Bout Of Whole-body Vibration Research Articles

Circulating microRNA responses to acute whole-body vibration and resistance exercise in postmenopausal women

Evaluating alterations in circulating microRNA (c-miRNA) expression may provide deeper insight into the role of exercise in the attenuation of the negative effects of aging on musculoskeletal health. Currently, there are sparse data on c-miRNA responses to acute exercise in postmenopausal women. The purpose of this study was to characterize the effects of acute bouts of resistance exercise and whole-body vibration on expression of selected c-miRNAs in postmenopausal women aged 65-76 years (n=10). We also examined relationships between c-miRNAs and muscle strength and bone characteristics. This randomized crossover design study compared c-miRNA responses to a bout of resistance exercise (RE) (3 sets 10 reps 70% 1 repetition maximum (1RM), 5 exercises) and a bout of whole-body vibration (WBV) (5 sets 1min bouts 20Hz 3.38mm peak to peak displacement, Vibraflex vibration platform). DXA was used to measure body composition and areal bone mineral density (aBMD) of the total body, AP lumbar spine, and dual proximal femur. pQCT was used to measure tibia bone characteristics (4%, 38%, 66% sites). Blood samples were collected before exercise (Pre), immediately-post (IP), 60 minutes post (60P), 24 hours (24H), and 48 hours (48H) after exercise to measure serum miR-21-5p, -23a-3p, -133a-3p, -148a-3p (qPCR) and TRAP5b (ELISA). There was a significant modality × time interaction for c-miR-21-5p expression (p=0.019), which decreased from 60P to 24H after WBV only. TRAP5b serum concentrations significantly increased IP then decreased below Pre at 24H for both WBV and RE (p<0.01). Absolute changes in TRAP5b were negatively correlated with c-miR-21-5p fold changes (r= -0.642 to -0.724, p<0.05) for both exercise modalities. There were significant negative correlations between baseline c-miRNAs and bone status variables (r= -0.639 to -0.877, p<0.05). Our findings suggest that whole-body vibration is a sufficient mechanical stimulus for altering c-miR-21-5p expression, whereas a high intensity resistance exercise protocol did not elicit any c-miRNA responses in postmenopausal women. Increases in the bone resorption marker, TRAP5b, were associated with greater downregulation of c-miR-21-5p expression.

Acute Response of Sclerostin to Whole-body Vibration with Blood Flow Restriction.

Blood flow restriction may augment the skeletal response to whole-body vibration. This study used a randomised, crossover design to investigate the acute response of serum sclerostin and bone turnover biomarkers to whole-body vibration with blood flow restriction. Ten healthy males (mean±standard deviation; age: 27±8 years) completed two experimental conditions separated by 7 days: (i) whole-body vibration (10 1-minute bouts of whole-body vibration with 30 s recovery) or (ii) whole-body vibration with lower-body blood flow restriction (10 cycles of 110 mmHg inflation with 30 s deflation during recovery). Fasting blood samples were obtained immediately before and immediately after exercise, then 1 hour, and 24 hours after exercise. Serum samples were analysed for sclerostin, cross-linked C-terminal telopeptide of type I collagen, and bone-specific alkaline phosphatase. There was a significant time × condition interaction for bone-specific alkaline phosphatase (p=0.003); bone-specific alkaline phosphatase values at 24 hours post-exercise were significantly higher following whole-body vibration compared to combined whole-body vibration and blood flow restriction (p=0.028). No significant time × condition interaction occurred for any other outcome measure (p>0.05). These findings suggest that a single session of whole-body vibration combined with blood flow restriction does not significantly affect serum sclerostin or bone turnover biomarkers.

Serum Cortisol and Clinical Response to a Single Session of Whole-Body Vibration in Healthy Adult Dogs.

This study evaluated the serum cortisol response to a single session of whole-body vibration (WBV) in healthy adult dogs. Ten healthy adult medium dogs, females and males, aged between 24 and 48 months and with body weight between 10.1 and 17.9 kg were used. A single WBV session at a frequency of 30 Hz for 5 min (3.10 mm peak displacement, 11.16 m/s2 peak acceleration, and 0.29 m/s velocity), then 50 Hz for 5 min (3.98 mm peak displacement, 39.75 m/s2 peak acceleration, and 0.62 m/s velocity), and finishing with 30 Hz for 5 min (3.10 mm peak displacement, 11.16 m/s2 peak acceleration, and 0.29 m/s velocity) was performed. Serum cortisol, heart and respiratory rate, and systolic blood pressure were evaluated at different time points: 1 min before WBV (1PRE) and 1 min (1POST), 60 min (60POST), and 360 min (360POST) after the WBV session. An increase (P = 0.0417) of the serum cortisol values was observed between 1PRE and 1POST and a decrease (P = 0.0417) between 1POST and 60POST and between 60POST and 360POST. However, the values remained within the reference range. The heart and respiratory rate and the systolic blood pressure remained unchanged. Our findings suggest that a single bout of WBV (5 min of 30 and 50 Hz) using a vibrating platform that delivered a vortex wave circulation does not modify the serum cortisol levels and clinical parameters of healthy adult dogs.

