The effect of slope on repeated sprint ability in young soccer players

This study aimed to describe a gradient repeated sprint ability (RSA) test in comparison with a standard level one by investigating performance, metabolic demand and muscular jumping performance as a proxy for running mechanics. Eighteen athletes performed two level RSA tests (40 m × 6) - for reliability evaluation - and one ±5% gradient RSA test, second leg downhill (RSAgrad). Rating of perceived exertion (RPE), blood lactate concentration (BLa) concentration, vertical jump heights were assessed as well. Level test measures resulted highly reliable (Intra-class correlation coefficient (ICC) ≥0.96). RSAgrad worsened only first sprints' performance (-2%) but not overall test performance (~45 s). RSAgrad resulted to be less deteriorating in terms of fatigue index (FI) (-36%), BLa (-23%), RPE (-11%), jumping performance (RSAgrad post-/pre-squat jump, countermovement jump heights (CMJh): -3%, -6%, respectively). RSAgrad could be used to diversify common training protocol without stressing excessively athletes' current metabolic-anaerobic capacity. Such physical conditioning procedures could improve acceleration/braking capability.

Lower Arm Muscle Activation during Indirect-Localized Vibration: The Influence of Skill Levels When Applying Different Acceleration Loads

We investigated the electromyographic response to synchronous indirect-localized vibration interventions in international and national table tennis players. Twenty-six male table tennis players, in a standing position, underwent firstly an upper arms maximal voluntary contraction and thereafter two different 30-s vibration interventions in random order: high acceleration load (peak acceleration = 12.8 g, frequency = 40 Hz; peak-to-peak displacement = 4.0 mm), and low acceleration load (peak acceleration = 7.2 g, frequency = 30 Hz, peak-to-peak displacement = 4.0 mm). Surface electromyography root mean square from brachioradialis, extensor digitorum, flexor carpi radialis, and flexor digitorum superficialis recorded during the two vibration interventions was normalized to the maximal voluntary contraction recording. Normalized surface electromyography root mean square was higher in international table tennis players with respect to national ones in all the interactions between muscles and vibration conditions (P < 0.05), with the exception of flexor carpi radialis (at low acceleration load, P > 0.05). The difference in normalized surface electromyography root mean square between international table tennis players and national ones increased in all the muscles with high acceleration load (P < 0.05), with the exception of flexor digitorum superficialis (P > 0.05). The muscle activation during indirect-localized vibration seems to be both skill level and muscle dependent. These results can optimize the training intervention in table tennis players when applying indirect-localized vibration to lower arm muscles. Future investigations should discriminate between middle- and long-term adaptations in response to specific vibration loads.

Repeated Sprint Ability in Young Basketball Players (Part 2): The Chronic Effects of Multidirection and of One Change of Direction Are Comparable in Terms of Physiological and Performance Responses

The aim of this study was to examine the effects of a 5-week training program, consisting of repeated 30-m sprints, on two repeated sprint ability (RSA) test formats: one with one change of direction (RSA) and the other with multiple changes of direction (RSM). Thirty-six young male and female basketball players (age 16.1 ± 0.9 years), divided into two experimental groups, were tested for RSA, RSM, squat jump, counter-movement jump, and the Yo-Yo Intermittent Recovery-Level-1 (Yo-Yo IR1) test, before and after a 4-week training program and 1 week of tapering. One group performed 30-m sprints with one change of direction (RSA group, RSAG), whereas the other group performed multidirectional 30-m sprints (RSM group, RSMG). Both groups improved in all scores in the post-intervention measurements (P < 0.05), except for the fatigue index in the RSM test. However, when comparing the two groups, similar effects were found for almost all parameters of the tests applied, except for RPE in the RSA test, which had a greater decrease in the RSAG (from 8.7 to 5.9) than in the RSMG (from 8.5 to 6.6, P = 0.021). We can conclude that repeated 30-m sprints, either with one change of direction or multidirectional, induce similar physiological and performance responses in young basketball players, but have a different psycho-physiological impact.

Repeated Sprint Ability in Young Basketball Players: Multi-direction vs. One-Change of Direction (Part 1)

The aim of the present study was to examine the reliability of a novel multi-direction repeated sprint ability (RSA) test [RSM; 10 × (6 × 5-m)] compared with a RSA with one change of direction [10 × (2 × 15-m)], and the relationship of the RSM and RSA with Yo-Yo intermittent recovery test level 1 (Yo-Yo IR1) and jump performances [squat jump (SJ) and counter-movement-jump (CMJ)]. Thirty-six (male, n = 14, female n = 22) young basketball players (age 16.0 ± 0.9 yrs) performed the RSM, RSA, Yo-Yo IR1, SJ, and CMJ, and were re-tested only for RSM and RSA after 1 week. The absolute error of reliability (standard error of the measurement) was lower than 0.212 and 0.617-s for the time variables of the RSA and RSM test, respectively. Performance in the RSA and RSM test significantly correlated with CMJ and SJ. The best time, worst time, and total time of the RSA and RSM test were negatively correlated with Yo-Yo IR1 distance. Based on these findings, consistent with previously published studies, it was concluded that the novel RSM test was valid and reliable.

Task complexity reveals expertise of table tennis players

BACKGROUND

The purpose of this study was to examine the effect of intensive practice in table tennis on perceptual, decision-making and motor-systems. Groups of elite (HL, N.=11), intermediate (LL, N.=6) and control players (CC, N.=11) performed tasks of different levels.

METHODS

All subjects underwent to reaction time test and response time test consisting of a pointing task to targets placed at distinct distances (15 and 25 cm away) on the right and left sides. Only the HL and LL groups were requested to perform the ball speed test in forehand and backhand condition.

