Search results for "Stretch-shortening cycle"

EMG amplitude of the biceps femoris during jumping compared to landing movements.

2013

Abstract Hamstrings injury is a common occurrence in athletic performance. These injuries tend to occur during a deceleration or landing task suggesting the negative work may be a key component in hamstrings injury. The purpose of this study was to investigate the muscular activity (EMG) of the biceps femoris (BF) in different phases (concentric vs. eccentric) of a Counter Movement Jump (CMJ), Squat Jump (SJ) and the Braking Phase (BP) of a landing task. Twelve female volleyball players performed 5 CMJs, SJs and BPs while surface EMG was recorded using a MuscleLab (BoscoSystemTM, Norway). EMG values were normalized to an maximal voluntary contraction. A repeated measures analysis of varianc…

Effects of marathon fatigue on running kinematics and economy

2007

International audience; The influence of marathon fatigue on both running kinematics and economy was investigated with 8 subjects. The measurements included a treadmill test at 3 steady submaximal speeds performed before and after the marathon. One complete left leg cycle was videotaped at 100 Hz from the left side at each speed. The analysis included contact time (braking and push-off') and flight time as well as displacements and angular velocities of the left hip and knee. This analysis was complemented by the measurements of the electromyographic (EMG) activity of the gastrocnemius muscle at each running velocity, and energy expenditure (E) of the last 30.s at the 2 slowest speeds. The …

Concentric force enhancement during human movement

2001

In order to understand the possible mechanisms contributing to enhanced concentric performance in stretch-shortening cycle exercises in vivo the present study examined knee extension torque, EMG activity and fascicle length of the vastus lateralis muscle in maximal and submaximal human movements. Maximal concentric knee extensions (120 s-1) were done after pre-stretch and pre-isometric conditions by nine volunteers. During shortening at the knee angle of 115 (180 = extended) the knee extension torque was found to be greater in pre-stretch condition (272 vs. 248 Nm, p < 0.05) although the torque level prior to shortening was smaller than in pre-isometric condition (268 vs. 314 Nm, p< 0.05…

Functional muscle architecture in aging

2014

Muscle and joint stiffness regulation during normal and fatiguing stretch-shortening cycle exercise

2010

Gene expressions of SREBP-2, PPARδ, MYH7 and blood lipid changes induced by stretch-shortening cycle exercise

2011

The present study was to investigate whether the mRNA levels of the transcription factors, sterol regulatory element-binding protein-2 (SREBP-2), peroxisome proliferator-activated receptor-δ (PPARδ) as well as slow type myosin heavy chain (MYH7) gene are modulated after exhaustive exercise and if so, whether such alterations are related to the percentage of MHC isoforms. In particular, this study was undertaken to examine whether the level of selected blood parameters are influenced by fatiguing stretch-shortening cycle (SSC) exercise. Ten healthy men performed unilateral exhaustive repeated jumps on a special sledge. The maximal voluntary contraction (MVC) was examined before, immediately,…