Published data related to javelin throwers remain poorly documented. The objectives of this study were therefore to compare isokinetic strength profile of the shoulder rotator muscles between javelin ...throwers and sedentary persons and to correlate isokinetic data with different field performance parameters. Eleven male javelin throwers and ten sedentary subjects participated in the study. Shoulder internal (IRs) and external rotators (ERs) were isokinetically assessed at 60, 240 and 400 degree /s in concentric and 60 degree /s in eccentric exertions. Subjects also performed throwing tests successively using a javelin and a ball (both of 800 g mass). Side to side comparison in the throwers group revealed a dominance effect in the concentric mode for the IRs at all speeds, and for the ERs at 240 degree /s. Sedentary subjects showed a dominance effect for the IRs at 60 degree /s and 240 degree /s. Simple isokinetic concentric-concentric ratios and mixed velocity DCRs (eccentric60/concentric240) of the dominant shoulder were significantly lower in comparison to the non-dominant side values, in the throwers population. Only the simple ratio at 400 degree /s and the mixed ratio were significantly lower in the sedentary subjects (dominant versus non dominant side). With respect to the dominant shoulder, no significant difference was noted between the groups the peak torque was bodyweight normalized. However, throwers showed a significant reduction of the DCR when compared to the control group. In addition, throwers exhibited moderate to strong correlations (0.61 less than or equal to r less than or equal to 0.89) between IRs and ERs strength and either the javelin throw test or the personal throwing record. For the sedentary subjects the javelin throw test was correlated only with the IRs concentric strength at 240 degree /s. In conclusion, javelin throwers showed a significantly reduced mixed ratio in comparison with a control group, even though body weight normalized peak torques did not differ between both populations. Significant correlation was established between rotator peak-torques and javelin throw test among the thrower athletes. Although training program in thrower athletes classically focuses on IRs strengthening, our findings strongly suggest the need for ERs performance improvement.
The TOTEM collaboration at the CERN LHC has measured the differential cross-section of elastic proton-proton scattering at \(\sqrt{s} = 8\ {\rm TeV}\) in the squared four-momentum transfer range ...\(0.2\ {\rm GeV^{2}} < |t| < 1.9\ {\rm GeV^{2}}\). This interval includes the structure with a diffractive minimum ("dip") and a secondary maximum ("bump") that has also been observed at all other LHC energies, where measurements were made. A detailed characterisation of this structure for \(\sqrt{s} = 8\ {\rm TeV}\) yields the positions, \(|t|_{\rm dip} = (0.521 \pm 0.007)\ {\rm GeV^2}\) and \(|t|_{\rm bump} = (0.695 \pm 0.026)\ {\rm GeV^2}\), as well as the cross-section values, \({{\rm d}\sigma/{\rm d} t}_{\rm dip} = (15.1 \pm 2.5)\ {\rm{\mu b/GeV^2}}\) and \({{\rm d}\sigma/{\rm d} t}_{\rm bump} = (29.7 \pm 1.8)\ {\rm{\mu b/GeV^2}}\), for the dip and the bump, respectively.
Current opinions on tendinopathy Kaux, Jean-François; Forthomme, Bénédicte; Goff, Caroline Le ...
Journal of sports science & medicine,
2011-Jun-01, 20110601, 2011-06, Letnik:
10, Številka:
2
Journal Article, Web Resource
Recenzirano
Odprti dostop
Tendinopathy is characterized by pain in the tendon and impaired performance sometimes associated with swelling of the tendon. Its diagnosis is usually clinical but ultrasonography and magnetic ...resonance imaging can refine the diagnosis. Tendinopathy is highly prevalent and is one of the most frequently self reported musculoskeletal diseases in physical workers and sports people. Nevertheless, it is very difficult to carry out general epidemiologic studies on tendinopathy because of the varying sports cultures and sports habits in different countries. The aetiology of tendinopathy seems to be multi-factorial, involving intrinsic and extrinsic factors. The role of inflammation is still debated but the absence of inflammatory cells does not mean that inflammatory mediators are not implicated. Different theories have been advanced to explain pain and chronicity mechanisms, but these mechanisms remain largely unknown. "Conventional "treatments are generally employed empirically to fight pain and inflammation but they do not modify the histological structure of the tendon. However, these treatments are not completely satisfactory and the recurrence of symptoms is common. Currently, eccentric training remains the treatment of choice for tendinopathy, even though some studies are contradictory. Moreover, many interesting new treatments are now being developed to treat tendinopathy, but there is little evidence to support their use in clinical practice. Key pointsThe word "tendinopathy "is the correct term for the clinical diagnosis of pain accompanied by impaired performance, and sometimes swelling in the tendon.The aetiology of tendinopathy seems to be a multi-factorial process, involving promoting factors that are intrinsic or extrinsic, working either alone or in combination.US (with color Doppler) and MRI are usually prescribed when tendinopathy is unresponsive to treatment and entails lingering symptoms.Eccentric training is currently considered to be the most efficient treatment for tendinopathy; nevertheless, in order to be effective, this treatment needs specific modalities: slow speed, low intensity and gradual intensification, with minimum 20 to 30 sessions of exercises often being needed.Many interesting new treatments are now being developed to treat tendinopathy, but currently there is little evidence to support their use in clinical practice.
