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.

Effects of altered stride frequency and contact time on leg-spring behavior in human running.

Many studies have demonstrated that contact time is a key factor affecting both the energetics and mechanics of running. The purpose of the present study was to further explore the relationships between contact time (t(c)), step frequency (f) and leg stiffness (k(leg)) in human running. Since f is a compound parameter, depending on both contact and aerial time, the specific goal of this study was to independently vary f and t(c) and to investigate their respective effects on spring-mass characteristics during running, seeking to determine if the changes in k(leg) observed when running at different f are mainly due to inherent changes in t(c).

Influence of the contact time on coupling time and a simple method to measure coupling time.

The enhancement of performance in stretch shortening cycle (SSC) exercises has been attributed to the recoil of elastic energy stored during the stretching phase and depends on the duration of the coupling time (T(coupling)) i.e., the duration of the isometric phase occurring between the stretch and the shortening of the muscle.

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 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.

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 the base-line determination on work efficiency during submaximal cycling.

Aim: The purpose of this study was to compare work efficiency values (WE = work accomplished/energy expenditure above exercising with 0 load) among different unloaded base-line correction techniques for different power outputs.

Methods: Twelve healthy men performed 6 5-min steady-state exercises of 0 (unloaded), 40, 80, 120, 160 and 200 W at a pedalling rate of 90 rpm on a cycle ergometer. Three different unloaded base-line corrections were used for WE calculation: an actual measurement of VO(2) corresponding to the unloaded pedalling exercise, the y-intercept value of the linear regression between VO(2) and power output and the y-intercept value of the curvilinear VO(2)-power regression.