing female athletes remains unclear.

  • 6.
    Carlsson, Lena
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Yu, Ji-Guo
    Department of Natural and Environmental Physiology, Mid Sweden University.
    Moza, Monica
    Department of Pathology and Neuroscience Program, Biomedicum Helsinki, University of Helsinki and University Central Hospital, Finland.
    Carpén, Olli
    Department of Pathology, University of Turku and Turku University Central Hospital, Finland.
    Thornell, Lars-Eric
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Myotilin: a prominent marker of myofibrillar remodelling2007In: Neuromuscular Disorders, ISSN 0960-8966, E-ISSN 1873-2364, Vol. 17, no 1, p. 61-68Article in journal (Refereed)
    Abstract [en]

    Myofibrillar remodelling with insertion of sarcomeres is a typical feature of biopsies taken from persons suffering of exercise-induced delayed onset muscle soreness. Here we studied the presence of the sarcomeric protein myotilin in eccentric exercise related lesions. Myotilin is a component of sarcomeric Z-discs and it binds several other Z-disc proteins, i.e. alpha-actinin, filamin C, F-actin and FATZ. Myotilin has previously been shown to be present in nemaline rods and central cores and to be mutated in limb girdle muscular dystrophy 1A (LGMD1A) and in a subset of myofibrillar myopathies, indicating an important role in Z-disc maintenance. Our findings on non-diseased muscle affected by eccentric exercise give new information on how myotilin is associated to myofibrillar components upon remodelling. We show that myotilin was present in increased amount in lesions related to Z-disc streaming and events leading to insertion of new sarcomeres in pre-existing myofibrils and can therefore be used as a marker for myofibrillar remodelling. Interestingly, myotilin is preferentially associated with F-actin rather than with the core Z-disc protein alpha-actinin during these events. This suggests that myotilin has a key role in the dynamic molecular events mediating myofibrillar assembly in normal and diseased skeletal muscle.

  • 7.
    Carlsson, Lena
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Yu, Ji-Guo
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Sports Medicine.
    Thornell, Lars-Eric
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    New aspects of obscurin in human striated muscles.2008In: Histochemistry and Cell Biology, ISSN 0948-6143, E-ISSN 1432-119X, Vol. 130, no 1, p. 91-103Article in journal (Refereed)
    Abstract [en]

    Obscurin is a giant protein (700-800 kDa) present in both skeletal muscles and myocardium. According to animal studies, obscurin interacts with myofibrillar Z-discs during early muscle development, but is translocalised to be predominantly associated with the M-bands in mature muscles. The proposed function for obscurin is in the assembly and organisation of myosin into regular A-bands during formation of new sarcomeres. In the present study, the precise localisation of obscurin in developing and mature normal human striated muscle is presented for the first time. We show that obscurin surrounded myofibrils at the M-band level in both developing and mature human skeletal and heart muscles, which is partly at variance with that observed in animals. At maturity, obscurin also formed links between the peripheral myofibrils and the sarcolemma, and was a distinct component of the neuromuscular junctions. Obscurin should therefore be regarded as an additional component of the extrasarcomeric cytoskeleton. To test this function of obscurin, biopsies from subjects with exercise-induced delayed onset muscle soreness (DOMS) were examined. In these subjects, myofibrillar alterations related to sarcomerogenesis are observed. Our immunohistochemical analysis revealed that obscurin was never lacking in myofibrillar alterations, but was either preserved at the M-band level or diffusely spread over the sarcomeres. As myosin was absent in such areas but later reincorporated in the newly formed sarcomeres, our results support that obscurin also might play an important role in the formation and maintenance of A-bands.

  • 8.
    Hallenstål, Tove
    et al.
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Sports medicine.
    Sundqvist, Ida
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Sports medicine.
    Svensson, Michael
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Sports medicine.
    Yu, Ji-Guo
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Sports medicine.
    Evaluation of a New Automated Pulmonary Gas Analysis System2015In: International Journal of Exercise Science, ISSN 1939-795X, Vol. 8, no 3, p. 287-296Article in journal (Refereed)
    Abstract [en]

    The study aimed to evaluate the validity and reliability of a new automated pulmonary gas analysis system - Exercise Physiology System (EPS). The Oxycon Pro, a well-established automated pulmonary gas analysis system was used as a reference system. Six well-trained cyclists were recruited and performed two identical submaximal exercises on a cycle ergometer over one week interval. During the exercises, pulmonary gas exchange: ventilation (VE), oxygen consumption (VO2), elimination of carbon dioxide (VCO2), and ratio between carbon dioxide and oxygen (RER) was measured using both systems in randomized order. The exercise was composed of three incremental work-loads (Watt) of low, medium, and high load corresponding to 40%, 60%, and 80% of individual maximal work-load. Each work-load was performed twice so that pulmonary gas exchange was analyzed twice on each work-load using both systems. EPS validity was assessed by comparing the measurements from the two systems. For measurements presenting agreement between the systems, Bland-Altman plot analysis was performed to identify outlier. Reliability was evaluated by comparisons of measurements from repeated tests through each system, and by calculations of intra-class correlation coefficient (ICC) and standard error of measurement (SEM). Validity evaluations revealed that the majority of the measurements were in disagreements between the systems and most of them appeared at lower work-loads. The results indicated that at lower work-loads, EPS had lower validity than Oxycon Pro. At higher work-loads, ESP had high and comparable validity with Oxycon Pro. Reliability assessments revealed that agreements between repeated tests appeared in almost all measurements through both systems. Excellent agreements (very high ICC) in measurements between repeated tests were observed in VE, VO2, and VCO2 from both systems, and very small measurement errors (SEM), close to zero were observed in VO2, VCO2, and RER. The results suggested that the two systems had high and comparable reliability in measurement of pulmonary gas exchange.

