46 research outputs found

    ANALYSIS OF PEDALING TECHNIQUE DURING A MAXIMAL CYCLING EXERCISE

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    The purpose of this study was to analyze the effects of the fatigue process during a maximal cycling exercise on the pedaling technique. Eight elite competitive male cyclists were evaluated in a two days protocol. On day 1, the cyclists were submitted to a VO2MAX test, and on day 2, they cycled to exhaustion on a cycle ergometer equipped with two 2-D pedals dynamometer to measure the forces applied on the pedals. The workload was set at 100% of their VO2MAX, as measured on day 1. The resultant and effective forces were calculated from normal and tangential forces to obtain the index of effectiveness (IE). No differences were observed in the IE throughout the entire test. This study suggests that under a fatigue protocol, elite cyclists are able to sustain the IE, which can be an important strategy in order to sustain the power output

    Spectral properties of muscle activation during incremental cycling test

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    It is uncertain whether fatigue and workload would affect muscle recruitment during cycling. To infer on changes in priority for recruitment of motor units, we assessed the combined effects of fatigue and workload during an incremental cycling test to exhaustion on frequency components of lower limbs muscle activation. Competitive cyclists performed an incremental maximal cycling test while muscle activations were recorded from the right and left vastus lateralis, biceps femoris and gastrocnemius medialis. Muscle activation signals were assessed using frequency band analyses and decomposed into overall, high and low frequency bands. Combined effects from workload/fatigue were assessed using t tests and Cohen¿s effect sizes (ES). There were increases in the overall muscle activation due to increased workload/fatigue for biceps femoris (40% vs. 90%, p<0.01 and ES = 1.85) and vastus lateralis (40% vs. 70%, p=0.01 and ES = 0.96, and 40% vs. 90%, p<0.01 and ES = 2.03, and 70% vs. 90%, p<0.01 and ES = 0.96), but not for gastrocnemius medialis. There was also greater contribution from low frequency component for biceps femoris (40% vs. 90%, p = 0.01 and ES = 1.12). Similar workload/fatigue effects have been observed between lower limbs. In conclusion, incremental cycling test lead to an increase in activation of main knee joint flexors and extensors but not in plantar flexors during cycling. Biceps femoris changes its recruitment profile due to increases in low frequency content

    Importance of static adjustment of knee angle to determine saddle height in cycling

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    Knee flexion angle is used to determine saddle height during pedaling. However, it is unclear if knee flexion angle at upright standing posture affects measures and interpretation of knee flexion angle during cycling. The objective of this study was to assess the importance of adjusting knee angle during pedaling according to the knee angle at upright posture. Seventeen cyclists performed three 10 min cycling trials at different saddle heights to induce knee flexion angles (40º, 30º or 20º when crank was at the 6 o'clock position). Knee flexion angle was determined at the sagittal plane during cycling using a 2D motion analysis system. Alteration of saddle height was performed by subtracting the knee flexion angle determined during an upright standing posture from the observed knee flexion angle during cycling. Repeatability of knee angles at upright posture in the three trials was very good (ICC=0.73). A reduction in knee flexion angle of 10.6° (95%CI [8.6, 12.6º]) during cycling was found using the adjustment for upright standing posture (p3.0). As a result, saddle height is affected by adjustments based on knee angle measured in upright standing posture. Determining saddle height without adjusting knee angle for upright standing posture could lead to errors with possible effects on performance and/or injury risk

    Pedal force asymmetries and performance during a 20-km cycling time trial

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    It is unclear if applying larger or more symmetrical pedal forces leads to better performance in cycling. The aims of this study were to assess the relationship between pedal force production and performance in a cycling time trial and to evaluate the relationship between asymmetries in pedal force production and performance. Fifteen competitive cyclists/triathletes performed a 20 km cycling time trial on a cycle trainer while bilateral forces applied to the pedals were recorded along with total time. Total forces applied to the pedals were computed and converted into dominant and non-dominant forces using a leg preference inventory. Pedal force asymmetries ranged from 43% (in favour of the dominant limb) to 34% (in favour of the non-dominant limb). The relationship between total pedal force (averaged from both pedals) and performance time was small (r=-.32, effect size=.66) as well as the association between the asymmetry indices and performance time (r=.01, effect size=.06). In conclusion, applying large forces on the pedals and balancing pedal force application between the dominant and non-dominant limbs did not lead to better performance in this cycling time trial

    Measuring the hadronic cross section via radiative return

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    Recently it has been demonstrated that particle factories, such as DAPHNE and PEP-II, operating at fixed center-of-mass energies, are able to measure hadronic cross sections as a function of the hadronic system energy using the raditive return. This paper is an experimental overview of the progress in this aera. Preliminary results from KLOE for the process e+e- -> \rho \gamma -> \pi+\pi-\gamma and a fit to the pion form factor are presented. Some first results from the BABAR collaboration are also shown.Comment: Invited talk presented at RADCOR/Loops and Legs 2002, Kloster Banz/Germany, September 8-13 2002, 6 pages, 2 Figures; v1: references added, typos correcte

