| dc.description.abstract | Intensity is recognized as a key component of strength training. For effective neuromuscular adaptations it has been suggested that high intensity repetitions should be accompanied by a concentric phase with a maximal intended velocity (MIV). However, it appears elusive if MIV yields a higher neuromuscular activation, and how a potential effect may be affected by advancing age. Thus, in the current study we aimed to investigate the effect of MIV on neuromuscular activity with increasing intensity in old and young individuals. Twelve old (76 ± 6 years) and twelve young (24 ± 2 years) untrained subjects were included in a cross-sectional design. Neuromuscular activation was assessed by electromyographic measurements (EMG) at increasing intensities; 0 – 90 % of 1 repetition maximum (1RM), with and without MIV, in vastus lateralis (VL) and rectus femoris (RF). The data were normalized to the maximal M-wave. Our results revealed that old and young displayed a similar percentage change in muscle activation with and without MIV. Time to maximal muscle activation with MIV was lower (x ms – y ms) in both groups, at every intensity (P < 0.05). Total muscle activation was lower in VL and RF (from - to) at; 30 – 90 % of 1RM in both RF and VL (P < 0.05) for old. In young, total muscle activation was lower (from – to) at; 0 – 70 % and 0 – 50 % (P < 0.05) in RF and VL, respectively. Maximal muscle activation in old was higher in RF at 0 and 30 % of 1RM and at 0 % in VL (P < 0.05), 30 % showed a tendency towards a higher activation (P = 0.07). In young, maximal muscle activation was higher in RF at 0 % of 1RM and at 30 and 70 % in VL (P < 0.05), 50 % showed a tendency towards a higher activation (P = 0.06). In conclusion, our results suggest a beneficial neuromuscular stimulus when MIV is applied, evident in particular as a shorter time to maximal muscle activation. Recognizing that this early phase of muscle contraction is advocated to play a critical role for neural factors following strength training, the increased stimulation with MIV in this phase may augment strength training-induced adaptations. | |
