Changes in muscle activation during 72 hours following an acute plyometric bout

• IntroductionPlyometric training (PT) has been used widely in sport training to improve characteristics such as power, strength and to induce beneficial neuromuscular improvements. Previous evidence has demonstrated a significant impact of this training method on muscle activation patterns during training, however there is a lack in research literature of studies examining its follow up effects in the recovery period. The purpose of this study was to examine any possible changes in the muscle activation of the lower extremities up to 72 hours after high intensity PT.MethodsAn experimental study design with repeated measures was used. Twelve (n=12) male subjects (mean age 24.33 ± 2.6) executed a high intensity PT protocol for the lower extremities. Countermovement jump test (CMJ) was performed pre, immediately post, 24, 48 and 72 hours after the PT. Surface electromyography (sEMG) evaluation examined the activation of Gluteus Maximus (GM), Vastus Lateralis (VL), Biceps Femoris (BF) and Gastrocnemius (GAS) during the CMJ in all the time points of the recovery. A one way ANOVA with repeated measures was used to analyze differences between the five time points (p≤0.05).ResultsThe results indicated a statistical significant decrease in CMJ performance at 24 and 48 hours, compared with the baseline, that peaked at 24 hours (-7.16%), and recovered at 72 hours. Muscle activation levels for GM, VL and BF followed the same pattern, decreasing significantly post training compared to the baseline, recovering at 72 hours post. Muscle activation decrease peaked immediately post training for GM (-21.8%), VL (-14.04%) and BF (-19.82%). Muscle activation for GAS decreased significantly post training (-6.77%), recovering faster than the other muscle groups, at 48 hours.DiscussionCMJ jump performance impairment was in accordance with previous research, peaking at 24-48 hours and recovering at 72 hours after the bout (Chatzinikolaou et al., 2010). The impairment pattern observed in the sEMG values peaked immediately post training, recovering at 72 hours; however the magnitude of the decrease was not as extended as observed after eccentric training (Hortobágyi et al, 1998). GAS activation recovered 24 hours faster than the rest of the tested muscle groups probably due to the higher percentage of slow twitch fibers which are less susceptible to muscle damage than fast twitch. In conclusion PT significantly decreases muscle activation and jump performance up to 72 hours after the bout in GM, VL and BF, while GAS recovered in 48 hours.ReferencesChatzinikolaou A, Fatouros IG, Gourgoulis V, Avloniti A, Jamurtas AZ, Nikolaidis MG, et al.. (2010). J Strength Cond Res, 24, 1389–98.Hortobágyi T, Houmard J, Fraser D, Dudek R, Lambert J, Tracy J. (1998). J Appl Physiol, 84, 492–8.Contact georgios.mavropalias@gmail.com

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MEDICIN OCH HÄLSOVETENSKAP  -- Hälsovetenskap -- Idrottsvetenskap (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Health Sciences -- Sport and Fitness Sciences (hsv//eng)

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