Reviewing the Variability-Overuse Injury Hypothesis: Does Movement Variability Relate to Landing Injuries?

Purpose: Overuse injuries are common in sport, but complete understanding of injury risk factors remains incomplete. Although biomechanical studies frequently examine musculoskeletal injury mechanisms, human movement variability studies aim to better understand neuromotor functioning, with proposed connections between overuse injury mechanisms and changes in motor variability. Method: In a narrative review, we discuss the variability-overuse injury hypothesis, which suggests repeated load application leads to mechanical tissue breakdown and subsequent injury when exceeding the rate of physiological adaptation. Due to the multidisciplinary nature of this hypothesis, we incorporate concepts from motor control, neurophysiology, biomechanics, as well as research design and data analysis. We therefore summarize multiple perspectives while proposing theoretical relationships between movement variability and lower extremity overuse injuries. Results: Experimental data are presented and summarized from published experiments examining interactions between experimental task demands and movement variability in the context of drop landing movements, along with comparisons to previous movement variability studies. Conclusion: We provide a conceptual framework for sports medicine researchers interested in predicting and preventing sports injuries. Under performance conditions with greater task demands, we predict reduced trial-to-trial movement variability that could increase the likelihood of overuse injuries.     

How Much Does Experience Matter in NCAA Division I Volleyball? A Retrospective Study

Purpose: To evaluate the relationship between years of collegiate playing experience and success of NCAA Division I volleyball programs. Methods: Data were gathered from the 2010–2015 seasons for each volleyball program in the “power five” conferences. Players that were involved in at least 66% of the sets were selected for analysis. Each player’s years of college experience were tabulated and a team average experience score was created. This score was correlated with the end of season Ratings Percentage Index (RPI). Years with a significant correlation between success and experience were further analyzed for differences in on-court statistics by years of experience. Results: The range for team average experience score was 2.52–2.66. Only the 2012 season showed a moderate correlation between the team average score and RPI (ρ = ?0.421, p = .001), indicating that more experienced teams finished with a higher national ranking. Within this year, teams with more experience had a statistically significant (p < .05) higher season win percentage, higher conference win percentage, higher hitting percentage, more kills/set, and more assists/set than teams with low or only moderate experience. Conclusions: These data suggest that more collegiate playing experience does not always result in a significantly more successful season, but trends indicate that a relationship does exist between experience and success. In the one year that showed significance, more experienced teams had more favorable statistics related to skills that terminate play (e.g., kills) rather than ball control skills (e.g., digs and passing).     

Does inside passing contribute to the high incidence of groin injuries in soccer? A biomechanical analysis

Groin injuries are common in soccer and often cause time-loss from training. While groin injuries have been linked to full effort kicking, the role of inside passing is unclear. Therefore, the purpose of this study was to investigate hip joint kinematics and muscle force, stress and contraction velocity for adductor longus and gracilis during inside passing. 3D kinematics of ten soccer players (23.4 yrs; 77.5 kg; 1.81 m) were captured with a motion capture system inside a Footbonaut. Muscle force and contraction velocity were determined with AnyBody Modelling System. Gracilis muscle forces were 9% lower compared to adductor longus (p = 0.005), but muscle stress was 183% higher in gracilis (p = 0.005). Contraction velocity reveals eccentric contraction of gracilis in the last quarter of the swing phase. Considering the combination of eccentric contraction, high muscle stress and the repetitive nature of inside passing, gracilis accumulates high loads in matches and training. These results indicate that the high incidence of groin injuries in soccer could be linked to isolated pass training. Practitioners need to be aware of the risk and refrain from sudden increases in the amount of pass training. This gives the musculoskeletal system time to adapt and might avoid career threatening injuries.     