The Effects of Acute Bouts of Whole Body Vibration on Central Hemodynamics in Frail Older Adults: A Pilot Study

Introduction: This study investigates whether an acute bout of whole body vibration (WBV): (i) improves measures of central hemodynamics and (ii) can be completed without inducing orthostatic intolerance in frail older adults. Methods: Nine rest home residents participated in a cross-over design incorporating WBV and non-vibrational control conditions (CON) on 2 separate testing days. The order of the two testing conditions was randomized. Participants completed 10 sets of 60 seconds of WBV training or CON with an inter-set rest period of 60 seconds. Results: During training, no interaction or between-condition effects were observed for any variable. Following training, there was an interaction effect reported for augmentation index (AIx) (P < 0.019) and a significant large increase in AIx for WBV (P = 0.020, Eta = 0.202). Three participants exhibited one-off notable decreases in either central systolic or diastolic blood pressure. Conclusion: An acute bout of WBV is a safe training method for frail older adults.

The Influence of an Acute Bout of Whole Body Vibration on Human Postural Control Responses

ABSTRACTThe use of vibrating platforms has become increasingly available, and popular at sports and rehabilitation institutes. Given the discrepancies in the literature regarding whole body vibration (WBV) and human reflexive responses, the purpose of this study was to examine the acute effects of WBV on postural response latencies, as well as associated electromyography measures of the lower extremities during balance perturbations. Reflexive responses during backward and forward balance perturbations were examined before, after, and 10 min after a bout of WBV. The findings suggest that following an acute bout of whole body vibration, muscle activity of the lower extremities is decreased during a reflexive response to an unexpected perturbation, and may be associated with faster reaction time.

Acute effect of whole body vibration on postural control in congenitally blind subjects: a preliminary evidence

Purpose: The purpose of this study was to investigate the acute effects of whole body vibration at optimal frequency, on postural control in blind subjects.Method: Twenty-four participants, 12 congenital blind males (Experimental Group), and 12 non-disabled males with no visual impairment (Control Groups) were recruited. The area of the ellipse and the total distance of the center of pressure displacements, as postural control parameters, were evaluated at baseline (T0), immediately after the vibration (T1), after 10 min (T10) and after 20 min (T20). Whole body vibration protocol consisted into 5 sets of 1 min for each vibration, with 1 min rest between each set on a vibrating platform.Results: The total distance of center of pressure showed a significant difference (p < 0.05) amongst groups, while the area remained constant. No significant differences were detected among times of assessments, or in the interaction group × time.Conclusion: No impairments in static balance were found after an acute bout of whole body vibration at optimal frequency in blind subjects and, consequently, whole body vibration may be considered as a safe application in individuals who are blind.

Effect of whole-body vibration on motor neuron excitability in healthy young men

Whole-body vibration (WBV) has been increasingly used for performance enhancement as well as for treatment of some conditions. There is much focus on the study of muscular performance accompanied by WBVs; however, little is known about its effect on motor units – whether it has excitatory or inhibitory effects. The purpose of this study was to investigate the effect of a single bout of WBV on motor neuron excitability in healthy individuals immediately and 30min after application. Sixty healthy men participated in this study; their ages ranged between 18 and 25 years. They were randomly divided into two equal groups – the study group and the control group – each containing 30 men who were selected by drawing ballots from sealed envelopes. The experimental group received WBV with a frequency of 50–60Hz and amplitude of 0–10mm for 1min, with a 1min rest period between each vibration set, which was repeated five times. The control group stood on the WBV device for the same duration while it was off. Hoffman reflex amplitude and H/ M ratio were measured from the soleus muscle (posterior tibial nerve) before and 0 and 30min after application in both groups using surface electromyography. There was significant decrease in Hoffman reflex amplitude at 0 and 30min in the study group compared with the control group (P=0.002 and 0.01, respectively). Moreover, there was significant decrease in H/M ratio at 0 and 30min in the study group compared with the control group (P=0.0001 and 0.03, respectively). WBV decreases motor neuron excitability and thus may have therapeutic implications for people with central nervous system disorders, in whom spasticity is a major manifestation.

