Lactacidemic variation and movement patterns during anaerobic power test.

BACKGROUND: After the Running Anaerobic Sprint Test (RAST) high blood lactate concentrations ([La-]) are found. However, no study verified the behavior of this metabolite during RAST. For this, the aim of the present study was to verify the implications of increase [La-] on movement patterns' in RAST performance. METHODS: Six healthy and active individuals (21.8±3.1 years, 70.9±10.8 kg and 179.7±3.3 cm) executed a standardized warm-up. Two minutes later, subjects performed RAST composed of six maximal 35-m bouts separated by 10 s of passive recovery. During RAST, 14 cameras monitored the subjects to determine tridimensional and bi-dimensional mechanics. [La-] were determined before warm-up, between each bout and after RAST. RESULTS: Significant difference in performance were found after the fifth (5.1±0.1 s) and sixth (5.4±0.3 s; P<0.04) bout in relation to the first up to fourth effort. Fatigue indexes (FI% and FIREAL) were higher from fifth bout (19.2±9.4%; 19.3±10.9%; P<0.05). No significant difference was observed in [La-] on fifth and sixth bout (8.2±2.4 mM and 9.2±2.1 mM) however, both were different from all other bouts. Flight time was different between the fifth bout (0.16±0.03 s) when compared with the first (0.12±0.01 s; P=0.01) and second (0.13±0.02s; P=0.03) bouts. CONCLUSIONS: RAST performance can be influenced by physiological changes. Biomechanical behavior does not alter performance without a sum of physiological events.

Relationship between field tests and match running performance in high-level young Brazilian soccer players.

BACKGROUND: The main aim of this study was to analyze the relationship between field tests and match running performance using computational tracking technology in high-level young Brazilian soccer players. METHODS: Twenty-five young male Brazilian soccer players participated in this study (U-15, N.=13; U-17, N.=12). In the same week, the players were submitted to field tests and actual matches. The field tests were: Maximum Speed (10-30 m), Zig-Zag, Running-based Anaerobic Sprint Test, and Yo-Yo Intermittent Recovery Test Level 1. Additionally, participants performed actual soccer match-play. Match running performance was collected using a fixed video-camera. Subsequently, computerized tracking video-analysis (30 Hz) was utilized to identify each physical performance indicator. Pearson's correlation and linear regression were used for statistical analysis. RESULTS: The results showed that the majority of field tests were not related to match running performance. The Zig-Zag Test, Running-based Anaerobic Sprint Test, and Yo-Yo Intermittent Recovery Test level 1 seem to be the most specific tests (r=0.41-0.47), however the explanatory powers of these field tests in relation to match running performance were low (R2=17-22%). CONCLUSIONS: Assessment of match running performance should be included in the evaluation periods of young soccer players, together with the most specific tests reported.

Periodization Training Focused on Technical-Tactical Ability in Young Soccer Players Positively Affects Biochemical Markers and Game Performance.

Aquino, RLQT, Cruz Gonçalves, LG, Palucci Vieira, LH, Oliveira, LP, Alves, GF, Pereira Santiago, PR, and Puggina, EF. Periodization training focused on technical-tactical ability in young soccer players positively affects biochemical markers and game performance. J Strength Cond Res 30(10): 2723-2732, 2016-The aim of this study was to investigate the effects of 22 weeks of periodized training, with an emphasis on technical-tactical ability, on indirect markers of muscle damage, and the on-field performance of young soccer players. Fifteen players (age 15.4 ± 0.2 years, height 172.8 ± 3.6 cm; body mass 61.9 ± 2.9 kg; % fat 11.7 ± 1.6; V[Combining Dot Above]O2max 48.67 ± 3.24 ml·kg·min) underwent 4 stages of evaluation: prepreparatory stage-T0; postpreparatory stage-T1; postcompetitive stage I-T2 and; postcompetitive stage II-T3. The plasmatic activity of creatine kinase (CK) and lactate dehydrogenase (LDH) were evaluated, as well as the on-field performance (movement patterns, tactical variables). Regarding the plasmatic activity of CK and LDH, there was a significant reduction (p ≤ 0.05) throughout the periodization training (T0: 350 U·L; T3: 150 U·L). Significant increases were observed (p ≤ 0.05) in the intensity of the game, high-intensity activities (HIA) (T0: 22%; T3: 27%), maximum speed (T0: 30 km·h; T3: 34 km·h) and tactical performance, team surface area (T0: 515 m; T3: 683 m), and spread (T0: 130 m; T3: 148 m). In addition, we found significant inverse correlations between the percentage variation of T0 to T3 in CK and LDH activities with percentage variation in high-intensity running (r = -0.85; p ≤ 0.05 and r = -0.84; p < 0.01, respectively) and HIA (r = -0.71 and r = -0.70; p ≤ 0.05, respectively) during the matches. We concluded that there was reduced activity in biochemical markers related to muscle damage, as well as increases in-game high-intensity performance and the tactical performance of the study participants. Furthermore, players who showed greater reduction in plasma activity of CK and LDH also obtained greater increases in-game high-intensity performance along the periodization. These results may contribute to the expansion and future consolidation of the knowledge of coaches and sport scientists to develop effective methodologies for training in soccer.

Effect of plyometric training on lower limb biomechanics in females.

OBJECTIVE: To verify the effects of plyometric training on lower limb kinematics, eccentric hip and knee torques, and functional performance. DESIGN: Cohort study. SETTING: Research laboratory. PARTICIPANTS: Thirty-six females were divided into a training group (TG; n = 18) that carried out the plyometric training for 8 weeks, and a control group (CG; n = 18) that carried out no physical training. INTERVENTIONS: Twenty-four plyometric training sessions during approximately 8 weeks with 3 sessions per week on alternate days. MAIN OUTCOMES MEASURES: Lower limb kinematics (maximum excursion of hip adduction, hip medial rotation, and knee abduction during the single leg squat), eccentric hip (abductor, adductor, medial, and lateral rotator) isokinetic peak torques and knee (flexor and extensor) isokinetic peak torques, and functional performance (triple hop test and the 6-m timed hop test). RESULTS: After 8 weeks, only the TG significantly reduced the values for the maximum excursion of knee abduction (P = 0.01) and hip adduction (P < 0.001). Similarly, only the TG significantly increased the eccentric hip abductor (P < 0.001) and adductor (P = 0.01) torques. Finally, only the TG significantly increased the values in the triple hop test (P < 0.001) and significantly decreased the values in the 6-m timed hop test (P < 0.001) after intervention. CONCLUSION: Plyometric training alters lower limb kinematics and increases eccentric hip torque and functional performance, suggesting the incorporation of these exercises in preventive programs for ACL injuries.