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Upsala Journal of Medical Sciences 2007Muscle tissue has an exceptional ability to regenerate, however, unresting damage to the muscles by intense and frequent exercises occasionally causes prolonged muscle...
BACKGROUND
Muscle tissue has an exceptional ability to regenerate, however, unresting damage to the muscles by intense and frequent exercises occasionally causes prolonged muscle fatigue, soreness, and underperformance in sports. Taking rest is generally considered to be crucial for regular training to avoid the accumulation of muscle damage. We hypothesized that differences in the resting intervals between two periods of exercise may result in histological differences in muscle regeneration.
METHOD
An eccentric contraction model of mouse gastrocnemius muscle was made using percutaneus electrical stimulation. The mice received eccentric exercises twice with resting intervals of 0, 12, 24 hours, 2, and 3 days. The authors investigated the ratio of myofibers with central nuclei to whole myofibers histologically (the centronuclear cell ratio; CNCR) at 14 days after the second exercise as an index of the muscle regeneration.
RESULTS
The CNCR of the group that exercised one-time was 29.5%. In the groups exercised twice, it increased from 31.8% with an interval of 0 hours to a peak of 43.9% with 24 hours, then decreased to 32.8% with an interval of 3 days. The ratios of the groups with intervals of 12 and 24 hours were higher than those with one-time exercise and those with the intervals of 0 hours, 2 days, and 3 days.
CONCLUSIONS
The resting interval between two periods of eccentric exercises affected the histology of muscle regeneration. The amount of muscle damage and/or the recovery process of damaged muscles should vary depending on the length of resting interval between strenuous exercises. An appropriate interval for rest must be necessary in order to avoid further muscle damage.
Topics: Animals; Male; Mice; Mice, Inbred C57BL; Muscle, Skeletal; Regeneration; Rest
PubMed: 17578817
DOI: 10.3109/2000-1967-191 -
Journal of Strength and Conditioning... Jan 2022Downey, RJ, Deprez, DA, and Chilibeck, PD. Effects of postactivation potentiation on maximal vertical jump performance after a conditioning contraction in upper-body and...
Downey, RJ, Deprez, DA, and Chilibeck, PD. Effects of postactivation potentiation on maximal vertical jump performance after a conditioning contraction in upper-body and lower-body muscle groups. J Strength Cond Res 36(1): 259-261, 2022-Postactivation potentiation (PAP) involves preperformance contractions that can condition a muscle to enhance subsequent force generation and power output. Our purpose was to examine the effects of conditioning contractions that are specific or nonspecific to the target performance on PAP. Resistance-trained subjects (14 males and 10 females) performed a 7-second isometric contraction involving back squat, bench press (as conditioning contractions), or a control condition (rest) on different days in random order, before maximal vertical jump performance. The back squat as a conditioning contraction increased maximal vertical jump by 1.1 ± 3.0 cm (p < 0.05); however, the bench press as a conditioning contraction unexpectedly reduced maximal vertical jump performance by 1.4 ± 2.7 cm (p < 0.05). Conditioning contractions used to elicit a PAP response should use muscles that are specific to the performance movement. Contractions that are not biomechanically similar to the performance movement may hinder subsequent performance.
Topics: Athletic Performance; Humans; Isometric Contraction; Male; Movement; Muscle Contraction; Muscle Strength; Muscle, Skeletal; Rest
PubMed: 34743147
DOI: 10.1519/JSC.0000000000004171 -
Oral Surgery, Oral Medicine, Oral... Dec 2009A primary goal of pain management for muscle-related pain is to reduce masticatory muscle activity. This study aimed to investigate masticatory muscle group activity and...
OBJECTIVES
A primary goal of pain management for muscle-related pain is to reduce masticatory muscle activity. This study aimed to investigate masticatory muscle group activity and heart rate variability change when the tongue was placed on the palate or the floor of the mouth in a healthy pain-free sample.
STUDY DESIGN
Participants were 23 females and 18 males with a mean age of 19.6 years (standard deviation = 1.5). Muscle activity was measured using surface electromyography and heart period were measured using electrocardiography. The experimental protocol consisted of 3 periods: baseline, tongue placement on the floor of mouth, and tongue placement on palate.
RESULTS
Results indicated significantly more activity in the temporalis and suprahyoid muscle regions as well as a significant reduction in heart rate variability when the tongue was positioned on the palate compared with tongue position on the floor of the mouth.
