Differences in gender and performance in off-road triathlon.

The aims of this study were: (1) to examine performance trends and compare elite male and female athletes at the off-road triathlon (1.5-km swim, 30-km mountain biking, and 11-km trail running) world championships since its inception in 1996, and (2) to compare gender-related differences between off-road triathlon and conventional road-based triathlon. Linear regression analyses and ANOVA were used to examine performance trends and differences between the sexes. Elite male performance times stabilized over the 2005-2009 period, whereas elite female performance times continued to improve, especially for the run leg. Differences in performance times between the sexes were less marked in swimm…

Effects of movement direction upon kinematic characteristics of vertical arm pointing movements in man

Vertical arm pointing movements in two directions (upwards and downwards), imposing two different loads (unload and 0.5 kg) and speeds (normal and fast) have been studied in six subjects. Movements were recorded using an optoelectronic system. Data analysis concentrated upon finger-tip kinematics. Significant effects of movement direction were recorded upon velocity profiles. The acceleration time, computed relative to total movement time, was greater for downward movements than for upward movements. In contrast however, no effects of load or speed were observed. Movement time was not affected by movement direction or load, for both speeds tested. These results suggest different planning pr…

''Limits in endurance performance of octogenarian athletes''

TO THE EDITOR: A recent study of Trappe et al. (3) showed that the aerobic power of octogenarian lifelong endurance athletes was approximately double that of untrained octogenarians (38 vs. 21 ml·kg 1 ·min 1 ). These remarkable aerobic capacities are the highest ever recorded in this age group. However, the impact of the identified physiological capacities on actual endurance performances has not been addressed, as no running performance indicators of the octogenarian athletes were provided in this study. We hereby suggest that, although trained octogenarian athletes can achieve levels of aerobic fitness well above their untrained counterpart, as a group they actually have not yet reached t…

Changes in cortico-spinal excitability following uphill versus downhill treadmill exercise

International audience; An acute bout of aerobic exercise induces neuroplasticity in the motor cortex. Moreover, paired associative stimulation (PAS) is known to induce neuroplasticity in M1. However, the possible influence of the type of exercise on the neuroplastic changes remains unknown. The present study investigated the effects of two different modes of muscle contraction produced during locomotor exercise on changes in corticospinal (CS) excitability. Subjects performed two 30-min treadmill exercises at an intensity corresponding to 60% of their maximal heart rate with either a +10% (uphill) or -10% (downhill) slope. These exercises were followed or not by paired associative stimulat…

Test–retest reliability and responsiveness of centre of pressure measurements in patients with hip osteoarthritis

International audience; Objective: The aim of this study was to determine a set of measures for the evaluation of balance in patients suffering from hip osteoarthritis (OA) that were both reliable and responsive to change.Design: Three groups of subjects; Healthy, hip OA patients without surgery, and hip OA with surgery (pre and post-surgery) were included in this study. Subjects had to perform balance tests in two positions: standard and narrowed stance. CoP-based measures test-retest reliability was assessed in hip OA without surgery group, responsiveness were assessed between all groups and between pre and postsurgery.Results: Intraclass Correlation Coefficient (ICC) values from hip OA w…

Analysis of marathon performances of disabled athletes

Le but de cette etude etait d’analyser la participation et les performances sur marathon des athletes handisports en fauteuils roulants classiques (WC) et en fauteuils avec pedalage des bras ou Handbike (HC). L’âge et les performances chronometriques de tous les athletes ayant participe au marathon de New-York, dans les categories WC et HC, ont ete analyses entre 1999 et 2010. Durant cette periode, un total de 698 athletes WC (132 femmes et 566 hommes) et 776 athletes HC (141 femmes et 635 hommes) ont termine la course. Les femmes representaient 20 % du total des arrivants dans les deux categories. Les athletes en categorie WC etait significativement (P < 0,01) plus jeunes en comparaison de…

Does the coordination between posture and movement during human whole-body reaching ensure center of mass stabilization?

The whole-body center of mass (CoM) has been classically regarded as the stabilized reference value for human voluntary movements executed upon a fixed base of support. Axial synergies (opposing displacements of head and trunk with hip segments) are believed to minimize antero-posterior (A/P) CoM displacements during forward trunk movements. It is also widely accepted that anticipatory postural adjustments (APAs) create forces of inertia that counteract disturbances arising from the moving segment(s). In the present study, we investigated CoM stabilization by axial synergies and APAs during a whole-body reaching task. Subjects reached towards an object placed on the ground in front of them …

Does the centre of mass remain stable during complex human postural equilibrium tasks in weightlessness?

In normal gravity conditions the execution of voluntary movement involves the displacement of body segments as well as the maintenance of a stable reference value for equilibrium control. It has been suggested that centre of mass (CM) projection within the supporting base (BS) is the stabilised reference for voluntary action, and is conserved in weightlessness. The purpose of this study was to determine if the CM is stabilised during whole body reaching movements executed in weightlessness. The reaching task was conducted by two cosmonauts aboard the Russian orbital station MIR, during the Franco-Russian mission ALTAIR, 1993. Movements of reflective markers were recorded using a videocamera…

Swimrun: An emerging new endurance sport

International audience; The swimrun is a new endurance team-sport based on two persons swimming and running alternatively through open water and mostly trails. The aim of this study was to analyse participation and performance trends for males, females and mixed duo team at the ÖTILLÖ Swimrun race (10 km open-water swimming and 65 km trail running). During the 2012–2016 period, the mean total time performance of the best athletes at the ÖTILLÖ Swimrun decreased significantly by 17 min/year for males, 40 min/year for mixed and 59 min/year for females duo, respectively. The difference in performance between the best males and females duo (26 ± 15%) was significantly greater compared to the di…