  • 9. Jianwei, Ju
    et al.
    Shizhang, Zhou
    Tiquan, Zhu
    Ji-Guo, Yu
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Sports Medicine.
    Yali, Shi
    Jingmin, Wang
    Effects of Chinese medicine supplementation on exercise capacity in mice1998In: Chinese journal of sports medicine, ISSN 1000-6710, Vol. 17, no 02, p. 158-161Article in journal (Refereed)
    Abstract [zh]

    动物试验表明中药“强身液”可提高机体抗氧化能力及抗氧化酶活性,降低脂质过氧化水平,具有外源性自由基防御物质的作用和提高机体各种能力的功效。人体试验表明该制剂具有提高运动能力,消除运动后疲劳与紧张情绪的作用。

  • 10.
    Malm, Christer
    et al.
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Sports Medicine. Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Yu, Ji-Guo
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Sports Medicine. Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Exercise-induced muscle damage and inflammation: re-evaluation by proteomics2012In: Histochemistry and Cell Biology, ISSN 0948-6143, E-ISSN 1432-119X, Vol. 138, no 1, p. 89-99Article in journal (Refereed)
    Abstract [en]

    Using proteomics combined with immunohistochemistry (IHC), we re-evaluated our previous hypothesis that voluntary eccentric exercise does not result in inflammation or necrosis while it does lead to muscular adaptation/remodeling through Z-band related proteins. Muscle biopsies from m. vastus lateralis were taken from five control and five exercised subjects 48 h after 45 min of downhill running. General muscle morphology was examined using histology and histochemistry. Proteomics was used to reveal protein profiles and novel proteins. IHC with specific antibody against three Z-band related proteins identified by proteomics was also performed. General morphology showed no muscle degeneration or inflammation in any exercised biopsy. Proteomics revealed that out of 612 individual protein spots, the exercised biopsy presented three proteins with significant (p < 0.05) higher expression ratio and four proteins of lower ratio compared to controls. Four of the proteins desmin, actin, Rab-35 and LDB3 are Z-band related; the former two have long been the focus of interest and were found to be up-regulated in the study; the latter two are Z-band assembly/stabilization protein and were for the first time observed to be down-regulated in exercised muscles. The other three proteins are related with either cellular metabolism or calcium homeostasis and none is related with muscle necrosis or inflammation. IHC observations that both desmin and actin were increased whereas LDB3 was completely absent in some focal areas are consistent with proteomic results and with our previous observations. The results of the study confirmed our previous findings and therefore strengthened the hypothesis that voluntary eccentric exercise does not cause human muscle necrosis or inflammation; instead, muscular remodeling occurs specifically through Z-band related proteins.

  • 11.
    Sandgren, Evelina
    et al.
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Sports Medicine.
    Karlsson, Mia
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Sports Medicine.
    Yu, Ji-Guo
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Sports Medicine.
    Correlation analysis between soccer game world ranking and player league distribution2013In: Sport and Art, ISSN 2331-6233, Vol. 1, no 2, p. 34-40Article in journal (Refereed)
    Abstract [en]

    Nowadays professional soccer player trading between clubs/leagues is very common. Soccer players could be employed in foreign clubs/leagues, but when international competitive events come, the elite players are recruited to compose a national team. One can expect that the higher ranking of a national team, the more players are employed by the top soccer leagues. However, the relationship between the two issues has never been studied early. In the study, seven national soccer teams were selected from a list of the world top 35 soccer teams of year 2010[created by the Federation of International Football Association (FIFA)]. The 7 teams are Spain, England, Argentina, Germany, USA, Ghana and Sweden, across the full range of the list, thus, representing different levels of the world. On basis of the position of the 7 teams in the world ranking, an order ranking for the 7 teams was created. To identify player distribution of the 7 teams in different quality/level of soccer leagues, a league ranking including the top 25 soccer leagues in the world created by the International Federation of Football History and Statistics (IFFHS) was used. For each of the 7 teams, its player distribution in different soccer leagues was classified. On basis of the league ranking and the number of player(s) of each team in different leagues, calculated team point was calculated for each team. According to the amount of the calculated point, a calculated team ranking was obtained. Correlation analysis was performed between the two rankings: the order ranking and the calculated team ranking. The results showed a high and positive correlation between the two variables. We concluded that the more players are employed in higher ranking leagues the higher world ranking of a national team.

