The acute effect of whole-body vibration on the vertical jump height

To determine the effectiveness of a single, 1-minute bout of whole-body vibration (WBV) as a viable warm-up activity, 90 subjects (30 men; 60 women, mean age = 19 ± 1 years) were recruited and randomly assigned to either a nonvibration control group or 1 of 8 WBV treatments (4 frequencies × 2 AMplitudes). Subjects stood with the feet shoulder width apart and the knees flexed 10° on a Next Generation Power Plate for 1 minute with the frequency (30, 35, 40, or 50 Hz) and amplitude (2-4 or 4-6 mm) settings at the assigned levels. Before, 1, 5, 10, 15, 20, 25, and 30 minutes after the WBV or control treatment, subjects performed a series of countermovement vertical jumps (CMJs) measured using a Vertec vertical jump tester. Comparisons were made of changes in the countermovement vertical jump height (CMJH) over time and between groups, frequencies, and amplitudes using repeated measures analysis of variance (α ≤ 0.05). There were significant differences in CMJH over time (p = 0.008); however, these were similar for all groups, frequencies, and amplitudes (p > 0.88). Some athletes may benefit from using WBV as a warm-up activity, if the timing of WBV is optimized. The effect of WBV on performance is likely variable and minimal, with a small window of effectiveness. Gender differences were not examined, and the optimal duration, intensity, and postural position are still unclear and warrant further study.     

The acute effect of different frequencies of whole-body vibration on countermovement jump performance

Whole-body vibration (WBV) has been shown to elicit acute and chronic improvements in neuromuscular function; however, there is little conclusive evidence regarding an optimum protocol for acute WBV. The aim of this study was to compare the effects of acute exposure to different frequencies of WBV on countermovement jump (CMJ) height. Twelve recreationally trained men (age, 31 ± 8 years; height, 177 ± 12 cm; weight, 83.0 ± 6.9 kg) completed maximal CMJs pre- and post-WBV in a half-squat position for 30 seconds. In a blinded design with randomized testing order, participants were exposed on different days to frequencies of 0, 30, 35, and 40 Hz. Significant main effects were found for time (pre-to-post WBV, p < 0.01) and frequency * time interaction (p < 0.01), with post hoc analysis highlighting that there was a significant mean improvement of 6% in CMJ as a result of WBV at 40 Hz but no significant change at other frequencies. This study demonstrates that for recreationally trained men, an acute 30-second bout of vertical WBV at 40 Hz and 8-mm peak-to-peak displacement significantly enhances explosive jumping performance in comparison to other frequencies. Acute vertical WBV for 30 seconds at 40 Hz may be incorporated into strength and conditioning training to enhance explosive power; however, the exact mechanisms for improvements remain to be elucidated and further well-controlled investigations on chronic WBV training and using well-trained athletes are recommended.     

Acute effect of whole-body vibration on electromechanical delay and vertical jump performance

Objectives:To determine if a change in vertical jump performance from acute whole-body vibration can be explained by indirectly assessing spindle sensitivity from electromechanical delay.Methods:Using a counter-balanced design, twenty college-aged participants performed whole-body vibration (WBV) and control treatments. WBV included 10 intervals (26 Hz, 3.6 mm) of 60 s in a half-squat followed by 60 s of rest. After 5 intervals, participants rested for 6-minutes before commencing the final 5 intervals. For the control, the exact same protocol of whole-body vibration was performed but without vibration. Electromechanical delay and vertical jump were assessed at baseline, during the 6-minute rest period and immediately after whole-body vibration and control.Results:There were no differences between treatments, for both electromechanical delay (F(2, 38)=1.385, p=0.263) and vertical jump (F(2, 38)=0.040, p<0.96). Whole-body vibration had no effect on vertical jump performance.Conclusion:The current whole-body vibration protocol is not effective for acute vertical jump or electromechanical delay enhancement. Also, since there was no effect on electromechanical delay, this suggests that whole-body vibration did not enhance muscle spindle sensitivity for the parameters examined.     

