Paulo Roberto Pereira Santiago

Effect of functional stabilization training on lower limb biomechanics in women.

PURPOSE This study aimed to verify the effects of functional stabilization training on lower limb kinematics, functional performance, and eccentric hip and knee torques. METHODS Twenty-eight women were divided into a training group (TG; n = 14), which carried out the functional stabilization training during 8 wk, and a control group (CG; n = 14), which carried out no physical training. The kinematic assessment of the lower limb was performed during a single-leg squat, and the functional performance was evaluated by way of the single-leg triple hop and the timed 6-m single-leg hop tests. The eccentric hip abductor, adductor, lateral rotator, medial rotator, and the knee flexor and extensor torques were measured using an isokinetic dynamometer. RESULTS After 8 wk, the TG significantly reduced the values for knee abduction (from -6.86° to 1.49°), pelvis depression (from -10.21° to -7.86°) and femur adduction (from 7.08° to 5.19°) as well as increasing the excursion of femur lateral rotation (from -0.55° to -3.67°). Similarly, the TG significantly increased the values of single-leg triple hop (from 3.52 to 3.92 m) and significantly decreased the values of timed 6-m single-leg hop tests (from 2.43 to 2.14 s). Finally, the TG significantly increased the eccentric hip abductor (from 1.31 to 1.45 N · m · kg(-1)), hip lateral rotator (from 0.75 to 0.91 N · m · kg(-1)), hip medial rotator (from 1.45 to 1.66 N · m · kg(-1)), knee flexor (from 1.43 to 1.55 N · m · kg(-1)), and knee extensor (from 3.46 to 4.40 N · m · kg(-1)) torques. CONCLUSIONS Strengthening of the hip abductor and lateral rotator muscles associated with functional training improves dynamic lower limb alignment and increases the strength and functional performance.

Performance comparisons of the kicking of stationary and rolling balls in a futsal context

Angular kinematics of the hip, knee, and ankle joints, as well as ball velocity and accuracy for stationary and rolling balls were compared in a futsal (Five-a-Side Indoor soccer) context. Ten futsal athletes performed five kicks each on stationary and rolling futsal balls. Six digital cameras (120 Hz) recorded the kicks. For both kick types, angles for hip, knee, and ankle joints were calculated using Euler angle conventions. Angular velocity, ball velocity, foot linear velocity, relative velocity, and accuracy also were analyzed. The kicking of both stationary and rolling balls showed similarities for ball velocity (24.2 ± 2.2 m/s and 23.8 ± 2.7 m/s, respectively), foot velocity (17.6 ± 1.8 m/s and 17.2 ± 2.2 m/s, respectively), and accuracy (26% and 24% target hits, respectively). We observed few differences in angular kinematics and angular joint velocities between kick types. Elite players can make online adjustments in the preparatory phase so that kicking a rolling ball is almost exactly like kicking a stationary ball.

Variations in dynamic knee valgus and gluteus medius onset timing in non-athletic females related to hormonal changes during the menstrual cycle ☆

It has been suggested that activities of daily living could contribute to the occurrence of ACL injury in females. Currently, no studies have focused on the lower extremity behavior of a non-athletic population to compare or understand the lower extremity adeptness towards daily movements that mimic athletic tasks. Our hypothesis was that increased knee valgus angles would occur during the late follicular phase of the menstrual cycle accompanied by different onset timing of the gluteus medius muscle. In a controlled laboratory study, 23 non-athletic collegiate females participated and 15 subjects comprised the final sample for statistical analysis. Subjects performed a single leg drop landing maneuver while 3-D knee kinematics and gluteus medius muscle onset timing were assessed throughout three distinct phases of the menstrual cycle, confirmed by blood hormone analysis. In general, knee valgus angles were significantly less in the luteal phase compared to both follicular phases (p<0.005), while differences were not observed for gluteus medius onset timing (p=0.936). As a decreased knee joint valgus angle was observed during the luteal phase, it was hypothesized that the hormone progesterone could significantly influence knee kinematics during a dynamic task. However, such influence was not observed for gluteus medius EMG onset timing as a significant correlation between gluteus medius onset timing and knee valgus angle could not be determined.

Relationship between aerobic and anaerobic parameters from 3-minute all-out tethered swimming and 400-m maximal front crawl effort.

