Can coordination variability identify performance factors and skill level in competitive sport? The case of race walking

AbstractBackgroundMarginal changes in the execution of competitive sports movements can represent a significant change for performance success. However, such differences may emerge only at certain execution intensities and are not easily detectable through conventional biomechanical techniques. This study aimed to investigate if and how competition standard and progression speed affect race walking kinematics from both a conventional and a coordination variability perspective.MethodsFifteen experienced athletes divided into three groups (elite, international, and national) were studied while race walking on a treadmill at two different speeds (12.0 and 15.5 km/h). Basic gait parameters, the angular displacement of the pelvis and lower limbs, and the variability in continuous relative phase between six different joint couplings were analyzed.ResultsMost of the spatio-temporal, kinematic, and coordination variability measures proved sensitive to the change in speed. Conversely, non-linear dynamics measures highlighted differences between athletes of different competition standard when conventional analytical tools were not able to discriminate between different skill levels. Continuous relative phase variability was higher for national level athletes than international and elite in two couplings (pelvis obliquity—hip flex/extension and pelvis rotation—ankle dorsi/plantarflexion) and gait phases (early stance for the first coupling, propulsive phase for the second) that are deemed fundamental for correct technique and performance.ConclusionMeasures of coordination variability showed to be a more sensitive tool for the fine detection of skill-dependent factors in competitive race walking, and showed good potential for being integrated in the assessment and monitoring of sports motor abilities

Estimates of running ground reaction force parameters from motion analysis

We compared running mechanics parameters determined from ground reaction force (GRF) measurements with estimated forces obtained from double differentiation of kinematic (K) data from motion analysis in a broad spectrum of running speeds (1.94\u20135.56 m c5s\u20131). Data were collected through a force-instrumented treadmill and compared at different sampling frequencies (900 and 300 Hz for GRF, 300 and 100 Hz for K). Vertical force peak, shape, and impulse were similar between K methods and GRF. Contact time, flight time, and vertical stiffness (kvert) obtained from K showed the same trend as GRF with differences < 5%, whereas leg stiffness (kleg) was not correctly computed by kinematics. The results revealed that the main vertical GRF parameters can be computed by the double differentiation of the body center of mass properly calculated by motion analysis. The present model provides an alternative accessible method for determining temporal and kinetic parameters of running without an instrumented treadmill

Recumbent vs. upright bicycles:3D trajectory of body centre of mass, limb mechanical work, and operative range of propulsive muscles

Recumbent bicycles (RB) are high performance, human-powered vehicles. In comparison to normal/upright bicycles (NB) the RB may allow individuals to reach higher speeds due to aerodynamic advantages. The purpose of this investigation was to compare the non-aerodynamic factors that may potentially influence the performance of the two bicycles. 3D body centre of mass (BCoM) trajectory, its symmetries, and the components of the total mechanical work necessary to sustain cycling were assessed through 3D kinematics and computer simulations. Data collected at 50, 70, 90 110\ua0rpm during stationary cycling were used to drive musculoskeletal modelling simulation and estimate muscle-tendon length. Results demonstrated that BCoM trajectory, confined in a 15-mm side cube, changed its orientation, maintaining a similar pattern across all cadences in both bicycles. RB displayed a reduced additional mechanical external power (16.1\ua0\ub1\ua09.7\ua0W on RB vs. 20.3\ua0\ub1\ua08.8\ua0W on NB), a greater symmetry on the progression axis, and no differences in the internal mechanical power compared to NB. Simulated muscle activity revealed small significant differences for only selected muscles. On the RB, quadriceps and gluteus demonstrated greater shortening, while biceps femoris, iliacus, and psoas exhibited greater stretch; however, aerodynamics still remains the principal benefit

Technical skills and movement coordination in elite, national and regional level race walkers

Introduction: Race walking (RW) is a very peculiar form of locomotion that requires athletes to walk as fast as possible following two main rules: keep the knee of the supporting leg locked “from the moment of first contact with the ground until the vertical upright position”; and, generate a progression of steps with no visible flight phase. Previous studies have attempted to characterize RW performance, but the use of conventional analytical tools, including kinematic, kinetic and physiological measures, has not been very successful in discriminating between different skill levels and identifying the factors for excellent performance. Improved experimental protocols and finer analytical tools are needed to unveil the subtle differences existing between athletes of different competitive standard.Aim: To compare coordination and coordination variability in RW, and highlight differences between elite-, national- and regional-standard athletes.Method: A cross-sectional design was used to study the changes in coordination variability as a factor of skill level. Fifteen competitive male race walkers were assigned to the Elite, National or Regional groups depending on their season best performance, and were asked to race walk on a treadmill at 15 km/h. Optoelectronic motion capture was used to record 40 gait cycles for each participant. Pelvis and lower limb kinematics was used to study coordination variability through a dynamical system approach [1]. Continuous relative phase and its variability across multiple strides were estimated (Figure 1a). Multiple joint couplings (e.g. hip-knee, knee-ankle) and movement phases (e.g. early and late stance, swing) were considered. Kruskal-Wallis tests were used to assess the between-group differences for each variable.Results and Discussion: Results appeared to support the hypothesis that coordination variability increases during transition phases (e.g. heel-strike and toe-off) (Figure 1b). Overall, less skilled athletes tended to produce larger coordination variability, with significantly higher values of deviation phase during the early-stance phase of the hip-knee (P=0.20), and pelvis-hip (P=0.09) couplings. Individual coordinative patterns showed the potential for characterizing individual peculiarities in specific phases of the movement and to improve the understanding of technical skills, however more work is needed to relate coordinative measures with features of the neuro-muscular-skeletal system organization.References[1] Preatoni, E., Hamill, J., Harrison, A.J., Hayes, K., Van Emmerik, R.E.A., Wilson, C., Rodano, R., 2013. Movement variability and skills monitoring in sports. Sports Biomechanics 12, 69-92.<br/