CONCLUSIONS
Instructions to place the tongue on the roof of the mouth are not instructions that will promote reduced physiological functioning (i.e., relaxation) but rather promote small, but potentially important increases in overall activity as indexed by muscle tone and cardiac function.
Topics: Adolescent; Analysis of Variance; Electromyography; Feedback, Physiological; Female; Heart Rate; Humans; Male; Masticatory Muscles; Muscle Contraction; Reference Values; Relaxation; Tongue; Young Adult
PubMed: 19773187
DOI: 10.1016/j.tripleo.2009.06.029 -
European Review For Medical and... Oct 2022The aim of the study was to determine the normative values for resting length of pectoralis minor muscle among males and females with an asymptomatic shoulder in South...
OBJECTIVE
The aim of the study was to determine the normative values for resting length of pectoralis minor muscle among males and females with an asymptomatic shoulder in South Bengaluru.
PATIENTS AND METHODS
Two hundred and forty-six subjects with asymptomatic shoulders were taken by convenience sampling. The subjects were divided into two groups: Group A (123 males) and Group B (123 females). Pectoralis minor muscle resting length was measured on their dominant side in all subjects. Post measurement, the PMI was calculated. The normative values for both groups were determined. The mean PMI was compared between Group A and Group B and was analyzed using statistical tools.
RESULTS
In Group A, the mean average Pectoralis minor length (PML) was 14.59 ± 1.61 cm and in Group B, the mean average PML was 12.95 ± 1.42 cm which was statistically significant (p-value <0.00001). In Group A, the mean Pectoralis Minor Index (PMI) was 8.54 ± 0.88 and in Group B, the mean PMI was 8.22 ± 0.90 which was statistically significant (p-value <0.005).
CONCLUSIONS
The normative values for resting length of pectoralis minor muscle for males are 8.54 ± 0.88 and for females 8.22 ± 0.90 with an asymptomatic shoulder. There is a difference in the normative values for the resting PML in the asymptomatic shoulder by gender.
Topics: Male; Female; Humans; Shoulder; Pectoralis Muscles; Pilot Projects; Cross-Sectional Studies; Rest
PubMed: 36263569
DOI: 10.26355/eurrev_202210_29870 -
Gait & Posture Apr 2014Although balance during quiet standing is postulated to be influenced by multiple factors, including ankle stiffness, it is unclear how different mechanisms underlying...
Although balance during quiet standing is postulated to be influenced by multiple factors, including ankle stiffness, it is unclear how different mechanisms underlying increases in stiffness affect balance control. Accordingly, this study examined the influence of muscle activation and passive ankle stiffness increases on the magnitude and frequency of postural sway. Sixteen young adults participated in six quiet stance conditions including: relaxed standing, four muscle active conditions (10%, 20%, 30% and 40% maximum voluntary contraction (MVC)), and one passive condition wearing an ankle foot orthotic (AFO). Kinetics were collected from a force plate, while whole-body kinematics were collected with a 12-sensor motion capture system. Bilateral electromyographic signals were recorded from the tibialis anterior and medial gastrocnemius muscles. Quiet stance sway amplitude (range and root mean square) and frequency (mean frequency and velocity) in the sagittal plane were calculated from time-varying centre of gravity (COG) and centre of pressure (COP) data. Compared to the relaxed standing condition, metrics of sway amplitude were significantly increased (between 37.5 and 63.2%) at muscle activation levels of 30% and 40% MVC. Similarly, frequency measures increased between 30.5 and 154.2% in the 20-40% MVC conditions. In contrast, passive ankle stiffness, induced through the AFO, significantly decreased sway amplitude (by 23-26%), decreased COG velocity by 13.8%, and increased mean COP frequency by 24.9%. These results demonstrate that active co-contraction of ankle musculature (common in Parkinson's Disease patients) may have differential effects on quiet stance balance control compared to the use of an ankle foot orthotic (common for those recovering from stroke).
Topics: Analysis of Variance; Ankle; Biomechanical Phenomena; Electromyography; Female; Foot Orthoses; Humans; Male; Muscle Contraction; Muscle, Skeletal; Postural Balance; Rest; Young Adult
PubMed: 24613374
DOI: 10.1016/j.gaitpost.2014.01.019 -
European Journal of Pharmacology May 2003Effects of 4-(3-chlorophenyl)-1,7-diethylpyrido[2,3-d]pyrimidin-2(1H)-one (YM976), a novel and selective phosphodiesterase type 4 inhibitor, on tension and adenosine...