Age-Related Adaptations of Lower Limb Intersegmental Coordination During Walking

Lower-limb intersegmental coordination is a complex component of human walking. Aging may result in impairments of motor control and coordination contributing to the decline in mobility inducing loss of autonomy. Investigating intersegmental coordination could therefore provide insights into age-related changes in neuromuscular control of gait. However, it is unknown whether the age-related declines in gait performance relates to intersegmental coordination. The aim of this study was to evaluate the impact of aging on the coordination of lower limb kinematics and kinetics during walking at a conformable speed. We then assessed the body kinematics and kinetics from gait analyses of 84 volunt…

The sensorimotor and cognitive integration of gravity.

In order to demonstrate that gravity is not only a load acting locally and continuously on the body limbs, but is also used by higher levels of the nervous system as a dynamic orienting reference for the elaboration of the motor act, a review of several experiments conducted both in 1 g and 0 g are presented. During various locomotor tasks, the strategy that consists of stabilizing the head with respect to gravity illustrates one of the solutions used by the CNS to optimize the control of dynamic equilibrium. A question which remains to be solved when considering experimental results obtained in weightlessness concerns, however, the maintenance of motor schema that has evolved under normal …

The role of anticipatory postural adjustments during whole body forward reaching movements

THE purpose of this study was to examine the role of anticipatory postural adjustments (APAs) in the execution of forward oriented whole body reaching movements. From the standing position, eight healthy subjects were asked to reach an object placed at 45 cm from the feet, at both naturally paced and fast speeds. Electromyographic signals of six antagonistic muscles were analysed in conjunction with centre of mass (CM) displacements, centre of foot pressure displacements and resultant ground reaction forces. Results revealed that APAs created necessary angular momentum of body segments for effective task execution. These results suggest that APAs can initiate movements conducted from a fixe…

Investigating centre of mass stabilisation as the goal of posture and movement coordination during human whole body reaching

In the light of experimental results showing significant forward centre of mass (CoM) displacements within the base of support, this study investigated if whole body reaching movements can be executed whilst keeping the CoM fixed in the horizontal axis. Using kinematic simulation techniques, angular configurations were recreated from experimental data imposing two constraints: a constant horizontal position of the CoM and an identical trajectory of the hand to grasp an object. The comparison between recorded and simulated trials showed that stabilisation of the CoM was associated with greater backward hip displacements, which became more marked with increasing object distance. This was in c…

Is Moderate Intensity Cycling Sufficient to Induce Cardiorespiratory and Biomechanical Modifications of Subsequent Running?

Walsh, JA, Dawber, JP, Lepers, R, Brown, M, and Stapley, PJ. Is moderate intensity cycling sufficient to induce cardiorespiratory and biomechanical modifications of subsequent running? J Strength Cond Res 31(4): 1078-1086, 2017-This study sought to determine whether prior moderate intensity cycling is sufficient to influence the cardiorespiratory and biomechanical responses during subsequent running. Cardiorespiratory and biomechanical variables measured after moderate intensity cycling were compared with control running at the same intensity. Eight highly trained, competitive triathletes completed 2 separate exercise tests; (a) a 10-minute control run (no prior cycling) and, (b) a 30-minut…

Neuromuscular and physiological variables evolve independently when running immediately after cycling

International audience; During the early period of running after cycling, EMG patterns of the leg are modified in only some highly trained triathletes. The majority of studies have analysed muscle EMG patterns at arbitrary, predetermined time points. The purpose of this study was to examine changes to EMG patterns of the lower limb at physiologically determined times during the cycle-run transition period to better investigate neuromuscular adaptations. Six highly trained triathletes completed a 10 min isolated run (IR), 30 min of rest, then a 20 min cycling procedure, before a 10 min transition run (C-R). Surface EMG activity of eight lower limb muscles was recorded, normalised and quantif…

Are Female Performances in Other Olympic Distance Running Events Equivalent to Paula Radcliffe's?

Gender differences in wheelchair marathon performance &amp;ndash; Oita International Wheelchair Marathon from 1983 to 2011

Romuald Lepers,1 Paul J Stapley,2 Beat Knechtle3,41INSERM U1093, University of Burgundy, Dijon, France; 2School of Health Sciences, University of Wollongong, Wollongong, New South Wales, Australia; 3Institute of General Practice and Health Services Research, University of Zurich, Zurich, Switzerland; 4Gesundheitszentrum St Gallen, St Gallen, SwitzerlandBackground: The purpose of the study was (1) to examine the changes in participation and performance of males and females at the Oita International Wheelchair Marathon in Oita, Japan, between 1983 and 2011, and (2) to analyze the gender difference in the age of peak wheelchair marathon performance.Methods: Age and time performance data for al…

Standing up from a chair as a dynamic equilibrium task: a comparison between young and elderly subjects.

The purpose of this study was to analyze and compare the features of center of mass (CoM) control along anterior/posterior axis in young and elderly subjects during sit-to-stand (STS). From a sitting position, seven healthy young subjects and seven healthy elderly subjects were asked to stand up from a chair under different experimental conditions (visual conditions: normal and blindfolded; speed: normal and as fast as possible). Analysis of results was based upon the concept of a “dynamic equilibrium area” (DEA), which in turn identified the dynamic limits of balance. The results showed that both the maximal CoM velocity in the horizontal axis and the CoM velocity at the instant of seat-of…