  • 12.
    Song, Yafeng
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Forsgren, Sture
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Liu, Jing Xia
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Yu, Jiguo
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Sports Medicine.
    Stål, Per
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Unilateral muscle overuse causes bilateral changes in muscle fibre composition and vascular supplyManuscript (preprint) (Other academic)
  • 13.
    Song, Yafeng
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Forsgren, Sture
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Liu, Jing-Xia
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Yu, Ji-Guo
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Sports Medicine.
    Stål, Per
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Unilateral muscle overuse causes bilateral changes in muscle fiber composition and vascular supply2014In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 9, no 12, p. e116455-Article in journal (Refereed)
    Abstract [en]

    Unilateral strength training can cause cross-transfer strength effects to the homologous contralateral muscles. However, the impact of the cross-over effects on the muscle tissue is unclear. To test the hypothesis that unilateral muscle overuse causes bilateral alterations in muscle fiber composition and vascular supply, we have used an experimental rabbit model with unilateral unloaded overstrain exercise via electrical muscle stimulation (E/EMS). The soleus (SOL) and gastrocnemius (GA) muscles of both exercised (E) and contralateral non-exercised (NE) legs (n = 24) were morphologically analyzed after 1w, 3w and 6w of EMS. Non-exercised rabbits served as controls (n = 6). After unilateral intervention the muscles of both E and NE legs showed myositis and structural and molecular tissue changes that to various degrees mirrored each other. The fiber area was bilaterally smaller than in controls after 3w of E/EMS in both SOL (E 4420 and NE 4333 µm2 vs. 5183 µm2, p<0.05) and GA (E 3572 and NE 2983 µm2 vs. 4697 µm2, p<0.02) muscles. After 6w of E/EMS, the percentage of slow MyHCI fibers was lower than in controls in the NE legs of SOL (88.1% vs. 98.1%, p<0.009), while the percentage of fast MyHCIIa fibers was higher in the NE legs of GA (25.7% vs. 15.8%, p = 0.02). The number of capillaries around fibers in the E and NE legs was lower (SOL 13% and 15%, respectively, GA 25% and 23%, respectively, p<0.05) than in controls. The overall alterations were more marked in the fast GA muscle than in the slow SOL muscle, which on the other hand showed more histopathological muscle changes. We conclude that unilateral repetitive unloaded overuse exercise via EMS causes myositis and muscle changes in fiber type proportions, fiber area and fiber capillarization not only in the exercised leg, but also in the homologous muscles in the non-exercised leg.

  • 14.
    Song, Yafeng
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Forsgren, Sture
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Yu, Jiguo
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Sports Medicine.
    Lorentzon, Ronny
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Sports Medicine.
    Stål, Per
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Effects on contralateral muscles after unilateral electrical muscle stimulation and exercise2012In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 7, no 12, p. e52230-Article in journal (Refereed)
    Abstract [en]

    It is well established that unilateral exercise can produce contralateral effects. However, it is unclear whether unilateral exercise that leads to muscle injury and inflammation also affects the homologous contralateral muscles. To test the hypothesis that unilateral muscle injury causes contralateral muscle changes, an experimental rabbit model with unilateral muscle overuse caused by a combination of electrical muscle stimulation and exercise (EMS/E) was used. The soleus and gastrocnemius muscles of both exercised and non-exercised legs were analyzed with enzyme-and immunohistochemical methods after 1, 3 and 6 weeks of repeated EMS/E. After 1 w of unilateral EMS/E there were structural muscle changes such as increased variability in fiber size, fiber splitting, internal myonuclei, necrotic fibers, expression of developmental MyHCs, fibrosis and inflammation in the exercised soleus muscle. Only limited changes were found in the exercised gastrocnemius muscle and in both non-exercised contralateral muscles. After 3 w of EMS/E, muscle fiber changes, presence of developmental MyHCs, inflammation, fibrosis and affections of nerve axons and AChE production were observed bilaterally in both the soleus and gastrocnemius muscles. At 6 w of EMS/E, the severity of these changes significantly increased in the soleus muscles and infiltration of fat was observed bilaterally in both the soleus and the gastrocnemius muscles. The affections of the muscles were in all three experimental groups restricted to focal regions of the muscle samples. We conclude that repetitive unilateral muscle overuse caused by EMS/E overtime leads to both degenerative and regenerative tissue changes and myositis not only in the exercised muscles, but also in the homologous non-exercised muscles of the contralateral leg. Although the mechanism behind the contralateral changes is unclear, we suggest that the nervous system is involved in the cross-transfer effects.

  • 15.
    Song, Yafeng
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Stål, Per
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Lorentzon, Ronny
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Sports Medicine.
    Backman, C
    Yu, Jiguo
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Sports Medicine.
    Forsgren, Sture
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Experimental studies favour that tachykinins are involved in the process of myositis and muscle derangement in an overuse animal modelManuscript (preprint) (Other academic)
  • 16.
    Song, Yafeng
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Stål, Per S
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Yu, Ji-Guo
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Sports Medicine.
    Lorentzon, Ronny
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Sports Medicine.
    Backman, Clas
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Hand Surgery.
    Forsgren, Sture
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Inhibitors of endopeptidase and angiotensin-converting enzyme lead to an amplification of the morphological changes and an upregulation of the substance P system in a muscle overuse model2014In: BMC Musculoskeletal Disorders, ISSN 1471-2474, E-ISSN 1471-2474, Vol. 15, p. 126-Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: We have previously observed, in studies on an experimental overuse model, that the tachykinin system may be involved in the processes of muscle inflammation (myositis) and other muscle tissue alterations. To further evaluate the significance of tachykinins in these processes, we have used inhibitors of neutral endopeptidase (NEP) and angiotensin-converting enzyme (ACE), substances which are known to terminate the activity of various endogenously produced substances, including tachykinins.