We determined the frequency of strength disorders in 26 athletes with a history of hamstring muscle injury and recurrent strains
and discomfort. We also assessed the effectiveness of rehabilitation ...to correct muscle performance. After concentric and eccentric
isokinetic assessment, 18 athletes were found to have strength deficits, as determined by statistically selected cutoffs of
peak torque, bilateral differences, and the flexors/quadriceps ratio. The discriminating character of the eccentric trial
was demonstrated, combining a preferential eccentric peak torque deficit and a significant reduction of the mixed eccentric
flexors/concentric quadriceps ratio. The athletes with muscle imbalances followed a rehabilitation program individually adapted
from their strength profile. Treatment length was from 10 to 30 sessions and resulted in isokinetic parameter normalization
in 17 of 18 subjects. Isokinetically corrected subjects were observed for 12 months after return to athletics. None sustained
a clinically diagnosed hamstring muscle reinjury. Subjective intensity of pain and discomfort were significantly reduced,
and they all returned to their prior level of competition. These results demonstrate that persistent muscle strength abnormalities
may give rise to recurrent hamstring injuries and discomfort. An individualized rehabilitation program emphasizing eccentric
training based on specific deficits contributes to a decrease in symptoms on return to sports.
Factors Correlated With Volleyball Spike Velocity Forthomme, Bénédicte; Croisier, Jean-Louis; Ciccarone, Guido ...
The American journal of sports medicine,
10/2005, Letnik:
33, Številka:
10
Journal Article, Web Resource
Recenzirano
Background: Spike effectiveness represents a determining element in volleyball. To compete at a high level, the player must, in particular,
produce a spike characterized by a high ball velocity.
...Hypothesis: Some muscular and physical features could influence ball velocity during the volleyball spike.
Study Design: Descriptive laboratory study.
Methods: A total of 19 male volleyball players from the 2 highest Belgian national divisions underwent an isokinetic assessment of
the dominant shoulder and elbow. Ball velocity performance (radar gun) during a spike test, morphological feature, and jump
capacity (ergo jump) of the player were measured. We tested the relationship between the isokinetic parameters or physical
features and field performances represented by spike velocity. We also compared first-division and second-division player
data.
Results: Spike velocity correlated significantly with strength performance of the dominant shoulder (internal rotators) and of the
dominant elbow (flexors and extensors) in the concentric mode. Negative correlations were established with the concentric
external rotator on internal rotator ratio at 400 deg/s and with the mixed ratio (external rotator at 60 deg/s in the eccentric
mode on internal rotator at 240 deg/s in the concentric mode). Positive correlations appeared with both the volleyball playersâ
jump capacity and body mass index. First-division players differed from second-division players by higher ball velocity and
increased jump capacity.
Conclusion: Some specific strength and physical characteristics correlated significantly with spike performance in high-level volleyball
practice.
Clinical Relevance: Our results could provide useful information for training management and propose some reflections on injury prevention.
Keywords:
volleyball
muscle strength
spike velocity
isokinetic
shoulder
jump
Injury prevalence data, muscle strength, and fatiguability differ between males and females. In addition, arm spatial orientation affects muscle activation and strength of the shoulder muscles. ...Nevertheless, little research has been conducted in relation to the shoulder rotator muscles comparing men and women. Therefore, the main aim of of this study was to perform a comparative investigation between two arm spatial orientations (45° and 90° of abduction in the frontal plane) during a fatigue assessment of the internal rotator (IR) and external rotator (ER) shoulder muscles. Secondly, the interaction between sex and dominance with muscular performance was assessed.
Forty healthy sedentary participants, 20 males and 20 females took part in this study. Participants performed a fatigue resistance protocol consisting of 30 consecutive maximal concentric contractions of the IR and ER shoulder muscles in a supine position at a speed of 180°/s. The upper limb was abducted to an angle of 45° or 90° in the frontal plane and each participant was tested on the dominant and nom-dominant side, counterbalanced in order of administration. Performance measures of Induced Fatigue (IF; %), Cumulated Performance (C.Perf; J) and Best Repetition (BR; J) were calculated and used for analysis. IF represents the % difference between the amount of work done over the last 3 and first 3 repetitions, BR represents the largest amount of work done during a single contraction, and C.Perf represents the total amount of work done during all repetitions.
