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  • 1
    ISSN: 1435-1803
    Keywords: Collagen ; cardiac muscle ; endurance training ; hypobaric condition ; mRNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The objective of this study was to examine the effects of prolonged exposure to hypobaric hypoxic condition, physical training and their combination on collagen type I, III and IV gene expression in the ventricles and atria of rat heart. Male rats were assigned to four groups: normobaric sedentary (NS) and trained (NT), and hypobaric sedentary (HS) and trained (HT). Exposure to and treadmill running training in hypobaric condition were carried out in a hypobaric chamber (770–740 mbar, 2250–2550 m). Experimental periods were 10, 21 and 56 days; the groups of 91 days served as recovery groups from experimental settings of 56 days. Exposure to hypobaric condition as such and in combination with endurance training for 10 days increased right ventricular weigth-to-body weight ratio (RV/BW) by 26% (p〈0.001) and 23% (p〈0.01), respectively, when compared to 10NS. RV/BW was significantly increased also in 21HT and 56HT. Left ventricular weight-to-body weight ratio was 13% (p〈0.01) and 14% (p〈0.01) higher in 21HT and 56HT, respectively, than in the respective NS. Right ventricular collagen type III mRNA level was 33% (p=0.065) and 38% (p〈0.01) higher in 10HT than in 10NS and 10NT, respectively. Right ventricular collagen type IV mRNA level was 29% (p〈0.001) higher in 10HT than in 10NS. Relatively slight left ventricular hypertrophy was not associated with significant changes in collagen mRNA levels. Decreased left ventricular subepicardial prolyl 4-hydroxylase activity in 10HS and 10HT suggests transient corresponding decrease in the rate of collagen synthesis. This study shows that combination of endurance training and moderate hypobaric hypoxic condition leads to increased right ventricular collagen type III and IV gene expression associated with right ventricular hypertrophy.
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  • 2
    ISSN: 1435-1803
    Keywords: Key words Collagen – cardiac muscle – endurance training – hypobaric condition – mRNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The objective of this study was to examine the effects of prolonged exposure to hypobaric hypoxic condition, physical training and their combination on collagen type I, III and IV gene expression in the ventricles and atria of rat heart. Male rats were assigned to four groups: normobaric sedentary (NS) and trained (NT), and hypobaric sedentary (HS) and trained (HT). Exposure to and treadmill running training in hypobaric condition were carried out in a hypobaric chamber (770–740 mbar, 2250–2550 m). Experimental periods were 10, 21 and 56 days; the groups of 91 days served as recovery groups from experimental settings of 56 days. Exposure to hypobaric condition as such and in combination with endurance training for 10 days increased right ventricular weight-to-body weight ratio (RV/BW) by 26 % (p 〉 0.001) and 23 % (p 〉 0.01), respectively, when compared to 10NS. RV/BW was significantly increased also in 21HT and 56HT. Left ventricular weight-to-body weight ratio was 13 % (p 〉 0.01) and 14 % (p 〉 0.01) higher in 21HT and 56 HT, respectively than in the respective NS. Right ventricular collagen type III mRNA level was 33 % (p = 0.065) and 38 b% (p 〉 0.01) higher in 10HT than in 10NS and 10NT, respectively. Right ventricular collagen type IV mRNA level was 29 % (p 〉 0.001) higher in 10HT than in 10NS. Relatively slight left ventricular hypertrophy was not associated with significant changes in collagen mRNA levels. Decreased left ventricular subepicardial prolyl 4-hydrosylase activity in 10HS and 10HT suggests transient corresponding decrease in the rate of collagen synthesis. This study shows that combination of endurance training and moderate hypobaric hypoxic condition leads to increased right ventricular collagen type III and IV gene expression associated with right ventricular hypertrophy.
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  • 3
    ISSN: 1439-6327
    Keywords: Fatigue ; Skeletal muscle ; Training ; Muscle soreness ; Strength
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effects of warm underwater water-jet massage on neuromuscular functioning, selected biochemical parameters (serum creatine kinase, lactic dehydrogenase, serum carbonic anhydrase, myoglobin, urine urea and creatinine) and muscle soreness were studied among 14 junior track and field athletes. Each subject spent, in a randomized order, two identical training weeks engaged in five strength/power training sessions lasting 3 days. The training weeks differed from each other only in respect of underwater water jet massage treatments. These were used three times (20 min each) during the treatment week and not used during the control week. During the treatment week continuous jumping power decreased and ground contact time increased significantly less (P 〈 0.05) and serum myoglobin increased more than during the control week. It is suggested that underwater water-jet massage in connection with intense strength/power training increases the release of proteins from muscle tissue into the blood and enhances the maintenance of neuro-muscular performance capacity.