    METHODS: Injections of inhibitors of NEP and ACE, as well as the tachykinin substance P (SP), were given locally outside the tendon of the triceps surae muscle of rabbits subjected to marked overuse of this muscle. A control group was given NaCl injections. Evaluations were made at 1 week, a timepoint of overuse when only mild inflammation and limited changes in the muscle structure are noted in animals not treated with inhibitors. Both the soleus and gastrocnemius muscles were examined morphologically and with immunohistochemistry and enzyme immunoassay (EIA).

    RESULTS: A pronounced inflammation (myositis) and changes in the muscle fiber morphology, including muscle fiber necrosis, occurred in the overused muscles of animals given NEP and ACE inhibitors. The morphological changes were clearly more prominent than for animals subjected to overuse and NaCl injections (NaCl group). A marked SP-like expression, as well as a marked expression of the neurokinin-1 receptor (NK-1R) was found in the affected muscle tissue in response to injections of NEP and ACE inhibitors. The concentration of SP in the muscles was also higher than that for the NaCl group.

    CONCLUSIONS: The observations show that the local injections of NEP and ACE inhibitors led to marked SP-like and NK-1R immunoreactions, increased SP concentrations, and an amplification of the morphological changes in the tissue. The injections of the inhibitors thus led to a more marked myositis process and an upregulation of the SP system. Endogenously produced substances, out of which the tachykinins conform to one substance family, may play a role in mediating effects in the tissue in a muscle that is subjected to pronounced overuse.

  • 17.
    Song, Yafeng
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Stål, Per
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Yu, Jiguo
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Sports Medicine.
    Forsgren, Sture
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Bilateral increase in expression and concentration of tachykinin in a unilateral rabbit muscle overuse model that leads to myositis2013In: BMC Musculoskeletal Disorders, ISSN 1471-2474, E-ISSN 1471-2474, Vol. 14, article id 134Article in journal (Refereed)
    Abstract [en]

    Background: Tachykinins can have pro-inflammatory as well as healing effects during tissue reorganization and inflammation. Recent studies report an up-regulation in the expression of the substance P (SP)-preferred receptor, the neurokinin-1 receptor, in marked muscle inflammation (myositis). There is, however, only very little information on the expression patterns and levels of tachykinins in this situation.

    Methods: The tachykinin system was analyzed using a rabbit experimental model of muscle overuse, whereby unilateral muscle exercise in combination with electrical stimulation led to muscle derangement and myositis in the triceps surae muscle (experimental length 1--6 weeks). Evaluations were made for both parts of the muscle (soleus and gastrocnemius muscles) in experimental and non-experimental (contralateral) sides. Morphologic evaluation, immunohistochemistry, in situ hybridization and enzyme immunoassay (EIA) analyses were applied.

    Results: Myositis and muscle derangement occurred focally not only in the experimental side but also in the non-experimental side. In the inflammatory areas (focal myositis areas), there were frequent nerve fibers showing tachykinin-like immunoreactivity and which were parts of nerve fascicles and which were freely dispersed in the tissue. Cells in the inflammatory infiltrates showed tachykinin-like immunoreactivity and tachykinin mRNA expression. Specific immunoreactivity and mRNA expression were noted in blood vessel walls of both sides, especially in focally affected areas. With increasing experimental length, we observed an increase in the degree of immunoreactivity in the vessel walls. The EIA analyses showed that the concentration of tachykinin in the tissue on both sides increased in a time-dependent manner. There was a statistical correlation in the concentration of tachykinin and the level of tachykinin immunoreactivity in the blood vessel walls between experimental and non-experimental sides.

    Conclusions: The observations show an up-regulation of the tachykinin system bilaterally during muscle derangement/myositis in response to pronounced unilateral muscle overuse. This up-regulation occurred in inflammatory areas and was related not only to increased tachykinin innervation but also to tachykinin expression in blood vessel walls and inflammatory cells. Importantly, the tachykinin system appears to be an important factor not only ipsilaterally but also contralaterally in these processes.

  • 18.
    Song, Yafeng
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Stål, Per
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Yu, Jiguo
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Sports Medicine.
    Forsgren, Sture
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Marked effects of tachykinin in myositis both in the experimental side and contralaterally: studies on NK-1 receptor expressions in an animal model2013In: ISRN Inflammation, ISSN 2090-8695, Vol. 2013, no 907821Article in journal (Refereed)
    Abstract [en]

    Muscle injury and inflammation (myositis) in a rabbit model of an unilateral muscle overuse were examined. It is unknown if the tachykinin system has a functional role in this situation. In this study, therefore, the neurokinin-1 receptor (NK-1R) expression patterns were evaluated. White blood cells, nerve fascicles, fine nerve fibers, and blood vessel walls in myositis areas showed NK-1R immunoreaction. NK-1R mRNA reactions were observable for white blood cells and blood vessel walls of these areas. NK-1R immunoreaction and NK-1R mRNA reactions were also seen for muscle fibers showing degenerative and regenerative features. There were almost no NK-1R immunoreactions in normal muscle tissue. Interestingly, marked NK-1R expressions were seen for myositis areas of both the experimental side and the contralateral nonexperimental side. EIA analyses showed that the concentration of substance P in the muscle tissue was clearly increased bilaterally at the experimental end stage, as compared to the situation for normal muscle tissue. These observations show that the tachykinin system is very much involved in the processes that occur in muscle injury/myositis. The effects can be related to proinflammatory effects and/or tissue repair. The fact that there are also marked NK-1R expressions contralaterally indicate that the tachykinin system has crossover effects.

