How much does the human medial gastrocnemius muscle contribute to ankle torques outside the sagittal plane?

Ankle movements in the frontal plane are less prominent though not less relevant than movements in the plantar or dorsal flexion direction. Walking on uneven terrains and standing on narrow stances are examples of circumstances likely imposing marked demands on the ankle medio-lateral stabilization. Following our previous evidence associating lateral bodily sways in quiet standing to activation of the medial gastrocnemius (MG) muscle, in this study we ask: how large is the MG contribution to ankle torque in the frontal plane? By arranging stimulation electrodes in a selective configuration, current pulses were applied primarily to the MG nerve branch of ten subjects. The contribution of populations of MG motor units of progressively smaller recruitment threshold to ankle torque was evaluated by increasing the stimulation amplitude by fixed amounts. From smallest intensities (12-32 mA) leading to the firstly observable MG twitches in force-plate recordings, current pulses reached intensities (56-90 mA) below which twitches in other muscles could not be observed from the skin. Key results show substantial MG torque contribution tending to rotate upward the foot medial aspect (ankle inversion). Nerve stimulation further revealed a linear relationship between the peak torque of ankle plantar flexion and inversion, across participants (Pearson R>0.81; P<0.01). Specifically, regardless of the current intensity applied, the peak torque of ankle inversion amounted to about 13% of plantar flexion peak torque. Physiologically, these results provide experimental evidence that MG activation may contribute to stabilize the body in the frontal plane, especially under situations of challenged stabilit

Effects of competitive standard, team formation and playing position on match running performance of Brazilian professional soccer players

This study examined the effects of competitive standard, team formation and playing position on match running performance in a Brazilian professional soccer team. Performance was investigated in 36 players in 48 matches at three competitive standards: 1st São Paulo State Championship; 3rd and 4th Brazilian leagues. Global Positioning System technology was used to determine total distance covered (TD), maximal running speed (MRS), mean speed (SMEAN) and frequency of high-intensity activities (HIA). Data were compared across competitive standards, team formations and playing positions. Magnitude-based inferences showed greater values for TD, SMEAN and HIA (likely to almost certain) in the lower national (3rd, 4th Brazilian) versus the top state division (1st São Paulo). Higher values for all variables were reported for the 1–4–3–3 versus the 1–4–4–2 formation (likely to almost certain). External defenders/midfielders and forwards reported greater values (likely to almost certain) versus central defenders/midfielders, especially in HIA. Linear regression analyses showed that playing position demonstrated a higher relative contribution to the variance in MRS (24%) and HIA (29%) compared to team formation (16% and 25%, respectively). In a Brazilian professional soccer team, match running performance was dependent upon competitive standard, playing formation and playing position