Kieran Collins

The acute:chonic workload ratio in relation to injury risk in professional soccer

OBJECTIVES To examine the association between combined sRPE measures and injury risk in elite professional soccer. DESIGN Observational cohort study. METHODS Forty-eight professional soccer players (mean±SD age of 25.3±3.1 yr) from two elite European teams were involved within a one season study. Players completed a test of intermittent-aerobic capacity (Yo-YoIR1) to assess players injury risk in relation to intermittent aerobic capacity. Weekly workload measures and time loss injuries were recorded during the entire period. Rolling weekly sums and week-to-week changes in workload were measured, allowing for the calculation of the acute:chronic workload ratio, which was calculated by dividing the acute (1-weekly) and chronic (4-weekly) workloads. All derived workload measures were modelled against injury data using logistic regression. Odds ratios (OR) were reported against a reference group. RESULTS Players who exerted pre-season 1-weekly loads of ≥1500 to ≤2120AU were at significantly higher risk of injury compared to the reference group of ≤1500AU (OR=1.95, p=0.006). Players with increased intermittent-aerobic capacity were better able to tolerate increased 1-weekly absolute changes in training load than players with lower fitness levels (OR=4.52, p=0.011). Players who exerted in-season acute:chronic workload ratios of >1.00 to <1.25 (OR=0.68, p=0.006) were at significantly lower risk of injury compared to the reference group (≤0.85). CONCLUSIONS These findings demonstrate that an acute:chronic workload of between 1.00 and 1.25 is protective for professional soccer players. A higher intermittent-aerobic capacity appears to offer greater injury protection when players are exposed to rapid changes in workload in elite soccer players. Moderate workloads, coupled with moderate-low to moderate-high acute:chronic workload ratios, appear to be protective for professional soccer players.

Protection Against Spikes in Workload With Aerobic Fitness and Playing Experience: The Role of the Acute:Chronic Workload Ratio on Injury Risk in Elite Gaelic Football

PURPOSE To examine the association between combined session rating of perceived exertion (RPE) workload measures and injury risk in elite Gaelic footballers. METHODS Thirty-seven elite Gaelic footballers (mean ± SD age 24.2 ± 2.9 y) from 1 elite squad were involved in a single-season study. Weekly workload (session RPE multiplied by duration) and all time-loss injuries (including subsequent-wk injuries) were recorded during the period. Rolling weekly sums and wk-to-wk changes in workload were measured, enabling the calculation of the acute:chronic workload ratio by dividing acute workload (ie, 1-weekly workload) by chronic workload (ie, rolling-average 4-weekly workload). Workload measures were then modeled against data for all injuries sustained using a logistic-regression model. Odds ratios (ORs) were reported against a reference group. RESULTS High 1-weekly workloads (≥2770 arbitrary units [AU], OR = 1.63-6.75) were associated with significantly higher risk of injury than in a low-training-load reference group (<1250 AU). When exposed to spikes in workload (acute:chronic workload ratio >1.5), players with 1 y experience had a higher risk of injury (OR = 2.22) and players with 2-3 (OR = 0.20) and 4-6 y (OR = 0.24) of experience had a lower risk of injury. Players with poorer aerobic fitness (estimated from a 1-km time trial) had a higher injury risk than those with higher aerobic fitness (OR = 1.50-2.50). An acute:chronic workload ratio of (≥2.0) demonstrated the greatest risk of injury. CONCLUSIONS These findings highlight an increased risk of injury for elite Gaelic football players with high (>2.0) acute:chronic workload ratios and high weekly workloads. A high aerobic capacity and playing experience appears to offer injury protection against rapid changes in workload and high acute:chronic workload ratios. Moderate workloads, coupled with moderate to high changes in the acute:chronic workload ratio, appear to be protective for Gaelic football players.

Positional Match Running Performance in Elite Gaelic Football.

