THE POST-ACTIVATION EFFECT OF COMBINED RESISTED AND ASSISTED SPRINTS

Resisted and assisted training methods aim to increase neural activation, or post-activation potentiation (PAP), to enhance sprint performance. A preloaded stimulus causes a temporary performance increase that is more significant than what warm-up alone can provide. Resistance activities have traditionally been used to induce post-activation potentiation. Little is known when assisted and resisted sprints are combined and their effect on PAP. Therefore, this study aimed to examine the acute potentiating effect of combined resisted and assisted sprints on subsequent 20 m sprint performance. Sixteen physically active young males performed a baseline 20 m sprint followed by four assisted 20 m and four 20 m resisted sprints using a bungee cord. After the assisted-resisted stimulus, the participants performed one 20 m sprint at 4, 6, and 8 minutes. There was no significant improvement in 5, 10, or 20-m sprint times following the assisted-resisted stimulus. Therefore, the additive effect of assisted-resisted sprints failed to induce post-activation potential. The additive effect of assisted-resisted sprints could not induce post-activation potential to enhance subsequence sprint performance

Is there an optimal whole-body vibration exposure ‘dosage’ for performance improvement?

International Journal of Exercise Science 7(3) : 169-178, 2014. Whole-body vibration exposure has been shown to improve performance in vertical jumping and knee extensions. Some studies have addressed the question of dose optimality, but are inconclusive and inappropriately designed. Our purpose was to more thoroughly seek an optimum combination of duration, amplitude and frequency of exposure to side-alternating whole-body vibration. We used experimental designs constructed for response surface fitting and optimisation, using both blocked and unblocked second order central composite designs with 12 participants. Immediately after each exposure a discomfort index was recorded, then peak and average torque, peak and average jump height, together with peak and average jump power were recorded over three trials both pre- and post-exposure at each treatment combination. ANOVA revealed that all performance measures improved after vibration exposure. However, no successful response surface fits could be achieved for any of the performance measures, except weakly for average jump height and average jump power for a single subject. Conversely, the discomfort index increased linearly with both vibration amplitude and frequency, more steeply as exposure duration increased. We conclude that although vibration exposure has a significant positive effect on performance, its effect is so variable both between and within individuals that no real optimum can be discerned; and that high amplitudes, frequencies and durations lead to excessive discomfort

No acute effect of whole-body vibration on Roundhouse kick and countermovement jump performance of competitive Taekwondo athletes

Little is known about the effect of whole body vibration (WBV) has on specific sports action such as taekwondo kicking technique.  Fifteen  individuals (10 males and 5 females; 18.6 ± 2.1 years), performed two experimental protocols on separate days: A) 1 minute exposure at 26 Hz frequency of WBV followed by countermovement jump (CMJ) test; B) 1 minute exposure at 26 Hz frequency of WBV followed by kick test. A Student’s t-Test analysis was performed to evaluate the difference between performance before and after vibration intervention. The CMJ height means (cm) were 34.1 ± 6.4 before and 34.2 ± 6.5 after WBV exposure. The CMJ maximal force means were 1582.6 ± 214.3 before WBV and 1595.7 ± 205.0 after WBV, while Impulse means (N.s) were 283.3 ± 48.6 before WBV and 282.6 ± 46.6 after WBV. The kick time means (ms) were 219.9±20.31 before WBV and 218.9±19.81 after WBV. No significant differences were found regarding the application of mechanical vibration for all variables. Thus, the vibration intervention (1 minute of WBV at 26 Hz and 6 mm) adopted in this present study may have not been substantial to improve Roundhouse kick time (p=0.73), jump height (p=0.80), maximal force (p=0.78) and impulse (p=0.38) of taekwondo athletes. Future studies should investigate new vibration protocols (amplitude, frequency) and training (intensity, exercise, duration) to determine optimal parameters

Potential Application of Whole Body Vibration Exercise for Improving the Clinical Conditions of COVID-19 Infected Individuals: A Narrative Review from the World Association of Vibration Exercise Experts (WAVex) Panel