  • 19.
    Yu, Ji-Guo
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Sports Medicine.
    Effects of fatigued swimming on erythrocyte membrane in rats1993In: Yantai Teachers University Journal, ISSN 1004-4930, Vol. 9, no 1, p. 56-59Article in journal (Refereed)
    Abstract [en]

    The effects of fatigued swimming on lipid peroxidation in erythrocyte membranae and plasma of rat have been studied. The results show that fatigued swimming can increase the MDA level and decrease the activities of Na+ , K+-ATPase and Ca++-ATPase in erythrocyte membranae.

  • 20. Yu, Ji-Guo
    Effects of Shen-Qi Preparation on Sports CapacityManuscript (preprint) (Other academic)
    Abstract [en]

    Shen-Qi preparation compounded using ginseng and astragalus as main ingre dients was taken by twelve sportsmen six weeks running.The aerobic working capacity of the sportsmen strengthen and accumulation of lactic acid in the body decrease.Lactic acid can be clean up fast in the period of recovery,and BUN level decrease after the sportsmen exercise for a long time

  • 21.
    Yu, Ji-Guo
    et al.
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Sports Medicine.
    Bonnerud, Patrik
    Department of Health Sciences, Luleå University of Technology, Luleå.
    Eriksson, Anders
    Department of Health Sciences, Luleå University of Technology, Luleå.
    Stål, Per S.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Tegner, Yelverton
    Department of Health Sciences, Luleå University of Technology, Luleå.
    Malm, Christer
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Sports Medicine.
    Effects of long term supplementation of anabolic androgen steroids on human skeletal muscle2014In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 9, no 9, article id e105330Article in journal (Refereed)
    Abstract [en]

    The effects of long-term (over several years) anabolic androgen steroids (AAS) administration on human skeletal muscle are still unclear. In this study, seventeen strength training athletes were recruited and individually interviewed regarding self-administration of banned substances. Ten subjects admitted having taken AAS or AAS derivatives for the past 5 to 15 years (Doped) and the dosage and type of banned substances were recorded. The remaining seven subjects testified to having never used any banned substances (Clean). For all subjects, maximal muscle strength and body composition were tested, and biopsies from the vastus lateralis muscle were obtained. Using histochemistry and immunohistochemistry (IHC), muscle biopsies were evaluated for morphology including fiber type composition, fiber size, capillary variables and myonuclei. Compared with the Clean athletes, the Doped athletes had significantly higher lean leg mass, capillary per fibre and myonuclei per fiber. In contrast, the Doped athletes had significantly lower absolute value in maximal squat force and relative values in maximal squat force (relative to lean body mass, to lean leg mass and to muscle fiber area). Using multivariate statistics, an orthogonal projection of latent structure discriminant analysis (OPLS-DA) model was established, in which the maximal squat force relative to muscle mass and the maximal squat force relative to fiber area, together with capillary density and nuclei density were the most important variables for separating Doped from the Clean athletes (regression  =  0.93 and prediction  =  0.92, p<0.0001). In Doped athletes, AAS dose-dependent increases were observed in lean body mass, muscle fiber area, capillary density and myonuclei density. In conclusion, long term AAS supplementation led to increases in lean leg mass, muscle fiber size and a parallel improvement in muscle strength, and all were dose-dependent. Administration of AAS may induce sustained morphological changes in human skeletal muscle, leading to physical performance enhancement.

  • 22.
    Yu, Ji-Guo
    et al.
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Sports Medicine.
    Carlsson, Lena
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Thornell, Lars-Eric
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Evidence for myofibril remodeling as opposed to myofibril damage in human muscles with DOMS: an ultrastructural and immunoelectron microscopic study.2004In: Histochemistry and Cell Biology, ISSN 0948-6143, E-ISSN 1432-119X, Vol. 121, no 3, p. 219-227Article in journal (Refereed)
    Abstract [en]

    The myofibrillar and cytoskeletal alterations observed in delayed onset muscle soreness (DOMS) caused by eccentric exercise are generally considered to represent damage. By contrast our recent immunohistochemical studies suggested that the alterations reflect myofibrillar remodeling (Yu and Thornell 2002; Yu et al. 2003). In the present study the same human muscle biopsies were further analyzed with transmission electron microscopy and immunoelectron microscopy. We show that the ultrastructural hallmarks of DOMS, Z-disc streaming, Z-disc smearing, and Z-disc disruption were present in the biopsies and were significantly more frequent in biopsies taken 2-3 days and 7-8 days after exercise than in those from controls and 1 h after exercise. Four main types of changes were observed: amorphous widened Z-discs, amorphous sarcomeres, double Z-discs, and supernumerary sarcomeres. We confirm by immunoelectron microscopy that the main Z-disc protein alpha-actinin is not present in Z-disc alterations or in the links of electron-dense material between Z-discs in longitudinal register. These alterations were related to an increase of F-actin and desmin, where F-actin was present within the strands of amorphous material. Desmin, on the other hand, was seen in less dense regions of the alterations. Our results strongly support that the myofibrillar and cytoskeletal alterations, considered to be the hallmarks of DOMS, reflect an adaptive remodeling of the myofibrils.