Abstract Malone, S, Solan, B, Collins, KD, and Doran, DA. Positional match running performance in elite Gaelic football. J Strength Cond Res 30(8): 2292–2298, 2016—There is currently limited information available on match running performance in Gaelic football. The objective of the current study was to report on the match running profile of elite male Gaelic football and assess positional running performance. In this observational study, 50 elite male Gaelic football players wore 4-Hz global positioning systems units (VX Sports) across 30 competitive games with a total of 215 full game data sets collected. Activity was classed according to total distance, high-speed distance (≥17 km·h−1), sprint distance (≥22 km·h−1), mean velocity (km·h−1), peak velocity (km·h−1), and number of accelerations. The average match distance was 8,160 ± 1,482 m, reflective of a relative distance of 116 ± 21 m·min−1, with 1,731 ± 659 m covered at high speed, which is reflective of a relative high-speed distance of 25 ± 9 m·min−1. The observed sprint distance was 445 ± 169 m distributed across 44 sprint actions. The peak velocity was 30.3 ± 1.8 km·h−1 with a mean velocity of 6.5 ± 1.2 km·h−1. Players completed 184 ± 40 accelerations, which represent 2.6 ± 0.5 accelerations per minute. There were significant differences between positional groups for both total running distance, high-speed running distance, and sprint distance, with midfielders covering more total and high-speed running distance, compared with other positions (p < 0.001). There was a reduction in high-speed and sprint distance between the first and second half (p < 0.001). Reductions in running performance were position dependent with the middle 3 positions experiencing the highest decrement in performance. The current study is the first to communicate a detailed description of match running performance during competitive elite Gaelic football match play.

Internal Sense of Direction: Sensing and Signaling from Cytoplasmic Chemoreceptors

SUMMARY Chemoreceptors sense environmental signals and drive chemotactic responses in Bacteria and Archaea. There are two main classes of chemoreceptors: integral inner membrane and soluble cytoplasmic proteins. The latter were identified more recently than integral membrane chemoreceptors and have been studied much less thoroughly. These cytoplasmic chemoreceptors are the subject of this review. Our analysis determined that 14% of bacterial and 43% of archaeal chemoreceptors are cytoplasmic, based on currently sequenced genomes. Cytoplasmic chemoreceptors appear to share the same key structural features as integral membrane chemoreceptors, including the formations of homodimers, trimers of dimers, and 12-nm hexagonal arrays within the cell. Cytoplasmic chemoreceptors exhibit varied subcellular locations, with some localizing to the poles and others appearing both cytoplasmic and polar. Some cytoplasmic chemoreceptors adopt more exotic locations, including the formations of exclusively internal clusters or moving dynamic clusters that coalesce at points of contact with other cells. Cytoplasmic chemoreceptors presumably sense signals within the cytoplasm and bear diverse signal input domains that are mostly N terminal to the domain that defines chemoreceptors, the so-called MA domain. Similar to the case for transmembrane receptors, our analysis suggests that the most common signal input domain is the PAS (Per-Arnt-Sim) domain, but a variety of other N-terminal domains exist. It is also common, however, for cytoplasmic chemoreceptors to have C-terminal domains that may function for signal input. The most common of these is the recently identified chemoreceptor zinc binding (CZB) domain, found in 8% of all cytoplasmic chemoreceptors. The widespread nature and diverse signal input domains suggest that these chemoreceptors can monitor a variety of cytoplasmically based signals, most of which remain to be determined.

The Helicobacter pylori CZB Cytoplasmic Chemoreceptor TlpD Forms an Autonomous Polar Chemotaxis Signaling Complex That Mediates a Tactic Response to Oxidative Stress