Spinal Reflex Excitability and Homosynaptic Depression Following Bouts of Whole-Body Vibration of Varying Frequencies.

Spinal Reflex Excitability and Homosynaptic Depression Following Bouts of Whole-Body Vibration of Varying Frequencies.

Immediate effects of whole body vibration on patellar tendon properties and knee extension torque

Reports about the immediate effects of whole body vibration (WBV) exposure upon torque production capacity are inconsistent. However, the changes in the torque-angle relationship observed by some authors after WBV may hinder the measurement of torque changes at a given angle. Acute changes in tendon mechanical properties do occur after certain types of exercise but this hypothesis has never been tested after a bout of WBV. The purpose of the present study was to investigate whether tendon compliance is altered immediately after WBV, effectively shifting the optimal angle of peak torque towards longer muscle length. Twenty-eight subjects were randomly assigned to either a WBV (n = 14) or a squatting control group (n = 14). Patellar tendon CSA, stiffness and Young's modulus and knee extension torque-angle relationship were measured using ultrasonography and dynamometry 1 day before and directly after the intervention. Tendon CSA was additionally measured 24 h after the intervention to check for possible delayed onset of swelling. The vibration intervention had no effects on patellar tendon CSA, stiffness and Young's modulus or the torque-angle relationship. Peak torque was produced at ~70° knee angle in both groups at pre- and post-test. Additionally, the knee extension torque globally remained unaffected with the exception of a small (-6%) reduction in isometric torque at a joint angle of 60°. The present results indicate that a single bout of vibration exposure does not substantially alter patellar tendon properties or the torque-angle relationship of knee extensors.

The acute effect of whole body vibration training on flexibility and explosive strength of young gymnasts.

The purpose of this study was to examine the acute effect of a single bout of whole body vibration (WBV) on flexibility and explosive strength of lower limbs in young artistic gymnasts. Thirty-two young competitive gymnasts volunteered to participate in this study, and were allocated to either the vibration group or traditional body weight training according to the vibration protocol. The vibration intervention consisted of a single bout of eccentric and concentric squatting movements on a vibration platform that was turned on (vibration group: VG n = 15), whereas the traditional body weight (no vibration) group performed the same training protocol with the WBV device turned off (NVG: n= 17). Flexibility (sit and reach test) and explosive strength tests [squat jump (SJ), counter movement jump (CMJ), and single leg squat (right leg (RL) and left leg (LL))] were performed initially (pre-test), immediately after the intervention (post-test 1), and 15 minutes after the end of the intervention programme (post-test 15). Four 2x3 ANOVAs were used to examine the interaction between group (VG vs NVG) and time (pre, post 1, and post 15) with respect to examined variables. The results revealed that a significant interaction between group and time was found with respect to SJ (p < 0.05). However, no significant interaction between group and time was found with respect to flexibility, CMJ, RL and LL after the end of the intervention programme (p > 0.05). Further, the percentage improvement of the VG was significantly greater in all examined variables compared to the NVG. This study concluded that WBV training improves flexibility and explosive strength of lower limbs in young trained artistic gymnasts and maintains the initial level of performance for at least 15 minutes after the WBV intervention programme.

The Influence of Whole-Body Vibration on Creatine Kinase Activity and Jumping Performance in Young Basketball Players

Purpose To quantify creatine kinase (CK) activity changes across time following an acute bout of whole-body vibration (WBV) and determine the association between changes in CK activity and jumping performance. Method Twenty-six elite young basketball players were assigned to 3 groups: 36-Hz and 46-Hz vibration groups (G36 and G46, respectively) and a control group. The study quantified CK activity and jumping performance following an acute bout of WBV at 2 vibration frequencies. Both WBV groups performed a protocol that consisted of 10 sets of 60 s of WBV while standing on a vibration plate in a quarter-squat position. CK activity, countermovement jumps (CMJ), and squat jumps (SJ) were measured immediately before and 24 hr and 48 hr after WBV. In addition, CMJ and SJ were also measured 5 min after WBV. Results CK activity was statistically significantly increased 24 hr following WBV in G36 and G46. At 48 hr after WBV, CK activity was similar to baseline levels in G36 but remained statistically significantly above baseline levels in G46. The CMJ and SJ heights were statistically significantly decreased at 5 min following the protocol for both WBV groups. Overall, the changes in CK activity did not present a strong relationship with the changes in jump heights for any of the comparisons. Conclusions These findings suggest that WBV protocols with such characteristics may not cause excessive muscle damage and may partly explain why many WBV training studies have failed to elicit increases in strength performance.