Effects of 4-(3-chlorophenyl)-1,7-diethylpyrido[2,3-d]pyrimidin-2(1H)-one (YM976), a novel and selective phosphodiesterase type 4 inhibitor, on tension and adenosine 3',5'-cyclic monophosphate (cAMP) content of bovine tracheal smooth muscle were compared with those of rolipram and theophylline. YM976, rolipram and theophylline relaxed the tracheal preparations contracted with histamine in a concentration-dependent manner. The relaxant effects of YM976 and rolipram were more potent than those of theophylline. These phosphodiesterase inhibitors-induced relaxations were dramatically diminished when tracheal smooth muscle was contracted with methacholine instead of histamine. Pretreatment of the tracheal preparations with YM976 (10 microM) or rolipram (10 microM), but not with theophylline (1 mM), shifted the concentration-response curves for contractile responses to histamine; however, the same procedure failed to affect concentration-response relationships for methacholine-induced contractions. At 1 and 10 microM, both YM976 and rolipram increased the tissues cAMP content. These results suggest that YM976 relaxes tracheal smooth muscle, probably through the cAMP-dependent mechanism.
Topics: 3',5'-Cyclic-AMP Phosphodiesterases; Animals; Cattle; Cyclic Nucleotide Phosphodiesterases, Type 4; Dose-Response Relationship, Drug; In Vitro Techniques; Muscle Relaxation; Muscle, Smooth; Phosphodiesterase Inhibitors; Pyridines; Pyrimidinones; Trachea
PubMed: 12787831
DOI: 10.1016/s0014-2999(03)01754-0 -
Experientia Apr 1976A method for the investigation of metabolism in the isolated rat extensor digitorum longus muscle has been described. This muscle was shown to be suitable for...
A method for the investigation of metabolism in the isolated rat extensor digitorum longus muscle has been described. This muscle was shown to be suitable for investigations of skeletal muscle metabolism during rest and activity.
Topics: Acetoacetates; Animals; Forelimb; Glucose; Glycogen; Hydroxybutyrates; Lactates; Male; Muscle Contraction; Muscles; Physiology; Rats; Rest
PubMed: 1269673
DOI: 10.1007/BF01920841 -
Journal of Strength and Conditioning... Oct 2023Wizenberg, AM, Gonzalez-Rojas, D, Rivera, PM, Proppe, CE, Laurel, KP, Stout, JR, Fukuda, DH, Billaut, F, Keller, JL, and Hill, EC. Acute effects of continuous and...
Wizenberg, AM, Gonzalez-Rojas, D, Rivera, PM, Proppe, CE, Laurel, KP, Stout, JR, Fukuda, DH, Billaut, F, Keller, JL, and Hill, EC. Acute effects of continuous and intermittent blood flow restriction on sprint interval performance and muscle oxygen responses. J Strength Cond Res 37(10): e546-e554, 2023-This investigation aimed to examine the acute effects of continuous and intermittent blood flow restriction (CBFR and IBFR, respectively) during sprint interval training (SIT) on muscle oxygenation, sprint performance, and ratings of perceived exertion (RPE). Fifteen men (22.6 ± 2.4 years; 176 ± 6.3 cm; 80.0 ± 12.6 kg) completed in random order a SIT session with CBFR, IBFR (applied during rest), and no blood flow restriction (NoBFR). Each SIT session consisted of two 30-second all-out sprint tests separated by 2 minutes. Peak power (PP), total work (TW), sprint decrement score (S dec ), RPE, and muscle oxygenation were measured during each sprint. A p value ≤0.05 was considered statistically significant. PP decreased to a greater extent from sprint 1 to sprint 2 during CBFR (25.5 ± 11.9%) and IBFR (23.4 ± 9.3%) compared with NoBFR (13.4 ± 8.6%). TW was reduced similarly (17,835.6 ± 966.2 to 12,687.2 ± 675.2 J) from sprint 1 to sprint 2 for all 3 conditions, but TW was lower (collapsed across time) for CBFR (14,320.7 ± 769.1 J) than IBFR (15,548.0 ± 840.5 J) and NoBFR (15,915.4 ± 771.5 J). There were no differences in S dec (84.3 ± 1.7%, 86.1 ± 1.5%, and 87.2 ± 1.1% for CBFR, IBFR, and NoBFR, respectively) or RPE, which increased from sprint 1 (8.5 ± 0.3) to sprint 2 (9.7 ± 0.1). Collective muscle oxygenation responses increased across time and were similar among conditions, whereas increases in deoxy[heme] and total[heme] were greatest for CBFR. Applying BFR during SIT induced greater decrements in PP, and CBFR resulted in greater decrements in work across repeated sprints. The larger increases in deoxy[heme] and total[heme] for CBFR suggested it may induce greater metabolite accumulation than IBFR and NoBFR when combined with SIT.
