COMPARING TIBIAL ACCELERATIONS BETWEEN DELIVERY AND FOLLOW-THROUGH FOOT STRIKES IN CRICKET FAST BOWLING

The kinematics of the fast bowling follow-through are often reported, yet the follow-through is unassessed. This study compared magnitudes of tibial accelerations across the delivery and follow-through foot strikes in fast bowlers. Fifteen sub-elite male fast bowlers performed 24 deliveries during training. Tibial accelerations were measured using tibial-mounted inertial measurement units. Peak tibial acceleration magnitudes were recorded at the foot contacts of the delivery and follow-through strides. A linear mixed model showed statistical significance between foot strike events (p \u3c .001) with the greatest magnitude of tibial acceleration occurring at back foot re-contact. The tibial acceleration peak reported at back foot re-contact may have implications for load quantification and injury risk, therefore representing an important avenue for future fast bowling research

Peak match acceleration demands differentiate between elite youth and professional football players

Youth footballers need to be developed to meet the technical, tactical, and physical demands of professional level competition, ensuring that the transition between competition levels is successful. To quantify the physical demands, peak match intensities have been measured across football competition tiers, with team formations and tactical approaches shown to influence these physical demands. To date, no research has directly compared the physical demands of elite youth and professional footballers from a single club utilising common formations and tactical approaches. The current study quantified the total match and peak match running demands of youth and professional footballers from a single Australian A-League club. GPS data were collected across a single season from both a professional (n = 19; total observations = 199; mean ± SD; 26.7 ± 4.0 years) and elite youth (n = 21; total observations = 59; 17.9 ± 1.3 years) team. Total match demands and peak match running demands (1–10 min) were quantified for measures of total distance, high-speed distance [>19.8 km-h-1] and average acceleration. Linear mixed models and effect sizes identified differences between competition levels. No differences existed between competition levels for any total match physical performance metric. Peak total and high-speed distances demands were similar between competitions for all moving average durations. Interestingly, peak average acceleration demands were lower (SMD = 0.63–0.69) in the youth players across all moving average durations. The data suggest that the development of acceleration and repeat effort capacities is crucial in youth players for them to transition into professional competition

Mechanical differences between men and women during overground load carriage at self-selected walking speeds

Few studies have directly compared physical responses to relative loading strategies between men and women during overground walking. This study aimed to compare gait mechanics of men and women during overground load carriage. A total of 30 participants (15 male, 15 female) completed three 10-min walking trials while carrying external loads of 0%, 20% and 40% of body mass at a self-selected walking speed. Lower-body motion and ground reaction forces were collected using a three-dimensional motion capture system and force plates, respectively. Female participants walked with a higher cadence (p = 0.002) and spent less absolute time in stance (p = 0.010) but had similar self-selected walking speed (p = 0.750), which was likely due to the female participants being shorter than the male participants. Except for ankle plantarflexion moments, there were no sex differences in spatiotemporal, kinematic, or kinetic variables (p > 0.05). Increasing loads resulted in significantly lower self-selected walking speed, greater stance time, and changes in all joint kinematics and kinetics across the gait cycle (p 0.05). In conclusion, there were few differences between sexes in walking mechanics during overground load carriage. The changes identified in this study may inform training programs to increase load carriage performance

The Society for Environmental Geochemistry and Health (SEGH): building for the future.

The challenges of sustainable development are ever more pressing, and the skills, interests and capabilities of the SEGH member are well-placed to continue to make more meaningful contributions to the environment, society and well-being. We reflect on the historical development of the society, its response to the dynamic international research landscape and the great opportunities ahead. In 2018, SEGH implemented a new board structure after 2–3 years of consultation, with approval of a new constitution and a new strategy across the large number of international board members. While regions were represented by sections in Europe, Asia/Pacific and the USA, the structure required renewal in order to be more representative of the distribution of members and website traffic that had evolved in preceding years. In addition, the society wanted to improve its position for future growth opportunities across rapidly developing regions

Temporal distribution of peak running demands relative to match minutes in elite football

The peak match running demands of football (soccer) have been quantified across time durations of 1–10 min, however, little is known as to when the peak match running demands occur within match play. Data were collected from 44 elite footballers, across 68 fixtures (Files = 413, mean ± SD; 11 ± 8 observations per player, range; 1–33), with peak match running demands quantified for each playing half at ten incremental rolling average durations (1 min rolling averages, 2 min rolling averages, etc.). Data were assessed if players completed the full match. Three measures of running performance were assessed total distance (TD), high-speed distance (> 19.8 km·h-1) (HSD) and average acceleration (AveAcc)], with the in-game commencement time of the peak running demands recorded. Descriptive statistics and normality were calculated for each rolling average duration, with the self-containment of shorter rolling average epochs within longer epochs also assessed (e.g. Do the 1 min peak running demands occur within the 10 min peak running demands). Peak TD and AveAcc demands occurred early in each half (median time = 7–17 min and 6–16 min, respectively). Conversely, peak HSD covered was uniformly distributed (Skewness = 0–0.5, Kurtosis = 1.7–2.0). There were low-moderate levels of self-containment for each peak match running period (10–51%), dependent upon metric. Peak match running demands for TD and AveAcc occurred at similar stages of a match where TD and acceleration volumes are typically greatest, whereas peak HSD demands appeared more unpredictable. These timings may help inform training prescriptions in preparation of athletes for competition