The short-term effect of whole-body vibration training on vertical jump, sprint, and agility performance

Previous studies have suggested that short-term whole-body vibration (WBV) training produces neuromuscular improvement similar to that of power and strength training. However, it is yet to be determined whether short-term WBV exposure produces neurogenic enhancement for power, speed, and agility. The purpose of this study was to investigate the effect short-term WBV training had on vertical jump, sprint, and agility performance in nonelite athletes. Twenty-four sport science students (16 men and 8 women) were randomly assigned to 2 groups: WBV training or control. Each group included 8 men and 4 women. Countermovement jump (CMJ) height, squat jump (SJ) height, sprint speed over 5, 10, and 20 m, and agility (505, up and back) were performed by each participant before and after 9 days of either no training (control) or WBV training. Perceived discomfort of every participant was recorded after daily WBV exposure and nonexposure. There were no significant differences between WBV and control groups for CMJ, SJ, sprints, and agility. Perceived discomfort differed between the first and subsequent days of WBV training (p < 0.05); however, there was no difference between the WBV and control groups. It is concluded that short-term WBV training did not enhance performance in nonelite athletes.     

The effect of whole-body vibration training and conventional strength training on performance measures in female athletes

The purpose of this study was to examine the effects of regular whole-body vibration (WBV) training on lower body strength and power. National Collegiate Athletic Association Division III softball athletes (n = 9) completed the 9-week protocol as part of their off-season strength and conditioning program. The athletes were randomly assigned to 1 of 2 groups. Week 1, pretesting included 3 repetition maximum (3RM) back squat, standing long jump (SLJ), and vertical countermovement jump (VCMJ). Phase I training (weeks 2-4) consisted of either WBV training (group 1) or conventional strength training (CST, group 2). The primary programmatic difference between WBV and CST was the inclusion of WBV sets after squat sets. Posttesting (3RM squat, SLJ, VCMJ) occurred at week 5. Phase II training (weeks 6-8) consisted of either WBV training (group 2) or CST (group 1). Posttesting was repeated at week 9 after the completion of phase II. Three 2 × 2 mixed factorial analyses of variance were computed. No significant differences (p > 0.05) were found between groups or between groups and testing period for the SLJ, VCMJ, and estimated 1RM back squat. Increases (p < 0.05) were observed in SLJ, VCMJ, and back squat from pretest to posttest 1. Back squat increased (p < 0.05) from posttest 1 to posttest 2. All the athletes experienced significantly greater (p < 0.05) percent changes from pretest to posttest 1 for SLJ and VCMJ. These results indicate that the inclusion of WBV as part of an off-season strength and conditioning program has no apparent benefit over CST methods for collegiate softball players.     

Effect of different rest intervals after whole-body vibration on vertical jump performance

Whole-body vibration (WBV) may potentiate vertical jump (VJ) performance via augmented muscular strength and motor function. The purpose of this study was to evaluate the effect of different rest intervals after WBV on VJ performance. Thirty recreationally trained subjects (15 men and 15 women) volunteered to participate in 4 testing visits separated by 24 hours. Visit 1 acted as a familiarization visit where subjects were introduced to the VJ and WBV protocols. Visits 2-4 contained 2 randomized conditions per visit with a 10-minute rest period between conditions. The WBV was administered on a pivotal platform with a frequency of 30 Hz and an amplitude of 6.5 mm in 4 bouts of 30 seconds for a total of 2 minutes with 30 seconds of rest between bouts. During WBV, subjects performed a quarter squat every 5 seconds, simulating a countermovement jump (CMJ). Whole-body vibration was followed by 3 CMJs with 5 different rest intervals: immediate, 30 seconds, 1 minute, 2 minutes, or 4 minutes. For a control condition, subjects performed squats with no WBV. There were no significant (p > 0.05) differences in peak velocity or relative ground reaction force after WBV rest intervals. However, results of VJ height revealed that maximum values, regardless of rest interval (56.93 ± 13.98 cm), were significantly (p < 0.05) greater than the control condition (54.44 ± 13.74 cm). Therefore, subjects' VJ height potentiated at different times after WBV suggesting strong individual differences in optimal rest interval. Coaches may use WBV to enhance acute VJ performance but should first identify each individual's optimal rest time to maximize the potentiating effects.     

