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.     

Acute effect of whole-body vibration on power, one-repetition maximum, and muscle activation in power lifters

The purpose of this study was to investigate the acute effect of whole-body vibration with a frequency of 50 Hz (WBV(50Hz)) on peak power in squat jump (SJ), 1 repetition maximum (1RM) in parallel squat, and electromyography (EMG) activity and compare them with no-vibration conditions in power lifters. Twelve national level male power lifters (age 24 ± 5 years, body mass 110 ± 24 kg, height 179 ± 7 cm) tested peak power in SJ and 1RM in parallel squat while they were randomly exposed to WBV(50Hz) or to no vibration. These tests were performed in a Smith Machine. Peak power output was higher while performed with a WBV(50Hz) compared with the no-WBV condition (p < 0.05). This increase in power output was accompanied by higher EMG starting values and EMG peak values of the investigated thigh muscles during WBV(50Hz) (p < 0.05). There was no difference between adding WBV(50Hz) and no-vibration conditions in 1RM parallel squat. In conclusion, the results of this study suggest that the application of WBV(50Hz) acutely increases peak power output during SJ in well strength trained individuals such as power lifters. This increase in power was accompanied by an increased EMG activity in the quadriceps muscles. However, in 1RM parallel squat, there was no difference between WBV50Hz and no-vibration conditions. Therefore, adding WBV(50Hz) has no acute additive effect on 1RM parallel squat in power lifters and, based on the present findings, may thus not be recommended in the training to improve 1RM in power lifters. However, WBV(50Hz) seems to have an acute additive effect on peak power output and may be used in well strength trained individuals for whom a high power output is important for performance.     

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.     

Effects of electromyostimulation training and volleyball practice on jumping ability

The aim of this study was to investigate the influence of a 4-week electromyostimulation (EMS) training program on the vertical jump performance of 12 volleyball players. EMS sessions were incorporated into volleyball sessions 3 times weekly. EMS consisted of 20-22 concomitant stimulations of the knee extensor and plantar flexor muscles and lasted approximately 12 minutes. No significant changes were observed after EMS training for squat jump (SJ) and counter movement jump (CMJ) performance, while the mean height and the mean power maintained during 15 seconds of consecutive CMJs significantly increased by approximately 4% (p < 0.05). Ten days after the end of EMS training, the jumping height significantly (p < 0.05) increased compared with baseline also for single jumps (SJ +6.5%, CMJ +5.4%). When the aim of EMS resistance training is to enhance vertical jump ability, sport-specific workouts following EMS would enable the central nervous system to optimize the control to neuromuscular properties.     

THE ACUTE EFFECT OF WHOLE BODY VIBRATION TRAINING ON FLEXIBILITY AND EXPLOSIVE STRENGTH OF YOUNG GYMNASTS

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

EFFECTS OF WHOLE BODY VIBRATION ON STRENGTH AND JUMPING PERFORMANCE IN VOLLEYBALL AND BEACH VOLLEYBALL PLAYERS

The primary aim of this study was to examine the effects of 6-week strength training with whole body vibration (WBV) on leg strength and jumping performance in volleyball and beach volleyball players. Twenty-three sub-elite male volleyball (VB; n=12) and beach volleyball players (BVB; n=11) aged 21.2±3.0 years were divided into two groups and subjected to 6 weeks of strength training (three one-hour sessions per week): (I) 12 players (6 VB and 6 BVB players) underwent training with WBV (30-40 Hz, 1.7-2.5 mm, 3.0-5.7 g), and (II) 11 players (6 VB and 5 BVB players) underwent traditional strength training. Squat jump (SJ) and countermovement squat jump (CMJ) measurements by the Ergo Tester contact platform and maximum leg press test (1RM) were conducted. Three-factor (2 time x 2 WBV use x 2 discipline) analysis of variance for SJ, CMJ and 1RM revealed a significant time main effect (p<0.001), a WBV use effect (p<0.001) and a discipline effect (p<0.001). Significantly greater improvements in the SJ (p<0.001) and CMJ (p<0.001) and in 1RM (p<0.001) were found in the WBV training groups than in traditional training groups. Significant 3-way interaction effects (training, WBV use, discipline kind) were also found for SJ, CMJ and 1RM (p=0.001, p<0.001, p=0.001, respectively). It can be concluded that implementation of 6-week WBV training in routine practice in volleyball and beach volleyball players increases leg strength more and leads to greater improvement in jump performance than traditional strength training, but greater improvements can be expected in beach volleyball players than in volleyball players.     