UNLABELLED Cytoplasmic chemoreceptors are widespread among prokaryotes but are far less understood than transmembrane chemoreceptors, despite being implicated in many processes. One such cytoplasmic chemoreceptor is Helicobacter pylori TlpD, which is required for stomach colonization and drives a chemotaxis response to cellular energy levels. Neither the signals sensed by TlpD nor its molecular mechanisms of action are known. We report here that TlpD functions independently of the other chemoreceptors. When TlpD is the sole chemoreceptor, it is able to localize to the pole and recruits CheW, CheA, and at least two CheV proteins to this location. It loses the normal membrane association that appears to be driven by interactions with other chemoreceptors and with CheW, CheV1, and CheA. These results suggest that TlpD can form an autonomous signaling unit. We further determined that TlpD mediates a repellent chemotaxis response to conditions that promote oxidative stress, including being in the presence of iron, hydrogen peroxide, paraquat, and metronidazole. Last, we found that all tested H. pylori strains express TlpD, whereas other chemoreceptors were present to various degrees. Our data suggest a model in which TlpD coordinates a signaling complex that responds to oxidative stress and may allow H. pylori to avoid areas of the stomach with high concentrations of reactive oxygen species. IMPORTANCE Helicobacter pylori senses its environment with proteins called chemoreceptors. Chemoreceptors integrate this sensory information to affect flagellum-based motility in a process called chemotaxis. Chemotaxis is employed during infection and presumably aids H. pylori in encountering and colonizing preferred niches. A cytoplasmic chemoreceptor named TlpD is particularly important in this process, and we report here that this chemoreceptor is able to operate independently of other chemoreceptors to organize a chemotaxis signaling complex and mediate a repellent response to oxidative stress conditions. H. pylori encounters and must cope with oxidative stress during infection due to oxygen and reactive oxygen species produced by host cells. TlpDs repellent response may allow the bacteria to escape niches experiencing inflammation and elevated reactive oxygen species (ROS) production.

A six stage operational framework for individualising injury risk management in sport

Managing injury risk is important for maximising athlete availability and performance. Although athletes are inherently predisposed to musculoskeletal injuries by participating in sports, etiology models have illustrated how susceptibility is influenced by repeat interactions between the athlete (i.e. intrinsic factors) and environmental stimuli (i.e. extrinsic factors). Such models also reveal that the likelihood of an injury emerging across time is related to the interconnectedness of multiple factors cumulating in a pattern of either positive (i.e. increased fitness) or negative adaptation (i.e. injury).The process of repeatedly exposing athletes to workloads in order to promote positive adaptations whilst minimising injury risk can be difficult to manage. Etiology models have highlighted that preventing injuries in sport, as opposed to reducing injury risk, is likely impossible given our inability to appreciate the interactions of the factors at play. Given these uncertainties, practitioners need to be able to design, deliver, and monitor risk management strategies that ensure a low susceptibility to injury is maintained during pursuits to enhance performance. The current article discusses previous etiology and injury prevention models before proposing a new operational framework.

The physical and physiological demands of small-sided games: How important is winning or losing?

The present study examined the effect that success (win) or failure (loss) during competitive small-sided games (SSG) has on physical and physiological demands. Twenty six outfield hurling players were monitored with GPS (4-Hz, VX Sport, New Zealand) and heart rate monitors (Polar Electro, Oy, Kempele, Finland). Total distance (m), high-speed distance (≥ 17 km·h-1; m), sprint distance (≥ 22 km·h-1; m) and peak velocities (km·h-1) during SSG were analysed. Time spent in different HR zones, maximum heart rate (HRmax), average HR and percentage of HRmax were also considered. Results showed significant effects for team success (win) on all collected variables, with successful teams showing significantly higher total distances (p = 0.013; d = 3.50 ± 0.30; very large) when compared to losing teams. Team success during SSG impacted high-speed performance with winning teams covering more distance (p = 0.002; d = 4.53 ± 0.46; very large). Similar trends were documented for physiological variables with significant effects reported for winning teams spending more time at higher percentages (≥95%) of HRmax when compared to losing teams (p = 0.013; d = 2.64 ± 0.34, very large). The current study has shown that success (win) or failure (loss) within SSG plays an important role for SSG design.