An active head-neck model in whole-body vibration: vibration magnitude and softening

An active head-neck model is introduced in this work to predict human-dynamic response to different vibration magnitudes during fore-aft whole-body vibration. The proposed model is a rigid-link dynamic system augmented with passive spring-damper tissue-like elements and additional active dampers that resemble the active part of the muscles. The additional active dampers are functions of the input displacement, velocity, and acceleration and are based on active control theories and a kd-tree data-searching scheme. Five human subjects exposed to random fore-aft vibration with frequency content of 0.5-10 Hz were tested under different vibration with magnitudes of 0.46 m/s(2), 1.32 m/s(2), and 1.66 m/s(2) rms. The results showed that the proposed model was able to reasonably capture the softening characteristics of the human head-neck response during fore-aft whole-body vibration of different magnitudes.     

The effect of multi-frequency whole-body vibration on night-shifted mouse model

The circadian rhythm controls several biological activities; therefore, a disorganized circadian rhythm may cause fatal health problems. The aim of this study was to assess the effects of circadian rhythm disturbances induced by simulated night shift activities on the abdominal adipose tissue, bone microstructures and muscle volume in the tibiae of mice. Moreover, we evaluated the effects of multi-frequency whole-body vibration as a countermeasure against the consequences of circadian rhythm disturbances. Twenty-four 5-week-old C57BL/6J male mice were equally assigned to three groups: the normal group (Nor), night shift group (NS), and night shift with multi-frequency whole-body vibration group (NS + V). The NS and NS + V groups were exposed to circadian rhythm disturbances for 4 weeks with 3-day intervals by changing the day and night cycle based on 7 o’clock. After 4 weeks, morphological changes in the adipose tissue, bone microstructures and muscle volume in the tibiae were evaluated from three-dimensional images using in vivo micro-computed tomography. As a result, the volume of the abdominal adipose tissue was significantly higher in the NS than in the Nor and NS + V groups. Also, the microstructures of the tibia were more enhanced in the NS + V than the NS group. The volume of tibial muscle was increased in all groups, while there were no significant changes in muscle volume. From these results, we can conclude that circadian rhythm disturbances induced by night shift activities may reduce bone condition and increase the accumulation of abdominal adipose tissue and these negative effects may be prevented or improved through applying multi-frequency whole-body vibration.

     

The acute effect of whole-body vibration on the hoffmann reflex

The extent to which motoneuron pool excitability, as measured by the Hoffmann reflex (H-reflex), is affected by an acute bout of whole-body vibration (WBV) was recorded in 19 college-aged subjects (8 male and 11 female; mean age 19 +/- 1 years) after tibial nerve stimulation. H/M recruitment curves were mapped for the soleus muscle by increasing stimulus intensity in 0.2- to 1.0-volt increments with 10-second rest intervals between stimuli, until the maximal M-wave and H-reflex were obtained. After determination of Hmax and Mmax, the intensity necessary to generate an H-reflex approximately 30% of Mmax (mean 31.5% +/- 4.1%) was determined and used for all subsequent measurements. Fatigue was then induced by 1 minute of WBV at 40 Hz and low amplitude (2-4 mm). Successive measurements of the H-reflex were recorded at the test intensity every 30 seconds for 30 minutes post fatigue. All subjects displayed a significant suppression of the H-reflex during the first minute post-WBV; however, four distinct recovery patterns were observed among the participants (alpha = 0.50). There were no significant differences between genders across time (P = 0.401). The differences observed in this study cannot be explained by level or type training. One plausible interpretation of these data is that the multiple patterns of recovery may display variation of muscle fiber content among subjects. Future investigation should consider factors such as training specificity and muscle fiber type that might contribute to the differing H-reflex response, and the effect of WBV on specific performance measures should be interpreted with the understanding that there may be considerable variability among individuals. Recovery times and sample size should be adjusted accordingly.     

The effects of movement velocity during squatting on energy expenditure and substrate utilization in whole-body vibration

