The aim of this study was to determine whether WBV helps in the management of symptoms of EIMD over a 72-hour recovery period and to determine the effects of WBV on jumping performance after exercise-induced muscle damage. Further research needs to be done, as literature shows some support for managing DOMS symptoms via WBV. Inappropriate damage methodology may have occurred in this study, damaging the subjects too much for WBV to be effective.
INTRODUCTION
Contraction: a reduction in the distance between the two ends of a muscle due to active shortening of the muscle. DOMS has been reported as an undesirable side effect of exercise due to its painful and debilitating effects on individuals (74). The exact mechanism for WBV is still unknown, but exposure to WBV has been shown to increase neuromuscular activity.
When WBV exposure was given prior to EIMD, there was less reduction in force compared to control treatments without vibration. It is not yet determined whether reduction in force or speed contributes more to the decrease in power output after EIMD, which most studies only have. It has been shown that peak power output is reduced immediately after eccentric muscle actions, while power continues to be reduced up to 2 days post-injury.
VJ performance with and without a countermovement has been shown to have immediate and long-lasting reductions in performance up to 4 days post-injury, but is dependent on jump type (19). Recently, WBV has been proposed as a new modality to reduce or control symptoms of EIMD (10, 68).
REVIEW OF LITERATURE
The changes of the Z line may be associated with amorphous structures of the fiber, such as the sarcomere, the Z line, or even the alignment of A or I bands (87). The inflammatory reaction is initiated due to damage at the muscle's cellular level. There is an increased presence of the granules in the damaged muscles 72 hours after exercise (41).
Maximum voluntary contraction (MVC) moment is related to force, and is one of the more practical. Torque is force times the moment arm and is dependent on the length and tension curve of the muscle, speed and joint angles. A needle biopsy, an invasive procedure that removes a small (10-50 mg) portion of the muscle, may be taken to more accurately measure muscle damage.
The sample is examined through an electron or light microscope to check for damage to the Z-lines and other structural features. Because of the small size of the biopsy, it is not representative of the entire injured muscle. Because of the 24-48 hour delay in DOMS, VAS correlates poorly with functional movements such as MVC torque (49).
An estimate of true maximal force can be determined by subtracting the ratio of the evoked to voluntary force. It is hypothesized that HRE will cause a PAP response and increase performance of the latter exercise (47). Prerequisite for strength and the intensity of the load used in the weight training part of the complex can be important i.
When this complex training is continued for an extended period of time, it is believed that there will be long-term changes in the ability of the muscle. It has been suggested that vibration can affect the activation of afferent input from the sensory units of the muscle fibers. These findings are consistent with the gate control hypothesis (64), which states that afferent signals mediated by large myelinated fibers presynaptically inhibit small pain fibers in the dorsal horn of the spinal cord.
The primary finding of the study was that jump height increased significantly after vibration, although there was no significant difference in the other variables measured in the study. This is due to an increased sensitivity of the musculature, which allows for a smaller amount of damage.
METHODS
To ensure consistency, marks were made on the belly of the rectus femoris (RF), at the midpoint between the patella and the proximal head of the femur. The participants were instructed to keep the quadriceps relaxed while the researcher placed a pressure algometer (Wagner Instruments, Greenwich, CT USA) at each test site. Mechanical pressure was applied to the muscle in the following order: VM, VL, RF during three trials and 20 seconds between each trial.
Participants were asked to indicate when the pressure switched from "uncomfortable" to "painful". The researcher immediately removed the pressure stimulus when the participant said "pain". VJ performance was assessed at each visit to the laboratory using a combination of a Vertec® (Sports Imports, Columbus, OH, USA) free standing jump height. Participants were instructed to perform three maximal CMVJ, with 15 s rest in between, with arm swing and were instructed to jump as fast and high as possible.
The Z index means that the GRF was measured in the vertical direction, in the Z plane. During split squats, the rear leg was placed on the support bench with 90 degrees of flexion, allowing for a focus on single-leg execution of the front leg. Immediately following the muscle injury protocol, participants in the control group performed two sets of one-quarter bodyweight squats on a flat surface, with 30 seconds of squatting followed by 30 seconds of rest.
Participants in the treatment group performed 2 sets of bodyweight squats on the vibration plate. Participants returned to the laboratory 24, 48, and 72 h after the muscle injury protocol to assess muscle soreness on movement and VJ performance. These sessions consisted of the initial assessment of PPTs and VJ followed immediately by the treatment or control protocol.
Three days of measurements were taken during familiarization sessions and a set of baseline measures on the first day of testing for rectus femoris PPT and vertical jump performance. Reliability measures were quantified through the calculation of the intraclass correlation coefficient (ICC) with a 95% confidence interval. A 12x2 (time by group) mixed-factor analysis of variance (ANOVA) was performed to test for changes in PPTs over time and between groups.
RESULTS
There was no significant (p>0.05) main effect for group, but there was a significant (p <0.001) main effect for time. Means of estimated peak Z force between groups and at all time points after exercise-induced muscle damage. The significant main effects of peak force Z for time were that 0Pre was greater than all other time points.
There was a significant main effect for time (p=0.002), but no significant main effect for group (p>0.05). Means of PPT for RF between groups and at all time points after exercise-induced muscle damage. The significant main effects of RF PPT for time were that 0Pre was greater than all time points at 24 and 48 hours. Significant (p<0.05) main effects of 0Pre are indicated by.
DISCUSSION
56), or the effects of WBV on muscle recovery, which characterize this study as novel in the performance and muscle recovery literature. The current study failed to incorporate WBV as a recovery modality with the aim of attenuating any reduction in performance as measured by VJH and peak Z. Previous literature has shown mixed results when examining the effects of WBV on VJ performance.
As mentioned previously, WBV has been researched as a recovery modality in the upper (55) and lower limbs (68) when measuring pain, force production and clinical variables with different damage and vibration protocols, but has not been investigated for VJ performance effects . The changes in muscle pain ratings during movement and PPTs observed in the present study are consistent with previous literature following EIMD (4,55,68). In the current investigation, no differences in muscle pain were found when WBV was administered.
It is important to note that the timing of vibration application may contribute to the different findings in the literature, as several studies have reported maximal effects of WBV on VJ. This investigation provides a new exercise to produce EIMD in the quadriceps that, to our knowledge, has not yet been identified. The use of WBV as a recovery method was shown to be ineffective in the current investigation.
Additionally, male and female athletes should be examined with similar protocols to determine the effects of different participant populations. Acute effect of whole body vibration on sprint and jump performance in elite skeleton athletes. Short-term effect of whole body vibration training on vertical jump, sprint and agility performance.
Acute whole-body vibration training increases vertical jump and flexibility performance in elite female field hockey players. Short-term effects of whole body vibration on maximal voluntary isometric knee extensor force and rate of force rise. The effects of acute whole-body vibration as a recovery modality after high-intensity interval training in well-trained, middle-aged runners.
The effects of a whole-body vibration program on muscle performance and flexibility in female athletes. Effects of local pressure and vibration on muscle pain from eccentric exercise and hypertonic saline.
