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Time-Course of Neuromuscular Changes during and after Maximal Eccentric Contractions.

Doguet V, Jubeau M, Dorel S, Couturier A, Lacourpaille L, Guével A, Guilhem G - Front Physiol (2016)

Bottom Line: Voluntary isometric torque (-48 ± 7%), evoked torque (-41 ± 14%) and voluntary activation (-13 ± 11%) decreased at POST, but only voluntary isometric torque (-19 ± 6%) and evoked torque (-10 ± 18%) remained depressed at 48 h.Our findings show that neuromuscular responses observed during eccentric contractions were not associated with muscle damage.Conversely, central and peripheral impairments observed immediately after the exercise reflect the long-lasting reduction in force-generating capacity.

View Article: PubMed Central - PubMed

Affiliation: Laboratory "Movement, Interactions, Performance" (EA 4334), Faculty of Sport Sciences, University of Nantes Nantes, France.

ABSTRACT
This study tested the relationship between the magnitude of muscle damage and both central and peripheral modulations during and after eccentric contractions of plantar flexors. Eleven participants performed 10 sets of 30 maximal eccentric contractions of the plantar flexors at 45°·s(-1). Maximal voluntary torque, evoked torque (peripheral component) and voluntary activation (central component) were assessed before, during, immediately after (POST) and 48 h after (48 h) the eccentric exercise. Voluntary eccentric torque progressively decreased (up to -36%) concomitantly to a significant alteration of evoked torque (up to -34%) and voluntary activation (up to -13%) during the exercise. Voluntary isometric torque (-48 ± 7%), evoked torque (-41 ± 14%) and voluntary activation (-13 ± 11%) decreased at POST, but only voluntary isometric torque (-19 ± 6%) and evoked torque (-10 ± 18%) remained depressed at 48 h. Neither changes in voluntary activation nor evoked torque during the exercise were related to the magnitude of muscle damage markers, but the evoked torque decrement at 48 h was significantly correlated with the changes in voluntary activation (r = -0.71) and evoked torque (r = 0.77) at POST. Our findings show that neuromuscular responses observed during eccentric contractions were not associated with muscle damage. Conversely, central and peripheral impairments observed immediately after the exercise reflect the long-lasting reduction in force-generating capacity.

No MeSH data available.


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Relative changes from set 1 (mean ± SD) for mean voluntary torque, lengthening evoked torque and central activation ratio (CAR) during the eccentric exercise. *Significantly different from set 1 (* < 0.05; ** < 0.01; *** < 0.001).
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Figure 3: Relative changes from set 1 (mean ± SD) for mean voluntary torque, lengthening evoked torque and central activation ratio (CAR) during the eccentric exercise. *Significantly different from set 1 (* < 0.05; ** < 0.01; *** < 0.001).

Mentions: Compared with the first set, the mean voluntary torque was significantly reduced from the second (89.1 ± 22.5 vs. 74.8 ± 18.9 N·m; p < 0.01; pη2 = 0.61; Figure 3) to the last set of the exercise (55.1 ± 16.0 N·m; p < 0.001). Both lengthening torque (Set 1: 1.30 ± 0.28 vs. Set 10: 0.86 ± 0.23 a.u.; p < 0.001; pη2 = 0.73) and CAR (Set 1: 87.4 ± 7.7 vs. Set 10: 75.7 ± 9.9%; p < 0.01; pη2 = 0.35) decreased during the eccentric contractions, with a significant drop from the second and the third set, respectively (Figure 3). Lengthening torque and CAR, either measured for the first set or averaged on the entire exercise, were not significantly correlated with muscle damage markers at 48 h (Table 1).


Time-Course of Neuromuscular Changes during and after Maximal Eccentric Contractions.

Doguet V, Jubeau M, Dorel S, Couturier A, Lacourpaille L, Guével A, Guilhem G - Front Physiol (2016)

Relative changes from set 1 (mean ± SD) for mean voluntary torque, lengthening evoked torque and central activation ratio (CAR) during the eccentric exercise. *Significantly different from set 1 (* < 0.05; ** < 0.01; *** < 0.001).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4834740&req=5

Figure 3: Relative changes from set 1 (mean ± SD) for mean voluntary torque, lengthening evoked torque and central activation ratio (CAR) during the eccentric exercise. *Significantly different from set 1 (* < 0.05; ** < 0.01; *** < 0.001).
Mentions: Compared with the first set, the mean voluntary torque was significantly reduced from the second (89.1 ± 22.5 vs. 74.8 ± 18.9 N·m; p < 0.01; pη2 = 0.61; Figure 3) to the last set of the exercise (55.1 ± 16.0 N·m; p < 0.001). Both lengthening torque (Set 1: 1.30 ± 0.28 vs. Set 10: 0.86 ± 0.23 a.u.; p < 0.001; pη2 = 0.73) and CAR (Set 1: 87.4 ± 7.7 vs. Set 10: 75.7 ± 9.9%; p < 0.01; pη2 = 0.35) decreased during the eccentric contractions, with a significant drop from the second and the third set, respectively (Figure 3). Lengthening torque and CAR, either measured for the first set or averaged on the entire exercise, were not significantly correlated with muscle damage markers at 48 h (Table 1).

Bottom Line: Voluntary isometric torque (-48 ± 7%), evoked torque (-41 ± 14%) and voluntary activation (-13 ± 11%) decreased at POST, but only voluntary isometric torque (-19 ± 6%) and evoked torque (-10 ± 18%) remained depressed at 48 h.Our findings show that neuromuscular responses observed during eccentric contractions were not associated with muscle damage.Conversely, central and peripheral impairments observed immediately after the exercise reflect the long-lasting reduction in force-generating capacity.

View Article: PubMed Central - PubMed

Affiliation: Laboratory "Movement, Interactions, Performance" (EA 4334), Faculty of Sport Sciences, University of Nantes Nantes, France.

ABSTRACT
This study tested the relationship between the magnitude of muscle damage and both central and peripheral modulations during and after eccentric contractions of plantar flexors. Eleven participants performed 10 sets of 30 maximal eccentric contractions of the plantar flexors at 45°·s(-1). Maximal voluntary torque, evoked torque (peripheral component) and voluntary activation (central component) were assessed before, during, immediately after (POST) and 48 h after (48 h) the eccentric exercise. Voluntary eccentric torque progressively decreased (up to -36%) concomitantly to a significant alteration of evoked torque (up to -34%) and voluntary activation (up to -13%) during the exercise. Voluntary isometric torque (-48 ± 7%), evoked torque (-41 ± 14%) and voluntary activation (-13 ± 11%) decreased at POST, but only voluntary isometric torque (-19 ± 6%) and evoked torque (-10 ± 18%) remained depressed at 48 h. Neither changes in voluntary activation nor evoked torque during the exercise were related to the magnitude of muscle damage markers, but the evoked torque decrement at 48 h was significantly correlated with the changes in voluntary activation (r = -0.71) and evoked torque (r = 0.77) at POST. Our findings show that neuromuscular responses observed during eccentric contractions were not associated with muscle damage. Conversely, central and peripheral impairments observed immediately after the exercise reflect the long-lasting reduction in force-generating capacity.

No MeSH data available.


Related in: MedlinePlus