The purpose of this study was to examine whether and how cycle time duration affects energy expenditure and substrate utilization during whole-body vibration (WBV). Nine men performed 3 squatting exercises in execution frequency cycles of 6, 4, and 2 seconds to 90 degrees knee flexion with vibration (Vb+) (frequency was set at 30 Hz and the amplitude of vibration was 4 mm) and without vibration (Vb-) during 3 minutes, each with an additional load of 30% of the subject's body weight. A 2-way analysis of variance for VO2 revealed a significant vibration condition main effect (p < 0.001) and a cycle time duration effect (p < 0.001). When differences were analyzed by Fisher's LSD test, cycle time duration of 2 seconds was significantly different from 4 and 6 seconds, both in Vb+ and Vb-. Total energy expenditure (EE(tot)), carbohydrate oxidation rate (EE(cho)), and fat oxidation rate (EE(fat)) demonstrated a significant vibration condition main effect (EE(tot): p < 0.01; EE(cho): p < 0.001; EE(fat): p < 0.001) and cycle time duration main effect (EE(tot) and EE(cho): p < 0.001; EE(fat): p < 0.01). EE(tot), EE(cho), and EE(fat) post hoc comparisons indicated that values for the 2-second test significantly differed from 4 and 6 seconds when compared in the same vibration condition. VO2 and EE values were greater in Vb+ than in Vb- conditions with the same cycle time duration. Our study confirms that squatting at a greater frequency helps to maximize energy expenditure during exercise with or without vibration. Therefore, cycle time duration must be controlled when vibration exercise is prescribed.     

Acute effects of whole-body vibration on jump force and jump rate of force development: a comparative study of different devices

The goal of this study was to compare the acute effects of whole-body vibration (WBV) delivered by 3 devices with different mechanical behavior on jump force (JF) and jump rate of force development (JRFD). Twelve healthy persons (4 women and 8 men; age 30.5 ± 8.8 years; height 178.6 ± 7.3 cm; body mass 74.8 ± 9.7 kg) were exposed to WBV for 15 and 40 seconds using 2 professional devices (power plate [PP; vertical vibration] and Galileo 2000 [GA; oscillatory motion around the horizontal axis in addition to vertical vibration]) and a home-use device [Power Maxx, PM; horizontal vibration]). The JF and JRFD were evaluated before, immediately after, and 5 minutes after WBV. The JF measured immediately after 40 seconds of vibration by the GA device was reduced (3%, p = 0.05), and JRFD measured after 5 minutes of rest after 40 seconds of vibration by the PM device was reduced (12%, p < 0.05) compared with the baseline value. The acute effects of WBV (15 or 40 seconds) on JF and JRFD were not significantly different among the 3 devices. In conclusion, our hypothesis that WBV devices with different mechanical behaviors would result in different acute effects on muscle performance was not confirmed.     

The effects of whole-body vibration in isolation or combined with strength training in female athletes

The aims of this study were to assess the behavior of a vibrating platform under different conditions and to compare the effects of an 8-week periodized training program with whole-body vibration (WBV) alone or in combination with conventional strength training (ST). Vibrating frequencies, displacements, and peak accelerations were tested through a piezoelectric accelerometer under different conditions of load and subjects' position. Eighteen national-level female athletes were assigned to 1 of 3 different groups performing WBV, conventional ST, or a combination of the 2 (WBV + ST). Isometric maximal voluntary contraction, dynamic maximal concentric force, and vertical jump tests were performed before and after the conditioning program. Vibrating displacements and maximum accelerations measured on the device were not always consistent with their expected values calculated from the display and manufacturers' information (sinusoidal waveforms). The WBV alone or in combination with low-intensity resistance exercise did not seem to induce significant enhancements in force and power when compared with ST. It appears that WBV cannot substitute parts of ST loading in a cohort of young female athletes. However, vibration effects might be limited by the behavior of the commercial platforms as the one used in the study. More studies are needed to analyze the performances of devices and the effectiveness of protocols.     

Effects of whole-body vibration training on explosive strength and postural control in young female athletes

This study aimed to evaluate the effectiveness of a whole-body vibration training program to improve neuromuscular performance in young elite female athletes. Twenty-three women basketball players (14-18 years old) were randomly assigned to a control group (CG, n = 11) or to a whole-body vibration group (WBVG, n = 12). During the study period, both groups continued their usual training program, but the WBVG also underwent a 15-week vibration training program. We analyzed the countermovement jump test (CMJ), the 1-leg hop test for the right leg and for the left leg, and the single-limb standing balance for both legs and with eyes open and closed at 3 time points: before training (T1), after an 8-week training period (T2), and after a further 7-week training period (T3). Compared with the CG, CMJ increased significantly in the WBVG from T1 to T2 (6.47%, p < 0.001), T1 to T3 (10.07%, p = 0.005), and T2 to T3 (3.38%, p < 0.001). One-leg hop test for the right and left legs also showed significantly higher values in WBVG from T1 to T2 (10.12%, p < 0.001 and 9.63%, p = 0.002, respectively) and T1 to T3 (14.17%, p = 0.001 and 15.17%, p = 0.004, respectively). Lateral deviation of the center of pressure in the closed eyes test decreased significantly in WBVG for both right and left leg, from T1 to T2 (-22.20%, p = 0.043 and -34.77%, p < 0.001, respectively) and from T1 to T3 (-33.14%, p = 0.027 and -33.58%, p = 0.043, respectively) compared with the CG. In conclusion, our results show that a 15-week whole-body vibration training program improves explosive strength and postural stability in adolescent female basketball players.     

