Neuromuscular Adaptations Associated with Knee Joint Angle-Specific Force Change

Abstract

The EMG/Mmax, although not VA%, results suggest that neural adaptations underpinned training-related changes at short quadriceps lengths, but hypertrophic changes predominated after training at long lengths. The findings of this study should contribute to the development of more effective and evidence-based rehabilitation and strength training protocols.

Training-induced changes in architecture of human skeletal muscles: Current evidence and unresolved issues

“…In the 2000s, some studies showed an increase in fascicle length following resistance or competitive training [43][44][45][46][47][48][49][50][51][52][53] . Overall, training-induced increases in fascicle length are accompanied by an increase in muscle size (muscle hypertrophy, which is defined as an increase in muscle fiber area, muscle thickness, anatomical crosssectional area or volume in this article), although four studies failed to find muscle hypertrophy 45,52,54,55) and two studies did not show the data on muscle size 56,57) . Two studies observed a decrease in fascicle length of the gastrocnemius with 58) and without 59) muscle hypertrophy, and Timmins et al 55) showed a decrease in the fascicle length of BF without muscle hypertrophy.…”

“…They demonstrated that only high muscle lengthening velocity training induced an increase in VL fascicle length. However, other research groups indicated an increase in fascicle length of VL after isometric training 54,64) , slow (30°/s) isokinetic concentriconly and eccentric-only training 46) and eccentric-only (60°/ s) training 44) . Therefore, it is difficult to conclude that eccentric training, especially at high speed, can induce a preferential increase in fascicle length.…”

“…Some reports measured a fascicle length at several sites along VL 45,48,54,65,67,68) , and observed regional differences in the changes before and after intervention 45,54) . Noorkoiv et al 54) demonstrated that isometric training at a long muscle length position induced an increase in VL fascicle length in the distal region, whereas at a short muscle length position, an increment was shown in the middle region.…”

Triceps Brachii Muscle Strength and Architectural Adaptations with Resistance Training Exercises at Short or Long Fascicle Length

“…However, although muscle thickness was increased similarly between groups, fascicle length was not altered after the two training interventions [5]. Likewise, isometric training at long muscle length resulted in greater increase in concentric muscle strength whereas training at short muscle lengths induced increases only in isometric strength, which was not related to changes in muscle size [6,7]. In another study, dynamic resistance training using machines and free weights at long muscle length was superior to training at short muscle length [8].…”

“…Recent studies aimed to investigate whether training at different muscle lengths of the knee extensors induces different muscle strength and mass adaptations [5][6][7][8]. Recently, it has been reported that 8 weeks of isometric knee extension training at long muscle length induced greater strength gains compared to training at short muscle length [5].…”