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.     

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 complex training on explosive strength in adolescent male basketball players

The purpose of this study was to evaluate the effects of a complex training program, a combined practice of weight training and plyometrics, on explosive strength development of young basketball players. Twenty-five young male athletes, aged 14-15 years old, were assessed using squat jump (SJ), countermovement jump (CMJ), Abalakov test (ABA), depth jump (DJ), mechanical power (MP), and medicine ball throw (MBT), before and after a 10-week in-season training program. Both the control group (CG; n = 10) and the experimental group (EG; n = 15) kept up their regular sports practice; additionally, the EG performed 2 sessions per week of a complex training program. The EG significantly improved in the SJ, CMJ, ABA, and MBT values (p < 0.05). The CG significantly decreased the values (p < 0.05) of CMJ, ABA, and MP, while significantly increasing the MBT values (p < 0.05). Our results support the use of complex training to improve the upper and lower body explosivity levels in young basketball players. In conclusion, this study showed that more strength conditioning is needed during the sport practice season. Furthermore, we also conclude that complex training is a useful working tool for coaches, innovative in this strength-training domain, equally contributing to a better time-efficient training.     

Influence of resistance training on cardiorespiratory endurance and muscle power and strength in young athletes

The purpose of this study was to investigate the influence of additional resistance training on cardiorespiratory endurance in young (15.8 ± 0.8 yrs) male basketball players. Experimental group subjects (n=23) trained twice per week for 12 weeks using a variety of general free-weight and machine exercises designed for strength acquisition, beside ongoing regular basketball training program. Control group subject (n=23) participated only in basketball training program. Oxygen uptake (VO(2max)) and related gas exchange measures were determined continuously during maximal exercise test using an automated cardiopulmonary exercise system. Muscle power of the extensors and flexors was measured by a specific computerized tensiometer. Results from the experimental group (VO(2max) 51.6 ± 5.7 ml.min(-1).kg(-1) pre vs. 50.9 ± 5.4 ml.min(-1).kg(-1) post resistance training) showed no change (p>0.05) in cardiorespiratory endurance, while muscle strength and power of main muscle groups increased significantly. These data demonstrate no negative cardiorespiratory performance effects on adding resistance training to ongoing regular training program in young athletes.     

Effects of 12-week medicine ball training on muscle strength and power in young female handball players

The purpose of this study was to examine the effects of medicine ball training on the strength and power in young female handball athletes. Twenty-one young female handball players (age, 16.9 ± 1.2 years) were randomly assigned to experimental and control groups. Experimental group (n = 11) participated in a 12-week medicine ball training program incorporated into the regular training session, whereas controls (n = 10) participated only in the regular training. Performance in the medicine ball throws in standing and sitting positions, 1 repetition maximum (1RM) bench and shoulder press, and power test at 2 different loads (30 and 50% of 1RM) on bench and shoulder press were assessed at pre- and posttraining testing. The athletes participating in the medicine ball training program made significantly greater gains in all medicine ball throw tests compared with the controls (p < 0.01). Also, the experimental group made significantly greater gains in bench and shoulder press power than control group (p < 0.05). Both training groups (E) and (C) significantly (p < 0.05) increased 1RM bench and shoulder strength, with no differences observed between the groups. Additionally, medicine ball throw tests showed stronger correlation with power tests, than with 1RM tests. These data suggest that 12-week medicine ball training, when incorporated into a regular training session, can provide greater sport-specific training improvements in the upper body for young female handball players.     

Effects of whole-body low-intensity resistance training with slow movement and tonic force generation on muscular size and strength in young men

Our previous study showed that relatively low-intensity (approximately 50% one-repetition maximum [1RM]) resistance training (knee extension) with slow movement and tonic force generation (LST) caused as significant an increase in muscular size and strength as high-intensity (approximately 80% 1RM) resistance training with normal speed (HN). However, that study examined only local effects of one type of exercise (knee extension) on knee extensor muscles. The present study was performed to examine whether a whole-body LST resistance training regimen is as effective on muscular hypertrophy and strength gain as HN resistance training. Thirty-six healthy young men without experience of regular resistance training were assigned into three groups (each n = 12) and performed whole-body resistance training regimens comprising five types of exercise (vertical squat, chest press, latissimus dorsi pull-down, abdominal bend, and back extension: three sets each) with LST (approximately 55-60% 1RM, 3 seconds for eccentric and concentric actions, and no relaxing phase); HN (approximately 80-90% 1RM, 1 second for concentric and eccentric actions, 1 second for relaxing); and a sedentary control group (CON). The mean repetition maximum was eight-repetition maximum in LST and HN. The training session was performed twice a week for 13 weeks. The LST training caused significant (p < 0.05) increases in whole-body muscle thickness (6.8 +/- 3.4% in a sum of six sites) and 1RM strength (33.0 +/- 8.8% in a sum of five exercises) comparable with those induced by HN training (9.1 +/- 4.2%, 41.2 +/- 7.6% in each measurement item). There were no such changes in the CON group. The results suggest that a whole-body LST resistance training regimen is as effective for muscular hypertrophy and strength gain as HN resistance training.     

