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EMG and heart rate responses decline within 5 days of daily whole-body vibration training with squatting.

Rosenberger A, Liphardt AM, Bargmann A, Müller K, Beck L, Mester J, Zange J - PLoS ONE (2014)

Bottom Line: The heart rate (HR) response was significantly higher (P<0.05) during SE+V than during SE on all training days, but showed a constant decline throughout the training days.On training day 1, blood lactate increased significantly more after SE+V than after SE (P<0.05).On the following training days, this difference became much smaller but remained significantly different.

View Article: PubMed Central - PubMed

Affiliation: Institute of Aerospace Medicine, German Aerospace Center (DLR), Cologne, Germany; Institute of Training Science and Sport Informatics, German Sport University Cologne, Cologne, Germany.

ABSTRACT
In this study, we examined the acute effects of a 5-day daily whole-body vibration (WBV) training on electromyography (EMG) responses of the m. rectus femoris and m. gastrocnemius lateralis, heart rate (HR, continuously recorded), and blood lactate levels. The purpose of the study was to investigate the adaptation of muscle activity, heart rate and blood lactate levels during 5 days of daily training. Two groups of healthy male subjects performed either squat exercises with vibration at 20 Hz on a side alternating platform (SE+V, n = 20, age  = 31.9±7.5 yrs., height  = 178.8±6.2 cm, body mass  = 79.2±11.4 kg) or squat exercises alone (SE, n = 21, age  = 28.4±7.3 years, height  = 178.9±7.4 cm, body mass  = 77.2±9.7 kg). On training day 1, EMG amplitudes of the m. rectus femoris were significantly higher (P<0.05) during SE+V than during SE. However, this difference was no longer statistically significant on training days 3 and 5. The heart rate (HR) response was significantly higher (P<0.05) during SE+V than during SE on all training days, but showed a constant decline throughout the training days. On training day 1, blood lactate increased significantly more after SE+V than after SE (P<0.05). On the following training days, this difference became much smaller but remained significantly different. The specific physiological responses to WBV were largest on the initial training day and most of them declined during subsequent training days, showing a rapid neuromuscular and cardiovascular adaptation to the vibration stimulus.

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A typical EMG spectrum of a contracting muscle.A typical EMG spectrum of one subject with narrow excluded frequency bands (light gray bars) at 20±2 Hz, 40.5±2.5 Hz, 61±2 Hz, and 82±2 Hz.
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pone-0099060-g001: A typical EMG spectrum of a contracting muscle.A typical EMG spectrum of one subject with narrow excluded frequency bands (light gray bars) at 20±2 Hz, 40.5±2.5 Hz, 61±2 Hz, and 82±2 Hz.

Mentions: In addition, mechano-sensing during WBVT triggers reflex responses of the leg muscles that may become visible as synchronous or non-synchronous EMG activity [9], [23], [24], [26]–[28]. Narrow banded stop filters at the vibration frequency and its harmonics applied to a bipolar surface EMG record erase electrical motion artifacts [27], [29], [30] and H-wave like sum action potentials potentially occurring at the vibration frequency [28]. In this study, we did not apply band stop filters on the time domain of the EMG signal but excluded narrow frequency bands from the EMG spectra. This allows the analysis of the non-synchronous natural EMG activity and the vibration-induced synchronous EMG activity. Therefore, we defined narrow frequency bands of 20.0±2.0 Hz, 40.5±2.5 Hz, 61.0±2.0 Hz, and 82.0±2.0 Hz within the EMG raw spectrum (Figure 1) to discriminate between non-synchronous natural EMG activity and motion artifacts (at the vibration frequency and its harmonics [27]). Because these narrow frequency bands also include natural EMG signal, they were applied to the EMG records of both groups (SE+V and SE). The EMG spectrum outside the narrow frequency bands was analyzed for the sum of amplitudes over the remaining frequencies (µV) and for the median frequencies (Hz). The mean values were calculated for each series of 10 squat cycles. The sum of amplitudes was also calculated for EMG content of the narrow frequency bands to get an estimate of the relative portion of the artifact signal and the natural EMG content by comparing the signals of SE+V and SE.


