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Efficacy of Whole-Body Vibration Board Training on Strength in Athletes After Anterior Cruciate Ligament Reconstruction: A Randomized Controlled Study

Costantino, Cosimo, MD, PhD; Bertuletti, Silvia, MD; Romiti, Davide, MD

Clinical Journal of Sport Medicine: July 2018 - Volume 28 - Issue 4 - p 339–349
doi: 10.1097/JSM.0000000000000466
Original Research

Objective: To evaluate whether an 8-week whole-body vibration training program may improve recovery of knee flexion/extension muscular strength in athletes after arthroscopic anterior cruciate ligament (ACL) reconstruction.

Design: Randomized controlled trial.

Setting: Single outpatient rehabilitation center.

Participants: Thirty-eight female volleyball/basketball players (aged between 20 and 30), randomized into 2 treatment groups.

Interventions: During a standardized six-month rehabilitation program, from week 13 to week 20 after surgery, the whole-body vibration group (n = 19) and the control group (n = 19) performed additional static knee flexor/extensor exercises on a vibration platform. For the whole-body vibration group, the vibration platform was set to 2.5 mm of amplitude and 26 Hz of frequency. The control group followed the same whole-body vibration board training with no vibrations.

Main Outcome Measures: All patients were evaluated using an isokinetic strength test with a Biodex dynamometer at the beginning and at the end of the additional treatment protocol. The parameters tested were the peak torque and the maximum power of knee flexor and extensor muscles performing strength and endurance tests.

Results: No vibration-related side effects were observed. Improvements were noticed in both groups, but increase in knee muscle isokinetic strength values was statistically significant in the whole-body vibration group when compared with the control group (differences in extension: peak torque 11.316/10.263 N·m and maximum power 13.684/11.211 W; flexion: peak torque 9.632/11.105 N·m and maximum power 10.158/9.474 W; P < 0.001).

Conclusions: When combined with a standardized rehabilitation program, whole-body vibration may increase muscular strength and be an effective additional treatment option in the rehabilitation of athletes after ACL arthroscopic reconstruction.

Unit of Rehabilitation Medicine, Department of Biomedical, Biotechnological and Translational Sciences, University of Parma, Parma, Italy.

Corresponding Author: Cosimo Costantino, MD, PhD, Unit of Rehabilitation Medicine, Department of Biomedical, Biotechnological and Translational Sciences, University of Parma, Via Gramsci, 14, 43126 Parma, Italy (cosimo.costantino@unipr.it).

The authors report no conflicts of interest.

Received July 09, 2015

Accepted April 06, 2017

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INTRODUCTION

Rupture of the anterior cruciate ligament (ACL) is a serious knee injury mainly affecting physically active young people, with more than 250 000 cases occurring annually in the United States.1,2 These injuries are increasingly common, especially amongst female athletes.2,3 The most dangerous sports are soccer, alpine skiing, rugby, football, volleyball, and basketball. The ligament is injured when the tensive and compressive forces exceed the capacity of the ligament to bear load.4–6 Anterior cruciate ligament injury is characterized by joint instability, leading to decreased activity, insufficient knee function, and poor knee-related quality of life in the short term7,8 and is associated with an increased risk of osteoarthritis of the knee.9 To prevent these and other symptoms, 2 main treatment options are available after ACL injury: conservative rehabilitation and reconstructive surgery.

Surgical reconstruction of the ligament is a common treatment for athletes with knee instability, especially in professional athletes who need to restore the physiologic functions of the injured knee.10–12 The consequent rehabilitation requires a long time to rebuild muscle strength and reestablish joint mobility and neuromuscular control.13,14 So far, it has not been established which is the best rehabilitation program in terms of achieving muscular strength and neuromuscular control.14

Whole-body vibration (WBV) is considered to be a recent and promising treatment modality in exercise physiology to enhance athletic performances and therefore, a valuable addition to rehabilitation protocols, but has not been well investigated among athletes.15–17 Whole-body vibration produces vertical sinusoidal oscillations, transferred to the body and perceived by the muscular-skeletal apparatus, which adapts to them rapidly through the activation of the neuromuscular reflexes.16

The mechanism inducing muscle performance enhancements is unknown. One hypothesis is that muscle mechanical vibration induces a reflex involuntary action. When applied to an active muscle, vibration seems to produce a shift in neuromuscular recruitment patterns by altering the excitation of muscles spindles primary afferent endings, which in turn activate alpha motoneurons.18

Moreover, Cardinale and Bosco suggested that WBV may improve neuromuscular performance because vibrations performed on several sensitive structures such as skin, joints, and secondary endings may facilitate the gamma system and enhance the sensitivity of the alpha motoneurons.15,19

According to the hypothesis of Salvarani et al,20 mechanical vibration may induce neural adaptation, improving neuromuscular efficiency, which could be due to a better recruitment of the motor units.