COVID-19 is a highly infectious respiratory disease which leads to several clinical conditions related to the dysfunction of the respiratory system along with other physical and psychological complaints. Severely affected patients are referred to intensive care units (ICUs), limiting their possibilities for physical exercise. Whole body vibration (WBV) exercise is a non-invasive, physical therapy, that has been suggested as part of the procedures involved with pulmonary rehabilitation, even in ICU settings. Therefore, in the current review, the World Association of Vibration Exercise Experts (WAVEX) reviewed the potential of WBV exercise as a useful and safe intervention for the management of infected individuals with COVID-19 by mitigating the inactivity-related declines in physical condition and reducing the time in ICU. Recommendations regarding the reduction of fatigue and the risk of dyspnea, the improvement of the inflammatory and redox status favoring cellular homeostasis and the overall improvement in the quality of life are provided. Finally, practical applications for the use of this paradigm leading to a better prognosis in bed bound and ICU-bound subjects is proposed

Acute whole-body vibration elicits post-activation potentiation

Whole-body vibration (WBV) leads to a rapid increase in intra-muscular temperature and enhances muscle power. The power-enhancing eVects by WBV can, at least in part, be explained by intra-muscular temperature. However, this does not exclude possible neural eVects of WBV occurring at the spinal level. The aim of this study was to examine if muscle twitch and patellar reXex properties were simultaneously potentiated from an acute bout of WBV in a static squat position. Six male and six female athletes performed three interventions for 5 min, static squat with WBV (WBV+, 26 Hz), static squat without WBV (WBV¡) and stationary cycling (CYCL, 70 W). Transcutaneous muscle stimulation consisting of a single 200 s pulse and three patellar tendon taps were administered prior to and then 90 s, 5, 10 min post-intervention. Ninety-seconds after WBV+ muscle twitch peak force (PF) and rate of force development (RFD) were signiWcantly higher (P < 0.01) compared to WBV¡ and CYCL. However the patellar tendon reXex was not potentiated. An acute continuous bout of WBV caused a post-activation potentiation (PAP) of muscle twitch potentiation (TP) compared to WBV¡ and CYCL indicating that a greater myogenic response was evident compared to a neural-mediated eVect of a reXex potentiation (RP)

THE POTENTIAL NEURAL MECHANISMS OF ACUTE INDIRECT VIBRATION

There is strong evidence to suggest that acute indirect vibration acts on muscle to enhance force, power, flexibility, balance and proprioception suggesting neural enhancement. Nevertheless, the neural mechanism(s) of vibration and its potentiating effect have received little attention. One proposal suggests that spinal reflexes enhance muscle contraction through a reflex activity known as tonic vibration stretch reflex (TVR), which increases muscle activation. However, TVR is based on direct, brief, and high frequency vibration (>100 Hz) which differs to indirect vibration, which is applied to the whole body or body parts at lower vibration frequency (5-45 Hz). Likewise, muscle tuning and neuromuscular aspects are other candidate mechanisms used to explain the vibration phenomenon. But there is much debate in terms of identifying which neural mechanism(s) are responsible for acute vibration; due to a number of studies using various vibration testing protocols. These protocols include: different methods of application, vibration variables, training duration, exercise types and a range of population groups. Therefore, the neural mechanism of acute vibration remain equivocal, but spinal reflexes, muscle tuning and neuromuscular aspects are all viable factors that may contribute in different ways to increasing muscular performance. Additional research is encouraged to determine which neural mechanism(s) and their contributions are responsible for acute vibration. Testing variables and vibration applications need to be standardised before reaching a consensus on which neural mechanism(s) occur during and post-vibratio

Shaking weight loss away - Can vibration exercise reduce body fat?

