Carmelo Bosco

The Use of Vibration as an Exercise Intervention

CARDINALE, M., and C. BOSCO. The use of vibration as an exercise intervention. Exerc. Sport Sci. Rev., Vol. 31, No. 1, pp. 3–7, 2003. The use of vibration as a means for enhancing athletic performance is a recent issue in exercise physiology. Current evidence suggests that vibration is effective in enhancing strength and the power capacity of humans, although the mechanisms mediating this effect are unknown.

Hormonal responses to whole-body vibration in men

Abstract The aim of this study was to evaluate the acute responses of blood hormone concentrations and neuromuscular performance following whole-body vibration (WBV) treatment. Fourteen male subjects [mean (SD) age 25 (4.6)u2009years] were exposed to vertical sinusoidal WBV, 10 times for 60u2009s, with 60u2009s rest between the vibration sets (a rest period lasting 6u2009min was allowed after 5 vibration sets). Neuromuscular performance tests consisting of counter-movement jumps and maximal dynamic leg presses on a slide machine, performed with an extra load of 160% of the subjects body mass, and with both legs were administered before and immediately after the WBV treatment. The average velocity, acceleration, average force, and power were calculated and the root mean square electromyogram (EMGrms) were recorded from the vastus lateralis and rectus femoris muscles simultaneously during the leg-press measurement. Blood samples were also collected, and plasma concentrations of testosterone (T), growth hormone (GH) and cortisol (C) were measured. The results showed a significant increase in the plasma concentration of T and GH, whereas C levels decreased. An increase in the mechanical power output of the leg extensor muscles was observed together with a reduction in EMGrms activity. Neuromuscular efficiency improved, as indicated by the decrease in the ratio between EMGrms and power. Jumping performance, which was measured using the counter-movement jump test, was also enhanced. Thus, it can be argued that the biological mechanism produced by vibration is similar to the effect produced by explosive power training (jumping and bouncing). The enhancement of explosive power could have been induced by an increase in the synchronisation activity of the motor units, and/or improved co-ordination of the synergistic muscles and increased inhibition of the antagonists. These results suggest that WBV treatment leads to acute responses of hormonal profile and neuromuscular performance. It is therefore likely that the effect of WBV treatment elicited a biological adaptation that is connected to a neural potentiation effect, similar to those reported to occur following resistance and explosive power training. In conclusion, it is suggested that WBV influences proprioceptive feedback mechanisms and specific neural components, leading to an improvement of neuromuscular performance. Moreover, since the hormonal responses, characterised by an increase in T and GH concentration and a decrease in C concentration, and the increase in neuromuscular effectiveness were simultaneous but independent, it is speculated that the two phenomena might have common underlying mechanisms.

Influence of vibration on mechanical power and electromyogram activity in human arm flexor muscles

Abstract The aim of this study was to evaluate the influence of vibration on the mechanical properties of arm flexors. A group of 12 international level boxers, all members of the Italian national team, voluntarily participated in the experiment: all were engaged in regular boxing training. At the beginning of the study they were tested whilst performing forearm flexion with an extra load equal to 5% of the subjects body mass. Following this, one arm was given the experimental treatment (E; mechanical vibration) and the other was the control (no treatment). The E treatment consisted of five repetitions lasting 1-min each of mechanical vibration applied during arm flexion in isometric conditions with 1u2009min rest between them. Further tests were performed 5u2009min immediately after the treatment on both limbs. The results showed statistically significant enhancement of the average power in the arm treated with vibrations. The root mean square electromyogram (EMGrms) had not changed following the treatment but, when divided by mechanical power, (P) as an index of neural efficiency, it showed statistically significant increases. It was concluded that mechanical vibrations enhanced muscle P and decreased the related EMG/P relationship in elite athletes. Moreover, the analysis of EMGrms recorded before the treatment and during the treatment itself showed an enormous increase in neural activity during vibration up to more than twice the baseline values. This would indicate that this type of treatment is able to stimulate the neuromuscular system more than other treatments used to improve neuromuscular properties.