Whole-body vibration is able to produce up to 50 accelerations per second, stimulating the body with a variation of gravitational acceleration similar to that which is obtained with power and strength training exercises and using weights or plyometrics.17,21

The biomechanical parameters determining WBV intensity are amplitude, frequency, and magnitude of the oscillations. The extension of the oscillatory motion determines the amplitude of the vibration (peak to peak, displacement in millimeter), the repetition rate of the cycles of oscillation denotes the frequency of the vibration (measured in Hertz), and the acceleration indicates the magnitude of the vibration (measured in g = 9.81 m/s2).16

As studies have demonstrated, WBV can reduce the frequency and intensity of electromyographic activity,20,22–24 while increasing muscular force similarly to what is achieved with muscular strength training.20

Recently, WBV has been adopted by high-profile sports teams as a response to the needs of athletes in intensive training, integrating or replacing muscle strength training sessions. Enhancement of muscular strength is one of the main benefits, without overloading the joints or the muscle–tendon attachments of the limbs.20

Several authors have reported that WBV may improve knee extensor strength, muscular power,25 physical exercise such as countermovement vertical jump,21 and flexibility performance.26–28 However, the literature reports conflicting results regarding the effects of WBV26: Several studies suggest that there are no effects after short-term as well as long-term WBV training on muscle strength recovery.29–31

The aim of this randomized controlled study was to evaluate the short-term effects of an 8-week WBV training program on knee flexion/extension muscular strength among female athletes after arthroscopic ACL reconstruction with patellar tendon.

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METHODS

This randomized, double-blind, controlled trial with a parallel group was conducted in a single rehabilitation center. During a 2-year period, consecutive female volleyball or basketball players were recruited from the department of Rehabilitation Medicine of Parma University Hospital, after arthroscopic reconstructive surgery of the ACL with autologous patellar tendon.

Participants were between 20 and 30 years of age. They were informed about the scope and procedures of the study and asked to take part in a clinical trial. They underwent a progressive 6-month conventional rehabilitation program and were randomly allocated to receive an additional treatment with WBV. The institutional local ethic review board approved the study, and all individuals provided written, informed consent to participate in this randomized controlled clinical study, in accordance with the National Health Council Resolution No. 196/96 and with the Helsinki Declaration of 1975, as revised in 2000.

Inclusion criteria were as follows:

  1. rupture of the ACL in young female volleyball or basketball players (aged between 20 and 30 years);
  2. sports activity for at least 6 years before the injury;
  3. first arthroscopic reconstruction of the ACL (no relapse on the same knee).

Exclusion criteria were as follows:

  1. any concomitant ligament or meniscus injury;
  2. previous orthopedic lower limb surgery;
  3. evidence of chondral lesion higher than grade 2;
  4. any injury to the contralateral knee or lower limb.

All subjects underwent arthroscopic ACL reconstruction (with autologous transplant of the patellar tendon) performed by the same surgeon. After the surgery, all individuals followed the same progressive conventional rehabilitation program for 6 months consistent with the consensus in the literature.13,14,20,32

In the first week after the surgery, the most important goals were controlling pain, swelling and inflammation, recovery of range of motion, and neuromuscular control. Medication, postsurgical compression wraps, elevation, and cryotherapy were advised as they significantly reduced postsurgical pain. After a short period, muscle control could be regained, and individuals commenced closed chain (safe range 0-60 degrees) and open chain (safe range 90-40 degrees) isometric exercises without additional weight. They walked full weight bearing without the aid of crutches within 15 days.