Sport to the Rescue of the Suburbs: Sport to Educate? Sport to Reassure? When Politicians Respond to the Signs of Disturbance of Law and Order

Since the beginning of the 1980s, sport has appeared to be the last recourse against the worsening of living conditions, lack of job security and the ghettoisation of certain boroughs that stand out mostly because of continuing urban riots and juvenile violence. All of this is continually exaggerated by the media and politicians in their continual desire to dramatise and exaggerate. Certain sub-issues immediately emerge: what are the theoretical or ideological foundations on which this concept of making sport a lever for preventive policies is based? And what sport are we talking about? Is it the physical activities and sport (PAS) practised in the schools and institutes, civil sport or sport in the streets? Why do young people increasingly abandon civil/federated sport to practise ‘adventure sports’ or self-organised sports? Can self-organised sports and, more precisely, sport played outside the tower blocks favour the ‘self-control of impulses’? And if they can, under what conditions can they favour socialisation and contribute to preventing vandalism or violent acts? If it must be admitted that the links between sport and education, sport and prevention, sport and insertion, etc., are considered to be self-evident, they are rarely analysed or questioned.     

Does shortening the pitch make junior cricketers bowl better?

In order to get bounce and movement seam bowlers need to bowl the ball “into” the pitch. Standard deliveries by elite players are typically projected at around 7° below horizontal. In contrast, young players currently often need to release the ball almost horizontally in an effort to get the ball to bounce close enough to the batter. We anticipated that shortening the pitch could be a simple way to help young bowlers to release the ball at a better angle and with more consistency. Twenty county or best in club age group under 10 and under 11 seam bowlers were analysed bowling indoors on two different pitch lengths. They were found to project the ball on average 3.4° further below horizontal on a 16 yard pitch compared with a 19 yard pitch, while ball speed and position at release changed negligibly. Pitch length did not affect the consistency of the release parameters. The shorter pitch led to a ball release angle closer to that of elite bowlers without changing release speed, and this should enable players to achieve greater success and develop more variety in their bowling.     

Does soccer cleat design influence the rotational interaction with the playing surface?

Non-contact injuries in soccer players may be related to the interplay between cleat type and playing surface, and bladed shoes were often blamed for non-contact injuries with no research support. The aim of this study was to compare the rotational resistance (stiffness and peak sustainable torque) among three types of soccer cleats (metal studs, molded rubber studs, and bladed) in a controlled laboratory environment. The shoes were tested on both natural and artificial turfs under a compressive preload of 1000 N and with internal and external rotations. The three shoe models showed comparable performances with a good repeatability for each individual test on both playing surfaces. A less stiff behavior was observed for the natural turf. A tendency toward highest peak torque was observed in the studded model on natural surface. The bladed cleats provided peak torque and rotational stiffness comparable to the other models. Studded and bladed cleats did not significantly differ in their interaction with the playing surface. Therefore, soccer shoes with bladed cleats should not be banned in the context of presumed higher risk for non-contact injuries.     

Does current behaviour predict the course of children's physical fitness?

Abstract

The secular trend of reduced physical fitness (PF) leads to increased health risks. The aim of the present paper is to analyse various current factors that affect health behaviour with respect to the course of PF over 2 years. A path analysis combined with a latent growth curve analysis was based on a study that was conducted between June 2008 and June 2010 with 145 primary German school children (52.1% male, average age at baseline 7.95 years ± 0.95). PF was tested with the German Motor Test 6–18. For the mean PF and the course of PF, direct and indirect influences were shown over three levels, including migration background on the first level and physical activity (PA) on the second level. Body mass index (BMI) impacted the mean PF but not the course of PF. The influence of sedentary behaviour on the mean PF was diminished (compared to bivariate analysis) due to its common variance mainly with BMI. PA affected not only current PF in children but also the course of PF (a_intercept = .28, P = .001; a_slope = .27, P = .21). Consequently, preventive measures should focus on early adoption and maintenance of PA.     

When Will China Win the World Cup? A Study of China’s Youth Football Development

Abstract

What is embarrassing for Chinese sports is that the supply of the sports cannot meet the needs of people with the rapid development in almost every field of sport in China. Furthermore, teenage sport has deteriorated year on year and is very short of backup talents in competitive sports. Faced with China’s devastated football, the appropriate attitude is neither seeking quick success and instant benefits nor ignoring it; the urgent thing for this moment is to establish a feasible and sustainable football system. An analysis of the history of Chinese football, the strategy of football development by the country’s leaders, and the policy of Youth Campus Football in 2009, coupled with sports humanism, suggests that the future lies in instilling a sharing sports concept, promoting the joint efforts of school, society, and family.     