Monitoring strength training: neuromuscular and hormonal profile

PURPOSEnThis study investigated changes induced by a single heavy resistance training session on neuromuscular and endocrine systems in trained athletes, using the same exercises for training and testing.nnnMETHODSnFive different groups volunteered: track and field male sprinters (MS, N = 6), track and field female sprinters (FS, N = 6), body builders (BB, N = 6), and weight lifters performing low-repetition exercise (WLL, N = 4) and high-repetition exercise (WLH, N = 4). In training, the work performed during half and full squat exercise was monitored for mechanical power output as well as EMG analysis on leg extensor muscles of the subjects belonging to the MS, FS, and BB groups. Just before and immediately after the training session, venous blood samples were obtained for RIA determination of testosterone (T), cortisol (C), lutropin (LH), human prolactin (PRL), and follitropin (FSH) in FS and MS. In the other three groups (BB, WLH, and WLL), the hormonal profile was limited to T and human growth hormone (hGH) only.nnnRESULTSnAfter training the power developed in full squat demonstrated a statistically significant decrease (P < 0.01) in MS and no changes in FS. The EMG activity remained constant during the training session. Consequently, the EMG/Power ratio increased in both MS and FS, although only in MS a statistical significance was noted (P < 0.05). In MS immediately after the session the levels of C, T, and LH were significantly lower (P < 0.05). No changes were found in FS. In both groups and in BB significant negative correlation was found between changes in T level and EMG/Power ratio in half squat performance.nnnCONCLUSIONSnIt is likely that adequate T level may compensate the effect of fatigue in FT fibers by ensuring a better neuromuscular efficiency.

Metabolic response of endurance athletes to training with added load

SummaryEndurance athletes were divided into experimental (n=12) and control (n=12) groups to investigate the effects of extra-load training on energy metabolism during exercise. A vest weighing 9%–10% body weight was worn every day from morning to evening for 4 weeks including every (n=6) or every other (n=6) training session. After 4 weeks the control group had a lower blood lactate concentration during submaximal running, whereas the experimental group had significantly higher blood lactate and oxygen uptake (p<0.01–p<0.05), and a lower 2 mmol lactate threshold (p<0.05) and an increased blood lactate concentration after a short running test to exhaustion (p<0.05). Those experimental subjects (n=6) who used the added load during every training session had a lower 2 mmol lactate threshold, improved running time to exhaustion, improved vertical velocity when running up stairs and an increased n

Glucocorticoid receptors in human peripheral blood mononuclear cells in relation to explosive performance in elite handball players.

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Mechanical behaviour of leg extensor muscles in male and female sprinters

n during submaximal running after the added load period. It is concluded that the additional loading increased anaerobic metabolism in the leg muscles during submaximal and maximal exercise. An increased recruitment and adaptation of the fast twitch muscle fibres is suggested as the principal explanation for the observed changes.

Leg extension test, sEMG and vibratory stimuli to assess functional recovery following knee joint surgery.

The mechanical behaviour of skeletal muscle is influenced by internal factors (e.g. re-use of elastic energy) and/or external conditions (e.g. floor compliance, shoe structure etc.). These factors have an effect on muscular work economy-this was investigated in the present study. Eight subjects were tested during three different series of jumps. Each series consisted of rhythmical vertical jumps performed at desired frequency and height for 1 min. The first (1) series was executed on the laboratory floor without rebound condition (subjects were asked to maintain 1 s period in an isometric condition before concentric work was performed), the second (II) and the third (III) series were performed in rebound conditions respectively on a laboratory floor (hard surface) and on a special panel possessing high compliance (a special foam rubber panel with stiffness of 14.4 kN/m). Expired air was collected during the test and recovery for determination of energy expenditure. Mechanical work was calculated from the vertical displacement of the body during the jumps. The results indicated that the net efficiency in the jumps without prestretch of the leg extensor muscles (series I) was the lowest (19.4%). In contrast, the net efficiency observed in rebound jumps (series II and III) was respectively 30.8% and 33.1%, demonstrating that the reuse of elastic energy (Wel) plays an important role for muscular work efficiency. However, the contribution of Wel to the total work performed was different p < 0.05, Students t-test) in jumps on the special panel (41%) compared to the normal surface (37%), even if the total amount of stored elastic energy was the same in both conditions. The different efficiency observed between series II and III was attributed to the compliance of the surface on which the tests were executed. It was suggested that man could change his neuromuscular pattern to adapt muscular behaviour for matching the damped properties shown by the high compliance surface. Finally, the soft surface may favour a very low rate of running injuries.