With the ongoing development of microtechnology, player tracking has become one of the most important components of load monitoring in team sports. The 3 main objectives of player tracking are better understanding of practice (provide an objective, a posteriori evaluation of external load and locomotor demands of any given session or match), optimization of training-load patterns at the team level, and decision making on individual players’ training programs to improve performance and prevent injuries (eg, top-up training vs unloading sequences, return to play progression). This paper discusses the basics of a simple tracking approach and the need to integrate multiple systems. The limitations of some of the most used variables in the field (including metabolic-power measures) are debated, and innovative and potentially new powerful variables are presented. The foundations of a successful player-monitoring system are probably laid on the pitch first, in the way practitioners collect their own tracking data, given the limitations of each variable, and how they report and use all this information, rather than in the technology and the variables per se. Overall, the decision to use any tracking technology or new variable should always be considered with a cost/benefit approach (ie, cost, ease of use, portability, manpower/ability to affect the training program).
Martin Buchheit and Ben Michael Simpson
Darcy M. Brown, Dan B. Dwyer, Samuel J. Robertson and Paul B. Gastin
The purpose of this study was to assess the validity of a global positioning system (GPS) tracking system to estimate energy expenditure (EE) during exercise and field-sport locomotor movements. Twenty-seven participants each completed a 90-min exercise session on an outdoor synthetic futsal pitch. During the exercise session, they wore a 5-Hz GPS unit interpolated to 15 Hz and a portable gas analyzer that acted as the criterion measure of EE. The exercise session was composed of alternating 5-minute exercise bouts of randomized walking, jogging, running, or a field-sport circuit (×3) followed by 10 min of recovery. One-way analysis of variance showed significant (P < .01) and very large underestimations between GPS metabolic power– derived EE and oxygen-consumption (VO2) -derived EE for all field-sport circuits (% difference ≈ –44%). No differences in EE were observed for the jog (7.8%) and run (4.8%), whereas very large overestimations were found for the walk (43.0%). The GPS metabolic power EE over the entire 90-min session was significantly lower (P < .01) than the VO2 EE, resulting in a moderate underestimation overall (–19%). The results of this study suggest that a GPS tracking system using the metabolic power model of EE does not accurately estimate EE in field-sport movements or over an exercise session consisting of mixed locomotor activities interspersed with recovery periods; however, is it able to provide a reasonably accurate estimation of EE during continuous jogging and running.
Yin-Chou Lin, Angela Thompson, Jung-Tang Kung, Liang-Wei Chieh, Shih-Wei Chou and Jung-Charng Lin
Elbow injuries are widely reported among baseball players. The elbow is susceptible to injury when elbow-flexor and -extensor forces are imbalanced during pitching or throwing. Assessment of muscle-strength ratios may prove useful for diagnosing elbow injury.
The purpose of this study was to assess the relationship between the elbow-flexor and -extensor functional isokinetic ratios and elbow injury in baseball players.
College baseball players with (n = 9) and without (n = 12) self-reported elbow pain or loss of strength were recruited.
Intervention and Main Outcome Measures:
Trials were conducted using a dynamometer to assess dominant-arm flexor and extensor concentric and eccentric strength at angular velocities of 60° and 240°/s. Functional isokinetic ratios were calculated and compared between groups.
Regression analysis revealed that a ratio of biceps concentric to triceps concentric strength greater than 0.76 (the median value) significantly predicted elbow injury (P = .01, odds ratio of injury = 24). No other ratios or variables (including position played) were predictive of injury status.
These findings suggest that the ratio of biceps concentric to triceps concentric functional strength strongly predicts elbow-injury status in baseball players. Assessment of this ratio may prove useful in a practical setting for training purposes and both injury diagnosis and rehabilitation.
Charles Thigpen and Ellen Shanley
The patient presented is a high school baseball pitcher who was unable to throw because of shoulder pain. He subsequently failed nonoperative management but was able to return to pitching after surgery and successful rehabilitation.
Clinical Outcomes Assessment:
The Disabilities of Arm, Shoulder and Hand (DASH) and the Pennsylvania Shoulder Score (PENN) were selected as clinical outcome assessment tools to quantify the patient’s perceived ability to perform common daily tasks and sport tasks and current symptoms such as pain and patient satisfaction.