Muscle group was the only factor to display significant variation when not considering other factors, with higher values for C.Perf (mean difference = 353.59 J, P < 0.0005), BR (mean difference = 14.21 J, P < 0.0005) and IF (mean difference = 3.65%, P = 0.0046). There was a significant difference between both angles, with higher values observed at 90° compared to 45° of abduction for C.Perf by ~ 7.5% (mean difference = 75 to 152 J) and ~ 10.8% (mean difference = 5.1 to 9.4 J) for BR in the ER, in males and females respectively (P < 0.0005). The dominant arm was significantly stronger than the non-dominant arm for C.Perf by 11.7% (mean difference = 111.58 J) for males and by 18% (mean difference = 82.77 J) for females in the ER at 45° abduction. At 90° abduction, only females were stronger in the dominant arm by 18.8% (mean difference = 88.17 J). Values for BR ranged from 9.2 to 21.8% depending on the abduction angle and sex of the athlete (mean difference = 2.44 - 4.85 J). Males were significantly stronger than females by 48.8 to 50.7% for values of C.Perf and BR in both the IR and ER (P < 0.0005). There was a significant difference between the ER and IR muscles, with significantly higher values observed for the IR in C.Perf (mean difference = 331.74 J) by 30.0% and in BR (mean difference = 13.31 J) by 26.64%.
Differences in shoulder performance fatiguability between sexes are affected by arm position, arm dominance and muscle groups. In agreement with the literature, performance values in males were approximately 50% higher than in females. However, the amount of IF was no different between both sexes. Based on findings in literature, it could be suggested that this is due to differences between males and females in motor control and/or coordination strategies during repetitive tasks. In addition, we also observed the IR muscles to be significantly stronger than the ER muscles. It has long been established in literature that these observations are due to the muscle-size differences between both muscle groups, where the IR muscles can produce a larger amount of force due to the larger cross-sectional area. Results of our study found similar ER:IR ratios compared to previous reports.
Therefore, these findings are useful for clinicians when monitoring rehabilitation programs in sedentary individuals following shoulder injuries.
Doppler-Resolved Kinetics of Saturation Recovery Forthomme, Damien; Hause, Michael L; Yu, Hua-Gen ...
The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory,
07/2015, Letnik:
119, Številka:
28
Journal Article
Recenzirano
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Frequency-modulated laser transient absorption has been used to monitor the ground-state rotational energy-transfer rates of CN radicals in a double-resonance, depletion recovery experiment. When a ...pulsed laser is used to burn a hole in the equilibrium ground-state population of one rotational state without velocity selection, the population recovery rate is found to depend strongly on the Doppler detuning of a narrow-band probe laser. Similar effects should be apparent for any relaxation rate process that competes effectively with velocity randomization. Alternative methods of extracting thermal rate constants in the presence of these non-thermal conditions are evaluated. Total recovery rate constants, analogous to total removal rate constants in an experiment preparing a single initial rotational level, are in good agreement with quantum scattering calculations, but are slower than previously reported experiments and show qualitatively different rotational state dependence between Ar and He collision partners. Quasi-classical trajectory studies confirm that the differing rotational state dependence is primarily a kinematic effect.
Abstract Objectives Some clinical series have evaluated the effect of platelet-rich plasma (PRP) in the treatment of proximal patellar tendinopathy. Although it is possible that a single infiltrative ...administration may prove to be an effective treatment for this indication, most of the existing studies evaluated the effects of two or three successive infiltrations. The aim of this study was to evaluate whether two infiltrations of PRP proves more effective than a single treatment. Design Prospective, randomized and comparative study of level 2. Methods Twenty patients suffering from chronic proximal patellar tendinopathy were enrolled into the study and split into two randomized groups (one or two infiltrations of PRP, respectively). The 3-month follow-up evaluation consisted of VAS, IKDC and VISA-P scores, along with algometer, isokinetic and ultrasounds evaluations. After 1 year, subjects were contacted to define their functional evolution. Results The concentration of the PRP used for each infiltration was similar in both groups, and contained no red or white cells. Results revealed no difference in treatment efficacy between the groups. Conclusions The comparison between one or two infiltrations of PRP did not reveal any difference between the two groups at short to mid term. A second closely-timed infiltration of PRP to treat proximal patellar tendinopathies is not necessary to improve the efficacy of this treatment in the short term.
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