Physiological and Psychological Effects of Short-Term Recreational Football in Adults 60.

Recreational football has shown growing evidence that it could be played safely in adults aged 60+ and that it is physically beneficial. Less is known about the psychological aspects, except for the lived experiences of players. The aim of the present study was to analyze both physiological and psychological effects of short-term recreational football.

Simple method for measuring center of mass work during field running.

The purpose of this study was to propose and validate a new simple method for calculation of center of mass work during field running, in order to avoid the use of costly and inconvenient measurement devices. This method relies on spring-mass model and measurements of average horizontal velocity, and contact and flight times during running. Ten male, recreational subjects ran on a dynamometer treadmill at different velocities ranging from 2.

Eight weeks of local vibration training increases dorsiflexor muscle cortical voluntary activation.

The aim of this study was to evaluate the effects of an 8-wk local vibration training (LVT) program on functional and corticospinal properties of dorsiflexor muscles. Forty-four young subjects were allocated to a training (VIB, = 22) or control (CON, = ) group. The VIB group performed twenty-four 1-h sessions (3 sessions/wk) of 100-Hz vibration applied to the right tibialis anterior.

Sex differences in active tibialis anterior stiffness evaluated using supersonic shear imaging.

This study aimed to evaluate the sex difference in active muscle stiffness of the tibialis anterior muscle (TA) through shear modulus measurements performed using supersonic shear imaging (SSI) technique. Twenty-five women and twenty-one men participated in this study. Joint torque, electromyographic (EMG) activity and shear modulus were measured during two sets of submaximal dorsiflexions performed at 20, 30, 40, 50 and 60% of maximal voluntary contraction (MVC) in a random order.

Forms of interdisciplinarity in four sport science research centres in Europe.

Interdisciplinarity is often presented as a significant element of sport science. We present here the results of an investigation conducted in four European Sport Science Research Centres applying interdisciplinarity. Four main dimensions, that we have called "forms", have been investigated.

Effects of a Non-Circular Chainring on Sprint Performance During a Cycle Ergometer Test.

Non-circular chainrings have been reported to alter the crank angular velocity profile over a pedal revolution so that more time is spent in the effective power phase. The purpose of this study was to determine whether sprint cycling performance could be improved using a non-circular chainring (Osymetric: ellipticity 1.25 and crank lever mounted nearly perpendicular to the major axis), in comparison with a circular chainring.

Force-velocity properties' contribution to bilateral deficit during ballistic push-off.

Purpose: The objective of this study is to quantify the contribution of the force-velocity (F-v) properties to bilateral force deficit (BLD) in ballistic lower limb push-off and to relate it to individual F-v mechanical properties of the lower limbs.

Methods: The F-v relation was individually assessed from mechanical measurements for 14 subjects during maximal ballistic lower limb push-offs; its contribution to BLD was then investigated using a theoretical macroscopic approach, considering both the mechanical constraints of movement dynamics and the maximal external capabilities of the lower limb neuromuscular system.

Results: During ballistic lower limb push-off, the maximum force each lower limb can produce was lower during bilateral than unilateral actions, thus leading to a BLD of 36.

Optimal force-velocity profile in ballistic movements--altius: citius or fortius?

Purpose: The study's purpose was to determine the respective influences of the maximal power (Pmax) and the force-velocity (F-v) mechanical profile of the lower limb neuromuscular system on performance in ballistic movements.

Methods: A theoretical integrative approach was proposed to express ballistic performance as a mathematical function of Pmax and F-v profile. This equation was (i) validated from experimental data obtained on 14 subjects during lower limb ballistic inclined push-offs and (ii) simulated to quantify the respective influence of Pmax and F-v profile on performance.

Mechanical work and metabolic cost of walking after weight loss in obese adolescents.

Purpose: This study was performed to investigate whether changes in biomechanical parameters of walking explain the reduction in net metabolic cost after weight loss in obese adolescents.

Methods: Body composition and metabolic and mechanical energy costs of walking at 1.25 m·s(-1) were assessed in 16 obese adolescents before and after a weight loss.

Jumping ability: a theoretical integrative approach.

A theoretical integrative approach is proposed to understand the overall mechanical characteristics of lower extremities determining jumping ability. This approach considers that external force production during push-off is limited by mechanical constraints imposed by both movement dynamics and force generator properties, i.e.

Do mechanical gait parameters explain the higher metabolic cost of walking in obese adolescents?

Net metabolic cost of walking normalized by body mass (C(W.BM(-1)); in J.kg(-1).

Timing of muscle activation of the lower limbs can be modulated to maintain a constant pedaling cadence.

This study investigated changes in muscle activity when subjects are asked to maintain a constant cadence during an unloaded condition. Eleven subjects pedaled for five loaded conditions (220 W, 190 W, 160 W, 130 W, 100 W) and one unloaded condition at 80 rpm. Electromyographic (EMG) activity of six lower limb muscles, pedal forces and oxygen consumption were calculated for every condition.