The effect of warm-up with whole-body vibration vs. cycle ergometry on isokinetic dynamometry

The purpose of this study was to compare the effects of warm-up protocols using either whole-body vibration (WBV) or cycle ergometry (CE) on peak torque at 3 different isokinetic speeds and on fatigue in the knee extension exercise. Twenty-seven recreationally trained (age = 23.59 ± 3.87 years) men (n = 14) and women (n = 13) were tested at 3 different isokinetic speeds (60, 180, 300°·s-1) after either WBV or CE warm-up. The WBV consisted of intermittent bouts of 30 seconds of isometric squats at various degrees of hip and knee flexion for a total of 5 minutes. The CE consisted of 5 minutes of pedaling a cycle ergometer at 65-85% of age-predicted max heart rate. Comparisons between the warm-up conditions were analyzed using repeated measures analysis of variance. For the fatigue comparison, subjects completed 50 continuous concentric knee extensions at 240°·s-1. Means from the first 3 repetitions were compared to means from the final 3 repetitions to establish a fatigue index. Conditions were compared through an independent T-test. No significant (p > 0.05) differences were discovered between warm-up conditions at any speed or on the fatigue index. Means were virtually identical at 60°·s-1 (WBV = 142.14 ± 43.61 ft lb-1; CE = 140.64 ± 42.72 ft lb-1), 180° s-1 (WBV = 93.88 ± 35.18 ft lb-1; CE = 96.36 ± 31.53 ft lb-1), and 300°·s-1 (WBV = 78.36 ± 26.04 ft lb-1; CE = 80.13 ± 26.08), and on fatigue percentage (WBV = 51.14 ± 10.06%; CE = 52.96 ± 9.19%). These data suggest that the more traditional 5-minute cycle ergometer warm-up elicits results comparable to a less common vibration warm-up. The findings of this study are that these modalities are comparable under the tested conditions.     

The effects of whole-body vibration on human biodynamic response

The objective of vibration research at the Armstrong Laboratory includes the expansion and improvement of the measurement, quantification, analysis, and modeling of human vibration response. The driving-point impedance and transmissibility techniques have been expanded and are rigorously applied in the research efforts. Driving-point impedance is defined as the ratio between the transmitted force and input velocity at the point of load application. Transmissibility is typically defined as the ratio between the acceleration level measured at some location on the body and the input acceleration at the seat. These two ratios are used to assess the magnitude and frequency location of resonance behaviors where maximum motions occur in the body. From these data, analytical models are developed which can simulate the motions and coupling behaviors, and predict the stiffness and damping characteristics of the affected anatomical structures. The ultimate goal of the research is to provide new and improved data and modeling capability for revising exposure standards and for developing equipment design guidelines and criteria for improving tolerance and reducing physiological consequences. This paper describes the results of recent studies conducted to identify the biodynamic behavior of major anatomical structures affected by seated whole-body vibration, to develop an analytical model for simulating human vibration response, and to apply the model to evaluate the effects of seat cushion materials on the transmission/attenuation pathways.     