The rehabilitation protocol consisted of strength training exercises of lower limb muscles (quadriceps, hamstring muscles, gastrocnemii, glutei medius, and maximus, etc.), joint and muscle flexibility exercises, balance, proprioceptive, and coordination training as shown in Table 1.13,14,20,32

TABLE 1

TABLE 1

At the beginning of week 13, the participants were subjected to an additional treatment protocol with a WBV platform as follows (Table 2):

  1. 8-week duration;
  2. 3 sessions per week;
  3. support on 1 foot and 2 feet;
  4. one set of 6 repetitions for each position, each repetition lasting 1 minute;
  5. 1 minute rest period between each repetition and 2 minute rest period between each set.
TABLE 2

TABLE 2

The program included 2 static exercises in isometric contraction on the platform:

  1. ¼ squatting, the subjects were requested to remain standing upright on the platform with knees slightly bent to approximately 25 degrees;
  2. ¼ squatting on one leg (operated limb) (Figure 1).
Figure 1

Figure 1

The device (Fitwave; Medisport, Latina, Italy) was set to a frequency of 26 Hz and an amplitude of 4 mm. Whole-body vibration was performed according to the procedure described by Bosco et al.21

While participants in group B performed conventional rehabilitation program and received mechanical vibration using the WBV platform, subjects in group A (the control group) followed the same rehabilitation protocol and the same static exercises on the WBV platform with the equipment switched off, therefore without any vibration. The athletes were randomly allocated using computer randomization software (RANDI2 software version 0.6.1). Although physicians were aware of the allocated arm of the trial, patients, the physiotherapist, and the data analyst were not informed about the allocation intervention group. To prevent selective assessment bias, each group of participants was treated at different times, and each participant was informed that she would have received an additional rehabilitative treatment on the WBV platform without seeing or knowing how the treatment was performed on the other group.

Treatments were performed by the same physiotherapist, and the same device was used in both groups. Each patient was evaluated with a knee isokinetic strength test using the Biodex System 3 Pro dynamometer (Biodex Medical Systems, Shirley, New York) at the beginning (T0, beginning of week 13 after surgery) and at the end of the 8-week additional WBV treatment protocol (T1, end of week 20 after surgery).

The isokinetic strength test was performed with a precise number of operations to reproduce equal test conditions in all subjects. The patients were all seated with the knee aligned to the rotation axis of the isokinetic dynamometer. The foot and ankle were firmly held with a rigid “pull-band,” and the trunk was strapped tightly to the backrest (Figure 2). Before beginning the test, each subject underwent 5 minutes of warm-up riding a stationary bicycle, hamstring and quadriceps muscle stretching, and performed 5 isokinetic repetitions to familiarize with the machine and prevent injuries.

Figure 2

Figure 2

The tested movements were knee flexion/extension of the surgically treated knee from a joint angle of 90 to 0 degrees. The considered parameters were the peak torque (measured in newton meter) and the maximum power (measured in watts) of knee flexor/extensor muscles (hamstring and quadriceps muscles). The study protocol consisted of 5 repetitions at an angular speed of 90 deg/s (strength test) followed by a 2-minute rest period and of 20 repetitions at an angular speed of 180 deg/s (endurance test). The highest values for each set were registered. Data have been normalized: the Biodex System 3 Pro dynamometer software calculated automatically normalized data for weight, height, and dominant side.

The purpose of this study was to evaluate the short-term effects of WBV training program in improving the recovery of the flexion/extension knee muscular strength in athletes after arthroscopic ACL reconstruction. The primary outcome was defined as the difference between the 2 groups in the improvement of peak torque and maximum power values of the surgically treated knee flexor/extensor muscles measured at the end of the 8-week WBV additional treatment protocol (T1) using the isokinetic strength test. The secondary outcome was defined as the difference in the percent increase from T0 to T1 in the WBV group in comparison to the control group.

The characteristics of the patients were described using the average, the SD, the median, and the quartiles for continuous variables. The demographic and anthropometric characteristics were examined to confirm normal distribution. The demographic and anthropometric characteristics, the difference between the groups at the initial and final isokinetic strength test evaluation and the difference in the percent increase were analyzed using the Mann–Whitney U test for independent samples; the analysis of the difference in the improvement of isokinetic strength test values (T0 − T1) was performed in both groups using the Wilcoxon signed-rank test for paired samples.

All analyses were performed on the basis of the principle of the intention to treat. A P value < 0.05 was considered significant. The confidence interval at 95% was also calculated. All statistic analyses were performed with SPSS software for Windows (version 20.0).

