Original Research: Central and peripheral quadriceps fatigue in young and middle-aged untrained and endurance-trained men: A comparative study

Abstract

This study aimed to compare quadriceps function (i.e. strength, endurance, central, and peripheral fatigue) of young (Young-UnTr) and middle-aged (MidAge-UnTr) untrained men and young endurance-trained men (Young-Tr). Twenty-four male subjects (eight Young-UnTr (26 AE 4 yr), eight Young-Tr (29 AE 3 yr), and eight MidAge-UnTr (56 AE 4 yr) performed a maximal cycling test to assess their fitness level. On a separate visit, subjects performed sets of 10 intermittent (5-s on/5-s off) isometric contractions starting at 10% maximum voluntary contraction (MVC), with 10% MVC increments from one set to another until exhaustion. Electrophysiological and mechanical (e.g. twitch) evoked responses elicited with magnetic femoral nerve stimulation in the relaxed muscle and during MVC (i.e. estimation of voluntary activation using the interpolated twitch technique) were measured at baseline and after each set to assess peripheral and central fatigue, respectively. Endurance (¼ total number of contractions) was also evaluated. Young-UnTr exhibited larger reductions in evoked quadriceps mechanical responses than MidAge-UnTr and Young-Tr after identical standardized muscle loading (e.g. after the 50% MVC set, reduction in single potentiated twitch was À36 AE 9%, À21AE16%, and À2 AE 4%, respectively). At both 50% MVC set and exhaustion, MidAge-UnTr exhibited similar reduction in maximal voluntary activation and displayed similar endurance compared to Young-UnTr. Young-Tr exhibited greater endurance than Young-UnTr without significant changes in maximal voluntary activation throughout the test. This study provides robust comparative data regarding the influence of chronic exposure to endurance training and middle-aged on central and peripheral quadriceps fatigability and endurance. Endurance-trained subjects showed smaller level of peripheral fatigue and displayed no significant central fatigue, even at exhaustion and despite greater endurance performance. Our findings also demonstrate that men in the sixth decade exhibit significant alterations in quadriceps function typically observed in much older subjects. These data emphasize the need for developing normative data for both central and peripheral quadriceps fatigability.

Exercise Preserves Lean Mass and Performance during Severe Energy Deficit: The Role of Exercise Volume and Dietary Protein Content

“…Indeed, our overweight volunteers had not been exercising regularly and, therefore, they might have been more susceptible to central mechanisms of fatigue (Bachasson et al, 2016; O'Leary et al, 2017). …”

Greater fatigability in knee‐flexors vs. knee‐extensors after a standardized fatiguing protocol

“…Importantly, knee-extensors were presently tested and fatigued at a 298 shorter muscle length compared to knee-flexors, due to the fixed seated position. In a previous 299 direct comparison, muscles at shorter vs longer length were shown to be more fatigue-resistant 300 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 standing or walking) compared to knee-flexors may have increased their tolerance to central fatigue 317 (Bachasson et al, 2016). Accordingly, after the same standardized fatiguing task, knee-extensors 318 may have been less affected than knee-flexors.…”

“…Sidhu, Mangum, Richardson, & Amann, 2016), other studies did not report any change after 310 intermittent(Bachasson et al, 2016) or continuous isometric knee-extensors fatiguing task 311(Marshall, Finn, & Siegler, 2015). However, these two studies recruited endurance-(Bachasson et 312 al., 2016) or strength-trained(Marshall et al, 2015) participants.…”

Clinical management of chronic obstructive pulmonary disease patients with muscle dysfunction

“…However, different techniques have been proposed, being generally based on the repetition of maneuvers against submaximal loads (10−80% according to different protocols) at a preset rate until task failure (48,141,142). Repeated maximal isometric maneuvers have also be employed (143)(144)(145)(146). Unfortunately, there are no reference values for these methods to date (4,5), so each laboratory should develop its own equations or have at least a control group of healthy subjects to make comparisons.…”