Acute effect of whole-body vibration on sprint and jumping performance in elite skeleton athletes

The winter sliding sport known as skeleton requires athletes to produce a maximal sprint followed by high speed sliding down a bobsled track. Athletes are required to complete the course twice in 1 hour and total time for the 2 runs determines overall ranking. The purpose of this investigation was to examine the effect of whole-body vibration (WBV) on lower body power to explore the utility of WBV as an ergogenic aid for skeleton competition. Elite skeleton athletes (1 male and 6 females) completed an unloaded squat jump (SQJ) immediately followed by 2 countermovement jumps (CMJs) and a maximal 30-m sprint before and after WBV or no vibration (CON) using a crossover design. The second 30-m sprint was slower following both CON (1.4% decrement; p = 0.05) and WBV (0.7% decrement; p = 0.03). Mean vertical velocity was maintained following WBV in the SQJ but decreased following CON (p = 0.03). There was a trend for athletes to commence the SQJ from a higher starting stance post-WBV compared to CON (p = 0.08). WBV decreased total vertical distance traveled compared to CON in the SQJ (p = 0.006). WBV had little effect on peak velocity, jump height, dip, and peak acceleration or any CMJ parameters. When sprint athletes' warm up and perform maximal jumps and a 30-m sprint with 15-20 minutes of recovery before repeating the sequence, the second series of performances tend to be compromised. However, when WBV is used before the second series of efforts, some aspects of maximal jumping and sprinting appear to be influenced in a beneficial manner. Further research is required to explore whether WBV can improve the second sprint for athletes in actual competition and/or what sort of WBV protocol is optimal for these populations.     

The effect of leg dominance and landing height on ACL loading among female athletes

Female athletes are more prone to anterior cruciate ligament (ACL) injury. A neuromuscular imbalance called leg dominance may provide a biomechanical explanation. Therefore, the purpose of this study was to compare the side-to-side lower limb differences in movement patterns, muscle forces and ACL forces during a single-leg drop-landing task from two different heights. We hypothesized that there will be significant differences in lower limb movement patterns (kinematics), muscle forces and ACL loading between the dominant and non-dominant limbs. Further, we hypothesized that significant differences between limbs will be present when participants land from a greater drop-landing height. Eight recreational female participants performed dominant and non-dominant single-leg drop landings from 30 to 60 cm. OpenSim software was used to develop participant-specific musculoskeletal models and to calculate muscle forces. We also predicted ACL loading using our previously established method. There were no significant differences between dominant and non-dominant leg landing except in ankle dorsiflexion and GMED muscle forces at peak GRF. Landing from a greater height resulted in significant differences among most kinetics and kinematics variables and ACL forces. Minimal differences in lower-limb muscle forces and ACL loading between the dominant and non-dominant legs during single-leg landing may suggest similar risk of injury across limbs in this cohort. Further research is required to confirm whether limb dominance may play an important role in the higher incidence of ACL injury in female athletes with larger and sport-specific cohorts.     

The effects of floor incline on lower extremity biomechanics during unilateral landing from a jump in dancers

Retrospective studies have suggested that dancers performing on inclined ("raked") stages have increased injury risk. One study suggests that biomechanical differences exist between flat and inclined surfaces during bilateral landings; however, no studies have examined whether such differences exist during unilateral landings. In addition, little is known regarding potential gender differences in landing mechanics of dancers. Professional dancers (N = 41; 14 male, 27 female) performed unilateral drop jumps from a 30 cm platform onto flat and inclined surfaces while extremity joint angles and moments were identified and analyzed. There were significant joint angle and moment effects due to the inclined flooring. Women had significantly decreased peak ankle dorsiflexion and hip adduction moment compared with men. Findings of the current study suggest that unilateral landings on inclined stages create measurable changes in lower extremity biomechanical variables. These findings provide a preliminary biomechanical rationale for differences in injury rates found in observational studies of raked stages.     

The effect of drop jump starting height and contact time on power, work performed, and moment of force

The purposes of this study are (a) to examine the effects of contact time manipulation on jump parameters and (b) to examine the interaction between starting height changes and contact time changes on important jump parameters. Fifteen male athletes performed a series of drop jumps from heights of 20, 40, and 60 cm. The instructions given to the subjects were (a) "jump as high as you can" and (b) "jump high a little faster than your previous jump." Jumps were performed at each height until the athlete could not achieve a shorter ground contact time. The data were divided into 5 groups where group 1 was made up of the longest ground contact times of each athlete and groups 2-4 were composed of progressively shorter contact times, with group 5 having the shortest contact times. The jumps of group 3 produced the highest maximum and mean mechanical power (p <0.05) during the positive phase of the drop jumps regardless of starting jump height. The vertical takeoff velocities for the first 3 groups did not show significant (p < 0.05) differences. These results indicate that the manipulation of jump technique plays larger role than jump height in the manipulation of important jump parameters.