Short-term effects of selected exercise and load in contrast training on vertical jump performance

The present study examined the short-term effects of loaded half squats (HSs) and loaded jump squats (JSs) with low and moderate loads on the squat jump (SJ) and the countermovement jump (CMJ) performance using a contrast training approach. Ten men (mean +/- SD age, 23 +/- 1.8 years) performed the HS and JS exercises twice with loads of 30% of 1 repetition maximum (1RM) (HS30% and JS30%, respectively) and 60% of 1RM (HS60% and JS60%, respectively). On each occasion, 3 sets of 5 repetitions with 3 minutes of rest were performed as fast as possible. Vertical jump performance was measured before exercise, 1 minute after each set, and at the fifth and 10th minutes of recovery. The CMJ increased significantly after the first and second set (3.9%; p < 0.05) compared with preexercise values following the JS30% protocol and 3.3% after the second and third sets of the JS60% protocol. Following the HS60% protocol, CMJ increased after the first and the second sets (3.6%; p < 0.05) compared with preexercise values, whereas SQ increased only after the first set (4.9%; p < 0.05) in this condition. These data show that contrast loading with the use of low and moderate loads can cause a short-term increase in CMJ performance. The applied loads do not seem to present different short-term effects after loaded JSs. When the classic form of dynamic HS exercise is performed, however, at least a moderate load (60% of 1RM) needs to be applied.     

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.     

Effects of drop jumps added to the warm-up of elite sport athletes with a high capacity for explosive force development

The purpose of this study was to evaluate the immediate influence of eccentric muscle action on vertical jump performance in athletes performing sports with a high demand of explosive force development. In this randomized, controlled crossover trial, 13 Swiss elite athletes (national team members in ski jump, ski alpine, snowboard freestyle and alpine, ski freestyle, and gymnastics) with a mean age of 22 years (range 20-28) were randomized into 2 groups. After a semistandardized warm-up, group 1 did 5 jumps from a height of 60 cm, landing with active stabilization in 90 degrees knee flexion. One minute after these modified drop jumps, they performed 3 single squat jumps (SJ) and 3 single countermovement jumps (CMJ) on a force platform. The athletes repeated the procedure after 1 hour without the modified drop jumps. In a crossover manner, group 2 did the first warm-up without and the second warm-up with the modified drop jumps. Differences of the performance (jump height and maximal power) between the different warm-ups were the main outcomes. The mean absolute power and absolute height (without drop jumps) were CMJ 54.9 W.kg(-1) (SD = 4.1), SJ 55.0 W.kg(-1) (SD = 5.1), CMJ 44.1 cm (SD = 4.1), and SJ 40.8 cm (SD = 4.1). A consistent tendency for improvement with added drop jumps to the warm-up routine was observed compared with warm-up without drop jumps: maximal power CMJ +1.02 W.kg(-1) (95% confidence interval [CI] = +0.03 to +2.38), p = 0.045; maximal power SJ +0.8 W.kg(-1) (95% CI = -0.34 to +2.02), p = 0.148; jump height CMJ +0.48 cm (95% CI = -0.26 to +1.2), p = 0.182; SJ +0.73 cm (95% CI = -0.36 to +1.18), p = 0.169. Athletes could add modified drop jumps to the warm-up before competitions to improve explosive force development.     

Longitudinal tracking of muscular power changes of NCAA Division I collegiate women gymnasts

Gymnastics relies upon power as a critical component of sports-specific fitness. The purpose of this study was to monitor long-term training adaptations in the power of National Collegiate Athletics Association Division I women gymnasts. Twenty members of a women's gymnastic team (aged 18-22) were tracked over 3 years with the first year a baseline year of testing. Whole body power for the counter-movement (CMJ) and squat (SJ) vertical jump was obtained via force plate analyses at 2 assessment time points during each year (February and November). Results showed significant (p < or = 0.05) and continued increases in peak power output in the CMJ and SJ at each biannual assessment. Improvements of 46% (+1010 W) for the CMJ and 43% (+900 W) for the SJ were observed at the end of the tracking period. Peak power for the CMJ and SJ were recorded at 3210 W (+/-350 W) and 3000 W (+/-152 W), respectively. Associated improvements in the time to peak power of 36% (-0.239 second) and 38% (-0.151 second) were also found for the CMJ and SJ. There were no significant changes in body mass or total skinfold thickness, however, a shift toward improved fat free mass (i.e., lean muscle mass) was apparent. These data underscore the importance that specificity, and more importantly power development, should play in the conditioning of collegiate women gymnasts' training programs.     