Effects of explosive type strength training on physical performance characteristics in cross-country skiers

To investigate the effects of a combination of simultaneous strength and endurance training on selected neuromuscular and aerobic performance characteristics seven male cross-country skiers underwent training for a period of 6 weeks. The experimental group trained 6-9 times per week with a programme consisting of 34% explosive type strength training and 66% endurance training during the first 3 weeks of the experiment and 42% and 58% respectively during the last 3 weeks of the experiment. The total volume of training of the control group (eight skiers) was of the same magnitude but consisted of 85% pure endurance training and 15% endurance type strength training. The experimental training regime resulted in specific changes in neuromuscular performance. This was demonstrated by improvements (P less than 0.01) in the maximal heights of rise of the centre of gravity in the squat and countermovement jumps. A significant decrease (P less than 0.05) took place also in the time of rapid isometric force production during experimental training, while no changes occurred in the maximal force of the trained muscles. Aerobic performance characteristics of the experimental group did not change during the experimental training period. No significant changes occurred in neuromuscular or aerobic performance characteristics in the control group. These findings indicated that training-induced improvements in explosive force production may not be fully inhibited by this kind of aerobic training. They also suggested that endurance athletes could undertake explosive type strength training programmes without a concomitant reduction in aerobic capacity, if the overall loading of training were within predefined limits.     

Effects of lunar phases on short-term,explosive physical performance among young trained athletes

Beliefs that lunar phases affect human physiology started in ancient times. Research has recently revealed that a physical fitness index increased in sedentary students at the new moon (NM) and full moon (FM) compared to other moon phases. However, the effect of lunar cycle (moon illumination and gravitational pull) on physical performance in athletes was not examined. Therefore, this study aimed to evaluate whether short-term explosive performance can be influenced by the different phases of the lunar cycle. Fourteen young male Taekwondo athletes (age: 16.9 ± 0.7 years, height: 159.7 ± 50.6 cm, body mass: 62.85 ± 7.84 kg) performed the following tests to assess the explosive physical performance during the different phases of the lunar cycle (NM, FQ (first quarter), FM, and LQ (last quarter)): maximal isometric manual contraction (dominant hand (MIMCD) and non-dominant hand (MIMCND)), maximal back isometric contraction (MBIC), squat jump (SJ), countermovement jump (CMJ), and 10-m sprint (10 m). The testing sessions during the different moon phases were performed in a counterbalanced order. The order of tests remained the same (MIMCD, MIMCND, MBIC, SJ, CMJ, and 10 m), and all sessions were performed in the evening (6:00 to 8:00 p.m.) on the first day of each evaluated lunar phase. Each parameter was measured over two consecutive lunar months in the calendar. Analysis of variance tests showed that there was no significant effect of lunar cycle on all explosive test measures, p > 0.05. Our results failed to identify any effect of lunar phase on evening explosive performance (mainly involving phosphagen pathway-based efforts) among young trained athletes. Therefore, it appears that moon phase/illumination does not affect short-term physical performance in young trained adolescents.     

Effects of a shoulder injury prevention strength training program on eccentric external rotator muscle strength and glenohumeral joint imbalance in female overhead activity athletes