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  • 4
    ISSN: 1439-6327
    Keywords: Fatigue ; Muscle damage ; Electromyography ; Reflex inhibition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The stretch-shortening cycle (SSC) is an effective and natural form of muscle function but, when repeated with sufficient intensity or duration, it may lead to muscle damage and functional defects. A reduced tolerance to impact has been reported, which may be partly attributed to a reduced stretch-reflex potentiation. The aim of the present study was to examine the influence of SSC-induced metabolic fatigue and muscle damage on the efficacy of stretch reflexes, as judged by the electromyograph (EMG) response of two shank muscles (lateral gastrocnemius LG, soleus SOL) to controlled ramp stretches. These EMG responses were recorded before and immediately after exhausting SSC-type leg exercise and 2 h, 2 days and 4 days later. Serum concentrations of creatine kinase ([CK]), myoglobin and lactate were measured repetitively along the protocol. Two maximal vertical drop jumps and counter-movement jumps were performed after each reflex test. The exhausting SSC-type exercise induced an immediate reduction (P 〈 0.05) with a delayed short-term recovery of the LG peak-to-peak reflex amplitude. This was not accompanied by significant changes in the reflex latency. The drop jump performance remained slightly but significantly reduced (P 〈 0.05) until the 2nd day postexercise. Peak [CK] appeared for all the subjects on the 2nd day, suggesting the presence of muscle damage. The increase in [CK] between the 2nd h and the 2nd day postexercise was found to be negatively related (P 〈 0.001) to the relative changes in the drop jump height. Furthermore, a significant relationship (P 〈 0.05) was found between recovery of the stretch reflex in LG and the decrease of [CK] between the 2nd and the 4th day. hese findings support the hypothesis of a reduced stretch-reflex sensitivity. While the exact mechanisms of the reflex inhibition remain unclear, it is emphasized that the delayed recovery of the reflex sensitivity could have resulted from the progressive inflammation that develops in cases of muscle damage.
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  • 5
    ISSN: 1432-2013
    Keywords: Oxygen uptake ; Blood lactate ; Blood acid base balance ; Endurance running ; Serum myoglobin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effects of 30 min running with stepwise increasing intensity (exhaustive, energy demand approx. 50 → 100% ofVO2max), 60 s supramaximal running (anaerobic, ≥125% ofVO2max) and 40–60 min low-intensity running (acrobic, 40–60% ofVO2max) on serum concentration of muscle-derived proteins were studied in 5 male and 5 female elite orienteerers. S-Carbonic anhydrase III (S-CA III) was used as a marker of protein leakage from type I (slow oxidative) muscle fibres and S-myoglobin (S-Mb) as a non-selective (type I+II) muscular marker. The fractional increase in S-CA III (ΔS-Ca III) was 0.37±0.09 (mean±SEM,p〈0.001), 0.10±0.05 (N. S.) and 0.46±0.09 (p〈0.001) 1 h after exhaustive, anaerobic and aerobic exercise, respectively. The corresponding values for ΔS-Mb were 1.45±0.36 (p〈0.001), 0.39±0.13 (p〈0.01) and 0.67±0.18 (p〈0.001). The value for the ΔS-CA III/ΔS-Mb ratio was 0.68±0.03 after the acrobic exercise, but only 0.25–0.26 (p vs. aerobic exercise 〈0.001) after the two high-intensity forms of exercise. Since type I fibres of skeletal muscle are known to be responsible for power production during low-intensity exercise, whereas fibres of both type I and type II are active at higher intensities, the ΔS-CA III/ΔS-Mb ratio may depend on the recruitment profile of type I vs. type I+II fibres.
