volume reductions. Potential mechanisms behind such changes were also explored. It was hypothesized that the higher intensity taper would produce greater improvements in neuromuscular performance. Methods Subjects The inclusion criteria for the study were (1) a current deadlift 1RM of at least 1.5 times
Hayden J. Pritchard, Matthew J. Barnes, Robin J. Stewart, Justin W. Keogh and Michael R. McGuigan
Ilenia Bazzucchi, Federica Patrizio, Francesco Felici, Andrea Nicolò and Massimo Sacchetti
To determine whether repeated carbohydrate (CHO) mouth rinsing would improve neuromuscular performance during high-intensity fatiguing contractions.
Eighteen young men (age 26.1 ± 5.0 y, BMI 22.9 ± 1.9) performed 3 maximal voluntary isometric contractions (MVICPRE). Immediately after, they completed 10-second mouth rinse with 6.4% maltodextrin solution (MAL), 7.1% glucose solution (GLU), water (W), artificially sweetened solution (PLA), or a control trial with no rinse (CON) in a crossover protocol. Subjects performed 5 sets of 30 isokinetic fatiguing contractions at 180°/s, and an MVICPOST with their elbow flexors was performed after each mouth rinse. Mechanical and electromyographic (EMG) signals were recorded from the biceps brachii and parameters of interest analyzed.
When rinsing the mouth with a solution containing CHO, independently of the sweetness, isokinetic performance was enhanced as shown by the greater total work achieved in comparison with CON. The decay of torque and mean fiber-conduction velocity (MFCV) recorded at the end of the fatiguing task was lower when rinsing the mouth with GLU than with CON. The torque recorded during the MVICPOST was greater with CHO with respect to CON, and this was associated to a lower decay of MFCV.
CHO mouth rinse counteracts fatigue-induced decline in neuromuscular performance, supporting the notion that CHO rinse may activate positive afferent signals able to modify motor output. Repeated mouth rinsing with sweet and nonsweet CHO-containing solutions can improve neuromuscular performance during an isokinetic intermittent fatiguing task.
Anni Rava, Anu Pihlak, Jaan Ereline, Helena Gapeyeva, Tatjana Kums, Priit Purge, Jaak Jürimäe and Mati Pääsuke
The purpose of this study was to evaluate the differences in body composition, neuromuscular performance, and mobility in healthy, regularly exercising and inactive older women, and examine the relationship between skeletal muscle indices and mobility. Overall, 32 healthy older women participated. They were divided into groups according to their physical activity history as regularly exercising (n = 22) and inactive (n = 10) women. Body composition, hand grip strength, leg extensor muscle strength, rapid force development, power output, and mobility indices were assessed. Regularly exercising women had lower fat mass and higher values for leg extensor muscle strength and muscle quality, and also for mobility. Leg extensor muscle strength and power output during vertical jumping and appendicular lean mass per unit of body mass were associated with mobility in healthy older women. It was concluded that long-term regular exercising may have beneficial effects on body composition and physical function in older women.
Thomas Cattagni, Clément Billet, Christophe Cornu and Marc Jubeau
Context: Prolonged tendon vibration may induce muscle fatigue, as assessed by a decrease in maximal force production. It remains unknown, however, whether the decrease in muscle strength after prolonged Achilles tendon vibration is related to the vibration frequency. Objective: To assess the maximal capacity of plantar-flexor (PF) neuromuscular function before and after prolonged Achilles tendon vibration at low and high frequencies generated using a portable device. Design: Pre- and posttest intervention with control.Setting: University laboratory. Participants: 10 healthy men age 22.6 ± 4.0 y. Intervention: Each subject participated in 3 experimental sessions that were randomly distributed and separated by 1 wk. During each experimental session, 1 of the following vibration protocols was applied for 30 min: 40-Hz vibration, 100-Hz vibration, or no vibration (control protocol). Main Outcome Measures: Maximal-voluntary-contraction torque, voluntary activation level, twitch torque, maximal electromyographic activity, and maximal M-wave of PF muscles (measured before and after each vibration or control protocol).Results: Statistical analysis exhibited no significant effect of vibration protocol on the measured variables. Conclusions: The current study demonstrates that 30 min of Achilles tendon vibration at a low or high frequency using a portable stimulator did not affect the neuromuscular performance of the PF muscles. These results emphasize the limits of tendon vibration, whatever the frequency applied, for inducing neuromuscular fatigue.
