TY  - JOUR
A1  - Martinez-Valdes, Eduardo Andrés
A1  - Falla, Deborah
A1  - Negro, Francesco
A1  - Mayer, Frank
A1  - Farina, Dario
T1  - Differential Motor Unit Changes after Endurance or High-Intensity Interval Training
T2  - Medicine and science in sports and exercise : official journal of the American College of Sports Medicine
N2  - Purpose Using a novel technique of high-density surface EMG decomposition and motor unit (MU) tracking, we compared changes in the properties of vastus medialis and vastus lateralis MU after endurance (END) and high-intensity interval training (HIIT). Methods Sixteen men were assigned to the END or the HIIT group (n = 8 each) and performed six training sessions for 14 d. Each session consisted of 8-12 x 60-s intervals at 100% peak power output separated by 75 s of recovery (HIIT) or 90-120 min continuous cycling at similar to 65% VO2peak (END). Pre- and postintervention, participants performed 1) incremental cycling to determine VO2peak and peak power output and 2) maximal, submaximal (10%, 30%, 50%, and 70% maximum voluntary contraction [MVC]), and sustained (until task failure at 30% MVC) isometric knee extensions while high-density surface EMG signals were recorded from the vastus medialis and vastus lateralis. EMG signals were decomposed (submaximal contractions) into individual MU by convolutive blind source separation. Finally, MU were tracked across sessions by semiblind source separation. Results After training, END and HIIT improved VO2peak similarly (by 5.0% and 6.7%, respectively). The HIIT group showed enhanced maximal knee extension torque by similar to 7% (P = 0.02) and was accompanied by an increase in discharge rate for high-threshold MU (50% knee extension MVC) (P < 0.05). By contrast, the END group increased their time to task failure by similar to 17% but showed no change in MU discharge rates (P > 0.05). Conclusions HIIT and END induce different adjustments in MU discharge rate despite similar improvements in cardiopulmonary fitness. Moreover, the changes induced by HIIT are specific for high-threshold MU. For the first time, we show that HIIT and END induce specific neuromuscular adaptations, possibly related to differences in exercise load intensity and training volume.
KW  - HIGH-DENSITY SURFACE EMG
KW  - MOTOR UNIT DECOMPOSITION
KW  - MOTOR UNIT TRACKING
KW  - MOTOR UNIT DISCHARGE RATE
KW  - MOTOR UNIT ADAPTATION
KW  - NEUROMUSCULAR ADAPTATION
Y1  - 2017
UR  - https://publishup.uni-potsdam.de/frontdoor/index/index/docId/46607
SN  - 0195-9131
SN  - 1530-0315
VL  - 49
SP  - 1126
EP  - 1136
PB  - Lippincott Williams & Wilkins
CY  - Philadelphia
ER  -