An exercise modality that requires little time and physical exertion whilst providing the benefits of increased force, power, balance, flexibility, and weight loss would appeal to most people that may be at risk from an imbalanced lifestyle. One such exercise modality that has received a lot of attention has been vibration exercise (VbX), which evokes muscular work and elevates metabolic rate could be a potential method for weight reduction. Popular press has purported that VbX is quick, convenient, and 10 minutes of VbX is equivalent to one hour of traditional exercise, where it has been marketed as the new weight-loss and body toning workout. However, research studies have shown that muscle activation is elicited but the energy demand in response to VbX is quite low. Exhaustive VbX has been reported to produce a metabolic demand of 23 ml/kg/min compared to 44 ml/kg/min from an exhaustive cycle test. Different vibration frequencies have been tested with varying amplitudes and loads, but only small increases in metabolic rate have been reported. Based on these findings it has been indirectly calculated that a VbX session of 26Hz for 3 continuous minutes would only incur a loss of ~ 10.7g fat/hr. Following a 24-week programme of VbX, no observed differences were found in body composition and following 12 months of VbX the time to reach peak O2 was significantly higher in conventional exercise compared to VbX. However, one study has reported that percentage body fat decreased by 3.2% after eight months after VbX in comparison to resistance and control groups that performed no aerobic conditioning. The evidence to date, suggests that VbX can increase whole and local oxygen uptake; however, with additional load, high vibration frequency and/or amplitude it cannot match the demands of conventional aerobic exercise. Therefore, caution is required when VbX programmes are solely used for the purpose of reducing body fat without considering dietary and aerobic conditioning guidelines

The effect of vibration exercise on aspects of muscle physiology and muscular performance : a thesis submitted in partial fulfilment of the requirements for the degree of Doctor of Philosophy, Massey University, Palmerston North, New Zealand

It has been proposed that the increases in muscle force and power following acute vibration exercise are similar to that of several weeks of conventional resistance or explosive power training. Further, it has been purported that vibration exercise operates via a stretch-reflex response which elicits a small change in muscle length. However, despite its wide use there remain gaps of knowledge on aspects such as physiological effects, mechanism of action, clinical effects, and even details of regimens for particular therapeutic use. Therefore, the aim of this thesis was to investigate the acute effects of vibration exercise on muscle performance and to examine the physiological aspects of its use in the young and older people, and competitive athletes. This thesis reported that acute upper-body vibration enhanced concentric peak power, but it was not significantly greater than concentric (arm-cranking) exercise. When matched for metabolic rate, vibration exercise elevated muscle temperature more quickly than traditional forms of warm-up by cycling or passive heating, but there were no significant differences in the increase in muscle power between the interventions, which suggested that the interventions were temperature dependent. There was no apparent benefit in performing a shallow, fast tempo dynamic squat with vibration because muscle temperature, cardiovascular indices, and metabolic rate were increased by the same amount and rate without vibration. Further, the Jendrassik manoeuvre did not potentiate the metabolic rate in young or older adults when superimposed with vibration exercise and the patellar reflex was not enhanced after vibration exercise, but muscle twitch potentiation was evident. However, low frequency vibration exercise induced a small change in muscle length and increased muscle activation, suggesting that spinal reflexes were involved. In conclusion, vibration exercise with a static squat could be used as a warm-up modality after interval breaks, as it would incur a low metabolic cost and be time efficient. It appears that the increases in muscle performance from vibration exercise are not caused by a neurogenic potentiation because patellar tendon reflex showed no significant augmentation and muscle twitch properties were enhanced. Vibration exercise elicited a small increase in metabolic rate and cardiovascular indices. Given that a main objective of a balanced exercise programme is to increase aerobic capcity it would be unwise to completely substitute conventional aerobic exercise with vibration. However, when conventional aerobic exercise is not possible, for example, in aged, cardiovascular compromised persons, vibration exercise could be implemented at an early stage because it could provide a safe induction of a low level of cardiovascular strain. Vibration exercise has the potential to benefit sport, exercise, and health however, it should be used to compliment other modalities but it should never be used in preference or in isolation to other programmes