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RESULTS

In our trial, we enrolled 48 female individuals who underwent arthroscopic reconstructive surgery of the ACL with autologous patellar tendon. Nine of 48 individuals assessed to the first evaluation were excluded: 2 individuals did not meet the inclusion criteria (one because of relapse of ACL injury and both because of sports activity time), 3 because of concomitant collateral ligament lesion and meniscus injury, one was excluded for a suspected chondral lesion, another one for a recent contralateral knee injury, and 2 declined to participate in the rehabilitation program.

One patient in the WBV group was lost after the beginning of the treatment because she did not complete the entire rehabilitation program. Therefore, the data for the 38 remaining patients (19 for each group, mean age 25.45 ± 2.18 years, range from 21 to 30 years) were included in our analysis (Figure 3).

Figure 3

Figure 3

The baseline demographic and anthropometric characteristics of participants are shown in Table 3. The baseline characteristics of group A and group B were comparable. No significant differences between the treatment groups were found with respect to age, height, weight, and body mass index. In addition, peak torque and maximum power values were analyzed at T0 using the knee flexion/extension isokinetic strength test, confirming the baseline homogeneity of the sample (Table 4). In this study, the within-trial coefficients of variations at the isokinetic strength test for all the obtained mean values were less than 10%.

TABLE 3

TABLE 3

TABLE 4

TABLE 4

At the end of the 8-week WBV additional treatment protocol, we observed an improvement in both groups. The analysis of the improvement of peak torque and maximum power values of knee flexor/extensor muscles measured between T0 and T1 demonstrated a highly significant statistical difference in all the isokinetic strength test parameters (P < 0.001) in both groups (Table 5).

TABLE 5

TABLE 5

The analysis between the 2 groups of peak torque and maximum power values of knee flexor/extensor muscles measured at T1 demonstrated a highly significant statistical difference in all the isokinetic strength test parameters (P < 0.001) in favor of the WBV group, reaching the primary outcome. The isokinetic strength test average values at T1 are shown in Table 6.

TABLE 6

TABLE 6

Comparisons between isokinetic strength parameters (quadriceps for knee extension and hamstring muscles for joint flexion) measured at T0 and T1 for both groups are shown in Figures 4-7.

Figure 4

Figure 4

Figure 5

Figure 5

Figure 6

Figure 6

Figure 7

Figure 7

Concerning the secondary outcome, the percent increases of tested isokinetic strength parameters in the WBV group in comparison to the control group in the strength test for the knee extensor muscles were respectively 8.93% and 10.90%, in peak torque and maximum power values, whereas the percent increases at endurance test for the knee extensor muscles were 7.66% and 7.00%, respectively.

In knee flexor muscles, the percentage increases at the strength test were as follows: peak torque 15.74% and maximum power 20.55%; the percent increases at endurance test were peak torque 25.51% and maximum power 16.48%. According to the statistical analysis, we observed a highly significant difference in all the percent improvement values (P < 0.001), completely reaching the secondary outcome (Table 7).

TABLE 7

TABLE 7

In our study, we noticed that the rehabilitation program and the additional treatment protocol with WBV platform had neither general and clinical side effects (variations in vital signs, lower limbs pain, and general malaise) nor complications related to vibratory therapy. There was high patient compliance with treatment.

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DISCUSSION

In our study, we obtained encouraging results in the recovery of strength of knee flexor/extensor muscles among athletes who underwent ACL arthroscopic reconstruction after an 8-week treatment with WBV board training. Although both groups improved values of peak torque and maximum power of knee flexor and extensor muscles, group B with WBV training obtained a meaningful significant increase (P < 0.001) in all parameters in comparison to the control group. The WBV protocol was well tolerated by all patients, and no adverse events were shown.

After ACL reconstruction, knee extensor muscle weakness remains a common enigma in postoperative patients, especially in the presence of pain and effusion.14

Rehabilitation plays an important role in facilitating muscle strength recovery among subjects who underwent ACL arthroscopic reconstruction. The recovery of muscle strength was positively influenced by mechanical vibration treatment integrated in the rehabilitation protocol. It could be hypothesized that neural adaptation responds to mechanical vibration, with an improvement in neuromuscular efficiency, attributed to a better motor units recruitment.20

The isokinetic strength test values in the group treated using WBV exercises were significantly higher than those recorded in the control group patients after the additional treatment protocol with WBV platform training. The difference in the percent increase of isokinetic strength peak torque values of knee extensor muscles measures was 8.93% (strength test) and 7.66% (endurance test), and therefore it should be not related to a placebo effect.