Race Walking Ground Reaction Forces at Increasing Speeds: A Comparison with Walking and Running

Race walking has been theoretically described as a walking gait in which no flight time is allowed and high travelling speed, comparable to running (3.6\u20134.2 m s1), is achieved. The aim of this study was to mechanically understand such a \u201chybrid gait\u201d by analysing the ground reaction forces (GRFs) generated in a wide range of race walking speeds, while comparing them to running and walking. Fifteen athletes race-walked on an instrumented walkway (4 m) and three-dimensional GRFs were recorded at 1000 Hz. Subjects were asked to performed three self-selected speeds corresponding to a low, medium and high speed. Peak forces increased with speeds and medio-lateral and braking peaks were higher than in walking and running, whereas the vertical peaks were higher than walking but lower than running. Vertical GRF traces showed two characteristic patterns: one resembling the \u201cM-shape\u201d of walking and the second characterised by a first peak and a subsequent plateau. These dierent patterns were not related to the athletes\u2019 performance level. The analysis of the body centre of mass trajectory, which reaches its vertical minimum at mid-stance, showed that race walking should be considered a bouncing gait regardless of the presence or absence of a flight phase

Training Effects on ROS Production Determined by Electron Paramagnetic Resonance in Master Swimmers

Acute exercise induces an increase in Reactive Oxygen Species (ROS) production dependent on exercise intensity with highest ROS amount generated by strenuous exercise. However, chronic repetition of exercise, that is, exercise training, may reduce exercise-induced oxidative stress. Aim of this study was to evaluate the effects of 6-weeks high-intensity discontinuous training (HIDT), characterized by repeated variations of intensity and changes of redox potential, on ROS production and antioxidant capacity in sixteen master swimmers. Time course changes of ROS generation were assessed by Electron Paramagnetic Resonance in capillary blood by a microinvasive approach. An incremental arm-ergometer exercise (IE) until exhaustion was carried out at both before (PRE) and after (POST) training (Trg) period. A significant (P<0.01) increase of ROS production from REST to the END of IE in PRE Trg (2.82±0.66 versus 3.28±0.66 µmol·min−1) was observed. HIDT increased peak oxygen consumption (36.1±4.3 versus 40.6±5.7 mL·kg−1·min−1 PRE and POST Trg, resp.) and the antioxidant capacity (+13%) while it significantly decreased the ROS production both at REST (−20%) and after IE (−25%). The observed link between ROS production, adaptive antioxidant defense mechanisms, and peak oxygen consumption provides new insight into the correlation between ROS response pathways and muscle metabolic function

A pilot study of brisk walking in sedentary combination antiretroviral treatment (cART)- treated patients: benefit on soluble and cell inflammatory markers

Background: Chronic HIV infection is associated with low-level inflammation and increased risk of chronic diseases and mortality. The objective was to assess the effects of moderate intensity exercise on metabolic and inflammatory markers in HIV-infected treated persons. Methods: This was a pilot study enrolling cART-treated, sedentary persons with metabolic complications in a 12-week protocol, consisting of three sessions per week of 60 min brisk walking with (strength-walk group) or without (walk group) 30 min circuit-training. Assessments at baseline and week 12 (W12) included body morphometrics and total body dual-energy X-ray absorptiometry; lipid and glucose blood profile; plasma level of high sensitivity C-reactive protein (hsCRP), interleukin-6 (IL-6), D-dimer, interleukin-18 (IL-18), soluble CD14, and CD38 and HLA-DR expression on CD4+ and CD8+ T-cells. Results: Forty-nine patients were included and 35 (71%) completed the program: 21 in the walk and 14 in the strength-walk group. At W12, significant improvements were observed of body mass index, waist and hip circumference, and total cholesterol both overall and in the walk group, and of LDL cholesterol in both training groups. In the whole group, significant reductions were observed in hsCRP, IL-6, D-dimer, IL-18, and of CD8 +/CD38+/HLA-DR+ cell frequencies. HsCRP and CD8+/CD38+/HLA-DR+ frequency decreased significantly in both training groups when examined separately whereas IL-6 and D-dimer in the walk group only. Conclusions: Brisk walking, with or without strength exercise, could improve lipid profile and inflammatory markers in chronic HIV infection

Can coordination variability identify performance factors and skill level in competitive sport? The case of race walking

Background: Marginal changes in the execution of competitive sports movements can represent a significant change for performance success. However, such differences may emerge only at certain execution intensities and are not easily detectable through conventional biomechanical techniques. This study aimed to investigate if and how competition standard and progression speed affect race walking kinematics from both a conventional and a coordination variability perspective.Methods: Fifteen experienced athletes divided into three groups (Elite, International, and National) were studied while race walking on a treadmill at two different speeds (12.0 and 15.5 km/h). Basic gait parameters, the angular displacement of the pelvis and lower limbs, and the variability in continuous relative phase between six different joint couplings were analyzed.Results: Most of the spatio-temporal, kinematic, and coordination variability measures proved sensitive to the change in speed. Conversely, non-linear dynamics measures highlighted differences between athletes of different competition standard when conventional analytical tools were not able to discriminate between different skill levels. Continuous relative phase variability was higher for National level athletes than International and Elite in two couplings (pelvis obliquity – hip flex/extension and pelvis rotation – ankle dorsi/plantarflexion) and gait phases (early stance for the first coupling, propulsive phase for the second) that are deemed fundamental for correct technique and performance.Conclusion: Measures of coordination variability showed to be a more sensitive tool for the fine detection of skill-dependent factors in competitive race walking, and showed good potential for being integrated in the assessment and monitoring of sports motor abilities.<br/