Influence of concentric and eccentric resistance training on architectural adaptation in human quadriceps muscles

Abstract

Studies using animal models have been unable to determine the mechanical stimuli that most influence muscle architectural adaptation. We examined the influence of contraction mode on muscle architectural change in humans, while also describing the time course of its adaptation through training and detraining. Twenty-one men and women performed slow-speed (30 degrees /s) concentric-only (Con) or eccentric-only (Ecc) isokinetic knee extensor training for 10 wk before completing a 3-mo detraining period. Fascicle length of the vastus lateralis (VL), measured by ultrasonography, increased similarly in both groups after 5 wk (Delta(Con) = +6.3 +/- 3.0%, Delta(Ecc) = +3.1 +/- 1.6%, mean = +4.7 +/- 1.7%; P < 0.05). No further increase was found at 10 wk, although a small increase (mean approximately 2.5%; not significant) was evident after detraining. Fascicle angle increased in both groups at 5 wk (Delta(Con) = +11.1 +/- 4.0%, Delta(Ecc) = +11.9 +/- 5.4%, mean = 11.5 +/- 3.2%; P < 0.05) and 10 wk (Delta(Con) = +13.3 +/- 3.0%, Delta(Ecc) = +21.4 +/- 6.9%, mean = 17.9 +/- 3.7%; P < 0.01) in VL only and remained above baseline after detraining (mean = 13.2%); smaller changes in vastus medialis did not reach significance. The similar increase in fascicle length observed between the training groups mitigates against contraction mode being the predominant stimulus. Our data are also strongly indicative of 1) a close association between VL fascicle length and shifts in the torque-angle relationship through training and detraining and 2) changes in fascicle angle being driven by space constraints in the hypertrophying muscle. Thus muscle architectural adaptations occur rapidly in response to resistance training but are strongly influenced by factors other than contraction mode.

The effect of Nordic hamstring strength training on muscle architecture, stiffness, and strength

“…We expected eccentric NH strength training to increase hamstring muscle fascicle length, as shown previously with eccentric strength training (Alegre et al 2006;Blazevich et al 2007;Potier et al 2009;Baroni et al 2013;Bourne et al 2016). However, fascicle length did not increase in the NH training group, possibly due to the joint positions assumed during training.…”

Effects of load magnitude, muscle length and velocity during eccentric chronic loading on the longitudinal growth of vastus lateralis muscle

“…In the past few years, some studies (Blazevich et al, 2007;Duclay et al, 2009;Potier et al, 2009;Reeves et al, 2009) have reported longitudinal growth in human muscles from 7% to 34% in response to eccentric exercise. However, to our knowledge, there is only one study (Butterfield and Herzog, 2006) that investigated the fiber kinetics during eccentric contractions and this was on rabbit muscles.…”

Changes in agonist neural drive, hypertrophy and pre-training strength all contribute to the individual strength gains after resistance training

“…Consequently, resistance training (RT) is frequently employed when aiming to: improve athletic performance (Wilson et al 1996;Comfort et al 2012); enhance mobility of middle-aged and older adults (Brochu et al 2002;Brandon et al 2003); reduce injury risk (Brooks et al 2006;Noyes and Barber Westin 2012); prevent or slow the progression of joint degeneration (Zhang and Jordan 2010). On a cohort level, neural (agonist activation, Komi et al 1978;Narici et al 1996;Tillin et al 2011Tillin et al , 2011antagonist co-activation, Carolan and Cafarelli 1992;Häkkinen et al 1998) andmorphological (hypertrophy, O'Hagan et al 1995;Tracy et al 1999;Erskine et al 2010a; muscle architecture, Aagaard et al 2001;Seynnes et al 2006;Blazevich et al 2007) adaptations have been widely documented to occur after RT and are presumed to explain the observed improvements in strength. However, on an individual basis there is great variability in the changes in strength after RT (Folland et al 2000;Hubal et al 2005), and relatively little is known about the contribution of specific physiological mechanisms to these individual changes, including which is the most important adaptation for determining strength gains.…”