Low load exercises targeting the gluteal muscle group acutely enhance explosive power output in elite athletes

The purpose of this study was to investigate the acute effect of 3 warm-up protocols on peak power production during countermovement jump (CMJ) testing. The intention was to devise and compare practical protocols that could be applied as a warm-up immediately before competition matches or weight training sessions. A group of 22 elite Australian Rules Football players performed 3 different warm-up protocols over 3 testing sessions in a randomized order. The protocols included a series of low load exercises targeting the gluteal muscle group (GM-P), a whole-body vibration (WBV) protocol (WBV-P) wherein the subjects stood on a platform vibrating at 30 Hz for 45 seconds, and a no-warm-up condition (CON). The CMJ testing was performed within 5 minutes of each warm-up protocol on an unloaded Smith machine using a linear encoder to measure peak power output. Peak power production was significantly greater after the GM-P than after both the CON (p < 0.05) and WBV-P (p < 0.01). No significant differences in peak power production were detected between the WBV-P and CON. These results have demonstrated that a low load exercise protocol targeting the gluteal muscle group is effective at acutely enhancing peak power output in elite athletes. The mechanisms for the observed improvements are unclear and warrant further investigation. Coaches may consider incorporating low load exercises targeting the gluteal muscle group into the warm-up of athletes competing in sports requiring explosive power output of the lower limbs.     

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.     

Acute effects of whole-body vibration on muscle activity, strength, and power

The purpose of this study was to investigate the effects of a single bout of whole-body vibration on isometric squat (IS) and countermovement jump (CMJ) performance. Nine moderately resistance-trained men were tested for peak force (PF) during the IS and jump height (JH) and peak power (PP) during the CMJ. Average integrated electromyography (IEMG) was measured from the vastus medialis, vastus lateralis, and biceps femoris muscles. Subjects performed the 2 treatment conditions, vibration or sham, in a randomized order. Subjects were tested for baseline performance variables in both the IS and CMJ, and were exposed to either a 30-second bout of whole-body vibration or sham intervention. Subjects were tested immediately following the vibration or sham treatment, as well as 5, 15, and 30 minutes posttreatment. Whole-body vibration resulted in a significantly higher (p < or = 0.05) JH during the CMJ immediately following vibration, as compared with the sham condition. No significant differences were observed in CMJ PP; PF during IS or IEMG of the vastus medialis, vastus lateralis, or biceps femoris during the CMJ; or IS between vibration and sham treatments. Whole-body vibration may be a potential warm-up procedure for increasing vertical JH. Future research is warranted addressing the influence of various protocols of whole-body vibration (i.e., duration, amplitude, frequency) on athletic performance.     

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.     

Effects of resistance training on the physical capacities of adolescent soccer players

This study examined the effects of a progressive resistance training program in addition to soccer training on the physical capacities of male adolescents. Eighteen soccer players (age: 12-15 years) were separated in a soccer (SOC; n = 9) and a strength-soccer (STR; n = 9) training group and 8 subjects of similar age constituted a control group. All players followed a soccer training program 5 times a week for the development of technical and tactical skills. In addition, the STR group followed a strength training program twice a week for 16 weeks. The program included 10 exercises, and at each exercise, 2-3 sets of 8-15 repetitions with a load 55-80% of 1 repetition maximum (1RM). Maximum strength ([1RM] leg press, bench-press), jumping ability (squat jump [SJ], countermovement jump [CMJ], repeated jumps for 30 seconds) running speed (30 m, 10 x 5-m shuttle run), flexibility (seat and reach), and soccer technique were measured at the beginning, after 8 weeks, and at the end of the training period. After 16 weeks of training, 1RM leg press, 10 x 5-m shuttle run speed, and performance in soccer technique were higher (p < 0.05) for the STR and the SOC groups than for the control group. One repetition maximum bench press and leg press, SJ and CMJ height, and 30-m speed were higher (p < 0.05) for the STR group compared with SOC and control groups. The above data show that soccer training alone improves more than normal growth maximum strength of the lower limps and agility. The addition of resistance training, however, improves more maximal strength of the upper and the lower body, vertical jump height, and 30-m speed. Thus, the combination of soccer and resistance training could be used for an overall development of the physical capacities of young boys.     

