Objective: To quantify the acute effect of whole body vibration (WBV) training on arm countermovement vertical jump (ACMVJ), grip strength, and flexibility performance. Methods: Eighteen female elite field hockey players each completed three interventions of WBV, control, and cycling in a balanced random manner. WBV was performed on a Galileo machine (26 Hz) with six different exercises being performed. For the control, the same six exercises were performed at 0 Hz, whilst cycling was performed at 50 W. Each intervention was 5 min in duration with ACMVJ, grip strength, and flexibility measurements being conducted pre and post intervention. Results: There was a positive interaction effect (intervention6pre-post) of enhanced ACMVJ (p,0.001) and flexibility (p,0.05) parameters following WBV; however no changes were observed after the control and cycling interventions. There was no interaction effect for grip strength following the three interventions. Conclusions: Acute WBV causes neural potentiation of the stretch reflex loop as shown by the improved ACMVJ and flexibility performance. Additionally, muscle groups less proportionally exposed to vibration do not exhibit physiological changes that potentiate muscular performance.

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Nonalcoholic fatty liver is frequently observed in obese individuals, yet the factors that predict its development and progression to liver disease are poorly understood. We proposed that proton magnetic resonance spectroscopy (

This study compared the rate of muscle temperature (Tm) increase during acute whole-body vibration (WBV), to that of stationary cycling and passive warm-up. Additionally we wanted to determine if the purported increase in counter-movement jump and peak power cycling from acute WBV could be explained by changes in muscle temperature. Eight active participants volunteered for the study, which involved a rest period of 30 min to collect baseline measures of muscle, core, skin temperature, heart rate (HR), and thermal leg sensation (TLS), which was followed by three vertical jumps and 5 s maximal cycle performance test. A second rest period of 40 min was enforced followed by the intervention and performance tests. The change in Tm elicited during cycling was matched in the hot bath and WBV interventions. Therefore cycling was performed first, proceeded by, in a random order of hot bath and acute WBV. The rate of Tm was significantly greater (P < 0.001) during acute WBV (0.30 degree C min(-1)) compared to cycle (0.15 degree C min(-1)) and hot bath (0.09 degree C min(-1)) however there was no difference between the cycle and hot bath, and the metabolic rate was the same in cycling and WBV (19 mL kg(-1) min(-1)). All three interventions showed a significant (P < 0.001) increase in countermovement jump peak power and height. For the 5 s maximal cycle test (MIC) there were no significant differences in peak power between the three interventions. In conclusion, acute WBV elevates Tm more quickly than traditional forms of cycling and passive warm-up. Given that all three warm-up methods yielded the same increase in peak power output, we propose that the main effect is caused by the increase in Tm.

BackgroundExercise-induced muscle damage (EIMD) is accompanied by localized oxidative stress / inflammation which, in the short-term at least, is associated with impaired muscular performance. Dietary antioxidants have been shown to reduce excessive oxidative stress; however, their effectiveness in facilitating recovery following EIMD is not clear. Blueberries demonstrate antioxidant and anti-inflammatory properties. In this study we examine the effect of New Zealand blueberries on EIMD after strenuous eccentric exercise.MethodsIn a randomized cross-over design, 10 females consumed a blueberry smoothie or placebo of a similar antioxidant capacity 5 and 10 hours prior to and then immediately, 12 and 36 hours after EIMD induced by 300 strenuous eccentric contractions of the quadriceps. Absolute peak and average peak torque across the knee, during concentric, isometric, and eccentric actions were measured. Blood biomarkers of oxidative stress, antioxidant capacity, and inflammation were assessed at 12, 36 and 60 hours post exercise. Data were analyzed using a two-way ANOVA.ResultsA significant (p < 0.001) decrease in isometric, concentric and eccentric torque was observed 12 hours following exercise in both treatment groups. During the 60 hour recovery period, a significant (p = 0.047) interaction effect was seen for peak isometric tension suggesting a faster rate of recovery in the blueberry intervention group. A similar trend was observed for concentric and eccentric strength. An increase in oxidative stress and inflammatory biomarkers was also observed in both treatment groups following EIMD. Although a faster rate of decrease in oxidative stress was observed in the blueberry group, it was not significant (p < 0.05) until 36 hours post-exercise and interestingly coincided with a gradual increase in plasma antioxidant capacity, whereas biomarkers for inflammation were still elevated after 60 hours recovery.ConclusionsThis study demonstrates that the ingestion of a blueberry smoothie prior to and after EIMD accelerates recovery of muscle peak isometric strength. This effect, although independent of the beverage’s inherent antioxidant capacity, appears to involve an up-regulation of adaptive processes, i.e. endogenous antioxidant processes, activated by the combined actions of the eccentric exercise and blueberry consumption. These findings may benefit the sporting community who should consider dietary interventions that specifically target health and performance adaptation.

