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Advisor(s)
Abstract(s)
This study examined the effects
of 3 wk of either endurance or strength training on plasticity of
the neural mechanisms involved in the soleus H reflex and V wave.
Twenty-five sedentary healthy subjects were randomized into an
endurance group (n 13) or strength group (n 12). Evoked
V-wave, H-reflex, and M-wave recruitment curves, maximal voluntary
contraction (MVC), and time-to-task-failure (isometric contraction
at 40% MVC) of the plantar flexors were recorded before and
after training. Following strength training, MVC of the plantar flexors
increased by 14.4 5.2% in the strength group (P 0.001), whereas
time-to-task-failure was prolonged in the endurance group (22.7
17.1%; P 0.05). The V wave-to-maximal M wave (V/Mmax) ratio
increased significantly (55.1 28.3%; P 0.001) following strength
training, but the maximal H wave-to-maximal M wave (Hmax/Mmax)
ratio remained unchanged. Conversely, in the endurance group the
V/Mmax ratio was not altered, whereas the Hmax/Mmax ratio increased
by 30.8 21.7% (P 0.05). The endurance training group also
displayed a reduction in the H-reflex excitability threshold while the
H-reflex amplitude on the ascending limb of the recruitment curve
increased. Strength training only elicited a significant decrease in
H-reflex excitability threshold, while H-reflex amplitudes over the
ascending limb remained unchanged. These observations indicate that
the H-reflex pathway is strongly involved in the enhanced endurance
resistance that occurs following endurance training. On the contrary,
the improvements in MVC following strength training are likely
attributed to increased descending drive and/or modulation in afferents
other than Ia afferents.
Description
Keywords
Electromiografia Neurofisiologia Treino de endurance Treino de força
Citation
Vila-Cha, Carolina; Falla, D.; Correia, M. V.; Farina, D. (2012) – Changes in H reflex and V wave following short-term endurance and strength training. Journal of Applied Physiology. ISSN 8750-7587. 112:1, p. 54-63
Publisher
Amer Physiological Soc