Characterization of the mechanical properties of backpacks and their influence on the energetics of walking.

The objectives of the experiment were (i) to characterize the mechanical properties of backpacks and (ii) to study the influence of a flexible backpack on the energetics and kinematics of walking. Twelve subjects walked at different speeds on a treadmill with each of two backpacks loaded with 25% bodyweight, with either a rigid or a flexible link between the body attachment and the suspended loads. A single degree of freedom linear model of the link between the pack and the trunk was used to calculate the stiffness and damping coefficient of the two backpacks.

A simple method for measuring force, velocity and power output during squat jump.

Our aim was to clarify the relationship between power output and the different mechanical parameters influencing it during squat jumps, and to further use this relationship in a new computation method to evaluate power output in field conditions. Based on fundamental laws of mechanics, computations were developed to express force, velocity and power generated during one squat jump. This computation method was validated on eleven physically active men performing two maximal squat jumps.

Effects of whole body vibration on the skeleton and other organ systems in man and animal models: what we know and what we need to know.

Previous investigations reported enhanced osseous parameters subsequent to administration of whole body vibration (WBV). While the efficacy of WBV continues to be explored, scientific inquiries should consider several key factors. Bone remodeling patterns differ according to age and hormonal status.

Effects of hiking pole inertia on energy and muscular costs during uphill walking.

Introduction/purpose: The purpose of the present study was to investigate the effects of using hiking poles with different inertia on oxygen cost (V O2) and muscular activity.

Methods: Eleven subjects walked at 3 km.h on a treadmill inclined at 20% grade.

Stiffness adaptations in shod running.

When mechanical parameters of running are measured, runners have to be accustomed to testing conditions. Nevertheless, habituated runners could still show slight evolutions of their patterns at the beginning of each new running bout. This study investigated runners' stiffness adjustments during shoe and barefoot running and stiffness evolutions of shoes.

Effects of the transition time between muscle-tendon stretch and shortening on mechanical efficiency.

The net mechanical efficiency of positive work (eta(pos)) has been shown to increase if it is immediately preceded by negative work. This phenomenon is explained by the storage of elastic energy during the negative phase and its release during the subsequent positive phase. If a transition time (T) takes place, the elastic energy is dissipated into heat.

Relationship between the increase of effectiveness indexes and the increase of muscular efficiency with cycling power.

We determined the index of effectiveness (IE), as defined by the ratio of the tangential (effective force) to the total force applied on the pedals, using a new method proposed by Mornieux et al. (J Biomech, 2005), while simultaneously measuring the muscular efficiency during sub-maximal cycling tests of different intensities. This allowed us to verify whether part of the changes in muscular efficiency could be explained by a better orientation of the force applied on the pedals.

A simple method for measuring stiffness during running.

The spring-mass model, representing a runner as a point mass supported by a single linear leg spring, has been a widely used concept in studies on running and bouncing mechanics. However, the measurement of leg and vertical stiffness has previously required force platforms and high-speed kinematic measurement systems that are costly and difficult to handle in field conditions. We propose a new "sine-wave" method for measuring stiffness during running.

A cycle ergometer mounted on a standard force platform for three-dimensional pedal forces measurement during cycling.

This report describes a new method allowing to measure the three-dimensional forces applied on right and left pedals during cycling. This method is based on a cycle ergometer mounted on a force platform. By recording the forces applied on the force platform and applying the fundamental mechanical equations, it was possible to calculate the instantaneous three-dimensional forces applied on pedals.

Influence of speed variation and age on the asymmetry of ground reaction forces and stride parameters of normal gait in children.

The purpose of this study was to assess the influence of age and speed on the asymmetry of ground reaction forces (GRFs) and spatiotemporal parameters (STPs) during normal gait in 4- to 10-year-old children. Forty-seven children walked at three speeds on a treadmill dynamometer (ADAL; Tecmachine, Andrézieux Bouthéon, France). Thirty steps were recorded at each speed for each foot for each child.

Supra-maximal cycling efficiency assessed in humans by using a new protocol.

This study proposed a non-invasive method to determine the gross (GE, no baseline correction), net (NE, resting metabolism as the baseline correction) and work (WE, unloaded cycling as the baseline correction) efficiencies during cycling at an intensity higher than the maximal aerobic power (MAP). Twelve male subjects performed two exercises consisting of 4 min at 50% MAP followed either by 8 min at 63% MAP or by 8 sequences of 60 s divided into 10 s at 130% MAP and 50 s at 50% MAP (i.e.

Influence of mechanical and metabolic strain on the oxygen consumption slow component during forward pulled running.

The possible influence of increased eccentric mechanical work on the increase in oxygen uptake ( V(.)O(2)) after 3 min of running (Delta V(.)O(2)) was investigated through forward pulled running.