Abstract Kalva-Filho, CA, Zagatto, AM, Araújo, MIC, Santiago, PRP, da Silva, ASR, Gobatto, CA, and Papoti, M. Relationship between aerobic and anaerobic parameters from 3-minute all-out tethered swimming and 400-m maximal front crawl effort. J Strength Cond Res 29(1): 238–245, 2015—The main aim of this investigation was to verify the relationship of the variables measured during a 3-minute all-out test with aerobic (i.e., peak oxygen uptake [ ] and intensity corresponding to the lactate minimum [LMI]) and anaerobic parameters (i.e., anaerobic work) measured during a 400-m maximal performance. To measure force continually and to avoid the possible influences caused by turns, the 3-minute all-out effort was performed in tethered swimming. Thirty swimmers performed the following tests: (a) a 3-minute all-out tethered swimming test to determine the final force (equivalent to critical force: CF3-MIN) and the work performed above CF3-MIN (W′3-MIN), (b) a LMI protocol to determine the LMI during front crawl swimming, and (c) a 400-m maximal test to determine the and total anaerobic contribution (WANA). Correlations between the variables were tested using the Pearsons correlation test (p ⩽ 0.05). CF3-MIN (73.9 ± 13.2 N) presented a high correlation with the LMI (1.33 ± 0.08 m·s−1; p = 0.01) and (4.5 ± 1.2 L·min−1; p = 0.01). However, the W′3-MIN (1,943.2 ± 719.2 N·s) was only moderately correlated with LMI (p = 0.02) and (p = 0.01). In summary, CF3-MIN determined during the 3-minute all-out effort is associated with oxidative metabolism and can be used to estimate the aerobic capacity of swimmers. In contrast, the anaerobic component of this model (W′3-MIN) is not correlated with WANA.

A Semi-Tethered Test for Power Assessment in Running

We analyzed the usefulness of a semi-tethered field running test (STR) and the relationships between indices of anaerobic power, anaerobic capacity and running performance in 9 trained male sprinters (22.2 ± 2.9 yrs, 176 ± 1 cm, 68.0 ± 9.4 kg). STR involved an all out 120 m run attached to an apparatus that enabled power calculation from force and velocity measures. Subjects also carried out a cycloergometer Wingate Anaerobic Test (WT), an all out 300 m run and had accessed their maximal accumulated oxygen deficit (MAOD) on a treadmill. Peak and mean powers attained in STR (1720 ± 221 and 1391 ± 201 W) were greater but significantly related (r = 0.82; P < 0.01) to those in the WT (808 ± 130 and 603 ± 87 W). In addition, power measures derived from the STR were stronger related to running performance compared to those from the WT (r = 0.81-0.94 vs. 0.68-0.84; P < 0.05). Relationships between MAOD and most power indices were only weak to moderate. These results support the usefulness of STR for specific power assessment in field running and suggest that anaerobic power and capacity are not related entities, irrespective of having been evaluated using similar or dissimilar exercise modes.

Dominant–non-dominant asymmetry of kicking a stationary and rolling ball in a futsal context

Abstract The aim of this study was to analyse the characteristics of the asymmetries in the dominant and non-dominant limbs when kicking stationary and rolling balls. Ten experienced Brazilian amateur futsal players participated in this study. Each participant performed kicks under two conditions (stationary ball vs. rolling ball) with the dominant and non-dominant limbs (five kicks per condition per limb). We analysed the kicking accuracy, ball and foot velocities, angular joint displacement and velocity. The asymmetry between the dominant and non-dominant limbs was analysed by symmetry index and two-way repeated measures ANOVA. The results did not reveal any interaction between the condition and limb for ball velocity, foot velocity and accuracy. However, kicking with the dominant limb in both kicks showed higher ball velocity (stationary ball: dominant – 24.27 ± 2.21 m · s‒1 and non-dominant – 21.62 ± 2.26 m · s‒1; rolling ball: dominant – 23.88 ± 2.71 m · s‒1 and non-dominant – 21.42 ± 2.25 m · s‒1), foot velocity (stationary ball: dominant – 17.61 ± 1.87 m · s‒1 and non-dominant – 15.58 ± 2.69 m · s‒1; rolling ball: dominant – 17.25 ± 2.26 m · s‒1 and non-dominant – 14.77 ± 2.35 m · s‒1) and accuracy (stationary ball: dominant – 1.17 ± 0.84 m and non-dominant – 1.56 ± 1.30 m; rolling ball: dominant – 1.31 ± 0.91 m and non-dominant – 1.97 ± 1.44 m). In addition, the angular joint adjustments were dependent on the limb in both kicks (the kicks with non-dominant limb showed lower hip external rotation than the kicks with the dominant limb), indicating that the hip joint is important in kick performance. In conclusion, the kicks with the non-dominant limb showed different angular adjustments in comparison to kicks with the dominant limb. In addition, kicking a rolling ball with the non-dominant limb showed higher asymmetry for accuracy, indicating that complex kicks are more asymmetric.

