Physiotherapy - Research Publications

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End date: 2019 × Author: Galea, Mary × Author: Lythgo, Noel ×

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    Voluntary activation of the ankle plantar flexors following whole-body vibration
    Pellegrini, MJ ; Lythgo, ND ; Morgan, DL ; Galea, MP (SPRINGER, 2010-03)
    This study investigated the effect of whole-body vibration (WBV) on the voluntary activation of the ankle plantar flexors. Twelve healthy young adults were randomly exposed to two treatments on separate occasions. The first (non-WBV) involved stretching of the plantar flexors at end range of dorsiflexion for five 1-min bouts. The second involved the same stretch with WBV (26 Hz) for five 1-min bouts. Attempted maximal voluntary contractions (AMVCs) of the plantar flexors were performed on an isokinetic dynamometer (30 degrees s(-1)) before and after each treatment. A twitch interpolation technique was used to investigate voluntary activation. Post-treatment data were normalised against pre-treatment data. Subjects were classified as maximally (n = 6) or sub-maximally (n = 6) activated using the pre-treatment twitch interpolation data. The effects of WBV were assessed by repeated measure (RM) MANOVA. After WBV, the group of subjects classified as sub-maximally activated increased peak voluntary torque and rate of voluntary torque production (P < 0.05), whereas angular displacement to peak torque reduced (P < 0.05); i.e. peak torque was produced at a longer muscle length. No significant non-WBV treatment effects were found for this group. No significant WBV effects were found for the group of subjects classified as maximally activated. This study found that the response to WBV was dependent on the level of voluntary activation of the ankle plantar flexors during a set of AMVCs.
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    Whole-body vibration dosage alters leg blood flow
    Lythgo, N ; Eser, P ; de Groot, P ; Galea, M (WILEY-BLACKWELL PUBLISHING, INC, 2009-01)
    The effect of whole-body vibration dosage on leg blood flow was investigated. Nine healthy young adult males completed a set of 14 random vibration and non-vibration exercise bouts whilst squatting on a Galileo 900 plate. Six vibration frequencies ranging from 5 to 30 Hz (5 Hz increments) were used in combination with a 2.5 mm and 4.5 mm amplitude to produce twelve 1-min vibration bouts. Subjects also completed two 1-min bouts where no vibration was applied. Systolic and diastolic diameters of the common femoral artery and blood cell velocity were measured by an echo Doppler ultrasound in a standing or rest condition prior to the bouts and during and after each bout. Repeated measures MANOVAs were used in the statistical analysis. Compared with the standing condition, the exercise bouts produced a four-fold increase in mean blood cell velocity (P<0.001) and a two-fold increase in peak blood cell velocity (P<0.001). Compared to the non-vibration bouts, frequencies of 10-30 Hz increased mean blood cell velocity by approximately 33% (P<0.01) whereas 20-30 Hz increased peak blood cell velocity by approximately 27% (P<0.01). Amplitude was additive to frequency but only achieved significance at 30 Hz (P<0.05). Compared with the standing condition, squatting alone produced significant increases in mean and peak blood cell velocity (P<0.001). The results show leg blood flow increased during the squat or non-vibration bouts and systematically increased with frequency in the vibration bouts.