EMG and heart rate responses decline within 5 days of daily whole-body vibration training with squatting.

Rosenberger A, Liphardt AM, Bargmann A, Müller K, Beck L, Mester J, Zange J - PLoS ONE (2014)

A typical EMG spectrum of a contracting muscle.A typical EMG spectrum of one subject with narrow excluded frequency bands (light gray bars) at 20±2 Hz, 40.5±2.5 Hz, 61±2 Hz, and 82±2 Hz.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4048290&req=5

pone-0099060-g001: A typical EMG spectrum of a contracting muscle.A typical EMG spectrum of one subject with narrow excluded frequency bands (light gray bars) at 20±2 Hz, 40.5±2.5 Hz, 61±2 Hz, and 82±2 Hz.
Mentions: In addition, mechano-sensing during WBVT triggers reflex responses of the leg muscles that may become visible as synchronous or non-synchronous EMG activity [9], [23], [24], [26]–[28]. Narrow banded stop filters at the vibration frequency and its harmonics applied to a bipolar surface EMG record erase electrical motion artifacts [27], [29], [30] and H-wave like sum action potentials potentially occurring at the vibration frequency [28]. In this study, we did not apply band stop filters on the time domain of the EMG signal but excluded narrow frequency bands from the EMG spectra. This allows the analysis of the non-synchronous natural EMG activity and the vibration-induced synchronous EMG activity. Therefore, we defined narrow frequency bands of 20.0±2.0 Hz, 40.5±2.5 Hz, 61.0±2.0 Hz, and 82.0±2.0 Hz within the EMG raw spectrum (Figure 1) to discriminate between non-synchronous natural EMG activity and motion artifacts (at the vibration frequency and its harmonics [27]). Because these narrow frequency bands also include natural EMG signal, they were applied to the EMG records of both groups (SE+V and SE). The EMG spectrum outside the narrow frequency bands was analyzed for the sum of amplitudes over the remaining frequencies (µV) and for the median frequencies (Hz). The mean values were calculated for each series of 10 squat cycles. The sum of amplitudes was also calculated for EMG content of the narrow frequency bands to get an estimate of the relative portion of the artifact signal and the natural EMG content by comparing the signals of SE+V and SE.

Bottom Line: The heart rate (HR) response was significantly higher (P<0.05) during SE+V than during SE on all training days, but showed a constant decline throughout the training days.On training day 1, blood lactate increased significantly more after SE+V than after SE (P<0.05).On the following training days, this difference became much smaller but remained significantly different.

View Article: PubMed Central - PubMed

Affiliation: Institute of Aerospace Medicine, German Aerospace Center (DLR), Cologne, Germany; Institute of Training Science and Sport Informatics, German Sport University Cologne, Cologne, Germany.

ABSTRACT
In this study, we examined the acute effects of a 5-day daily whole-body vibration (WBV) training on electromyography (EMG) responses of the m. rectus femoris and m. gastrocnemius lateralis, heart rate (HR, continuously recorded), and blood lactate levels. The purpose of the study was to investigate the adaptation of muscle activity, heart rate and blood lactate levels during 5 days of daily training. Two groups of healthy male subjects performed either squat exercises with vibration at 20 Hz on a side alternating platform (SE+V, n = 20, age  = 31.9±7.5 yrs., height  = 178.8±6.2 cm, body mass  = 79.2±11.4 kg) or squat exercises alone (SE, n = 21, age  = 28.4±7.3 years, height  = 178.9±7.4 cm, body mass  = 77.2±9.7 kg). On training day 1, EMG amplitudes of the m. rectus femoris were significantly higher (P<0.05) during SE+V than during SE. However, this difference was no longer statistically significant on training days 3 and 5. The heart rate (HR) response was significantly higher (P<0.05) during SE+V than during SE on all training days, but showed a constant decline throughout the training days. On training day 1, blood lactate increased significantly more after SE+V than after SE (P<0.05). On the following training days, this difference became much smaller but remained significantly different. The specific physiological responses to WBV were largest on the initial training day and most of them declined during subsequent training days, showing a rapid neuromuscular and cardiovascular adaptation to the vibration stimulus.

Show MeSH