Energy Systems Contribution in the Running-based Anaerobic Sprint Test

The aims of the present study were to verify the contributions of the energy systems during repeated sprints with a short recovery time and the associations of the time- and power-performance of repeated sprints with energetic contributions and aerobic and anaerobic variables. 13 healthy men performed the running-based anaerobic sprint test (RAST) followed by an incremental protocol for lactate minimum intensity determination. During the RAST, the net energy system was estimated using the oxygen consumption and the blood lactate responses. The relative contributions of oxidative phosphorylation, glycolytic, and phosphagen pathways were 38, 34, and 28%, respectively. The contribution of the oxidative pathway increased significantly during RAST especially from the third sprint, at the same time that power- and time-performances decreases significantly. The phosphagen pathway was associated with power-performance (peak power=432±107 W, r=0.65; mean power=325±80 W, r=0.65; minimum power=241±77 W, r=0.57; force impulse=1 846±478 N·s, r=0.74; p<0.05). The time-performance (total time=37.9±2.5 s; best time=5.7±0.4 s; mean time=6.3±0.4 s; worst time=7.0±0.6 s) was significantly correlated with the oxidative phosphorylation pathway (0.57+0.65; p<0.05) and glycolytic pathway (0.57+<+r>0.58; p<0.05). The oxidative pathway appears to play an important role in better recovery between sprints, and the continued use of the glycolytic metabolic pathway seems to decrease sprint performances. Finally, the phosphagen pathway was linked to power production/maintenance.

Upper extremity coordination strategies depending on task demand during a basic daily activity

Injury conditions affecting the upper extremity may lead to severe functional impairment and an accurate evaluation is needed in order to select the most effective treatment in a rehabilitation program. This study focused on simultaneous electromyographic and kinematic analysis to assess movement patterns of upper extremity during a basic daily activity, considering different demands existing within the task. Twenty-five healthy subjects, average age 19.8 ys SD 1.7 ys, with no upper extremity impairment, were assessed by means of electromyography (EMG) and a 3D motion capture system while performing a task that required reach, transport and release. Integrated EMG (iEMG), timing of muscle onset and active range of motion (AROM) were calculated for each subject. Data were compared within each phase and between the three phases and a repeated measure ANOVA was used for statistical analysis. We found early activation of upper trapezius associated with high activity of serratus anterior for proximal stability while anterior deltoid and triceps brachii performed shoulder flexion and elbow extension, in Reach phase. In Transport phase there was early and higher activation of upper trapezius, higher muscle activity of almost all muscles and increased AROM of all joints. No change in flexion/extension wrist posture with increased forearm muscles activity were identified as the main control strategy to keep optimal grasping. Triceps brachii was found to act as an important synergist in shoulder abduction and extension in free load conditions. Such information can lead clinicians to more specific assessment and subsequent better intervention in upper extremity rehabilitation.

A comparison between flexible electrogoniometers, inclinometers and three-dimensional video analysis system for recording neck movement

This study compared neck range of movement recording using three different methods goniometers (EGM), inclinometers (INC) and a three-dimensional video analysis system (IMG) in simultaneous and synchronized data collection. Twelve females performed neck flexion-extension, lateral flexion, rotation and circumduction. The differences between EGM, INC, and IMG were calculated sample by sample. For flexion-extension movement, IMG underestimated the amplitude by 13%; moreover, EGM showed a crosstalk of about 20% for lateral flexion and rotation axes. In lateral flexion movement, all systems showed similar amplitude and the inter-system differences were moderate (4-7%). For rotation movement, EGM showed a high crosstalk (13%) for flexion-extension axis. During the circumduction movement, IMG underestimated the amplitude of flexion-extension movements by about 11%, and the inter-system differences were high (about 17%) except for INC-IMG regarding lateral flexion (7%) and EGM-INC regarding flexion-extension (10%). For application in workplace, INC presents good results compared to IMG and EGM though INC cannot record rotation. EGM should be improved in order to reduce its crosstalk errors and allow recording of the full neck range of movement. Due to non-optimal positioning of the cameras for recording flexion-extension, IMG underestimated the amplitude of these movements.

Analysis of Soccer Players’ Positional Variability During the 2012 UEFA European Championship: A Case Study

Abstract The purpose of this study was to analyse players’ positional variability during the 2012 UEFA European Championship by applying principal component analysis (PCA) to data gathered from heat maps posted on the UEFA website. We analysed the teams that reached the finals and semi-finals of the competition. The players’ 2D coordinates from each match were obtained by applying an image-processing algorithm to the heat maps. With all the players’ 2D coordinates for each match, we applied PCA to identify the directions of greatest variability. Then, two orthogonal segments were centred on each player’s mean position for all matches. The segments’ directions were driven by the eigenvectors of the PCA, and the length of each segment was defined as one standard deviation around the mean. Finally, an ellipse was circumscribed around both segments. To represent player variability, segment lengths and elliptical areas were analysed. The results demonstrate that Portugal exhibited the lowest variability, followed by Germany, Spain and Italy. Additionally, a graphical representation of every player’s ellipse provided insight into the teams’ organisational features throughout the competition. The presented study provides important information regarding soccer teams’ tactical strategy in high-level championships that allows coaches to better control team organisation on the pitch.