    Measurement of sigma(e+ e- -> pi+ pi-) from threshold to 0.85 GeV^2 using Initial State Radiation with the KLOE detector

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    We have measured the cross section of the radiative process e+e- -> pi+pi-gamma with the KLOE detector at the Frascati phi-factory DAPHNE, from events taken at a CM energy W=1 GeV. Initial state radiation allows us to obtain the cross section for e+e- -> pi+pi-, the pion form factor |F_pi|^2 and the dipion contribution to the muon magnetic moment anomaly, Delta a_mu^{pipi} = (478.5+-2.0_{stat}+-5.0_{syst}+-4.5_{th}) x 10^{-10} in the range 0.1 < M_{pipi}^2 < 0.85 GeV^2, where the theoretical error includes a SU(3) ChPT estimate of the uncertainty on photon radiation from the final pions. The discrepancy between the Standard Model evaluation of a_mu and the value measured by the Muon g-2 collaboration at BNL is confirmed.Comment: 17 pages, 11 figures, revised treatment of FSR uncertainty, version to appear on Physics Letters

    Measurement of σ(e+eπ+πγ)\sigma(e^+e^-\to \pi^+ \pi^- \gamma) and extraction of σ(e+eπ+π)\sigma(e^+e^-\to \pi^+\pi^-) below 1 {\rm GeV} with the KLOE detector

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    We have measured the cross section σ(e+eπ+πγ)\sigma(e^+e^-\to \pi^+\pi^- \gamma) at an energy W=mϕ=1.02W=m_\phi=1.02 GeV with the KLOE detector at the electron-positron collider DAΦ\PhiNE. From the dependence of the cross section on the invariant mass of the two-pion system, we extract σ(e+eπ+π)\sigma(e^+e^-\to \pi^+\pi^-) for the mass range 0.35<s<0.950.35<s<0.95 GeV2^2. From this result, we calculate the pion form factor and the hadronic contribution to the muon anomaly, aμa_\mu.Comment: 20 pages, 12 figure

    Measurement of σ(e+eπ+πγ(γ))\sigma(e^+e^-\to\pi^+\pi^-\gamma(\gamma)) and the dipion contribution to the muon anomaly with the KLOE detector

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    We have measured the cross section σ(e+eπ+πγ(γ))\sigma(e^+e^-\to\pi^+\pi^-\gamma(\gamma)) at DAΦ\PhiNE, the Frascati \phi-factory, using events with initial state radiation photons emitted at small angle and inclusive of final state radiation. We present the analysis of a new data set corresponding to an integrated luminosity of 240 pb1^{-1}. We have achieved a reduced systematic uncertainty with respect to previously published KLOE results. From the cross section we obtain the pion form factor and the contribution to the muon magnetic anomaly from two pion states in the mass range 0.592<Mππ<0.9750.592 < M_{\pi\pi} < 0.975 GeV. For the latter we find Δaμππ=(387.2±0.5stat±2.4exp±2.3th)×1010\Delta a^{\pi\pi}_\mu = (387.2\pm0.5_{\rm stat}\pm2.4_{\rm exp}\pm2.3_{\rm th})\times 10^{-10}Comment: Minor text revisions, version to appear on Physics Letters

    Physics with the KLOE-2 experiment at the upgraded DAϕ\phiNE

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    Investigation at a ϕ\phi--factory can shed light on several debated issues in particle physics. We discuss: i) recent theoretical development and experimental progress in kaon physics relevant for the Standard Model tests in the flavor sector, ii) the sensitivity we can reach in probing CPT and Quantum Mechanics from time evolution of entangled kaon states, iii) the interest for improving on the present measurements of non-leptonic and radiative decays of kaons and eta/eta^\prime mesons, iv) the contribution to understand the nature of light scalar mesons, and v) the opportunity to search for narrow di-lepton resonances suggested by recent models proposing a hidden dark-matter sector. We also report on the e+ee^+ e^- physics in the continuum with the measurements of (multi)hadronic cross sections and the study of gamma gamma processes.Comment: 60 pages, 41 figures; added affiliation for one of the authors; added reference to section

    Prospects for e+e- physics at Frascati between the phi and the psi

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    We present a detailed study, done in the framework of the INFN 2006 Roadmap, of the prospects for e+e- physics at the Frascati National Laboratories. The physics case for an e+e- collider running at high luminosity at the phi resonance energy and also reaching a maximum center of mass energy of 2.5 GeV is discussed, together with the specific aspects of a very high luminosity tau-charm factory. Subjects connected to Kaon decay physics are not discussed here, being part of another INFN Roadmap working group. The significance of the project and the impact on INFN are also discussed. All the documentation related to the activities of the working group can be found in http://www.roma1.infn.it/people/bini/roadmap.html.Comment: INFN Roadmap Report: 86 pages, 25 figures, 9 table
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