  • 23.
    Yu, Ji-Guo
    et al.
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Sports Medicine.
    Che, Baoren
    Dept. Physical Education, Yantai Teacher's University, Yantai, China.
    Effects of exercise intensity on muscle tissue free radical metabolism and serum enzymes1996In: Journal of Physical Education, ISSN 1006-7116, Vol. 4, no 2, p. 20-22Article in journal (Refereed)
    Abstract [zh]

    以二种不同强度运动,测定运动结束后不同时间内股四头肌MDA含量及SOD、GSH-PX活性,并测定了相应时间内的血清酶活性.结果发现长时间力竭性运动引起肌组织MDA含量增加的同时,SOD和GSH-PX活性下降,血清CK、LDH及Mb含量上升;短时间间歇运动后,尽管MDA变化不明显,但SOD和GSH-PX趋于上升,且血清酶活性也在运动后有上升表现.

  • 24.
    Yu, JiGuo
    et al.
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Sports Medicine.
    Che, Baoren
    Dept. Physical Education, Yantai Teacher's University, Yantai, China.
    Effects of exercise intensity on oxygen transportation capacity of red blood cells1995In: Shandong Sports Science & Technology, ISSN 1009-9840, Vol. 18, no 1, p. 5-8Article in journal (Refereed)
    Abstract [zh]

    本文以二种不同的运动强度对受试者进行为期六周的身体训练,并在训练的不同阶段进行4×400m间歇性剧烈运动,测定剧烈运动前后血液载氧能力各参数的变化。结果表明,运动训练在增加血容量的同时,降低了Hb浓度及Her,但机体VO_2max仍然明显提高。剧烈运动后Hb及Hct均明显升高,PV减少,显示运动对血液系统产生浓缩作用。由于酸性代谢产物的积累及机械损伤作用,血液中老化红细胞增多。

  • 25.
    Yu, Ji-Guo
    et al.
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Sports Medicine.
    Che, Baoren
    Exercise training induces increased lipid peroxidation in red blood cells1997In: Chinese Journal of Sports Medicine, ISSN 1000-6710, Vol. 16, no 2, p. 145-147Article in journal (Refereed)
    Abstract [zh]

    本文采用2种不同的运动强度对受试者进行6周的运动训练,并在训练的不同阶段进行剧烈运动,测定了运动前后反映红细胞老化状态的各项指标:膜MDA含量、Na,K-ATPase活性、SOD活性以及红细胞唾液酸含量。结果表明,不同强度的运动训练均引起血液系统中年轻红细胞比例上升,但影响的程度有所差异。不同训练阶段进行剧烈运动,由于血液系统对训练的适应状态不同,其影响也有所不同,但剧烈运动的结果仍引起红细胞老化加速。

  • 26.
    Yu, JiGuo
    et al.
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Sports Medicine.
    Che, Baoren
    Dept. Physical Education, Yantai Teacher's University.
    Mechanisms of Sport Anemia1996In: Shandong Sports Science & Technology, ISSN 1009-9840, Vol. 15, no 3, p. 45-47Article, review/survey (Refereed)
    Abstract [zh]

    运动员是贫血发生的高危人群,研究运动性贫血发生、发展的规律并采取相应的措施预防运动性贫血的发生一直是许多研究者所关心的问题。本文综述了国内外这方面的研究成果,从三个方面加以系统的论述,以期为进一步的研究提供有益的线索。

  • 27.
    Yu, Ji-Guo
    et al.
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Sports Medicine.
    Che, Baoren
    Oxidative damage in red blood cells induced by exercise training1996In: Yantai Teachers University Journal, ISSN 1004-4930, Vol. 12, no 2, p. 138-141Article in journal (Refereed)
    Abstract [en]

    The effects of two different intensitive training on red ceils are studied,and the relationship between oxidant damage and ageing of red cells is analysed.

  • 28.
    Yu, Ji-Guo
    et al.
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Sports Medicine.
    Fürst, Dieter O
    Department of Cell Biology, Institute for Biochemistry and Biology, University of Potsdam, Potsdam, Germany.
    Thornell, Lars-Eric
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    The mode of myofibril remodelling in human skeletal muscle affected by DOMS induced by eccentric contractions.2003In: Histochemistry and Cell Biology, ISSN 0948-6143, E-ISSN 1432-119X, Vol. 119, no 5, p. 383-93Article in journal (Refereed)
    Abstract [en]

    Myofibrillar Z-disc streaming and loss of the desmin cytoskeleton are considered the morphological hallmarks of eccentric contraction-induced injury. The latter is contradicted by recent studies where a focal increase of desmin was observed in biopsies taken from human muscles with DOMS. In order to determine the effects of eccentric contraction-induced alterations of the myofibrillar Z-disc, we examined the distribution of alpha-actinin, the Z-disc portion of titin and the nebulin NB2 region in relation to actin and desmin in DOMS biopsies. In biopsies taken 2-3 days and 7-8 days after exercise, we observed a significantly higher number of fibres showing focal areas lacking staining for alpha-actinin, titin and nebulin than in biopsies taken from control or 1 h after exercise. None of these proteins were part of Z-disc streamings but instead they were found in distinct patterns in areas characterised by altered staining for desmin and actin. These were preferentially seen in regions with increased numbers of sarcomeres in parallel myofibrils. We propose that these staining patterns represent different stages of sarcomere formation. These findings therefore support our previous suggestion that muscle fibres subjected to eccentric contractions adapt to unaccustomed activity by the addition of new sarcomeres.

