Neural adaptations underlying cross-education after unilateral strength training.
The purpose of this study was to investigate the effects of 4-week (16 sessions) unilateral, maximal isometric strength training on contralateral neural adaptations. Subjects were randomised to a strength training group (TG, n = 15) or to a control group (CG, n = 11). Both legs of both groups were tested for plantar flexion maximum voluntary isometric contractions (MVCs), surface electromyogram (EMG), H-reflexes and V-waves in the soleus (SOL) and gastrocnemius medialis (GM) superimposed during MVC and normalised by the M-wave (EMG/M(SUP), H(SUP)/M(SUP), V/M(SUP), respectively), before and after the training period. For the untrained leg, the TG increased compared to the CG for MVC torque (33%, P < 0.01), SOL EMG/M(SUP) (32%, P < 0.05) and SOL V/M(SUP) (24%, P < 0.05). For the trained leg, the TG increased compared to the CG for MVC torque (40%, P < 0.01), EMG/M(SUP) (SOL: 38%, P < 0.05; GM: 60%, P < 0.05) and SOL V/M(SUP) (72%, P < 0.01). H(SUP)/M(SUP) remained unchanged for both limbs. No changes occurred in the CG. These results reinforce the concept that enhanced neural drive to the contralateral agonist muscles contributes to cross-education of strength.
Fimland
Marius S
MS
Department of Circulation and Imaging, Faculty of Medicine, Norwegian University of Science and Technology, 7489 Trondheim, Norway. marius.fimland@ntnu.no
Helgerud
Jan
J
Solstad
Gerd Marie
GM
Iversen
Vegard Moe
VM
Leivseth
Gunnar
G
Hoff
Jan
J
D000222:Adaptation, Physiological / Q000502:physiology*; D000328:Adult; D005260:Female; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology*; D008297:Male; D053580:Muscle Strength / Q000502:physiology*; D018482:Muscle, Skeletal / Q000294:innervation / Q000502:physiology; D055070:Resistance Training; D055815:Young Adult