As a result, we could conclude that the increase in muscular strength values both in strength and endurance test in the WBV group will allow athletes in this group to recover lower limb dynamic stability better and faster, which is particularly important in returning to competition and obtaining high-level performances. Current rehabilitation programs focus on strengthening exercises, and also on proprioceptive and neuromuscular control drills, which provide a neurological stimulus that helps athletes in regaining the dynamic stability needed in athletic competition.14

The neural component is one of the supposed mechanisms for explaining the improvement of muscular performances because the vibration is thought to produce an effect similar to explosive impulse training. Whole-body vibration training has the potential to induce strength gains similar to those obtained with traditional resistance training program.18,33

Different frequencies of WBV have been used in literature, but the optimal frequency has not been identified yet. Frequencies greater than 20 Hz and amplitudes around 3 to 4 mm showed beneficial effects on athletes' performance.34,35 The greater amplitudes used in our studies (26 Hz) could have accounted for the positive effects.18

The results of our study agree with the current literature, affirming that low amplitude and high frequency WBV may be safe and effective in enhancing both strength and power muscle capacity in a rehabilitation program after surgery. The quick increase in strength recovery is also induced by neural factors, and it is probably related to the raising awareness of the stretch reflex that starts with a muscle contraction.15,17,19,33,36

The current literature shows better effects on strength among elite and professional athletes,16,26,28 but more positive results have also been shown among healthy and untrained subjects.19,37

A recent systematic review (Rehn et al38) has shown that there is strong to moderate evidence that exercises performed using WBV for a long time period may determine an increase in muscular performance, especially among untrained and elderly subjects in the long term.

Our study was performed on young subjects with muscular hypotrophy due to the arthroscopic reconstruction and the postsurgery rest, therefore it could be considered similar to a study with untrained patients who could benefit from neuronal adaptations induced by vibration.

Our aim was to test the rehabilitative exercise protocol performed on a group using the additional WBV treatment versus the control group treated with the same exercises without vibration, in patients after reconstruction of the ACL, also considering that only a few studies were performed on patients with functional disability.20,39

Our results agree with those shown by Salvarani et al20 who used WBV in 20 patients after reconstruction of the ACL (10 patients treated with WBV, 10 controls): this study showed an increase in both static and dynamic knee extensor muscle strength after 10 WBV treatment sessions (5 sets that lasted 1 minute per session) over a 2-week period.20

In our study, we have increased the total number of sessions (3 sessions per week for 8 weeks) to obtain a greater increase of knee flexor/extensor muscle strength in patients with muscular hypotrophy induced by the surgical ACL reconstruction.

The muscle performance benefit could be caused by neurogenic potentiation involving spinal reflexes and muscle activation, which are based on the tonic vibration reflex. The neural factors are responsible for muscular function increases, which are similar to the neural changes seen after several weeks of conventional resistance and impulse training.18

The simplicity of vibration exercise is paramount. Less time is needed to perform sessions on vibration platforms, and it requires less technical ability than free-weight resistance training program.

Moreover, in our study, patients of the WBV group showed a higher strength increase of knee flexor muscles when compared with the control group (+15.74% and +25.51% in strength and endurance test, respectively), which has not, however, been analyzed in other studies. It would be appreciated if, in patients undergoing the rehabilitation for the reconstruction of ACL, the increase of strength could be evaluated not only on the knee extensor muscles but also on knee flexor muscles, considering the relationship between agonistic and antagonistic muscles.

There are several limitations to consider. First, to make the groups more homogeneous, our study included only women athletes. It would be interesting to study the efficacy of the exercises in male/female participants. Second, our study included only a small number of participants. Future studies should ensure a larger sample size (athletes and untrained and sedentary people) to confirm our results.

A further limitation is that functional outcomes, such as ability to play volleyball or basketball or physical tests (eg, speed of running, endurance running or jump tests), have not been considered, as our outcomes are entirely physiological.