Influence of preactivity and eccentric muscle activity on concentric performance during vertical jumping

The purpose of this investigation was to observe the influence of increasing amounts of preactivity and eccentric muscle activity imposed by three different jump types on concentric vertical jumping performance. Sixteen athletes involved in jumping-related sports at Appalachian State University, which is a Division IA school, performed a static jump (SJ), counter-movement jump (CMJ), and drop jump (DJ). Force, power, velocity, and jump height were measured during each jump type. In addition, muscle activity was measured from two agonist muscles (vastus lateralis, vastus medialis) and one antagonist muscle (biceps femoris). Preactivity and eccentric phase muscle activity of the agonist muscles (average integrated electromyography) was significantly (p < or = 0.05) higher during the DJ (preactivity, 0.2 +/- 0.11 mV; eccentric phase, 1.00 +/- 0.36 mV) in comparison with the CMJ (preactivity, 0.11 +/- 0.10 mV; eccentric phase, 0.45 +/- 0.17 mV). Peak concentric force was highest during the DJ and was significantly different among all three jump types (SJ, CMJ, DJ). Maximal jump height was significantly higher during the DJ (0.41 +/- 0.05 m) and CMJ (0.40 +/- 0.06 m) compared with the SJ (0.37 +/- 0.07 m). However, no significant difference in jump height existed between the CMJ and DJ. A positive energy balance, as assessed by force-displacement curves during the eccentric and concentric phases, was observed during the CMJ, and a negative energy balance was observed during the DJ. The data from this investigation indicate that a significant increase in concentric vertical jump performance is associated with increased levels of preactivity and eccentric phase muscle activity (SJ to CMJ). However, higher eccentric loading (CMJ to DJ) leads to a negative energy balance during the eccentric phase, which may relate to a non-significant increase in vertical jump height, even with coincidental increases in peak concentric force. Practitioners may want to focus on improving eccentric phase muscle activity through the use of plyometrics to improve overall jumping performance in athletes.     

Effects of general,specific and combined warm-up on explosive muscular performance

The purpose of this study was to compare the acute effects of general, specific and combined warm-up (WU) on explosive performance. Healthy male (n = 10) subjects participated in six WU protocols in a crossover randomized study design. Protocols were: passive rest (PR; 15 min of passive rest), running (Run; 5 min of running at 70% of maximum heart rate), stretching (STR; 5 min of static stretching exercise), jumping [Jump; 5 min of jumping exercises – 3x8 countermovement jumps (CMJ) and 3x8 drop jumps from 60 cm (DJ60)], and combined (COM; protocols Run+STR+Jump combined). Immediately before and after each WU, subjects were assessed for explosive concentric-only (i.e. squat jump – SJ), slow stretch-shortening cycle (i.e. CMJ), fast stretch-shortening cycle (i.e. DJ60) and contact time (CT) muscle performance. PR significantly reduced SJ performance (p =0.007). Run increased SJ (p =0.0001) and CMJ (p =0.002). STR increased CMJ (p =0.048). Specific WU (i.e. Jump) increased SJ (p =0.001), CMJ (p =0.028) and DJ60 (p =0.006) performance. COM increased CMJ performance (p =0.006). Jump was superior in SJ performance vs. PR (p =0.001). Jump reduced (p =0.03) CT in DJ60. In conclusion, general, specific and combined WU increase slow stretch-shortening cycle (SSC) muscle performance, but only specific WU increases fast SSC muscle performance. Therefore, to increase fast SSC performance, specific fast SSC muscle actions must be included during the WU.     

Effect of loading on enhancement of power performance over three consecutive trials

The acute effects of maximal voluntary isometric contractions (MVICs) in the squat position on subsequent measures of power output over 3 consecutive sets were investigated. Sixteen trained men experienced with back squats participated in the study. A 7-second MVIC was performed 4 minutes before the execution of 5 maximal countermovement jumps (CMJs) and was repeated for 3 consecutive sets (protocol 1). The results were compared to power output performance in a similar protocol (protocol 2) that excluded the 7-second MVICs. No significant differences occurred in any of the power output measurements between protocol 1 and protocol 2, nor did significance occur linearly across the 4 sets of CMJ, with the exception of a decrease in peak power in protocol 2 (p < or = 0.05). Using both mean and maximal values only one significant correlation between either relative strength and performance enhancement or absolute strength and performance enhancement was present at p < or = 0.01. At p < or = 0.05, significant correlations were found between absolute strength and mean peak power (PP), mean peak acceleration (PA), mean peak force (PF), max PP, max PA, max PF, and max peak velocity. These data indicate that the execution of an MVIC performed before a power exercise was inadequate to acutely enhance power output over any of 3 consecutive trials.     

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.