Biomedical subjects

G Sarre

Publications and source records attributed to G Sarre.

4 recordsLinked to original sources

PubMed2006

Cycling exercise and the determination of electromechanical delay.

The main aim of the present paper was to address the validity of a methodology proposed in a previous paper [Li L, Baum BS. Electromechanical delay estimated by using electromyography during cycling at different pedaling frequencies. J Electromyogr Kinesiol 2004;14(6):647-52], aimed at determining the electromechanical delay from pedaling exercise performed at various cadences. Twelve trained subjects undertook pedaling bouts corresponding to combinations of cadences ranging from 50 to 100 RPM and power output from 37.5% to 75% of Pmax. As cadence increased, peak torque angle was found to shift forward in crank cycle (from 60-65 degrees at 50 RPM to 75-80 degrees at 100 RPM, depending on the power output level), while muscle bursts shifted backward in accordance with previous works. It is therefore suggested to take into account this peak torque angle lag to improve the methodology proposed by Li and Baum. The present results also evidenced that the central strategy, consisting in earlier muscle activation in crank cycle as cadence increases, is only partial. Neural strategy seems to be a trade-off between mechanical efficiency of muscular force output and coactivation.

Adult↗

PubMed2005

Stability of pedalling mechanics during a prolonged cycling exercise performed at different cadences.

The aim of this study was to analyse the effect of pedalling rate on the pattern of mechanical torque application and on neuromuscular fatigue during prolonged cycling exercise. Eleven well-trained individuals performed three 1-h pedalling sessions, at 50 rev.min-1, 110 rev.min-1 and a freely chosen cadence, at an intensity corresponding to 65% of their maximal aerobic power. The mechanical torque applied on the right pedal was recorded for 30 s every 5 min while pedalling. Contractile and neural properties of the quadriceps and hamstring muscles were analysed before and immediately after each of the three pedalling sessions. The post-exercise reduction in knee extensors maximal voluntary contraction was significant (P<0.01) irrespective of the cadence, but no difference was found between cadences. The use of a particular cadence did not lead to preferentially central or peripheral fatigue. An increase in cadence resulted in greater positive and negative work generated during pedalling. The mechanical pattern was not altered during the exercise, whatever the selected cadence. The present study demonstrates that despite the occurrence of neuromuscular fatigue, trained individuals maintained a stable pedalling pattern throughout an endurance cycling exercise for cadences ranging from 50 to 110 rev.min-1.

Adult↗

PubMed2005

Neuromuscular function during prolonged pedalling exercise at different cadences.

AIM: The purpose of the present work was to assess the strategies set by the central nervous system in order to provide the power output required throughout a prolonged (1-h) pedalling exercise performed at different cadences (50 rpm, 110 rpm and the freely chosen cadence). METHODS: Neuromuscular (NM) activity of vastus lateralis, rectus femoris, biceps femoris and gastrocnemius lateralis muscles was studied quantitatively [root-mean square (RMS) and mean power frequency (MPF)] and qualitatively (timing of onset and offset of muscle bursts during crank cycle). RESULTS: The present results showed that increased cadence resulted in earlier muscle activation in crank cycle. The influence of cadence on RMS and MPF depended on the considered muscle and its functional role during pedalling. Timing of onset and offset of muscle bursts was not altered by fatigue throughout the prolonged exercise. In contrast, RMS and MPF of some muscles was found to increase during prolonged exercise. CONCLUSION: In summary, the present study revealed that tonic aspects of the NM activity (RMS, MPF) are altered during prolonged pedalling exercise, while phasic aspects are remained unchanged. These results suggest that the strategies set by the central nervous system in order to provide the power output required by the exercise are held constant throughout the exercise, but that quantitative aspects of the central drive are increased in order to adapt to the progressive occurrence of the NM fatigue.

Adaptation, Physiological↗

PubMed2002

Influence of cycling cadence on neuromuscular activity of the knee extensors in humans.

The aim of the present study was to investigate the influence of pedalling rate and power output in cycling on the neuromuscular activity of the knee extensor muscles. Ten subjects took part in 15 randomised trials, which consisted of three levels of power outputs (60%, 80% and 100% maximal aerobic power) and five cadences (70%, 85%, 100%, 115% and 130% of the freely chosen cadence, FCC). Root mean square (rms) was utilized to quantify electromyographic activity of the vastus lateralis (VL), vastus medialis (VM) and rectus femoris (RF) muscles. The mean (SD) FCC did not change with power output, ranging from 85.0 (11.9) to 88.0 (11.1) rpm. A significant power effect ( P<0.01) for the rms of VL, VM and RF muscles was observed. Results showed no significant cadence effect on neuromuscular activity of the VL and VM muscles, while the rms of the RF muscle was significantly greater ( P<0.05) at 70% FCC when compared to other cadences. In conclusion, the neuromuscular activity of the knee extensor muscles was not significantly influenced by cadence manipulations. Thus, minimisation of the neuromuscular activity of these muscles would not seem to lead to the choice of a cadence in cycling.

Adult↗