Rachel Venter

Perceptions of team athletes on the importance of recovery modalities

Abstract The aim of this study was to determine how elite team athletes perceive the importance of various recovery modalities. Differences between men and women, players from various team sports and different levels of participation were determined. A total of 890 athletes who volunteered to participate in the study were team players from field hockey (n=213; mean age 21.8±3.3 years), netball (n=215; mean age 22.0±4.0 years), rugby union (n=317; mean age 23.2±3 years) and soccer (n=145; mean age 21.3±2.2 years). The total group of players consisted of 507 (57%) men and 383 (43%) women. At the time of the study, players who participated in the study competed at the highest level of the major competitions and tournaments in their sport, both locally and internationally. Data were collected by means of a questionnaire specifically designed for the study. A one-page, alphabetical list consisted of 32 words or phrases relating to physiological, psychological, social as well as complimentary and alternative strategies, which could be used for the recovery of athletes. Recovery modalities that were rated as important by all players, regardless of gender, type of sport or level of participation, were sleep, fluid replacement and socialise with friends. Gender differences could play a role in how the importance of recovery modalities was perceived. Men rated an ice bath and supplements as significantly more important (P<0.001) than women. Women rated discussions with their teammates and coaches after training and matches as significantly more important (P<0.001) than men. Significant differences were also found between the different sport codes and levels of participation in regard to the perceived importance of various modalities that could affect recovery of team sport players.

Wireless Tri-Axial Trunk Accelerometry Detects Deviations in Dynamic Center of Mass Motion Due to Running-Induced Fatigue

Small wireless trunk accelerometers have become a popular approach to unobtrusively quantify human locomotion and provide insights into both gait rehabilitation and sports performance. However, limited evidence exists as to which trunk accelerometry measures are suitable for the purpose of detecting movement compensations while running, and specifically in response to fatigue. The aim of this study was therefore to detect deviations in the dynamic center of mass (CoM) motion due to running-induced fatigue using tri-axial trunk accelerometry. Twenty runners aged 18–25 years completed an indoor treadmill running protocol to volitional exhaustion at speeds equivalent to their 3.2 km time trial performance. The following dependent measures were extracted from tri-axial trunk accelerations of 20 running steps before and after the treadmill fatigue protocol: the tri-axial ratio of acceleration root mean square (RMS) to the resultant vector RMS, step and stride regularity (autocorrelation procedure), and sample entropy. Running-induced fatigue increased mediolateral and anteroposterior ratios of acceleration RMS (p < .05), decreased the anteroposterior step regularity (p < .05), and increased the anteroposterior sample entropy (p < .05) of trunk accelerometry patterns. Our findings indicate that treadmill running-induced fatigue might reveal itself in a greater contribution of variability in horizontal plane trunk accelerations, with anteroposterior trunk accelerations that are less regular from step-to-step and are less predictable. It appears that trunk accelerometry parameters can be used to detect deviations in dynamic CoM motion induced by treadmill running fatigue, yet it is unknown how robust or generalizable these parameters are to outdoor running environments.

Surface effects on dynamic stability and loading during outdoor running using wireless trunk accelerometry

Despite frequently declared benefits of using wireless accelerometers to assess running gait in real-world settings, available research is limited. The purpose of this study was to investigate outdoor surface effects on dynamic stability and dynamic loading during running using tri-axial trunk accelerometry. Twenty eight runners (11 highly-trained, 17 recreational) performed outdoor running on three outdoor training surfaces (concrete road, synthetic track and woodchip trail) at self-selected comfortable running speeds. Dynamic postural stability (tri-axial acceleration root mean square (RMS) ratio, step and stride regularity, sample entropy), dynamic loading (impact and breaking peak amplitudes and median frequencies), as well as spatio-temporal running gait measures (step frequency, stance time) were derived from trunk accelerations sampled at 1024Hz. Results from generalized estimating equations (GEE) analysis showed that compared to concrete road, woodchip trail had several significant effects on dynamic stability (higher AP ratio of acceleration RMS, lower ML inter-step and inter-stride regularity), on dynamic loading (downward shift in vertical and AP median frequency), and reduced step frequency (p<0.05). Surface effects were unaffected when both running level and running speed were added as potential confounders. Results suggest that woodchip trails disrupt aspects of dynamic stability and loading that are detectable using a single trunk accelerometer. These results provide further insight into how runners adapt their locomotor biomechanics on outdoor surfaces in situ.

Barefoot Training Improved Ankle Stability and Agility in Netball Players

The primary aim of the study was to determine the effects of an eight-week barefoot training programme on ankle stability, agility and speed in 20 competitive female netball players (age 20 ±2 years). Before and after the intervention, all players were assessed for stability, agility and speed. The barefoot training group (n = 10) significantly improved their overall stability of the right leg (p = 0.01; d = 1.62), anterior-posterior stability of the right leg (p = 0.01; d = 1.63), the medial-lateral stability of the right leg (p = 0.04; d = 1.14) and performance in the 505-Agility test to the left (p = 0.01; d = 1.04) and right (p = 0.002; d = 1.4). The shod or control group (n=10) showed no statistically significant improvements in any of the performance tests. A large practical significant difference between the barefoot and control group was found in their 10 m (d = 1.01) and 20 m sprint (d = 0.8) performances after the intervention period. It could be concluded that barefoot training had a positive effect on agility and ankle stability, which could possibly enhance netball performance and play a role in the prevention of ankle injuries.

