On the reliability and validity of central fatigue determination

Dotan, Raffy; Woods, Stacey; Contessa, Paola

doi:10.1007/s00421-021-04700-w

Cited by 25 publications

(18 citation statements)

References 122 publications

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“…Although the interpolated twitch technique can give a valid estimation of the VA, it presents several methodological issues; for example, the compliance of the tendons and the myograph and/or the coupling to the myograph during contraction (Taylor 2009 ). Moreover, the inability to detect possible interference from the antagonist muscles (Allen et al 1998 ), its sensitivity in assessing the post-activation potentiation mechanisms that could limit the comparison among different populations (e.g., children vs adults) (Dotan et al 2021 ), and unfeasibility to detect possible differences between synergistic muscles in a given task should be also taken in consideration (Behm et al 2002 ). This last point is particularly important, since most movements require several muscles acting in synergy, and the interpolated twitch technique cannot distinguish the VA of each individual muscle.…”

Section: Introductionmentioning

confidence: 99%

Determining voluntary activation in synergistic muscles: a novel mechanomyographic approach

et al. 2022

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Purpose Drawing on correlations between the mechanomyographic (MMG) and the force signal, we devised a novel approach based on MMG signal analysis to detect voluntary activation (VA) of the synergistic superficial heads of the quadriceps muscle. We hypothesized that, after a fatiguing exercise, the changes in the evoked MMG signal of each quadriceps head would correlate with the changes in the level of VA in the whole quadriceps. Methods Twenty-five men underwent a unilateral single-leg quadriceps exercise to failure. Before and after exercise, VA was assessed by interpolated-twitch-technique via nerve stimulation during and after maximum voluntary contraction (MVC). The force and MMG signal were recorded from vastus lateralis, vastus medialis, and rectus femoris. The MMG peak-to-peak was calculated and the voluntary activation index (VAMMG), defined as the superimposed/potentiated MMG peak-to-peak ratio, was determined from the MMG signal for each head. Results VAMMG presented a very high intraclass correlation coefficient (0.981–0.998) and sensitivity (MDC95%: 0.42–6.97%). MVC and VA were decreased after exercise in both the exercising [MVC:−17(5)%, ES −0.92; VA: −7(3)%, ES −1.90] and the contralateral limb [MVC: −9(4)%, ES −0.48; VA: −4(1)%, ES −1.51]. VAMMG was decreased in both the exercising [~ −9(6)%, ES −1.77] and contralateral limb [~ −3(2)%, ES −0.57], with a greater decrease in VAMMG noted only in the vastus medialis of the exercising limb. Moderate-to-very high correlations were found between VAMMG and VA (R-range: 0.503–0.886) before and after exercise. Conclusion VAMMG may be implemented to assess VA and provide further information when multiple synergistic muscle heads are involved in fatiguing exercises.

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Section: Introductionmentioning

confidence: 99%

Determining voluntary activation in synergistic muscles: a novel mechanomyographic approach

et al. 2022

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“…Its validity and reliability in estimating VA have recently been questioned ( 26 , 62 ), because its results may be influenced by factors such as muscle length, composition, potentiation, or technical application. Specifically, these factors seem to influence the mechanical properties or output of the muscle and consequently affect superimposed-to-resting twitch ratios used to estimate VA ( 26 ) Notably, children have lower musculotendinous stiffness compared with adults ( 27 , 63 ), which can affect the resting twitch force (i.e., length–tension relationship). As was demonstrated by Hill ( 64 ), lower stiffness (or greater compliance) will result in dampened twitch torque and a delay in twitch onset.…”

Section: Discussionmentioning

confidence: 99%

Increase in Volitional Muscle Activation from Childhood to Adulthood: A Systematic Review and Meta-analysis

Woods

O'Mahoney

Maynard

et al. 2021

Medicine &Amp; Science in Sports &Amp; Exercise

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Introduction Children’s maximal muscle strength is consistently lower than adults’, even when normalized to body size. Lower volitional muscle activation (VA) in children is often considered one of the main reasons for age-related differences in muscular performance. However, some recent studies have reported similar VA in children and adults, bringing into question whether there is indeed an age-related increase in VA. The purpose of this review was to determine the effect of age on VA during maximal isometric contractions. Methods Literature examining VA differences, using twitch interpolation in children (7–14 yr) and adults (16–28 yr), was systematically reviewed. Of the 1915 studies initially identified, 19 data sets were eligible for inclusion in the qualitative analysis and 14 in the quantitative meta-analysis (comprising 207 children and 193 adults). Results Significantly lower VA in children was reported in 9/19 (47%) studies. A random-effects meta-analysis found a strong effect of age on VA, supporting lower VA in children compared with adults (Hedges’ g = 1.55; confidence interval: 0.9–2.13). Moderator analysis included muscle group, sex, children’s age, stimulation number (singlet, multiple), type (electric, magnetic), and location (muscle, nerve), of which only muscle group was significant ( P < 0.001). A significant Egger’s regression test and asymmetrical funnel plot suggest that publication bias may be present. Conclusions Overall, these findings suggest that compared with adults, children activate their motor-unit pool less compared with adults. Moreover, that the degree of VA increase with age may be influenced by the muscle examined (upper vs lower extremity). However, more research is needed to elucidate the influence of this possible factor, as the current review contains limited data from upper body muscles. The developmental mechanism responsible for children’s lower VA requires further research.

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“…In conclusion, the arguments presented here by Dotan et al (2021) should be considered by scientists, who should be aware of the limitations of the technique. Using multiple indicators of central fatigue is advised to obtain a more comprehensive view of the complex neural adaptations occurring during exercise and recovery.…”

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confidence: 86%

“…This led to an open debate 12 years ago (De Haan et al 2009;Taylor 2009) that is still ongoing (Gandevia et al 2013;Cheng et al 2013;Neyroud et al 2016;Contessa et al 2016). In their review published in this issue of the European Journal of Applied Physiology, Dotan et al (2021) summarize evidence questioning the validity and reliability of the twitch interpolation technique to quantify central fatigue.…”

mentioning

confidence: 99%

“…The twitch interpolation technique offers the advantage to be easily quantified but it is mostly limited to maximal isometric contraction and the relevance of the reduction in voluntary activation to exercise performance during submaximal intensity tasks is unclear (Brownstein et al 2021). In their review, Dotan et al (2021) advance several arguments suggesting that the variables used for the calculation of voluntary activation are affected by peripheral factors or factors independent of muscle fatigue, questioning the use of the twitch interpolation technique to determine central fatigue.…”

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confidence: 99%

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