Positional and temporal differences in peak match running demands of elite football

Temporal changes in the total running demands of professional football competition have been well documented, with absolute running demands decreasing in the second half. However, it is unclear whether the peak match running demands demonstrate a similar decline. A total of 508 GPS files were collected from 44 players, across 68 matches of the Australian A-League. GPS files were split into the 1st and 2nd half, with the peak running demands of each half quantified across 10 moving average durations (1–10 min) for three measures of running performance (total distance, high-speed distance [> 19.8 km·h −1 ] and average acceleration). Players were categorised based on positional groups: attacking midfielder (AM), central defender (CD), defensive midfielder (DM), striker (STR), wide defender (WD) and winger (WNG). Linear mixed models and effect sizes were used to identify differences between positional groups and halves. Peak running demands were lower in the second half for STR across all three reported metrics (ES = 0.60–0.84), with peak average acceleration lower in the second half for DM, WD and WNG (ES = 0.60–0.70). Irrespective of match half, AM covered greater peak total distances than CD, STR, WD and WIN (ES = 0.60–2.08). Peak high-speed distances were greater across both halves for WIN than CD, DM and STR (ES = 0.78–1.61). Finally, STR had lower peak average acceleration than all positional groups across both halves (ES = 0.60–1.12). These results may help evaluate implemented strategies that attempt to mitigate reductions in second half running performance and inform position specific training practices

Temporal distribution of peak running demands relative to match minutes in elite football

The peak match running demands of football (soccer) have been quantified across time durations of 1–10 min, however, little is known as to when the peak match running demands occur within match play. Data were collected from 44 elite footballers, across 68 fixtures (Files = 413, mean ± SD; 11 ± 8 observations per player, range; 1–33), with peak match running demands quantified for each playing half at ten incremental rolling average durations (1 min rolling averages, 2 min rolling averages, etc.). Data were assessed if players completed the full match. Three measures of running performance were assessed total distance (TD), high-speed distance (> 19.8 km · h-1) (HSD) and average acceleration (AveAcc)], with the in-game commencement time of the peak running demands recorded. Descriptive statistics and normality were calculated for each rolling average duration, with the self-containment of shorter rolling average epochs within longer epochs also assessed (e.g. Do the 1 min peak running demands occur within the 10 min peak running demands). Peak TD and AveAcc demands occurred early in each half (median time = 7–17 min and 6–16 min, respectively). Conversely, peak HSD covered was uniformly distributed (Skewness = 0–0.5, Kurtosis = 1.7–2.0). There were low-moderate levels of self-containment for each peak match running period (10–51%), dependent upon metric. Peak match running demands for TD and AveAcc occurred at similar stages of a match where TD and acceleration volumes are typically greatest, whereas peak HSD demands appeared more unpredictable. These timings may help inform training prescriptions in preparation of athletes for competition

Positional and temporal differences in peak match running demands of elite football

Temporal changes in the total running demands of professional football competition have been well documented, with absolute running demands decreasing in the second half. However, it is unclear whether the peak match running demands demonstrate a similar decline. A total of 508 GPS files were collected from 44 players, across 68 matches of the Australian A-League. GPS files were split into the 1st and 2nd half, with the peak running demands of each half quantified across 10 moving average durations (1-10 min) for three measures of running performance (total distance, high-speed distance [> 19.8 km·h-1] and average acceleration). Players were categorised based on positional groups: attacking midfielder (AM), central defender (CD), defensive midfielder (DM), striker (STR), wide defender (WD) and winger (WNG). Linear mixed models and effect sizes were used to identify differences between positional groups and halves. Peak running demands were lower in the second half for STR across all three reported metrics (ES = 0.60-0.84), with peak average acceleration lower in the second half for DM, WD and WNG (ES = 0.60-0.70). Irrespective of match half, AM covered greater peak total distances than CD, STR, WD and WIN (ES = 0.60-2.08). Peak high-speed distances were greater across both halves for WIN than CD, DM and STR (ES = 0.78-1.61). Finally, STR had lower peak average acceleration than all positional groups across both halves (ES = 0.60-1.12). These results may help evaluate implemented strategies that attempt to mitigate reductions in second half running performance and inform position specific training practices

Between-match variation of peak match running intensities in elite football

Peak match running intensities have recently been introduced to quantify the peak running demands of football competition, across incremental time intervals, to inform training practices. However, their between-match variation is yet to be comprehensively reported, limiting the ability to determine meaningful changes in peak match running intensities. The current study aimed to quantify the between-match variability in peak match running intensities across discrete moving average durations (1–10 min). GPS data were collected from 44 elite football players across 68 matches (mean ± SD; 13 ± 10 observations per player). For inclusion players must have completed 70mins of a match across a minimum of two matches. Performance metrics included total and high-speed (> 19.8 km·h-1) running distances and average acceleration (m·s -2), expressed relative to time. For each metric, the coefficient of variation and smallest worthwhile difference were calculated. The peak match running intensity data was similar to previously reported data from various football competitions. The between-match CV of relative total distance ranged between 6.8–7.3%, with the CV for average acceleration and relative high-speed running being 5.4–5.8% and 20.6–29.8%, respectively. The greater variability observed for relative high-speed running is likely reflective of the varying constraints and contextual factors that differ between matches. The reported between-match variability helps to provide context when interpreting match performance and prescribing training drills using peak match running intensity data