Imbalance of the eccentrically-activated external rotator cuff muscles versus the concentrically-activated internal rotator cuff muscles is a primary risk factor for glenohumeral joint injuries in overhead activity athletes. Nonisokinetic dynamometer based strength training studies, however, have focused exclusively on resulting concentric instead of applicable eccentric strength gains of the external rotator cuff muscles. Furthermore, previous strength training studies did not result in a reduction in glenoumeral joint muscle imbalance, thereby suggesting that currently used shoulder strength training programs do not effectively reduce the risk of shoulder injury to the overhead activity athlete. Two collegiate women tennis teams, consisting of 12 women, participated in this study throughout their preseason training. One team (n = 6) participated in a 5-week, 4 times a week, external shoulder rotator muscle strength training program next to their preseason tennis training. The other team (n = 6) participated in a comparable preseason tennis training program, but did not conduct any upper body strength training. Effects of this strength training program were evaluated by comparing pre- and posttraining data of 5 maximal eccentric external immediately followed by concentric internal contractions on a Kin-Com isokinetic dynamometer (Chattecx Corp., Hixson, Tennessee). Overall, the shoulder strength training program significantly increased eccentric external total work without significant effects on concentric internal total work, concentric internal mean peak force, or eccentric external mean peak force. In conclusion, by increasing the eccentric external total exercise capacity without a subsequent increase in the concentric internal total exercise capacity, this strength training program potentially decreases shoulder rotator muscle imbalances and the risk for shoulder injuries to overhead activity athletes.     

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.     

Effects of a 6-week periodized squat training with or without whole-body vibration upon short-term adaptations in squat strength and body composition

The purpose of this study was to examine the effects of a 6-week, periodized squat training program, with or without whole-body low-frequency vibration (WBLFV), applied before and between sets to 1RM squat strength and body composition. Thirty men aged between 20 and 30 years with at least 6 months of recreational weight training experience completed the study. Subjects were randomly assigned to either 1 of 2 training groups or to an active control group (CON). Group 1 (CON; n = 6) did not participate in the training protocol but participated only in testing sessions. Group 2 (SQTV, n = 13) performed 6 weeks of squat training while receiving WBLFV (50 Hz), before, and in-between sets. The third group (SQT, n = 11) performed 6 weeks of squat training only. Subjects completed 12 workouts with variable loads (55-90% one repetition maximum [1RM]) and sets (), performing squats twice weekly separated by 72 hours. The RM measures were recorded on weeks (W) 1, 3, and 7. During the second workout of a week, the load was reduced by 10-15%, with "speed squats" performed during the final 3 weeks. Rest periods in between sets were set at 240 seconds. The WBLFV was applied while subjects stood on a WBLFV platform holding an isometric quarter squat position (knee angle 135 ± 5°). Initially, WBLFV was applied at 50 Hz for 30 seconds at low amplitude (peak-peak 2-4 mm). A rest period of 180 seconds followed WBLFV exposure before the first set of squats. The WBLFV was then applied intermittently (3 × 10 seconds) at 50 Hz, high amplitude (peak-peak, 4-6 mm) at time points, 60, 120, and 180 seconds into the 240-second rest period. Total body dual x-ray absorptiometry scans were performed at W0 (week before training) and W7 (week after training). Measures recorded included total body mass (kg), total body lean mass (TLBM, kg), trunk lean mass (kg), leg lean mass (kg), total body fat percentage, trunk fat percentage, and leg fat percentage (LF%). Repeated-measures analysis of variance and analysis of covariance revealed 1RM increased significantly between W1-W3, W3-W7, and W1-W7 for both experimental groups but not for control (p = 0.001, effect size [ES] = 0.237, 1 - β = 0.947). No significant differences were seen for %Δ (p > 0.05). Significant group by trial and group effects were seen for TLBM, SQTV > CON at W7 (p = 0.044). A significant main effect for time was seen for LF%, W0 vs. W7 (p = 0.047). No other significant differences were seen (p > 0.05). "Practical trends" were seen favoring "short-term" neuromuscular adaptations for the SQTV group during the first 3 weeks (p = 0.10, ES = 0.157, 1 - β = 0.443, mean diff; SQTV week 3 4.72 kg > CON and 2.53 kg > SQT). Differences in motor unit activation patterns, hypertrophic responses, and dietary intake during the training period could account for the trends seen.     

Effects of localized and general fatigue on static and dynamic postural control in male team handball athletes

In team sports, sensorimotor impairments resulting from previous injuries or muscular fatigue have been suggested to be factors contributing to an increased injury risk. Although it has been widely shown that physical fatigue affects static postural sway, it is still questionable as to what extent these adaptations are relevant for dynamic, sports-related situations. The objective of this study was to determine the effects of whole-body and localized fatigue on postural control in stable and unstable conditions. Nineteen male team handball players were assessed in 2 sessions separated by 1 week. Treadmill running and single-leg step-up exercises were used to induce physical fatigue. The main outcome measures were center of pressure (COP) sway velocity during a single-leg stance on a force plate and maximum reach distances of the star excursion balance test (SEBT). The COP sway velocity increased significantly (p < 0.05) after general (+47%) and localized fatigue (+10%). No fatigue effects were found for the SEBT. There were no significant correlations between COP sway velocity and SEBT mean reach in any condition. The results showed that although fatigue affects static postural control, sensorimotor mechanisms responsible for regaining dynamic balance in healthy athletes seem to remain predominantly intact. Thus, our data indicate that the exclusive use of static postural sway measures might not be sufficient to allow conclusive statements regarding sensorimotor control in the noninjured athlete population.     