Influence of outdoor running fatigue and medial tibial stress syndrome on accelerometer-based loading and stability

Medial tibial stress syndrome (MTSS) is a common overuse running injury with pathomechanics likely to be exaggerated by fatigue. Wearable accelerometry provides a novel alternative to assess biomechanical parameters continuously while running in more ecologically valid settings. The purpose of this study was to determine the influence of outdoor running fatigue and MTSS on both dynamic loading and dynamic stability derived from trunk and tibial accelerometery. Runners with (n=14) and without (n=16) history of MTSS performed an outdoor fatigue run of 3200m. Accelerometer-based measures averaged per lap included dynamic loading of the trunk and tibia (i.e. axial peak positive acceleration, signal power magnitude, and shock attenuation) as well as dynamic trunk stability (i.e. tri-axial root mean square ratio, step and stride regularity, and sample entropy). Regression coefficients from generalised estimating equations were used to evaluate group by fatigue interactions. No evidence could be found for dynamic loading being higher with fatigue in runners with MTSS history (all measures p>0.05). One significant group by running fatigue interaction effect was detected for dynamic stability. Specifically, in MTSS only, decreases mediolateral sample entropy i.e. loss of complexity was associated with running fatigue (p<0.01). The current results indicate that entire acceleration waveform signals reflecting mediolateral trunk control is related to MTSS history, a compensation that went undetected in the non-fatigued running state. We suggest that a practical outdoor running fatigue protocol that concurrently captures trunk accelerometry-based movement complexity warrants further prospective investigation as an in-situ screening tool for MTSS individuals.

Acceleratory match-play demands of a Super Rugby team over a competitive season

Abstract The match-play demands of rugby union have increased over time, and these demands should be quantified so as to provide a basis for optimal player loading during training. The primary aim of this article was to quantify accelerations, decelerations, impacts and aggregated body demands during the first half of match-play in a Super Rugby team. The secondary aim was to determine whether these characteristics are position-specific. Thirty-three players were monitored for 14 matches using global positioning system units with inbuilt microtechnology. Players were grouped according to positional roles and data were analysed for those who completed the entire duration of the first half of a given match. Forwards sustained more (d = 0.44) high-intensity impacts and greater (d = 0.26) aggregated body demands, while backs had more moderate (d = 0.55) and heavy accelerations (d = 0.76), and moderate (d = 0.23) and heavy decelerations (d = 0.54). These differences suggest that conditioning and recovery strategies should reflect the physical demands placed on players in different playing positions. Forwards should be conditioned with a focus on impacts and require longer recovery for the same duration of playing time, whereas conditioning for backs should emphasise rapid accelerations and decelerations.

Effect of minimalist shoe training on lower limb joint moments

The results show a slight improvement in balance for both groups across the intervention period of 12 weeks. Primarily, significant differences were found for the COG path length in the balance task on the force platform during tandem standing with open eyes. The results showed that both kinds of intervention had a small effect on balance performance in elderly women, especially after a period of 12 weeks. But there were no statistically significant differences found between the two shoes (TSA, TSB).

The Relationship between the Bunkie-Test and Physical Performance in Rugby Union Players

It is suggested that restrictions in the fascia along the kinetic chains could inhibit muscle function and therefore influence movement patterns, such as those required by skilled rugby players. The Bunkie-test has been proposed as a tool to identify fascia restrictions in five kinetic chains. The purpose of this study was to use the isometric Bunkie-test to determine its relationship with performance in selected physical tests (agility, speed, explosive power, and muscle endurance) in rugby union players. The participants (n = 121) were rugby union players from three academies. Results indicated significant relationships (p < 0.05) between performance in the Bunkie-test and the physical tests. Players who performed better on the Bunkie-test achieved better results in the physical tests. The Bunkie-test might be a tool for coaches, trainers and therapists to identify weaknesses and imbalances in the kinetic chains of players. Addressing these problems could lead to improvements in sport performance, as well as assessing readiness of players to return to play after injuries.

Energy cost of running instability evaluated with wearable trunk accelerometry

Maintaining stability under dynamic conditions is an inherent challenge to bipedal running. This challenge may impose an energetic cost (Ec) thus hampering endurance running performance, yet the underlying mechanisms are not clear. Wireless triaxial trunk accelerometry is a simple tool that could be used to unobtrusively evaluate these mechanisms. Here, we test a cost of instability hypothesis by examining the contribution of trunk accelerometry-based measures (triaxial root mean square, step and stride regularity, and sample entropy) to interindividual variance in Ec (J/m) during treadmill running. Accelerometry and indirect calorimetry data were collected concurrently from 30 recreational runners (16 men; 14 women) running at their highest steady-state running speed (80.65 ± 5.99% V̇o2max). After reducing dimensionality with factor analysis, the effect of dynamic stability features on Ec was evaluated using hierarchical multiple regression analysis. Three accelerometry-based measures could explain an additional 10.4% of interindividual variance in Ec after controlling for body mass, attributed to anteroposterior stride regularity (5.2%), anteroposterior root mean square ratio (3.2%), and mediolateral sample entropy (2.0%). Our results lend support to a cost of instability hypothesis, with trunk acceleration waveform signals that are 1) more consistent between strides anteroposterioly, 2) larger in amplitude variability anteroposterioly, and 3) more complex mediolaterally and are energetically advantageous to endurance running performance. This study shows that wearable trunk accelerometry is a useful tool for understanding the Ec of running and that running stability is important for economy in recreational runners. NEW & NOTEWORTHY This study evaluates and more directly lends support to a cost of instability hypothesis between runners. Moreover, this hypothesis was tested using a minimalist setup including a single triaxial trunk mounted accelerometer, with potential transferability to biomechanical and performance analyses in typical outdoor settings.