  • 29.
    Yu, Ji-Guo
    et al.
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Sports Medicine.
    Liu, Jing-Xia
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Carlsson, Lena
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Thornell, Lars-Eric
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Stål, Per S
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Re-evaluation of sarcolemma injury and muscle swelling in human skeletal muscles after eccentric exercise2013In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 8, no 4, article id e62056Article in journal (Refereed)
    Abstract [en]

    The results regarding the effects of unaccustomed eccentric exercise on muscle tissue are often conflicting and the aetiology of delayed onset muscle soreness (DOMS) induced by eccentric exercise is still unclear. This study aimed to re-evaluate the paradigm of muscular alterations with regard to muscle sarcolemma integrity and fibre swelling in human muscles after voluntary eccentric exercise leading to DOMS. Ten young males performed eccentric exercise by downstairs running. Biopsies from the soleus muscle were obtained from 6 non-exercising controls, 4 exercised subjects within 1 hour and 6 exercised subjects at 2-3 days and 7-8 days after the exercise. Muscle fibre sarcolemma integrity, infiltration of inflammatory cells and changes in fibre size and fibre phenotype composition as well as capillary supply were examined with specific antibodies using enzyme histochemistry and immunohistochemistry. Although all exercised subjects experienced DOMS which peaked between 1.5 to 2.5 days post exercise, no significant sarcolemma injury or inflammation was detected in any post exercise group. The results do not support the prevailing hypothesis that eccentric exercise causes an initial sarcolemma injury which leads to subsequent inflammation after eccentric exercise. The fibre size was 24% larger at 7-8 days than at 2-3 days post exercise (p<0.05). In contrast, the value of capillary number per fibre area tended to decrease from 2-3 days to 7-8 days post exercise (lower in 5 of the 6 subjects at 7-8 days than at 2-3 days; p<0.05). Thus, the increased fibre size at 7-8 days post exercise was interpreted to reflect fibre swelling. Because the fibre swelling did not appear at the time that DOMS peaked (between 1.5 to 2.5 days post exercise), we concluded that fibre swelling in the soleus muscle is not directly associated with the symptom of DOMS.

  • 30.
    Yu, Ji-Guo
    et al.
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Sports Medicine.
    Malm, Christer
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Sports Medicine.
    Thornell, Lars-Eric
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Eccentric contractions leading to DOMS do not cause loss of desmin nor fibre necrosis in human muscle.2002In: Histochemistry and Cell Biology, ISSN 0948-6143, E-ISSN 1432-119X, Vol. 118, no 1, p. 29-34Article in journal (Refereed)
    Abstract [en]

    High force eccentric muscle contractions can result in delayed onset muscle soreness (DOMS), prolonged loss of muscle strength, decreased range of motion, muscle swelling and an increase of muscle proteins in the blood. At the ultrastructural level Z-line streaming and myofibrillar disruptions have been taken as evidence for muscle damage. In animal models of eccentric exercise-induced injury, disruption of the cytoskeleton and the sarcolemma of muscle fibres occurs within the first hour after the exercise, since a rapid loss of staining of desmin, a cytoskeletal protein, and the presence of fibronectin, a plasma and extracellular protein, are observed within the muscle fibres. In the present study, biopsies from subjects who had performed different eccentric exercises and had developed DOMS were examined. Our aim was to determine whether eccentric exercise leading to DOMS causes sarcolemmal disruption and loss of desmin in humans. Our study shows that even though the subjects had DOMS, muscle fibres had neither lost staining for desmin nor contained plasma fibronectin. This study therefore does not support previous conclusions that there is muscle fibre degeneration and necrosis in human skeletal muscle after eccentric exercise leading to DOMS. Our data are in agreement with the recent findings that there is no inflammatory response in skeletal muscle following eccentric exercise in humans. In combination, these findings should stimulate the search for other mechanisms explaining the functional and structural alterations in human skeletal muscle after eccentric exercise.

  • 31.
    Yu, Ji-Guo
    et al.
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Sports Medicine.
    Russell, Brenda
    Cardiomyocyte remodeling and sarcomere addition after uniaxial static strain in vitro.2005In: J Histochem Cytochem, ISSN 0022-1554, Vol. 53, no 7, p. 839-44Article in journal (Refereed)
  • 32.
    Yu, Ji-Guo
    et al.
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Sports Medicine.
    Sewright, Kimberly
    Hubal, Monica
    Liu, Jing-Xia
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Schwartz, Lawrence
    Hoffman, Eric
    Clarkson, Priscilla
    Investigation of gene expression in C(2)C(12) Myotubes following simvastatin application and mechanical strain2009In: Journal of Atherosclerosis and Thrombosis, ISSN 1880-3873, E-ISSN 1340-3478, Vol. 16, no 1, p. 21-29Article in journal (Refereed)
    Abstract [en]

    Aim: The 3-hydroxy-3methylgutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) are the most effective prescribed drugs for lowering serum cholesterol; however, although statins are extremely safe medications and have brought significant benefits to patients with hypercholesterolemia, they have been shown to produce myalgia, cramps, exercise intolerance and fatigue. The aim of the study was to investigate the molecular mechanisms that may mediate statin myopathy.