This study examined the role of skin temperature on self-selected exercise intensity (i.e., power output). Eight well-trained, male cyclists completed two 60 min self-paced cycling bouts during which they completed as much work as possible. Using a liquid-perfused suit, skin temperature (T (Sk)) was changed during the two trials such that T (Sk) either started hot and was cooled (H to C) or started cold and was heated (C to H) throughout exercise. Pre-exercise core temperatures (T (C)) and heart rates (HR) were similar between trials, while T (Sk), thermal comfort and thermal sensation were higher in H to C. The change in T (Sk) was similar in magnitude during the two trials. Work completed was greatest in C to H, which was attributed to a higher initial power output. T (C) was similar between trials. HR was similar until 35 min had elapsed, after which it became lower in H to C. The perception of effort increased similarly between the two trials, while thermal comfort and thermal sensation generally reflected the changes observed in T (Sk). These results indicate that upon exercise commencement T (Sk) and the accompanying thermal perceptions are important inputs in the initial selection of exercise intensity.

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, undertook a water-only fast for 84 h. Vastus lateralis IMCL content was determined using proton magnetic resonance spectroscopy after 12 and 84 h of fasting. Venous blood was sampled at 12-h intervals throughout the fast. IMCL-(CH2)n/water and IMCL-(CH2)n/total creatine ratios increased from 0.00623 Ϯ 0.00065 to 0.0142 Ϯ 0.0015 (P ϭ 0.002) and 6.82 Ϯ 0.87 to 14.96 Ϯ 1.73 (P ϭ 0.001), respectively. Plasma free fatty acid (FFA), serum triglyceride, and whole blood 3-hydroxybutyrate concentrations increased (P Ͻ 0.001, Ͻ0.05, Ͻ0.03, respectively), whereas plasma glucose and serum insulin concentrations decreased (both P Ͻ 0.001) during fasting. In conclusion, 72-h water-only fasting produces a large increase in plasma FFA concentration, a drop in serum insulin concentration, and accumulation of IMCL in the vastus lateralis muscle of nondiabetic, physically fit men. muscle triglyceride; free fatty acids; insulin TYPE 2 DIABETIC PATIENTS show an increase in resting intramyocellular lipid (IMCL) content (14). Correspondingly, insulin sensitivity alone in nondiabetic humans appears to be well predicted by IMCL content, as determined from muscle biopsy samples (24, 31) or proton magnetic resonance spectroscopy ( 1 H-MRS) (23). It is not clear whether the increase in IMCL is a cause or an effect of insulin resistance, although it has been recently suggested that a very high content of IMCL creates a physical barrier to GLUT4 translocation (21).In normal-weight nondiabetics, fasting plasma free fatty acid (FFA) concentration is correlated inversely with whole body insulin-stimulated glucose uptake (23) and positively with IMCL content (8). Indeed, an acute increase in plasma FFA concentration is associated with reduced insulin sensitivity and increased IMCL content (3, 4), whereas an acute reduction in FFA concentration improves insulin sensitivity (36).Three to four days of fasting results in elevated plasma FFA concentration (15, 47) and impaired glucose uptake (25,47). However, the glucose-"sparing" effect in this condition is understood to be mediated by the increase in circulating ketones, whose metabolism inhibits hexokinase via operation of the glucose-fatty acid cycle (32).The effect of fasting on IMCL content is equivocal in animals (17) and unknown in humans. However, in 60-h-fasted nonobese men, whole body FFA esterification appears in excess of splanchnic FFA uptake, esterification, and release as triglyceride (20), suggesting an unidentified nonhepatic site of triglyceride accumulation, possibly muscle. Furthermore, 3-hydroxybutyrate infusion into the brachial artery arrests the release of glycerol and FFAs from deep forearm veins (49), suggesting cessation of intramuscular lipolysis. Arterial concentrations of 3-hydroxybutyrate substantially increase during fasting (30). Thus it is conceivable that the reduced insulin-mediated glucose uptake during fasting may be mediated, at least in part, by an increase in IMCL content.It was, therefore, the objective of the present study to test the hypothesis that a pr...