B-27 Free Communication/Poster - EMG/MMG

INTRODUCTION: Whole-body vibration (WBV) has been shown to increase muscle fiber recruitment during isotonic contractions. No prior published studies have used elastic resistance. PURPOSE: The main purpose of this study is to investigate the acute effects of a single bout of WBV on electromyography (EMG) activity during exercise when using elastic resistance. METHOD: 30 participants (14 male; 16 female) aged 18-30 were recruited for this study. EMG activity was then determined while participants performed the arm curl and squats using elastic resistance under three conditions: no vibration exposure, during acute vibration exposure, and following acute vibration exposure. Three upper extremity muscles were monitored during the arm curl. Vibration was administered using a vibration platform (Wave®; ProElite, Windsor, ON Canada) at a frequency of 35Hz at 4mm displacement amplitude. RESULTS: Results indicate no statistically significant differences between the three conditions for the upper body but there was a decrease in the primary muscles involved in the concentric phase of the squat immediately after vibration exposure. CONCLUSION: These results suggest that there may be an effect of vibration on muscles in the lower body following vibration.

Impact of an acute bout of vibration on muscle contractile properties, creatine kinase and lactate dehydrogenase response

The aim of this study was to assess the effects of a bout of whole body vibration (WBV) on muscle response and to determine whether this stimulus leads to muscle damage. Thirty healthy and physically active participants (mean±SD; age: 21.8±2.0 years; height: 176.7±5.8 cm; body mass: 76±6.8 kg and BMI: 23.1±3.7 kg·m−2) participated in this study. Participants were randomly allocated in one of two groups, one of them performed a bout of 360 s WBV (frequency: 30 Hz; peak-to-peak displacement: 4 mm) (VIB) and the other one adopted a sham position (CON). Muscle contractile properties were analysed in the rectus femoris (RF) by using tensiomyography (TMG) 2 min before the warm-up and 2 min after intervention. Muscle damage was assessed by determining plasma creatine kinase (CK) and lactate dehydrogenase (LDH) levels at three time points; 5 min before warm-up and 1 h and 48 h after the intervention. TMG results showed a significant decrease in maximal displacement (p<0.05) and delay time (p<0.05) in VIB and in delay time (p<0.05) and relaxation time (p<0.05) in CON. Muscle damage markers showed significant group differences (p<0.05) for CK 1 h after the intervention. In addition, differences for CK 1 h after the intervention from baseline (p<0.05) were also observed in VIB. In conclusion, a 6-min bout of WBV results in an increase of muscle stiffness in RF and increased CK levels 1 h after intervention (returning to baseline within 48 h).

Spectral Properties of H-Reflex Recordings After an Acute Bout of Whole-Body Vibration

Although research supports the use of whole-body vibration (WBV) to improve neuromuscular performance, the mechanisms for these improvements remain unclear. The purpose of this study was to identify the effect of WBV on the spectral properties of electrically evoked H-reflex recordings in the soleus (SOL) muscle. The H-reflex recordings were measured in the SOL muscle of 20 participants before and after a bout of WBV. The H-reflexes were evoked every 15 seconds for 150 seconds after WBV. A wavelet procedure was used to extract spectral data, which were then quantified with a principle components analysis. Resultant principle component scores were used for statistical analysis. The analysis extracted 1 principle component associated with the intensity of the myoelectric spectra and 1 principle component associated with the frequency. The scores of the principle component that were related to the myoelectric intensity were smaller at 30 and 60 milliseconds after WBV than before WBV. The WBV transiently decreased the intensity of myoelectric spectra during electrically evoked contractions, but it did not influence the frequency of the spectra. The decrease in intensity likely indicates a smaller electrically evoked muscle twitch response, whereas the lack of change in frequency would indicate a similar recruitment pattern of motor units before and after WBV.