The Integration of Internal and External Training Load Metrics in Hurling

Abstract The current study aimed to assess the relationship between the hurling player’s fitness profile and integrated training load (TL) metrics. Twenty-five hurling players performed treadmill testing for VO2max, the speed at blood lactate concentrations of 2 mmol•L-1 (vLT) and 4 mmol•L-1 (vOBLA) and the heart rate-blood lactate profile for calculation of individual training impulse (iTRIMP). The total distance (TD; m), high speed distance (HSD; m) and sprint distance (SD; m) covered were measured using GPS technology (4-Hz, VX Sport, Lower Hutt, New Zealand) which allowed for the measurement of the external TL. The external TL was divided by the internal TL to form integration ratios. Pearson correlation analyses allowed for the assessment of the relationships between fitness measures and the ratios to performance during simulated match play. External measures of the TL alone showed limited correlations with fitness measures. Integrated TL ratios showed significant relationships with fitness measures in players. TD:iTRIMP was correlated with aerobic fitness measures VO2max (r = 0.524; p = 0.006; 95% CI: 0.224 to 0.754; large) and vOBLA (r = 0.559; p = 0.003; 95% CI: 0.254 to 0.854; large). HSD:iTRIMP also correlated with aerobic markers for fitness vLT (r = 0.502; p = 0.009; 95% CI: 0.204 to 0.801; large); vOBLA (r = 0.407; p = 0.039; 95% CI: 0.024 to 0.644; moderate). Interestingly SD:iTRIMP also showed significant correlations with vLT (r = 0.611; p = 0.001; 95% CI: 0.324 to 0.754; large). The current study showed that TL ratios can provide practitioners with a measure of fitness as external performance alone showed limited relationships with aerobic fitness measures.

Injury Scheme Claims in Gaelic Games: A Review of 2007-2014.

CONTEXT Gaelic games (Gaelic football and hurling) are indigenous Irish sports with increasing global participation in recent years. Limited information is available on longitudinal injury trends. Reviews of insurance claims can reveal the economic burden of injury and guide cost-effective injury-prevention programs. OBJECTIVE To review Gaelic games injury claims from 2007-2014 for male players to identify the costs and frequencies of claims. Particular attention was devoted to lower limb injuries due to findings from previous epidemiologic investigations of Gaelic games. DESIGN Descriptive epidemiology study. SETTING Open-access Gaelic Athletic Association Annual Reports from 2007-2014 were reviewed to obtain annual injury-claim data. PATIENTS OR OTHER PARTICIPANTS Gaelic Athletic Association players. MAIN OUTCOME MEASURE(S) Player age (youth or adult) and relationships between lower limb injury-claim rates and claim values, Gaelic football claims, hurling claims, youth claims, and adult claims. RESULTS Between 2007 and 2014, €64 733 597.00 was allocated to 58 038 claims. Registered teams had annual claim frequencies of 0.36 with average claim values of €1158.4 ± 192.81. Between 2007 and 2014, average adult claims were always greater than youth claims (6217.88 versus 1036.88), while Gaelic football claims were always greater than hurling claims (5395.38 versus 1859.38). Lower limb injuries represented 60% of all claims. The number of lower limb injury claims was significantly correlated with annual injury-claim expenses (r = 0.85, P = .01) and adult claims (r = 0.96, P = .01) but not with youth claims (r = 0.69, P = .06). CONCLUSIONS Reducing lower limb injuries will likely reduce injury-claim expenses. Effective injury interventions have been validated in soccer, but whether such changes can be replicated in Gaelic games remains to be investigated. Injury-claim data should be integrated into current elite injury-surveillance databases to monitor the cost effectiveness of current programs.

Effects of various concentrations of carbohydrate mouth rinse on cycling performance in a fed state

Abstract The objective of this study was to identify the effects of mouth rinsing with a 6% and 16% carbohydrate solution (CHO) on time trial performance when compared to a 0% control (PLA) when in a fed state. Twelve recreationally active males underwent three trials by which they had to complete a set workload (600 ± 65 W) in a fed state. Throughout each trial, participants rinsed their mouths with a 25 ml bolus of a 0% PLA, 6% or 16% CHO (maltodextrin) for every 12.5% of work completed. Rating of perceived exertion (RPE) and heart rate were recorded every 12.5% of total work. Performance times and power output improved significantly when using the 6% and 16% CHO versus the PLA trial (6% versus PLA, p = .002 and 16% versus PLA, p = .001). When comparing the performance times of the 6% to 16% CHO, no significance was observed (p = .244). There was no significant difference between heart rate levels or RPE values across the three trials. In conclusion, mouth rinsing with a 6% or 16% CHO solution has a positive effect on a cycling time trial performance undertaken in a fed state.