TY  - JOUR
A1  - Gruber, Markus
A1  - Linnamo, Vesa
A1  - Strojnik, Vojko
A1  - Rantalainen, Tuomas
A1  - Avela, Janne
T1  - Excitability at the motoneuron pool and motor cortex is specifically modulated in lengthening compared to isometric contractions
N2  - Neural control of muscle contraction seems to be unique during muscle lengthening. The present study aimed to determine the specific sites of modulatory control for lengthening compared with isometric contractions. We used stimulation of the motor cortex and corticospinal tract to observe changes at the spinal and cortical levels. Motor- evoked potentials (MEPs) and cervicomedullary MEPs (CMEPs) were evoked in biceps brachii and brachioradialis during maximal and submaximal lengthening and isometric contractions at the same elbow angle. Sizes of CMEPs and MEPs were lower in lengthening contractions for both muscles ( by similar to 28 and similar to 16%, respectively; P < 0.01), but MEP-to-CMEP ratios increased (by similar to 21%; P < 0.05). These results indicate reduced excitability at the spinal level but enhanced motor cortical excitability for lengthening compared with isometric muscle contractions.
Y1  - 2009
UR  - http://jn.physiology.org/
U6  - https://doi.org/10.1152/jn.91104.2008
SN  - 0022-3077
ER  - 
TY  - JOUR
A1  - Granacher, Urs
A1  - Gruber, Markus
A1  - Gollhofer, Albert
T1  - Resistance training and neuromuscular performance in seniors
N2  - Age-related processes in the neuromuscular and the somatosensory system are responsible for decreases in maximal and explosive force production capacity and deficits in postural control. Thus, the objectives of this study were to investigate the effects of resistance training on strength performance and on postural control in seniors. Forty healthy seniors (67 +/- 1 yrs) participated in this study. Subjects were randomly assigned to a resistance training (n = 20) and a control group (n = 20). Resistance training for the lower extremities lasted for 13 weeks at 80% of the one repetition maximum. Pre and post tests included the measurement of maximal isometric leg extension force with special emphasis on the early part of the force-time-curve and the assessment of static (functional reach test) and dynamic (tandem walk test, platform perturbation) postural control. Resistance training resulted I in an enhanced strength performance with increases I in explosive force exceeding those in maximal strength. Improved performances in the functional reach and in the tandem walk test were observed. Resistance training did not have an effect: on the compensation of platform perturbations. Increases in strength performance can primarily be explained by an improved neural drive of the agonist muscles. The inconsistent effect of resistance training on postural control may be explained by heterogeneity of testing methodology or by the incapability of isolated resisiance training to improve postural control.
Y1  - 2009
UR  - http://www.thieme-connect.de/ejournals/toc/sportsmed
U6  - https://doi.org/10.1055/s-0029-1224178
SN  - 0172-4622
ER  -