Relationships Between Running Economy and Temporal EMG Characteristics of Bi-Articular Leg Muscles

Abstract

Relationships between running economy (RE; submaximal VO(2) for a given running speed) and the temporal EMG characteristics of bi-articular leg muscles were quantified in a group of well-trained runners. Nine subjects completed three test sessions: a determination of maximal aerobic demand (VO(2)max); an accommodation session at the experimental speed of 4.13 m.s(-1) and a session during which EMG and RE data were collected simultaneously at the experimental speed of 4.13 m.s(-1) Measures of muscle onset, on-time durations, and on-time coactivation durations were calculated from the following muscles: rectus femoris, medial hamstrings, lateral hamstrings, and gastrocnemius. Nonparametric correlations between RE and EMG characteristics displayed both positive and negative relationships and exhibited a wide range of values. Two EMG measures were significantly correlated (r > 0.67) with RE. Earlier onset of rectus femoris during swing phase and a shorter duration of hamstring - gastrocnemius coactivation during swing were associated with more economical runners. Although not statistically significant, correlation coefficients calculated for measures of coactivation during stance and RE ranged from -0.42 to -0.65. This trend indicates that individuals who exhibited a greater amount of coactivation between bi-articular muscles during the stance phase of the running cycle tended to be more economical. These relationships suggest different activation patterns in bi-articular muscles between economical and uneconomical runners.

Are variations in running economy in humans associated with ground reaction force characteristics?

“…The dierence between the least and most economical subjects expressed as a percentage of the mean RE, 26.5%, also was consistent with results of previous studies (Conley and Krahenbuhl 1980;Heise et al 1996;Martin and Morgan 1992). There existed no distinct pattern between subjects' _ V O 2peak and their RE as was veri®ed by the poor correlation between these two variables (r=±0.08).…”

“…ámin ±1 ] and the magnitude and range of RE for the sample [(mean RE 44.6 (SD 3.3) ml O 2 ákg ±1 ámin ±1 ] were typical of those which have been reported previously for similar speeds (Conley and Krahenbuhl 1980;Heise et al 1996;Williams and Cavanagh 1987). The dierence between the least and most economical subjects expressed as a percentage of the mean RE, 26.5%, also was consistent with results of previous studies (Conley and Krahenbuhl 1980;Heise et al 1996;Martin and Morgan 1992).…”

Research on Some Problems on Endurance Training Effectiveness

“…They also noted a trend mentioned is to increase muscle activation time synchronizing can improve the economics of the operation. They assume that a large number of muscle fibers are activated simultaneously may cause joints stiffen, it would be involved in muscle movement and better recovery elastic potential energy, thereby improving the operation of the economy [14] . Other studies have found that the greater the elastic tissue while running the role, the more economic action [15] .…”

Activité musculaire des membres inférieurs en course à pied sur le plat

“…Ces deux résultats pouvant être expliqués par une action de « griffé » préalable à la phase d'appui chez les coureurs entraînés à la course. Dans un autre domaine, Heise et al (1995) ont centré leurs investigations sur les relations entre le coût énergétique de l'athlète et le niveau d'activité musculaire de certains muscles. En course, cette notion de coût énergétique exprime le rapport entre la dépense énergétique (en mlO2.mn-1.kg-1) et la vitesse de déplacement (en m.s-1 ou en km.h-1).…”

“…Plus ce rapport est faible, plus le sujet est économique. Heise et al (1995) mentionnent que les durées de coactivité entre les muscles bi-articulaires pendant les phases d'appui et d'oscillation ont une influence sur le coût énergétique. Kyrölaïnen et al (2001), observent également une augmentation de coactivité entre agoniste/antagoniste (VL et BF d'une part, Ga et TA de l'autre) qui aboutirait à l'augmentation de la raideur du genou et de la cheville au début de la phase de contact.…”