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.

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.

The acute effect of whole body vibration on repeated shuttle-running in young soccer players.

The aim of this study was to investigate the acute effects of whole-body vibration (WBV) on Repeated Sprint Ability (RSA). Seventeen male soccer players (16.71±0.47 y) performed three RSA tests (Randomized crossover study design). The second RSA test was done with WBV (RSA2) to assess the effect of WBV. The studied variables were: best time (BT), worst time (WT), total time (TT), the fatigue index (FI) of RSA, and post-test blood lactate (BLa). ANOVA with repeated measures showed no differences between RSA1 and RSA3, while there were significant differences in all variables studied. TT= [RSA2 0.93% and 1.68% lower than RSA1 and RSA3 respectively; p<0.05], BLa= [RSA2 16.97% and 14.73% greater than RSA1 and RSA3 respectively; p<0.001], WT= [RSA2 1.90% and 2.93% lower than RSA1 and RSA3 respectively; p<0.01], and FI = [RSA2 30.64% and 40.15% lower than RSA1 and RSA3 respectively; p<0.0001]. When comparing individual sprints, WBV showed a significant effect at the 5th sprint: RSA2 2.29% and 2.95% lower than RSA1 and RSA3 respectively (p<0.005), while at the 6th sprint: RSA2 2.75% and 4.09% lower than RSA1 and RSA3 respectively; p<0.005. In conclusion, when applying WBV during the recovery periods of Repeated Sprint Ability efforts, most of the performance variables improved.

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.

Uphill running at iso-efficiency speed.

The purpose of this study was to investigate the effects of slopes (0%, 2% and 7%) on temporal gait kinematics during running at iso-efficiency speed (IES). 65 male marathon runners were selected for this study. A single digital camera (210 Hz) was used to record motion; Dartfish5.5Pro was used to perform 2-dimensional (2D) video analysis and heart rate was recorded during the test. The parameters considered in this study were: step length (SL), flight time (FT), step frequency (SF), contact time (CT) and heart rate (HR). The results showed SL, FT and SF decreased as a result of the increasing treadmill gradient; SL=[(0-2%=8.38%, p<0.0001), (0-7%=23.61%, p<0.0001)]; FT=[(0-2%=8.92%, p<0.02), (0-7%=23.40%, p<0.0001)]; SF=[(0-2%=1.18%), (0-7%=4.02%, p<0.001)]. The CT and HR however increased with the increasing gradient CT=[(0-2%=9.06% p<0.0001), (0-7%=25.64%, p<0.0001)]; HR=[(0-2%=1.65%), (0-7%=3.58%)]. These results show a different trend of the footstep's kinematic parameters when running on a slope at IES. Moreover, we can calculate the optimal run speed on a slope without increasing the metabolic demand.