Effects of whole-body vibration on acute bone turnover marker responses to resistance exercise in young men

Objective:

We investigated acute bone turnover marker (BTM) responses to high-intensity resistance exercise with and without whole-body vibration (WBV) in young men (n=10).

Methods:

In this randomized crossover study, subjects performed 2 protocols separated by 2-week wash out periods: 1) resistance exercise only (RE) (3 sets 10 repetitions 80% 1RM for 9 exercises); and 2) WBV + RE (side-alternating vibration platform 5 intermittent, 1-minute bouts 20 Hz, 3.38 mm peak-to-peak displacement followed by RE). Fasting morning blood draws were taken before RE or WBV (PRE), immediately post RE (IP), and 30 minutes post RE (30P). WBV + RE also had a blood draw after the WBV exposure (POST WBV). Blood samples were analyzed for lactate, hematocrit, bone-specific alkaline phosphatase (Bone ALP, U/L), C-terminal telopeptide of type I collagen (CTX-I, ng/mL) and tartrate-resistant acid phosphatase 5b (TRAP5b, U/L).

Results:

Lactate, hematocrit, and Bone ALP significantly increased (p<0.05) IP for both protocols. Bone resorption markers did not change during RE only. CTX-I significantly decreased POST WBV. TRAP5b increased POST WBV, then significantly decreased at 30P.

Conclusions:

Generally, BTM changes to RE only were not significant when adjusted for hemoconcentration. The WBV stimulus altered bone resorption marker but not bone formation marker responses.     

Concurrent endurance and explosive type strength training increases activation and fast force production of leg extensor muscles in endurance athletes

The purpose of this experiment was to examine the effects of concurrent endurance and explosive strength training on electromyography (EMG) and force production of leg extensors, sport-specific rapid force production, aerobic capacity, and work economy in cross-country skiers. Nineteen male cross-country skiers were assigned to an experimental group (E, n = 8) or a control group (C, n = 11). The E group trained for 8 weeks with the same total training volume as C, but 27% of endurance training in E was replaced by explosive strength training. The skiers were measured at pre- and post training for concentric and isometric force-time parameters of leg extensors and EMG activity from the vastus lateralis (VL) and medialis (VM) muscles. Sport-specific rapid force production was measured by performing a 30-m double poling test with the maximal velocity (V(30DP)) and sport-specific endurance economy by constant velocity 2-km double poling test (CVDP) and performance (V(2K)) by 2-km maximal double poling test with roller skis on an indoor track. Maximal oxygen uptake (Vo(2)max) was determined during the maximal treadmill walking test with the poles. The early absolute forces (0-100 ms) in the force-time curve in isometric action increased in E by 18 +/- 22% (p < 0.05), with concomitant increases in the average integrated EMG (IEMG) (0-100 ms) of VL by 21 +/- 21% (p < 0.05). These individual changes in the average IEMG of VL correlated with the changes in early force (r = 0.86, p < 0.01) in E. V(30DP) increased in E (1.4 +/- 1.6%) (p < 0.05) but not in C. The V(2K) increased in C by 2.9 +/- 2.8% (p < 0.01) but not significantly in E (5.5 +/- 5.8%, p < 0.1). However, the steady-state oxygen consumption in CVDP decreased in E by 7 +/- 6% (p < 0.05). No significant changes occurred in Vo(2)max either in E or in C. The present concurrent explosive strength and endurance training in endurance athletes produced improvements in explosive force associated with increased rapid activation of trained leg muscles. The training also led to more economical sport-specific performance. The improvements in neuromuscular characteristics and economy were obtained without a decrease in maximal aerobic capacity, although endurance training was reduced by about 20%.     