Finally, our study is also limited by the short period (from the 13th till the 20th week after surgery) during which the treatment with WBV was performed and by the absence of a long-term follow-up, considering the fact that a rehabilitation program for the reconstruction of ACL usually lasts from 4 to 6 months.

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CONCLUSIONS

Rehabilitation programs play an important role in facilitating the recovery of muscle strength. Neural adaptation occurs in response to mechanical vibration, causing an improvement in neuromuscular efficiency.20

This study suggests that WBV treatment (frequency 26 Hz and amplitude 4 mm) combined with standardized rehabilitation program may be a valid rehabilitation intervention after ACL reconstruction. Thanks to its high therapeutic efficiency, patients' satisfaction, and simple and repeatable protocol for use, WBV treatment seems to be a suitable training tool to improve motor and sporting performances, as it increases knee flexor/extensor muscle strength and therefore muscular function especially among athletes.

Moreover, the use of WBV should be considered for a longer period of time to evaluate strength increases at the end of a training program.

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References

1. Mohtadi N, Chan D, Barber R, et al. A randomized clinical trial comparing patellar tendon, hamstring tendon, and double-bundle ACL reconstructions: patient-reported and clinical outcomes at a minimal 2-year follow-up. Clin J Sport Med. 2015;25:321–331.
2. Silvers HJ, Mandelbaum BR. Prevention of anterior cruciate ligament injury in the female athlete. Br J Sports Med. 2007;41(suppl 1):i52–i59.
3. Giugliano DN, Solomon JL. ACL tears in female athletes. Phys Med Rehabil Clin N Am. 2007;18:417–438, viii.
4. Majewski M, Susanne H, Klaus S. Epidemiology of athletic knee injuries: a 10-year study. Knee. 2006;13:184–188.
5. Prodromos CC, Han Y, Rogowski J, et al. A meta-analysis of the incidence of anterior cruciate ligament tears as a function of gender, sport, and a knee injury-reduction regimen. Arthroscopy. 2007;23:1320–1325.
6. Deitch JR, Starkey C, Walters SL, et al. Injury risk in professional basketball players: a comparison of Women's National Basketball Association and National Basketball Association athletes. Am J Sports Med. 2006;34:1077–1083.
7. Spindler KP, Warren TA, Callison JC Jr, et al. Clinical outcome at a minimum of five years after reconstruction of the anterior cruciate ligament. J Bone Joint Surg Am. 2005;87:1673–1679.
8. Spindler KP, Wright RW. Clinical practice. Anterior cruciate ligament tear. N Engl J Med. 2008;359:2135–2142.
9. Lohmander LS, Englund PM, Dahl LL, et al. The long-term consequence of anterior cruciate ligament and meniscus injuries: osteoarthritis. Am J Sports Med. 2007;35:1756–1769.
10. Roi GS, Nanni G, Tencone F. Time to return to professional soccer matches after ACL reconstruction. Sport Sci Health. 2006;1:142–145.
11. Dye SF, Wojtys EM, Fu FH, et al. Factors contributing to function of the knee joint after injury or reconstruction of the anterior cruciate ligament. Instr Course Lect. 1999;48:185–198.
12. Kvist J. Rehabilitation following anterior cruciate ligament injury: current recommendations for sports participation. Sports Med. 2004;34:269–280.
13. Frobell RB, Roos EM, Roos HP, et al. A randomized trial of treatment for acute anterior cruciate ligament tears. N Engl J Med. 2010;363:331–342.
14. Wilk KE, Reinold MM, Hooks TR. Recent advances in the rehabilitation of isolated and combined anterior cruciate ligament injuries. Orthop Clin North Am. 2003;34:107–137.
15. Cardinale M, Bosco C. The use of vibration as an exercise intervention. Exerc Sport Sci Rev. 2003;31:3–7.
16. Bosco C, Cardinale M, Tsarpela O, et al. The influence of whole body vibration on jumping performance. Biol Sport. 1998;15:157–164.
17. Bosco C, Colli R, Introini E, et al. Adaptive responses of human skeletal muscle to vibration exposure. Clin Physiol. 1999;19:183–187.