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  • 6
    ISSN: 1432-2013
    Keywords: Key words Collagen ; Skeletal muscle ; Prolyl 4-hydroxylase ; Lysyl oxidase ; Hydroxyproline ; Damage
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The purpose of the study was to investigate pre-translational regulation of collagen expression after a single bout of exercise. We analysed steady-state messenger ribonucleic acid (mRNA) levels for collagen types I, III and IV, α- and β-subunits of prolyl 4-hydroxylase and lysyl oxidase (enzymes modifying procollagen chains), and enzyme activity of prolyl 4-hydroxylase from rat soleus muscle (MS) and the red parts of quadriceps femoris muscle (MQF) after 12 h and after 1, 2, 4, 7 and 14 days of downhill (–13.5°) treadmill running at a speed of 17 m·min–1 for 130 min. Histological and biochemical assays revealed exercise-induced muscle damage in MQF but not MS. Steady-state mRNA levels for the α- and β-subunits of prolyl 4-hydroxylase in MQF, lysyl oxidase in MS and MQF were increased 12 h after running, whereas prolyl 4-hydroxylase activity did not increase until 2 days after exercise. The mRNA levels for the fibrillar collagens (I and III) and basement membrane type IV collagen significantly increased 1 day and 12 h after exertion, respectively. Peak mRNA levels were observed 2–4 days after running, the increases being more pronounced in MQF than in MS. No significant changes were observed in types I or III collagen at the protein level. Strenuous downhill running thus causes an increase in gene expression for collagen types I and III and their post-translational modifying enzymes in skeletal muscle in a co-ordinated manner. These changes, together with the increased gene expression of type IV collagen, may represent the regenerative response of muscle extracellular matrix to exercise-induced injury and an adaptive response to running exertion.
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  • 7
    ISSN: 1600-0838
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine , Sports Science
    Notes: The present study examines changes in muscle structure and neuromuscular performance induced by 15 weeks of power training with explosive muscle actions. Twenty-three subjects, including 10 controls, volunteered for the study. Muscle biopsies were obtained from the gastrocnemius muscle before and after the training period, while maximal voluntary isometric contractions (MVC) and drop jump tests were performed once every fifth week. No statistically significant improvements in MVC of the knee extensor (KE) and plantarflexor muscles were observed during the training period. However, the maximal rate of force development (RFD) of KE increased from 18 836±4282 to 25 443±8897 N (P〈0.05) during the first 10 weeks of training. In addition, vertical jump height (vertical rise of the center of body mass) in the drop jump test increased significantly (P〈0.01). Simultaneously, explosive force production of KE muscles measured as knee moment and power increased significantly; however, there was no significant change (P〉0.05) in muscle activity (electromyography) of KE. The mean percentage for myosin heavy chain and titin isoforms, muscle fiber-type distributions and areas were unchanged. The enhanced performance in jumping as a result of power training can be explained, in part, by some modification in the joint control strategy and/or increased RFD capabilities of the KE.
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  • 8
    ISSN: 1600-0838
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine , Sports Science
    Notes: In the present study the release of proteins degrading extracellular matrix compounds to circulation was measured after damaging exercise in humans. Muscle damage was induced by downhill running; furthermore, the exercise was performed at both cold temperature (5 °C) and room temperature (22 °C) to study also the possible effect of environmental temperature on serum concentrations of matrix metalloproteinases MMP-2 and MMP-9, tissue inhibitors of metalloproteinases TIMP-1 and TIMP-2, and MMP-2/TIMP-2 complex, and muscle damage monitored by serum creatine kinase measurements. Results were compared with those obtained from patients having rhabdomyolysis, myositis and Becker muscular dystrophy. The present study demonstrates an acute increase in serum concentrations of MMP-9, TIMP-1, and MMP-2/TIMP-2 complex, but no changes in serum MMP-2 concentrations in response to eccentric exercise. Serum creatine kinase activity data suggest greater muscle damage after downhill running in a cold environment than at room temperature. The present observations about at most slight changes in serum MMP and TIMP concentrations and lack of their correlation to increased serum creatine kinase after exercise indicate that serum measurements of MMPs and TIMPs do not sensitively respond to exercise induced skeletal muscle damage and extracellular matrix regeneration. On the other hand, severe skeletal muscle damage, such as rhabdomyolysis, myositis and Becker muscular dystrophy, seemed to have an effect on serum MMP and TIMP concentrations.
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