Kettlebell swing training improves maximal and explosive strength

The aim of this study was to establish the effect that kettlebell swing (KB) training had on measures of maximum (half squat-HS-1 repetition maximum [1RM]) and explosive (vertical jump height-VJH) strength. To put these effects into context, they were compared with the effects of jump squat power training (JS-known to improve 1RM and VJH). Twenty-one healthy men (age = 18-27 years, body mass = 72.58 ± 12.87 kg) who could perform a proficient HS were tested for their HS 1RM and VJH pre- and post-training. Subjects were randomly assigned to either a KB or JS training group after HS 1RM testing and trained twice a week. The KB group performed 12-minute bouts of KB exercise (12 rounds of 30-second exercise, 30-second rest with 12 kg if <70 kg or 16 kg if >70 kg). The JS group performed at least 4 sets of 3 JS with the load that maximized peak power-Training volume was altered to accommodate different training loads and ranged from 4 sets of 3 with the heaviest load (60% 1RM) to 8 sets of 6 with the lightest load (0% 1RM). Maximum strength improved by 9.8% (HS 1RM: 165-181% body mass, p < 0.001) after the training intervention, and post hoc analysis revealed that there was no significant difference between the effect of KB and JS training (p = 0.56). Explosive strength improved by 19.8% (VJH: 20.6-24.3 cm) after the training intervention, and post hoc analysis revealed that the type of training did not significantly affect this either (p = 0.38). The results of this study clearly demonstrate that 6 weeks of biweekly KB training provides a stimulus that is sufficient to increase both maximum and explosive strength offering a useful alternative to strength and conditioning professionals seeking variety for their athletes.     

The acute effects of different training loads of whole body vibration on flexibility and explosive strength of lower limbs in divers

The purpose of this study was to examine the acute effects of different vibration loads (frequency and amplitude) of whole-body vibration (WBV) on flexibility and explosive strength of lower limbs in springboard divers. Eighteen male and female divers, aged 19 ± 2 years, volunteered to perform 3 different WBV protocols in the present study. To assess the vibration effect, flexibility and explosive strength of lower limbs were measured before (Pre), immediately after (Post 1) and 15 min after the end of vibration exposure (Post 15). Three protocols with different frequencies and amplitudes were used in the present study: a) low vibration frequency and amplitude (30 Hz/2 mm); b) high vibration frequency and amplitude (50 Hz/4 mm); c) a control protocol (no vibration). WBV protocols were performed on a Power Plate platform, whereas the no vibration divers performed the same protocol but with the vibration platform turned off. A two-way ANOVA 3 x 3 (protocol × time) with repeated measures on both factors was used. The level of significance was set at p < 0.05. Univariate analyses with simple contrasts across time were selected as post hoc tests. Intraclass coefficients (ICC) were used to assess the reliability across time. The results indicated that flexibility and explosive strength of lower limbs were significantly higher in both WBV protocols compared to the no vibration group (NVG). The greatest improvement in flexibility and explosive strength, which occurred immediately after vibration treatment, was maintained 15 min later in both WBV protocols, whereas NVG revealed a significant decrease 15 min later, in all examined strength parameters. In conclusion, a bout of WBV significantly increased flexibility and explosive strength in competitive divers compared with the NVG. Therefore, it is recommended to incorporate WBV as a method to increase flexibility and vertical jump height in sports where these parameters play an important role in the success outcome of these sports.     

Effects of muscular strength, exercise order, and acute whole-body vibration exposure on bat swing speed

The purposes for this study were to investigate effects of acute whole-body vibration (WBV) exposure and exercise order on bat speed and to examine relationship between muscular strength and bat speed. All participants were recreationally trained men (n = 16; 22 ± 2 years; 181.4 ± 7.4 cm; 84.7 ± 9 kg), with previous baseball experience and were tested for 1 repetitive maximum (1RM) strength in squat and bench press. Subjects then participated in 4 randomized sessions on separate days, each consisting of 3 sets of 5 bat swings. Exercises (upper and lower body dynamic and static movements related to bat swing) with or without WBV exposure were performed after sets 1 and 2. Trials were as follows: no-exercise Control (CTRL), upper body followed by lower body exercises without WBV (Arm-Leg NOVIB), upper body followed by lower body exercises with WBV (Arm-Leg VIB), and lower body followed by upper body exercises with WBV (Leg-Arm VIB). Bat speed was recorded during each swing and averaged across sets. Statistical analyses were performed to assess differences across sets and trials. Linear regressions analyzed relationship between strength and bat speed. A significant relationship existed between bat speed and lower body strength (r = 0.406, p = 0.008) but not for upper body strength. The exercise order of Arm-Leg VIB significantly increased bat speed by 2.6% (p = 0.02). Performing identical order of exercises without vibration (Arm-Leg NOVIB) significantly decreased bat speed by 2% (p = 0.039). It was concluded that adding vibration exposure to total-body exercises can provide acute enhancements in bat speed. Additionally, leg strength was shown to influence bat speed suggesting that increasing leg strength may enhance bat speed.     