RESULTS

In the CC group reaction time was higher compared to the HL (P<0.05) group. In the response time test, there was a significant main effect of distance (P<0.0001) and the tennis table expertise (P=0.011). In the ball speed test HL players were consistently faster compared to LL players in both forehand stroke (P<0.0001) and backhand stroke (P<0.0001). Overall, the forehand stroke was significantly faster than the backhand stroke.

CONCLUSIONS

We can conclude that table tennis players have shorter response times than non-athletes and the tasks of reaction time and response time are incapable to distinguish between the performance of well-trained table tennis players and that of intermediate players, but the ball speed test seems to be able to do it.

The effects of one-week training camp on motor skills in Karate kids

AIM

The purpose of this study was to evaluate the effects of short-term increased hours of specific high-intensity karate training on motor skills in young karate athletes aged between 8 and 12 years.

METHODS

Seventy-three children, who regularly trained three karate sessions per-week were divided in two groups: high-intensity karate group (HG=53) and low-intensity karate group (LG=20). HG trained for 7 days: with two sessions per-day (one hour per-session) including specific karate techniques as well as coordination, balance, and flexibility exercises. LG, however, followed the same number of karate training sessions as before the beginning of the study (i.e., three sessions per-week with one hour per-session). Participants performed a battery of tests, 24 hours pre- and one week post-training: a medicine ball throw (MBT), standing long jump (SLJ), active joint flexibility (JM) and lateral/frontal jumps (JLT).

RESULTS

Significant differences between results of pre and post karate training (ANOVA with repeated measures) included: MBT (P<0.05), SLJ (P<0.0001), JM (P<0.0001), JLT (P<0.0001); whilst the interaction training × time was: MBT (P=0.145), SLJ (P<0.0001), JM (P<0.0001), JLT (P< 0.0001). The HG significantly improved their performance on MBT by 3.23% (P<0.05), SLJ by 5.09% (P<0.001), JM by 1.51% (P<0.001), and JLT by 21.36% (P<0.001). For LG group, there were no significant differences between pre and post-testing in all fitness tests.

CONCLUSION

Muscular power, flexibility and coordination represent the basics of karate fitness component. In this regard, short term high-intensity karate training represents an effective method for enhancing muscular power and range of motion (i.e. flexibility) in young karate athletes aged between 8 and 12 years. Further studies are needed to support these findings with deeper data.

Quality of life, cortisol blood levels and exercise in older adults: results of a randomized controlled trial

INTRODUCTION

Cortisol plays a central role in the stress response; while high stress can determine physical and psychological impairment, moderate stress, with a mild increase in cortisol level, may have a positive effect on coping and physical performance. This trial attempted to determine whether cortisol levels were associated with Quality of Life (QoL) in a sample of elderly subjects undertaking an exercise program.

METHODS

42 subjects aged ≥65 years were randomlyassigned in a 1:1 fashion either to a vigorous physical activity (VAG: N=21) or to a postural gimnastic group (PGG: N=21). Differences between the two groups in QoL (on SF-12), and blood cortisol levels were assessed by ANOVA at different times.

RESULTS

In both the VAG and PGG, cortisol levels rose at the end of the trial, with statistically significant differences as compared to the baseline. QoL at the end of the trial was higher than in the national normative sample. Cortisol and QoL in both groups decreased slightly 12 weeks after the end of the trial (T2); however, only in the VAG did the difference from the initial level remain statistically significant. At T1 and T2, subjects with higher SF-12 scores were found in subsamples in both groups with cortisol levels moderately increased (between 200 and 300 mg/ml).

CONCLUSION

In a sample of elderly subjects undergoing two different kinds of exercise, a better perception of Quality of Life was associated with a moderate, non-pathological increase in cortisol. The results need to be confirmed by trials on larger samples.

Measurement of pulmonary gas exchange variables and lactic anaerobic capacity during field testing in elite indoor football players

AIM

The aims of this study were: 1) to examine the gas exchange responses of elite indoor football players to a repeated sprint ability (RSA) test; and 2) to verify whether or not the excess of carbon dioxide production (CO2excess) correlates with blood lactate accumulation during RSA field testing.

METHODS

Eleven elite male indoor football players were recruited. A preliminary incremental exercise test on a treadmill was performed to elicit V'O2max. Then, participants underwent an RSA test consisting in a shuttle running through a course with various changes of direction while wearing a portable gas analyzer able to provide values of oxygen uptake, carbon dioxide production, and CO2excess. BLa concentrations during recovery were also measured.

RESULTS

The main results were that: 1) during the RSA test subjects did not reached the V'O2max level achieved in the preliminary test; 2) during the RSA test BLa levels were higher compared with the preliminary test; 3) the peak BLa concentration during recovery was significantly correlated with the average CO2excess

CONCLUSION

It was concluded that the RSA test did not appear to be useful to elicit V'O2max. Rather, it seemed suitable to recruit subjects' lactic anaerobic capacity. Moreover, CO2excess appeared suitable for qualitatively estimate BLa accumulation during field testing.

Footstep manipulation during uphill running

The present study investigated the effects of step frequency manipulation during training on slopes (2%) on biomechanical parameters at Iso-Efficiency Speed (without increasing the metabolic demand). 24 male marathon runners were randomly allocated to one of 2 training groups for 3 weeks: step frequency manipulation group (SFM, n=12) and free step frequency group (SFF, n=12). Lower limb kinematic parameters were measured before and after the 3 weeks training. The SFM group increased step length 4.30% (p<0.001), flight time 29.48% (p<0.001) and decreased contact time 14% (p<0.01). These findings coincide with characteristics of better running performances. The SFF group did not elicit such results. The results from the study could help coaches to devise training methods which could improve an athlete's performance through increasing step length. The method provided may aid faster race times for athletes.