The Acute Effects of Whole Body Vibration on Postural Control Measures in Elderly Women

Injuries resulting from a fall incident have been documented as a leading cause of trauma in older adults in the United States. Resistance training and chronic whole body vibration (WBV) have been employed to reduce age related attenuation of reflexive postural control measures. Due to differences in study designs, the acute results of WBV have been mixed. PURPOSE: The purpose of this project was to analyze the acute effects of WBV on functional postural control measures in women between the ages of 60-75 years. METHODS: Fifteen healthy females (68.3 + 5.0 yrs), able to complete "3 up and go tests" in less than 8.5 seconds, were included in the study. After a standard warm-up, sway velocity and root-mean-square (RMS) sway measures were obtained using an Equitest Posture Platform (NeuroCom, Inc.) sensory organization test (SOT) battery, which elicits responses from each of the 3 sensory systems individually or in combination. Following a 5 minute rest, participants were exposed to 3 20 second bouts of WBV (30 Hz, 2-4 mm @ 135° knee flexion), separated by 1 minute. At the conclusion of the vibration exposure, participants completed the same postural control tests preceded by a 1 minute rest. RESULTS: Analysis of variance was measured independently for the 6 postural stability-testing conditions. Statistically significant (p < 0.05) within participants main effects were seen in the eyes closed with the platform and visual surrounds stable (EC), eyes closed with the platform sway referenced (ECSR), and the eyes open with the platform and visual surround sway referenced (EOSRVR) conditions in both medial/lateral and anterior/posterior directions. CONCLUSIONS: Results suggest that WBV had no significant effects on overall postural control measures in the population. Future research should assess balance at distinct time points post vibration exposure to determine the residual effects of exposure to WBV.

Spinal reflex excitability and homosynaptic depression after a bout of whole‐body vibration

Although whole-body vibration (WBV) affects neuromuscular performance, it remains unclear whether the effects are due to spinal reflex potentiation or inhibition, or differ between muscle groups. This study aimed to identify the effect of WBV on measures of spinal reflex excitability (H-reflex) and homosynaptic depression (HD) in the soleus (SOL) and medial gastrocnemius (MG) muscles. H-reflex and HD measurements were made in the SOL and MG muscle of 20 participants before and after a bout of WBV. H-reflex and HD were measured every 15 seconds for 10 minutes post-WBV and averaged at 1-minute increments. H-reflex amplitude was depressed for the first minute post-vibration, whereas the effect of HD was reduced for the first 2 minutes post-vibration. WBV significantly decreases spinal reflex excitability and HD, but it does so transiently and independent of muscle group.

Does Whole-Body Vibration Training Have Acute Residual Effects on Postural Control Ability of Elderly Women?

The purpose of this study was to investigate acute residual effects of a single vibration session on balance control in a group of elderly women. Several studies, in fact, have shown that whole-body vibration (WBV) training may improve balance in the elderly, but possible side effects of acute exposure to WBV, such as temporary reduction of balance control ability because of perturbations of the vestibular system, have not been investigated. Twenty-two healthy elderly women (71.8 ± 4.7 years of age) were trained with a 9.5-minute bout of static and dynamic knee-extensor exercises executed on a vibrating platform (Well-net Vibe Revolution). The vibration frequency was set at 35 Hz. A subgroup of 14 subjects performed the same exercise protocol also without the vibrations to discriminate between vibration and exercise effects. Balance control ability was assessed through computerized posturography: a force plate (Bertec Co, Columbus, OH, USA) was used to measure the center of pressure trajectories during 4 different experimental trials: before, immediately after, 15 minutes after, and 60 minutes after the training. A set of postural parameters, typically adopted to assess elderly subjects, was then computed and 2-way analysis of variance was used to determine differences between values found in the 4 postural tests (level of significance p = 0.05) in the 2 groups. The results showed no significant variations in the postural parameters recorded during the 4 sessions. A significant group effect was found for 2 postural parameters, with no interaction between the 2 factors. In conclusion, the proposed single bout of WBV does not induce dangerous acute effects on elderly women balance control ability and could be safely administered as part of a long-term intervention program.