Clinical Decision Making:
The DASH and PENN provide important information that can be used to target specific interventions, set appropriate patient goals, assess between-sessions changes in patient status, and quantify patients’ functional loss.
Clinical Bottom Line:
Best clinical practice involves the use of clinical outcome assessment tools to garner an objective measure of the impact of a patient’s disease process on functional expectations. This process should facilitate a patient-centered approach by clinicians while they select the optimal intervention strategies and establish prognostic timelines.
Vassilios Gourgoulis, Nikolaos Aggeloussis, Georgios Mavridis, Alexia Boli, Panagiotis Kasimatis, Nikolaos Vezos, Argyris Toubekis, Panagiotis Antoniou and Georgios Mavrommatis
The purpose of the current study was to investigate the acute effect of sprint resisted front crawl swimming on the propulsive forces of the hand. Eight female swimmers swam 25 m with maximal intensity, with and without added resistance. A bowl with a capacity of 2.2, 4 and 6 L was used as low, moderate and high added resistance, respectively. The underwater motion of the swimmer’s right hand was recorded using 4 cameras (60 Hz) and the digitization was undertaken using the Ariel Performance Analysis System. Repeated-measures ANOVA revealed that the velocity of the hand, the pitch and the sweepback angles of the hand, as well as the magnitude and the relative contribution of the drag and lift forces were not significantly modified and thus the magnitude of the resultant force did not change. Moreover, the magnitude of the effective force, as well as the angle formed between the resultant force and the axis of the swimming propulsion were not significantly affected. Thus, it could be concluded that resistance added as in this study did not alter the pattern of the propulsive hand forces associated with front crawl sprinting.
L. R. Brawley, R. C. Powers and K. A. Phillips
This experiment examined if a general expectancy for male superiority biased subjective evaluation of motor performance. Alternatively, sex bias could be specific to tasks involving muscular work. If the former, rather than the latter explanation is viable, a bias favoring males would be generalized to a task not obviously sex typed: motor accuracy. Observers, 22 of each sex, watched the softball pitching accuracy of performers of both sexes. Performer accuracy was trained and tested to ensure equality. Observers estimated preperformance accuracy, then observed three throws, estimating postperformance after each. Unlike the muscular endurance experiments, neither preperformance nor postperformance analysis revealed a sex bias. Thus a task-specific expectancy rather than general expectancy for male superiority was suggested to explain evaluation sex bias of previous muscular endurance experiments. Surprisingly, mean error magnitude of postperformance estimates was significantly greater for performers observed second than those viewed first, although actual performer accuracy was not different. This finding appears analogous to psychophysical judgment results in which successive stimulus judgments were conditions sufficient to cause estimation error. Suggestions are made for future research.
Ketra L. Armstrong
Women’s sports is at an all-time high, as evidenced by the emergence of a number of professional women’s sport leagues (such as basketball, baseball, and fast-pitch softball). Notwithstanding the growth and popularity of women’s sports, these leagues will have to compete with other forms of leisure for consumers’ discretionary time and resources. Since financial stability is vital to the longevity of the developing women’s leagues, the competition for consumers will require a greater need for the marketers of women’s professional sport organizations to understand the variety of factors that influence sport consumers’ behavior and shape the composition of their respective markets. Presented in this article are the results of a study in which the consumers of one of the professional women’s basketball teams that competed in the American Basketball League (ABL)were investigated. The teams’ spectators are profiled as sport consumers, factors that influenced their attendance, are identified and implications for effective marketing strategies are noted.