Maria Angelika Peer and Nigel Gleeson
sensorimotor and neuromuscular performance of the knee flexors in males. Methods Study Design A randomized control trial involving comparison of the performance of 2 groups, intervention (short-term sensorimotor conditioning [3 weeks]), and control (no exercise). The study period lasted 6 weeks and included a
Mathieu Lacome, Christopher Carling, Jean-Philippe Hager, Gerard Dine and Julien Piscione
the frequency of player involvements in tackles and game contact events. 10 Concomitant alterations in neuromuscular performance via measures of jump height and peak power output also occur following match play. West et al 11 reported that peak power output was reduced by ∼7% at 36 hours before
Nicolas Berryman, Iñigo Mujika and Laurent Bosquet
adaptations. Side 1: The Effects of Concurrent Training on Neuromuscular Performance Chronic Effects While pursuing his postdoctoral studies, Robert C. Hickson gradually included some running sessions to his habitual strength-training program. This anecdote later led to a research project, which became a
Konstantinos Sotiropoulos, Ilias Smilios, Helen Douda, Marios Christou and Savvas P. Tokmakidis
This study examined the effect of rest interval after the execution of a jump-squat set with varied external mechanical-power outputs on repeated-jump (RJ) height, mechanical power, and electromyographic (EMG) activity.
Twelve male volleyball players executed 6 RJs before and 1, 3, 5, 7, and 10 min after the execution of 6 repetitions of jump squats with a load: maximized mechanical-power output (Pmax), 70% of Pmax, 130% of Pmax, and control, without extra load.
RJ height did not change (P = .44) after the jump squats, mechanical power was higher (P = .02) 5 min after the 130%Pmax protocol, and EMG activity was higher (P = .001) after all exercise protocols compared with control. Irrespective of the time point, however, when the highest RJ set for each individual was analyzed, height, mechanical power, and EMG activity were higher (P = .001–.04) after all loading protocols compared with control, with no differences observed (P = .53–.72) among loads.
Rest duration for a contrast-training session should be individually determined regardless of the load and mechanical-power output used to activate the neuromuscular system. The load that maximizes external mechanical-power output compared with a heavier or a lighter load, using the jump-squat exercise, is not more effective for increasing jumping performance afterward.
Asier Los Arcos, Javier Yanci, Jurdan Mendiguchia, Juan J. Salinero, Matt Brughelli and Carlo Castagna
The aim of this study was to compare the effects of 2 strength and conditioning programs involving either purely vertically oriented or combining vertically and horizontally oriented exercises on soccer-relevant performance variables (ie, acceleration, jumping ability, peak power, and endurance).
Twenty-two professional male soccer players were randomly assigned to 2 training groups: vertical strength (VS, n = 11) and vertical and horizontal strength (VHS, n = 11). Players trained 2 times per week during all the preseason (5 wk) and 3 weeks of the competitive season. The effect of the training protocols was assessed using doubleand single-leg vertical countermovement jumps (CMJ), half-squat peak power (PP), sprint performance over 5 and 15 m, and blood lactate concentration at selected running speeds.
Both groups obtained significant improvements in PP (P < .05; ES = 0.87 and 0.80 for VS and VHS, respectively) and small practical improvements in 5-m- (P < .05; ES = 0.27 and 0.25 for VS and VHS, respectively) and 15-m-sprint time (P < .05; ES = 0.19 and 0.24 for VS and VHS, respectively). The CMJ performance showed a small improvement (P < .05, ES = 0.34) only in the VHS group. Submaximal aerobic-fitness changes were similar in both groups (P < .05; ES = 1.89 and 0 .71 for VS and VHS, respectively).
This study provided a small amount of practical evidence for the consideration of preseason training protocols that combine exercises for vertical- and horizontal-axis strength development in professional male soccer players. Further studies using more aggressive training protocols involving horizontally oriented conditioning exercises are warranted.
Fabrice Vercruyssen, Mathieu Gruet, Serge S. Colson, Sabine Ehrstrom and Jeanick Brisswalter
Physiological mechanisms behind the use of compression garments (CGs) during off-road running are unknown.
To investigate the influence of wearing CGs vs conventional running clothing (CON) on muscle contractile function and running economy before and after short-distance trail running.
Knee-extensor neuromuscular function and running economy assessed from two 5-min treadmill runs (11 and 14 km/h) were evaluated before and after an 18.6-km short-distance trail run in 12 trained athletes wearing either CGs (stocking + short-tight) or CON. Quadriceps neuromuscular function was assessed from mechanical and EMG recording after maximal percutaneous electrical femoral-nerve stimulations (single-twitch doublets at 10 [Db10] and 100 Hz [Db100] delivered at rest and during maximal quadriceps voluntary contraction [MVC]).
Running economy (in mL O2 · km–1 · kg–1) increased after trail running independent of the clothing condition and treadmill speeds (P < .001). Similarly, MVC decreased after CON and CGs conditions (–11% and –13%, respectively, P < .001). For both clothing conditions, a significant decrease in quadriceps voluntary activation, Db10, Db100, and the low-to-high frequency doublet ratio were observed after trail running (time effect, all P < .01), without any changes in rectus femoris maximal M-wave.
Wearing CGs does not reduce physiological alterations induced during short-distance trail running. Further studies should determine whether higher intensity of compression pressure during exercises of longer duration may be effective to induce any physiological benefits in experienced trail runners.