Topics: Humans; Male; Heme; High-Intensity Interval Training; Muscles; Oxygen; Rest; Young Adult
PubMed: 37639655
DOI: 10.1519/JSC.0000000000004518 -
The Journal of Physiology Oct 1983The mechanical properties of glycerol-extracted fibres from the dorsal longitudinal muscle of Lethocerus have been determined by sinusoidal and transient analysis in the...
The mechanical properties of glycerol-extracted fibres from the dorsal longitudinal muscle of Lethocerus have been determined by sinusoidal and transient analysis in the time range 1 ms-1000 s, and from rest length to 10% strain for fibres in relaxing and rigor solutions. The fibres behave reversibly up to strains of about 5%, but reach an elastic limit in the range 5-9% strain, depending upon the rate of strain. Electron micrographs of fibres at different degrees of stretch, and after partial extraction of the contractile proteins, suggest that a connexion between the end of the A filament and the Z line, named a C filament, is responsible for the high stiffness of the relaxed muscle. Estimates are made of the compliance of the A, I and C filaments. The mechanical response of the relaxed muscle, over the entire frequency range studied, is assignable to the C filaments. An analysis of the stiffness of the fibres at different tensions in activating and relaxing solutions, and in fibres relaxed by orthovanadate, shows that the C filaments still exert their mechanical effect in the active muscle. That is, the response of the active muscle consists of the contribution from the cross-bridges plus that of the C filaments, acting mechanically in parallel. This situation is incompatible with earlier explanations of the fully activated mechanical dynamics of fibrillar muscle. Alternative explanations at the cross-bridge level are described in the paper that follows this one.
Topics: Animals; Calcium; Elasticity; Flight, Animal; Hemiptera; Microscopy, Electron; Models, Biological; Muscle Contraction; Muscle Relaxation; Muscles; Stress, Mechanical; Vanadates; Vanadium
PubMed: 6557139
DOI: 10.1113/jphysiol.1983.sp014880 -
Biophysical Journal Aug 2015In isolated thick filaments from many types of muscle, the two head domains of each myosin molecule are folded back against the filament backbone in a conformation...
In isolated thick filaments from many types of muscle, the two head domains of each myosin molecule are folded back against the filament backbone in a conformation called the interacting heads motif (IHM) in which actin interaction is inhibited. This conformation is present in resting skeletal muscle, but it is not known how exit from the IHM state is achieved during muscle activation. Here, we investigated this by measuring the in situ conformation of the light chain domain of the myosin heads in relaxed demembranated fibers from rabbit psoas muscle using fluorescence polarization from bifunctional rhodamine probes at four sites on the C-terminal lobe of the myosin regulatory light chain (RLC). The order parameter 〈P2〉 describing probe orientation with respect to the filament axis had a roughly sigmoidal dependence on temperature in relaxing conditions, with a half-maximal change at ∼19°C. Either lattice compression by 5% dextran T500 or addition of 25 μM blebbistatin decreased the transition temperature to ∼14°C. Maximum entropy analysis revealed three preferred orientations of the myosin RLC region at 25°C and above, two with its long axis roughly parallel to the filament axis and one roughly perpendicular. The parallel orientations are similar to those of the so-called blocked and free heads in the IHM and are stabilized by either lattice compression or blebbistatin. In relaxed skeletal muscle at near-physiological temperature and myofilament lattice spacing, the majority of the myosin heads have their light chain domains in IHM-like conformations, with a minority in a distinct conformation with their RLC regions roughly perpendicular to the filament axis. None of these three orientation populations were present during active contraction. These results are consistent with a regulatory transition of the thick filament in skeletal muscle associated with a conformational equilibrium of the myosin heads.
Topics: Animals; Dextrans; Heterocyclic Compounds, 4 or More Rings; Isometric Contraction; Muscle Fibers, Skeletal; Muscle Relaxation; Myosins; Neuromuscular Agents; Rabbits; Rest; Rigor Mortis; Transition Temperature
PubMed: 26287630
DOI: 10.1016/j.bpj.2015.06.038