Does english football warrant the rooney rule? assessing the thoughts of british asian coaches

This article examines the Rooney Rule and offers the thoughts of British Asian football coaches working in English football in response to this policy implementation. The Rooney Rule, first piloted by English Football League (EFL) clubs during the 2016–17 season, makes it compulsory for all 72 EFL clubs to interview at least one black, Asian or minority ethnic (BAME) candidate (if an application has been received) for all managerial and first-team coaching roles. And, on 9 January 2018, the Football Association revealed that they had also adopted the Rooney Rule for all coaching jobs relating to the England national team. Because English football harbours so few BAME coaches, calls for the Rooney Rule to be introduced in English football had started to increase in volume, and led to its trial inception. But, is this policy welcomed or opposed among British Asian coaches? What fundamental barriers does this policy overlook? Is English football ready for the Rooney Rule? And, do British Asian coaches, a group believed to benefit from this positive action policy, deem that this rule is the answer to help facilitate positive change? With the aid of empirical research, this article critically examines and assesses the potential impact of the Rooney Rule and recommends additional inclusionary practices.

Abbreviations: BAME: Black, Asian or Minority Ethnic; CBP: The Coach Bursary Programme; EFL: English Football League; EPL: English Premier League; HLCE: Higher Level Coach Education; FA: Football Association; FBL: Football Bowl Subdivision; LMA: League Managers Association; NFL: National Football League; PFA: Professional Footballers' Association; UEFA: Union of European Football Associations.     

Does sensorimotor training improve the static balance of young volleyball players?

The aim of this investigation is to assess the effectiveness of a 6-week balance training (BT) protocol, integrated in regular training sessions, on postural sway of young female volleyball players (n = 26, age 13.0 ± 0.2 years) divided into two groups (intervention and control; 13 per group). Trials were performed for bipedal and unipedal stance conditions before and after the BT protocol, using a pressure platform to collect center-of-pressure (COP) time series that were processed to calculate sway area, COP path length, and maximum displacement range in anteroposterior and mediolateral directions. The intervention group exhibited smaller sway areas in eyes closed conditions (intervention = 42.76 mm², control = 67.60 mm²; p < 0.05) and Romberg quotients (intervention = 1.11 mm, control = 1.82 mm) in bipedal stance, while all the other parameters were unaffected. BT also reduced sway area (intervention = 122.70 mm², control = 187.18 mm²) and anteroposterior COP displacements (intervention = 20.18 mm, control = 22.38 mm) of the non-dominant limb for single-leg stance. No significant change was found for the dominant limb. Although it is possible to hypothesize a beneficial effect of BT on young athletes, further investigations are required to clarify its actual effect on balance performance with respect to normal volleyball training.     

Does sensorimotor training improve the static balance of young volleyball players?

The aim of this investigation is to assess the effectiveness of a 6-week balance training (BT) protocol, integrated in regular training sessions, on postural sway of young female volleyball players (n = 26, age 13.0 +/- 0.2 years) divided into two groups (intervention and control; 13 per group). Trials were performed for bipedal and unipedal stance conditions before and after the BT protocol, using a pressure platform to collect center-of-pressure (COP) time series that were processed to calculate sway area, COP path length, and maximum displacement range in anteroposterior and mediolateral directions. The intervention group exhibited smaller sway areas in eyes closed conditions (intervention = 42.76 mm2, control = 67.60 mm2; p < 0.05) and Romberg quotients (intervention = 1.11 mm, control = 1.82 mm) in bipedal stance, while all the other parameters were unaffected. BT also reduced sway area (intervention = 122.70 mm2, control = 187.18 mm2) and anteroposterior COP displacements (intervention = 20.18 mm, control = 22.38 mm) of the non-dominant limb for single-leg stance. No significant change was found for the dominant limb. Although it is possible to hypothesize a beneficial effect of BT on young athletes, further investigations are required to clarify its actual effect on balance performance with respect to normal volleyball training.     

From the cradle to the grave: how fast can we run?