    Methods: We used DNA microarray analysis to examine the changes in gene expression profiles induced by 1 hour and 6 hours of statin treatment on differentiated C(2)C(12) myotubes. Four genes were selected for analysis at the protein level using Western blot analysis on myotubes treated with statin with or without additional mechanical stretching.

    Results: Eighty-five genes exhibited more than a 2-fold up- or down-regulation in expression, of which 46 have known biological functions related primarily to transmembrane transport, signal transduction, cell growth/maintenance, protein metabolism, or apoptosis. At protein level, three of the four proteins were induced (Adrb1, Socs4 and Cflar) and one was repressed (Birc4). Changes in protein expression largely mirrored the changes in their corresponding transcripts, although the fold-change was less dramatic. The addition of imposed muscle fiber stretching did not exacerbate the expression of these genes at the protein level with the exception of Cflar, a pro-apoptotic protein.

    Conclusion: These data suggested that alterations in the expressions of some statin-regulated genes could be causative factors for statin toxicity in muscle. Repression of the anti-apoptosis gene (Birc4) and activation of the pro-apoptosis gene (Cflar) indicated that cell death may play an important role in statin-induced myopathy.

  • 33.
    Yu, Ji-Guo
    et al.
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Sports Medicine.
    Sun, Gaofeng
    Dept. Physical Education, Yantai Teacher's University.
    Zhang, Benqiang
    Dept. Physical Education, Yantai Teacher's University.
    Exercise training and Blood Volume1995In: Journal of Shandong Physical Education Institute, ISSN 1006-2076, Vol. 11, no 1, p. 31-35Article, review/survey (Refereed)
    Abstract [en]

    Both an acute sport and long-term exercise can result in changes in blood volume.Studying these changes, finding their changing patterns and knowing their effects on sport ability have been the problems of a lot of reserchers. In this review. previous works of other peoples were reviewed and analysed in order to provide a clue forfurther studies.

  • 34.
    Yu, Ji-Guo
    et al.
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Sports Medicine.
    Thornell, Lars-Eric
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Desmin and actin alterations in human muscles affected by delayed onset muscle soreness: a high resolution immunocytochemical study.2002In: Histochemistry and Cell Biology, ISSN 0948-6143, E-ISSN 1432-119X, Vol. 118, no 2, p. 171-9Article in journal (Refereed)
    Abstract [en]

    Lack of staining for desmin in muscles in animal models of eccentric exercise has been suggested to reflect disruption of the desmin intermediate filament network and proposed to cause disruption of the myofibrillar apparatus and deterioration of muscle fibers. In a recent study, we examined muscle biopsies from persons who had performed different eccentric exercise protocols, which induced delayed onset muscle soreness (DOMS). We were unable to verify that loss of staining for desmin was a feature of sore muscles. Nevertheless, we observed changes in the desmin cytoskeleton, but the meaning of the observations was not conclusive. In the present study, a high resolution immunocytochemical method was used to investigate the changes of desmin and actin in human muscles following a bout of eccentric exercise that lead to DOMS 2-3 days post-exercise. Biopsies were taken before exercise and 1 h and 2-3 and 7-8 days after exercise. Phalloidin, a ligand that labels filamentous actin, and anti-desmin antibodies were used to stain semithin (approximately 0.5 micro m) cryosections. At 1 h post-exercise, the staining of actin and desmin did not differ from the controls, whereas in biopsies taken 2-3 and 7-8 days after exercise, 12.5% (SD 5.8%) and 6.1% (SD 2.3%) fibers showed areas of increased staining for actin. Corresponding values for fibers with increased staining for both actin and desmin were 8.7% (SD 3.9%) and 11.4% (SD 4.6%), respectively. We suggest that the increased staining of actin and desmin reflects an increased synthesis of these proteins as part of an adaptation process following the unaccustomed eccentric exercise.

  • 35.
    Yu, Ji-Guo
    et al.
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Sports Medicine.
    Xu, Haowen
    Dept. Physical Education, East China Normal University, Shanghai, China.
    Destructive effects of exercise-induced lipid peroxidation on erythrocyte1994In: Sport Science, ISSN 1000-677X, Vol. 14, no 6, p. 67-72Article in journal (Refereed)
  • 36.
    Yu, Ji-Guo
    et al.
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Sports Medicine.
    Zhu, Tiquan
    Dept. Physical Education, Yantai Teacher's University, Yantai, China.
    Zhou, Shizhang
    Yantai Yu-Huang-Ding Hospital,Yantai, China .
    Ginseng and Astragalus supplementation improves aerobic capacity in humans1994In: YANTAI TEACHERS COLLEGE JOURNAL, ISSN 1673-8020, Vol. 10, no 2, p. 129-133Article in journal (Refereed)
    Abstract [en]

    Shen-Qi preparation containing ginseng and astragalus as main ingredients was taken by twelve sportsmen during six weeks running training. The aerobic capacity of the sportsmen, strength and accumulation of lactic acid in the blood were examined. The results showed that lactic acid can be cleaned up faster in the period of recovery, and BUN level was lower after a long time running in the subjects.

1 - 36 of 36
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