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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.


Related in: MedlinePlus

Relative changes from baseline (mean ± SD) for voluntary isometric peak torque, potentiated evoked torque and voluntary activation level (VAL) after the exercise. *Significantly different from baseline (* < 0.05; *** < 0.001).
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Figure 2: Relative changes from baseline (mean ± SD) for voluntary isometric peak torque, potentiated evoked torque and voluntary activation level (VAL) after the exercise. *Significantly different from baseline (* < 0.05; *** < 0.001).

Mentions: Compared with baseline, voluntary peak torque (144.2 ± 30.1 vs. 75.1 ± 21.4 N·m; p < 0.001, pη2 = 0.92), potentiated torque (44.9 ± 7.4 vs. 26.6 ± 7.2 N·m; p < 0.001, pη2 = 0.81) and VAL (99.5 ± 0.8 vs. 86.3 ± 11.9%; p < 0.001, pη2 = 0.58) significantly decreased at POST (Figure 2). At 48 h, voluntary peak torque (116.3 ± 26.6 N·m; p < 0.001) and potentiated torque (40.4 ± 9.5 N·m; p = 0.041) remained significantly lower than baseline, while VAL was not significantly different from baseline (95.5 ± 6.6%; p = 0.139). As shown in Table 1, the potentiated torque decrement at 48 h was positively correlated (r = 0.77; p < 0.01) with the decrease in potentiated torque at POST and negatively correlated (r = –0.71; p < 0.05) with the decrease in VAL at POST. Muscle soreness did not differ from baseline (3.2 ± 4.6 mm) at POST (12.8 ± 18.2 mm), but increased (p < 0.001, pη2 = 0.82) at 48 h (55.9 ± 19.1 mm).


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 baseline (mean ± SD) for voluntary isometric peak torque, potentiated evoked torque and voluntary activation level (VAL) after the exercise. *Significantly different from baseline (* < 0.05; *** < 0.001).
© Copyright Policy
Related In: Results  -  Collection

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

Figure 2: Relative changes from baseline (mean ± SD) for voluntary isometric peak torque, potentiated evoked torque and voluntary activation level (VAL) after the exercise. *Significantly different from baseline (* < 0.05; *** < 0.001).
Mentions: Compared with baseline, voluntary peak torque (144.2 ± 30.1 vs. 75.1 ± 21.4 N·m; p < 0.001, pη2 = 0.92), potentiated torque (44.9 ± 7.4 vs. 26.6 ± 7.2 N·m; p < 0.001, pη2 = 0.81) and VAL (99.5 ± 0.8 vs. 86.3 ± 11.9%; p < 0.001, pη2 = 0.58) significantly decreased at POST (Figure 2). At 48 h, voluntary peak torque (116.3 ± 26.6 N·m; p < 0.001) and potentiated torque (40.4 ± 9.5 N·m; p = 0.041) remained significantly lower than baseline, while VAL was not significantly different from baseline (95.5 ± 6.6%; p = 0.139). As shown in Table 1, the potentiated torque decrement at 48 h was positively correlated (r = 0.77; p < 0.01) with the decrease in potentiated torque at POST and negatively correlated (r = –0.71; p < 0.05) with the decrease in VAL at POST. Muscle soreness did not differ from baseline (3.2 ± 4.6 mm) at POST (12.8 ± 18.2 mm), but increased (p < 0.001, pη2 = 0.82) at 48 h (55.9 ± 19.1 mm).

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