GH responses to two consecutive bouts of whole body vibration, maximal voluntary contractions or vibration alternated with maximal voluntary contractions administered at 2-h intervals in healthy adults

Background Pharmacological or exercise stimuli repeated at a short interval (but not electrical muscle stimulation) are associated with a blunting of GH responsiveness. Aim To compare GH responses to repeated bout of three different GH-releasing stimuli. Methods The effects of two consecutive bouts (with a 2-h interval) of whole body vibrations (WBV), maximal voluntary contractions alone (MVC), or alternated with WBV (MVC–WBV) on blood GH and lactate (LA) were assessed in nine young males. Results Baseline levels of both GH and LA increased significantly after the first bout of all the tested stimuli, and were significantly lower after WBV than after MVC or MVC alternated with WBV, no difference being detected between these last. The administration of a second bout resulted in significantly lower GH increases than those elicited in the first bout in the three different tests; significantly lower LA responses were recorded after the second bout of MVC and MVC–WBV when compared with those obtained after the first bout, while no significant differences were observed after the two WBV bouts for LA. All responses after the second bout of MVC and MVC–WBV were significantly higher than those observed after WBV alone. GH concentrations were significantly correlated with LA after all stimuli, although LA concentrations after the second bout were associated with markedly lower GH levels. Conclusions A significant blunting of GH responsiveness ensues after a second bout of different GH-releasing stimuli, independent from the amount of GH released after the first bout. This is a pattern also observed for other pharmacological stimuli and exercise modalities, and suggests a common mechanism underlying different GH-releasing stimuli.

Effect of an Acute Bout of Whole Body Vibration Exercise on Muscle Force Output and Motor Neuron Excitability

The purpose of the current investigation was to assess the effect of an acute bout of whole body vibration (WBV) exercise on muscle force output and motor neuron excitability. Nineteen recreationally trained college-aged males were randomly assigned to a WBV (n = 10) or a sham (S, n = 9) group. The WBV group completed a series of static, body weight squats on a vibrating platform at 30 Hz and an amplitude of approximately 3.5 mm (vertical), whereas the S group performed the same series of exercises but without vibration. Measurements were performed before (Pre) and then immediately post-exercise (Imm Post), 8 minutes post-exercise (8-Min Post), or 16 minutes post-exercise (16-Min Post) during 3 different testing sessions. The measurements involved a ballistic isometric maximum voluntary contraction (MVC) of the triceps surae muscle complex and electrical stimulation of the tibial nerve for assessment of motor neuron excitability by analyzing H-reflex and M-wave responses (H(max)/M(max) ratio). Electromyography was also obtained from the triceps surae muscle complex during the MVCs. The WBV group significantly (p < or = 0.05) increased peak force at Imm Post (9.4%) and 8-Min Post (10.4%). No significant change in peak force was observed in the S group. No significant changes were observed in either group for average integrated EMG, H(max)/M(max) ratio, or rate of force development at Imm Post, 8-Min Post, or 16-Min Post. The results from this investigation indicate that an acute bout of static, body weight squat exercises, combined with WBV, increases muscle force output up to 8 minutes post-exercise. However, this increase in muscle force is not accompanied by a significant increase in motor neuron excitability or muscle activation. Thus, it is plausible to use WBV as a method for acute increase in muscle force output for athletes immediately before competition.

Displacement and Frequency for Maximizing Power Output Resulting From A Bout of Whole-Body Vibration

Whole-body vibration (WBV) has been shown to be effective for increasing lower-body power; however, the combination of frequency, displacement, and duration that elicits the best acute response has yet to be determined. The purpose of this study was to identify the protocol eliciting the greatest improvement in power after an acute bout of WBV. Forty men and women participated in this study, in which 8 different combinations of 30, 35, 40, and 50 Hz with 2-mm and 5-mm displacements were tested over 3 days. For all protocols, randomized to reduce potential order effects, subjects underwent 30 seconds of WBV while holding an isometric squat at a knee angle of 2.27 rad. Power was assessed by countermovement jumps. Subjects performed 3 jumps before WBV, immediately afterward, and 1, 5, and 10 minutes later. The highest normalized peak power (nPP) at each time point was determined using a 4 (frequency) x 2 (displacement) x 5 (time) repeated-measures analysis of variance. Significant effects were seen for frequency (p < or = 0.026) and time (p < or = .0001). Post hoc analyses revealed that the 30-Hz condition (1.010 +/- 0.003) produced a higher nPP than 35 Hz (1.00 +/- 0.003, p < or = 0.026) and 40 Hz (1.002 +/- 0.002, p < or = 0.028) but not 50 Hz (1.004 +/- .002). We also found a significantly higher nPP for the 1-minute post-treatment time point (1.011 +/- .0003) vs. all other time points (p < or = 0.006). Our data show that an acute WBV bout can significantly increase power output at 1 minute post-treatment across all frequencies and displacements, although 30 Hz appears to have a greater effect on power output than either 35 Hz or 40 Hz, but not 50 Hz, at all post-treatment time points.