I model average running speed on distances from 5000 m to the marathon as a function of age, distance and sex. Using data on US age-dependent road-racing records, I simulate optimal performance forages ranging from 3 to 95 years. The results of the correlation between running speed and age are in line with medical results on the relation between age and maximal oxygen uptake. The results show that official track and field age-grading overestimates human performance at older ages.     

Does national pride from international sporting success contribute to well-being? An international investigation

The sports industry is viewed as being of growing economic significance, reflected in its promotion in public policy. One specific aspect of this policy is to argue that investment in international sporting success creates pride from sporting success, which contributes to subjective well-being (SWB). However, though it has been argued that indicators of sporting success, such as the number of medals won at major sports events like the Olympics, act as a proxy for pride from sporting success, there have not been any direct tests of this hypothesis. Controlling for the impact of physical activity, attendance at sports events and other standard covariates, this paper addresses this hypothesis by focusing on a variable which directly measures pride felt from sporting success (Pride) by individuals. Because of the possibility that a latent characteristic such as nationalism, or overall national pride, might be linked to both Pride and SWB, i.e. an endogeneity problem is present, an instrumental variable technique is employed. The findings do not support the hypothesis that pride following from sporting success can contribute distinctly to SWB. Moreover, the hosting of events may be more important than success at them, a point suggested by the positive association between attendance at sporting events and SWB. As such the goals of public sector investment in both hosting major sports events as well as investment in sports development to achieve international sporting success are shown to be more distinct than implied in much of the policy announcements and require more careful scrutiny.     

What Are the Barriers to Mobilizing Intensive Care Patients?

Purpose

Recently there has been increased interest in early mobilization of critically ill patients. Proposed benefits include improvements in respiratory function, muscle wasting, intensive care unit (ICU), and hospital length of stay. We studied the frequency of early mobilization in our intensive care unit in order to identify barriers to early mobilization.

Methods

A 4-week prospective audit of 106 patients admitted to a mixed medical-surgical tertiary ICU (mean age 60 ± 20 years, mean APACHE II score 14.7 ± 7.8) was performed. Outcome measures included number of patient days mobilized, type of mobilization, adverse events, and reasons for inability to mobilize.

Results

Patients were mobilized on 176 (54%) of 327 patient days. Adverse events occurred in 2 of 176 mobilization episodes (1.1%). In 71 (47%) of the 151 patient days where mobilization did not occur, potentially avoidable factors were identified, including vascular access devices sited in the femoral region, timing of procedures and agitation or reduced level of consciousness.

Conclusions

Critically ill patients can be safely mobilized for much of their ICU stay. Interventions that may allow more patients to mobilize include: changing the site of vascular catheters, careful scheduling of procedures, and improved sedation management.Key Words: intensive care units, mobility, physical therapy     

Does slow motion impact on the perception of foul play in football?

Objectives: Slow-motion replays of foul play situations are now used in the education and training of sports officials. We investigated the impact of video speed on the decision-making process of association football referees and how this interacted with expertise. Methods: Three different groups of referees, varying in level of expertise, assessed video clips from an in-game perspective. Video clips represented corner kick and open play situations in which a foul occurred or not. For these foul/no foul situations, the referees had to make a technical (no foul; indirect free kick; direct free kick; or penalty kick) and a disciplinary decision (no card; yellow card; or red card), under both slow-motion and real-time viewing conditions. Accuracy scores were determined by comparing participant’s responses with the decisions of an expert panel. Results: Significant differences were observed across groups for foul/no foul situations, suggesting that the experts were able to process the available information more effectively than their less expert colleagues. The accuracy scores for the technical decision were higher in slow motion (67%) compared to a real-time viewing condition (56%), particularly for corner kick situations. No differences were found between real time and slow motion for the disciplinary decision. Conclusions: Slow-motion footage results in higher accuracy scores for complex technical decisions. These findings have implications for the use of slow-motion replays in the decision-making process of referees.     

Do sporting activities convey benefits to bone mass throughout the skeleton?