This study examines racial tolerance through the intersection of the media, fans, and the Boston Red Sox. Through the 1998 season Red Sox home games in which Dominican Pedro Martinez pitched attracted large numbers of Latinos. This marked the first time that large numbers of people of color regularly attended Fenway Park. Media reports simultaneously promoted both an awareness of this cultural phenomenon and portrayed it as widely applauded. In presenting a story of Boston’s “embracing the ace,” the media reports also wound up pushing a view of widespread approval of the new Latino presence both in Fenway and society at large. This study sought to compare the impressions of widespread exuberance for Martinez and the Dominicans at the Park with actual interviews of those Anglos at the Park. It also sought to examine what motivated the Dominicans to attend in such large numbers and to so publicly celebrate their identity. The results showed that Anglos held a fractured view about Dominicans: a very positive view of Pedro Martinez as a Dominican but a fairly evenly split view of Dominicans in general. For their part, Dominicans were unconcerned with what Anglos thought and came to the game only to lend support to their Latino hero, as well as bask in his reflected glow. One methodological conclusion arrived at is that media content analysis must be cross checked against some sort of data and must not be assumed to accurately reflect social reality.
Matthew J. Cross, Sean Williams, Grant Trewartha, Simon P.T. Kemp and Keith A. Stokes
To explore the association between in-season training-load (TL) measures and injury risk in professional rugby union players.
This was a 1-season prospective cohort study of 173 professional rugby union players from 4 English Premiership teams. TL (duration × session-RPE) and time-loss injuries were recorded for all players for all pitch- and gym-based sessions. Generalized estimating equations were used to model the association between in-season TL measures and injury in the subsequent week.
Injury risk increased linearly with 1-wk loads and week-to-week changes in loads, with a 2-SD increase in these variables (1245 AU and 1069 AU, respectively) associated with odds ratios of 1.68 (95% CI 1.05–2.68) and 1.58 (95% CI 0.98–2.54). When compared with the reference group (<3684 AU), a significant nonlinear effect was evident for 4-wk cumulative loads, with a likely beneficial reduction in injury risk associated with intermediate loads of 5932–8651 AU (OR 0.55, 95% CI 0.22–1.38) (this range equates to around 4 wk of average in-season TL) and a likely harmful effect evident for higher loads of >8651 AU (OR 1.39, 95% CI 0.98–1.98).
Players had an increased risk of injury if they had high 1-wk cumulative loads (1245 AU) or large week-to-week changes in TL (1069 AU). In addition, a U-shaped relationship was observed for 4-wk cumulative loads, with an apparent increase in risk associated with higher loads (>8651 AU). These measures should therefore be monitored to inform injury-risk-reduction strategies.
Amee L. Seitz, Michael Reinold, Robert A. Schneider, Thomas J. Gill and Charles Thigpen
Differences in 3-dimensional (3D) scapular motion have been reported between healthy baseball position players and healthy nonoverhead athletic controls, as well as players diagnosed with shoulder impingement syndrome. These alterations are theorized to be the result of adaptations due to the demands of repetitive throwing. However, comparisons between the throwing and nonthrowing shoulders are commonly used to infer normal motion.
The purpose of this study was to compare 3D scapular kinematics between the throwing and nonthrowing shoulders in asymptomatic professional male baseball pitchers.
45 asymptomatic professional baseball pitchers participating without restrictions during preseason training.
An electromagnetic tracking system was used to assess 3D scapular orientation at rest and during weighted (2.3-kg) shoulder flexion across discrete humeral-flexion angles (rest, 30°, 60°, 90°, 120°, and maximum).
Main Outcome Measure:
3D scapular upward/downward rotation (UR/DR), anteroposterior (AP) tilt, and internal/external rotation (IR/ER). Separate mixed-model ANOVAs (Side × Angle) for each scapular motion were used to compare the throwing and the nonthrowing shoulder across all angles.
There were significant side-to-side differences with scapular UR/DR (P < .001), AP tilt (P < .001), and IR/ER (P < .001). The throwing scapula displayed greater mean UR (increase = 3.6°, SE = 0.50) and anterior/posterior tilt (increase = 2.1°, SE = 0.60) and less mean IR (decrease = 2.1°, SE = 0.66) than the nonthrowing shoulder averaged across all arm angles.
In asymptomatic professional pitchers, the throwing shoulder’s scapular position differs across all arm angles from that of the nonthrowing shoulder, but the motion does not differ. Scapular asymmetry that is consistent throughout arm elevation may be indicative not of pathology but, potentially, of a normal adaptation of the pitching shoulder.