18. Costantino C, Gimigliano R, Olvirri S, et al. Whole body vibration in sport: a critical review. J Sports Med Phys Fitness. 2014;54:757–764.
19. Rønnestad BR. Comparing the performance-enhancing effects of squats on a vibration platform with conventional squats in recreationally resistance-trained men. J Strength Cond Res. 2004;18:839–845.
20. Salvarani A, Agosti M, Zanré A, et al. Mechanical vibration in the rehabilitation of patients with reconstructed anterior cruciate ligament. Eur Med Phys. 2003;39:19–25.
21. Bosco C, Cardinale M, Tsarpela O. Influence of vibration on mechanical power and electromyogram activity in human arm flexor muscles. Eur J Appl Physiol Occup Physiol. 1999;79:306–311.
22. Bongiovanni LG, Hagbarth KE, Stjernberg L. Prolonged muscle vibration reducing motor output in maximal voluntary contractions in man. J Physiol. 1990;423:15–26.
23. Rittweger J, Beller G, Felsenberg D. Acute physiological effects of exhaustive whole-body vibration exercise in man. Clin Physiol. 2000;20:134–142.
24. Seidel H. Myoelectric reactions to ultra-low frequency and low-frequency whole body vibration. Eur J Appl Physiol Occup Physiol. 1988;57:558–562.
25. Bosco C, Iacovelli M, Tsarpela O, et al. Hormonal responses to whole-body vibration in men. Eur J Appl Physiol. 2000;81:449–454.
26. Cochrane DJ, Stannard SR. Acute whole body vibration training increases vertical jump and flexibility performance in elite female field hockey players. Br J Sports Med. 2005;39:860–865.
27. Delecluse C, Roelants M, Verschueren S. Strength increase after whole-body vibration compared with resistance training. Med Sci Sports Exerc. 2003;35:1033–1041.
28. Fagnani F, Giombini A, Di Cesare A, et al. The effects of a whole-body vibration program on muscle performance and flexibility in female athletes. Am J Phys Med Rehabil. 2006;85:956–962.
29. Melnyk M, Kofler B, Faist M, et al. Effect of a whole-body vibration session on knee stability. Int J Sports Med. 2008;29:839–844.
30. de Ruiter CJ, Van Raak SM, Schilperoort JV, et al. The effects of 11 weeks whole body vibration training on jump height, contractile properties and activation of human knee extensors. Eur J Appl Physiol. 2003;90:595–600.
31. de Ruiter CJ, van der Linden RM, van der Zijden MJ, et al. Short-term effects of whole-body vibration on maximal voluntary isometric knee extensor force and rate of force rise. Eur J Appl Physiol. 2003;88:472–475.
32. Risberg MA, Holm I, Myklebust G, et al. Neuromuscular training versus strength training during first 6 months after anterior cruciate ligament reconstruction: a randomized clinical trial. Phys Ther. 2007;87:737–750.
33. Torvinen S, Kannu P, Sievänen H, et al. Effect of a vibration exposure on muscular performance and body balance. Randomized cross-over study. Clin Physiol Funct Imaging. 2002;22:145–152.
34. Cardinale M, Wakeling J. Whole body vibration exercise: are vibrations good for you? Br J Sports Med. 2005;39:585–589; discussion 589.
35. Kinser AM, Ramsey MW, O'Bryant HS, et al. Vibration and stretching effects on flexibility and explosive strength in young gymnasts. Med Sci Sports Exerc. 2008;40:133–140.
36. Abercromby AF, Amonette WE, Layne CS, et al. Variation in neuromuscular responses during acute whole-body vibration exercise. Med Sci Sports Exerc. 2007;39:1642–1650.
37. Costantino C, Pogliacomi F, Soncini G. Effect of the vibration board on the strength of ankle dorsal and plantar flexor muscles: a preliminary randomized controlled study. Acta Biomed. 2006;77:10–16.
38. Rehn B, Lidström J, Skoglund J, et al. Effects on leg muscular performance from whole-body vibration exercise: a systematic review. Scand J Med Sci Sports. 2007;17:2–11.
39. Rittweger J, Just K, Kautzsch K, et al. Treatment of chronic lower back pain with lumbar extension and whole-body vibration exercise: a randomized controlled trial. Spine (Phila Pa 1976). 2002;27:1829–1834.
Keywords:

vibration; whole-body vibration; anterior cruciate ligament; athletes rehabilitation; strength recovery; isokinetic strength test

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