Effects of tibialis anterior vibration on postural control when exposed to support surface translations

The sensory re-weighting theory suggests unreliable inputs may be down-weighted to favor more reliable sensory information and thus maintain proper postural control. This study investigated the effects of tibialis anterior (TA) vibration on center of pressure (COP) motion in healthy individuals exposed to support surface translations to further explore the concept of sensory re-weighting. Twenty healthy young adults stood with eyes closed and arms across their chest while exposed to randomized blocks of five trials. Each trial lasted 8?s, with TA vibration either on or off. After 2?s, a sudden backward or forward translation occurred. Anterior–posterior (A/P) COP data were evaluated during the preparatory (first 2?s), perturbation (next 3?s), and recovery (last 3?s) phases to assess the effect of vibration on perturbation response features. The knowledge of an impending perturbation resulted in reduced anterior COP motion with TA vibration in the preparatory phase relative to the magnitude of anterior motion typically observed during TA vibration. During the perturbation phase, vibration did not influence COP motion. However, during the recovery phase vibration induced greater anterior COP motion than during trials without vibration. The fact that TA vibration produced differing effects on COP motion depending upon the phase of the perturbation response may suggest that the immediate context during which postural control is being regulated affects A/P COP responses to TA vibration. This indicates that proprioceptive information is likely continuously re-weighted according to the context in order to maintain effective postural control.     

Effects of whole-body vibration on bone properties in aged rats

Objective:This study aimed to explore optimal conditions of whole-body vibration (WBV) for improving bone properties in aged rats.Methods:Eighty-week-old rats were divided into baseline control (BC), age-matched control (CON) and experimental groups, which underwent WBV (0.5 g) at various frequencies (15, 30, 45, 60 or 90 Hz) or WBV (45 Hz) with various magnitudes (0.3, 0.5, 0.7 or 1.0 g) for 7 weeks. After interventions, femur bone size, bone mechanical strength and circulating bone formation/resorption markers were measured, and trabecular bone microstructure (TBMS) and cortical bone geometry (CBG) of femurs were analyzed by micro-CT.Results:Several TBMS parameters and trabecular bone mineral content were significantly lower in the 15 Hz WBV (0.5 g) group than in the CON group, suggesting damage to trabecular bone. On the other hand, although frequency/magnitude of WBV did not influence any CBG parameters, the 0.7 g and 1.0 g WBV (45 Hz) group showed an increase in tissue mineral density of cortical bone compared with the BC and CON groups, suggesting the possibility of improving cortical bone properties.Conclusion:Based on these findings, it should be noted that WBV conditions are carefully considered when applied to elderly people.     

Acute enhancement of lower-extremity dynamic strength and flexibility with whole-body vibration

The purpose of this investigation was to examine the acute effects of whole-body vibration (WBV) on muscular strength, flexibility, and heart rate (HR). Twenty adults (10 men, 10 women) untrained to WBV participated in the study. All subjects completed assessment of lower-extremity isokinetic torque, flexibility, and HR immediately before and after 6 minutes of WBV and 6 minutes of leg cycling ergometry (CYL), in randomized order. During WBV, subjects stood upright on a vibration platform for a total of 6 minutes. Vibration frequency was gradually increased during the first minute to a frequency of 26 Hz, which was maintained for the remaining 5 minutes. During CYL, power output was gradually increased to 50 W during the first minute and maintained at that power output for the remaining 5 minutes. Lower-extremity flexibility was determined using the sit-and-reach box test. Peak and average isokinetic torque of knee extension and flexion were measured by means of a motor-driven dynamometer with velocity fixed at 120 degrees .s. Change scores for the outcome measures were compared between treatments using Student's paired t-tests. Analysis revealed significantly greater HR acceleration with CYL (24.7 bpm) than after WBV (15.8 bpm). The increase of sit-and-reach scores after WBV (4.7 cm) was statistically greater (p < 0.05) than after CYL (0.8 cm). After WBV, increases in peak and average isokinetic torque of knee extension, 7.7% and 9.6%, were statistically greater than after CYL (p < 0.05). Average torque of knee flexion also increased more with WBV (+7.8%) than with CYL (-1.5%) (p < 0.05). The findings of this study indicate that short-term WBV standing elicits acute enhancements of lower-extremity muscular torque and flexibility, suggesting the application of this technology as a preparatory activity before more intense exercise.