It is well known that sport and exercise play an important role in stimulating site-specific bone mineral density (BMD). However, what is less well understood is how these benefits dissipate throughout the body. Hence, the aim of the present study was to compare the BMD (recorded at nine sites throughout the skeleton) of 106 male athletes (from nine sports) with that of 15 male non-exercising age-matched controls. Given that BMD is known to increase with body mass and peak with age, multivariate and univariate analyses of covariance were performed to compare the BMD of the nine sports groups with controls (at all sites) using body mass and age as covariates. Our results confirmed a greater adjusted BMD in the arms of the upper-body athletes, the right arm of racket players and the legs of runners (compared with controls), supporting the site-specific nature (i.e. specific to the externally loaded site) of the bone remodelling response (all P <0.01). However, evidence that bone mass acquisition is not just site-specific comes from the results of the rugby players, strength athletes, triathletes and racket players. The rugby players' adjusted BMD was the greatest of all sports groups and greater than controls at all nine sites (all P <0.01), with differences ranging from 8% greater in the left arm to 21% in the lumbar spine. Similarly, the strength athletes' adjusted BMD was superior to that of controls at all sites (P <0.05) except the legs. The adjusted BMD of the triathletes was significantly greater than that of the controls in both the arms and the legs as well as the thoracic and lumbar spine. The racket players not only had significantly greater right arm BMD compared with the controls but also a greater BMD of the lumbar spine, the pelvis and legs. In contrast, the low-strain, low-impact activities of keep-fit, cycling and rowing failed to benefit BMD compared with the age-matched controls. These results suggest that sporting activities involving high impact, physical contact and/or rotational forces or strains are likely to convey significant benefits not only to the loaded sites, but also to other unloaded peripheral and axial sites throughout the skeleton.     

Does installation of the backstroke start device reduce 15-m start time in swimming?

The purpose of this study was to determine the installation of the backstroke start device reduces 15-m time. Thirteen college swimmers participated in this study. The aerial start and underwater motions were recorded with two digital video cameras. The center of mass (CM) of the swimmer, angular displacements and velocities of the shoulder, hip and knee joints were calculated. As an indicator of performance, the 5- and 15-m times were measured. The 5- and 15-m times in the backstroke start device condition were significantly shorter than in the non-backstroke start device condition. The vertical velocities of the CM at hand-off and toe-off in the backstroke start device condition were significantly greater than in the non-backstroke start device condition, while there was no significant difference in the CM horizontal velocity at toe-off. As a result, the height of the great trochanter at entry of the fingertips, with the backstroke start device, was 15 cm higher than in the non-backstroke start device condition. In addition, the CM horizontal velocities at 5 m in the backstroke start device condition were significantly greater than those of the non-backstroke start device. Thus, the use of the backstroke start device may reduce the 15-m time by diminution of the entry area.     

Validating the Sedentary Sphere method in children: Does wrist or accelerometer brand matter?

This study aimed to validate the Sedentary Sphere posture classification method from wrist-worn accelerometers in children. Twenty-seven 9–10-year-old children wore ActiGraph GT9X (AG) and GENEActiv (GA) accelerometers on both wrists, and activPAL on the thigh while completing prescribed activities: five sedentary activities, standing with a phone, walking (criterion for all 7: observation) and 10-min free-living play (criterion: activPAL). In an independent sample, 21 children wore AG and GA accelerometers on the non-dominant wrist and activPAL for two days of free-living. Per cent accuracy, pairwise 95% equivalence tests (±10% equivalence zone) and intra-class correlation coefficients (ICC) analyses were completed. Accuracy was similar, for prescribed activities irrespective of brand (non-dominant wrist: 77–78%; dominant wrist: 79%). Posture estimates were equivalent between wrists within brand (±6%, ICC > 0.81, lower 95% CI ≥ 0.75), between brands worn on the same wrist (±5%, ICC ≥ 0.84, lower 95% CI ≥ 0.80) and between brands worn on opposing wrists (±6%, ICC ≥ 0.78, lower 95% CI ≥ 0.72). Agreement with activPAL during free-living was 77%, but sedentary time was underestimated by 7% (GA) and 10% (AG). The Sedentary Sphere can be used to classify posture from wrist-worn AG and GA accelerometers for group-level estimates in children, but future work is needed to improve the algorithm for better individual-level results.