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New Opportunities in Assessing Return to Performance in the Elite Athlete: Unifying Sports Medicine, Data Analytics, and Sports Science

Open AccessPublished:September 06, 2022DOI:https://doi.org/10.1016/j.asmr.2022.08.001

      Abstract

      Sports medicine literature has historically reported return to sport rates, but recent interest has shifted to return to previous performance. However, the measurement and understanding of performance in the elite athlete population has continued to evolve. Recent advancements in sport analytics, wearable technology, and player-tracking systems have improved our understanding of performance in the elite athlete. Sports medicine researchers should collaborate with sports science teams to continue investigating the validity and reliability of emerging technology, assist in interpretation of big data, and remain accountable to the goals of our athletic population. Future studies in sports medicine should consider using these detailed, granular assessments to address the demands of the elite athlete population.
      Outcomes reporting continues to evolve as clinicians seek better methods of assessing the subjective and objective implications of injury and treatment.
      • Christensen D.L.
      • Dickens J.F.
      • Freedman B.
      • et al.
      Patient-reported outcomes in orthopaedics.
      The sports medicine literature has historically reported return to sport rates, but there is a ceiling effect to this measure, as patients may continue to subjectively improve even after returning to sport.
      • Singer K.M.
      • Roy S.P.
      Osteochondrosis of the humeral capitellum.
      • Conway J.E.
      • Jobe F.W.
      • Glousman R.E.
      • Pink M.
      Medial instability of the elbow in throwing athletes. Treatment by repair or reconstruction of the ulnar collateral ligament.
      • Agarwalla A.
      • Puzzitiello R.N.
      • Liu J.N.
      • et al.
      Timeline for maximal subjective outcome improvement after anterior cruciate ligament reconstruction.
      As a result, recent interest has shifted to return to previous performance to address the high expectations of the competitive athlete. However, defining and measuring meaningful performance has remained difficult for sports medicine clinicians and injury researchers. Although early studies used return to the same level of competition as a proxy of performance, recent studies have examined patient-reported subjective ratings and traditional player statistics to evaluate performance upon return from injury.
      • Singer K.M.
      • Roy S.P.
      Osteochondrosis of the humeral capitellum.
      ,
      • Conway J.E.
      • Jobe F.W.
      • Glousman R.E.
      • Pink M.
      Medial instability of the elbow in throwing athletes. Treatment by repair or reconstruction of the ulnar collateral ligament.
      ,
      • Trofa D.P.
      • Miller J.C.
      • Jang E.S.
      • Woode D.R.
      • Greisberg J.K.
      • Vosseller J.T.
      Professional athletes’ return to play and performance after operative repair of an Achilles tendon rupture.
      ,
      • Frangiamore S.J.
      • Mannava S.
      • Briggs K.K.
      • McNamara S.
      • Philippon M.J.
      Career length and performance among professional baseball players returning to play after hip arthroscopy.
      Although traditional statistics have long provided information on a player’s involvement in game events, these measures often are influenced by situational factors and sequencing, teammate abilities, and other game factors outside of a player’s control. Because these statistics may not sufficiently represent individual performance, researchers have questioned their utilization and have recommended exploring new outcome measures to directly assess performance.
      • Reider B.
      ,
      • Gray A.D.
      • Cook J.L.
      Return to pitching after Tommy John surgery: Letter to the editor.
      In search for competitive advantages, many professional and collegiate sporting organizations have established sports science departments to develop and implement new methods of assessing and improving performance in their athletes. This interest has produced both statistical and technological advancements leading to an exponential increase in data seeking to further evaluate sport performance.
      • Pritchard S.
      Marginal gains: the rise of data analytics in sport.
      Within these large datasets, there is ample opportunity for collaboration between sports scientists and sports medicine practitioners to decipher relevant measurable data and better align our professional goals with those of our athletes.
      The purpose of this review is to describe how the understanding of sport performance has evolved with the development of data analytics, player tracking systems, and wearable technology, as well as to illustrate the opportunities for integration of these new measures in the sports medicine literature to address the demands of the elite athlete.

      Data Analytics

      In his book Moneyball, Michael Lewis chronicles the low-budget Oakland Athletics and their general manager, Billy Beane, while he sought new analytical measures to acquire undervalued players and gain competitive advantages against the wealthy, large-market organizations.
      • Lewis M.
      Moneyball: The Art of Winning an Unfair Game. New York.
      The book’s publication and critical acclaim brought attention to the field of sabermetrics, defined by Bill James in 1980 as “the search for objective knowledge about baseball.”
      • Birnbaum P.
      A Guide to Sabermetric Research | Society for American Baseball Research.
      The subsequent proliferation of advanced analytics has changed the understanding of individual and team performance in the 21st century, and its utilization is commonplace at the professional level of many modern sports.
      • Streib N.
      • Young S.J.
      • Sokol J.
      A major league baseball team uses operations research to improve draft preparation.
      • Broadie M.
      Assessing golfer performance on the PGA tour.
      • Mcclure B.
      • Cassady R.
      • Rainwater C.
      • Chimka J.R.
      Optimizing the Sunday singles lineup for a Ryder cup captain.
      • Fry M.J.
      • Ohlmann J.W.
      Introduction to the special issue on analytics in sports, part I: General sports applications.
      • Chan T.C.Y.
      • Cho J.A.
      • Novati D.C.
      Quantifying the contribution of NHL player types to team performance.
      • Clark K.
      The NFL’s Analytics Revolution Has Arrived - The Ringer.
      The National Football League (NFL) has seen increases in passing plays, 2-point conversion attempts, and fourth-down conversions while the National Basketball Association (NBA) has seen a drastic rise in 3-point attempts due to data-driven adjustments to team game strategy.
      • Clark K.
      The NFL’s Analytics Revolution Has Arrived - The Ringer.
      ,
      • Shea S.
      The 3-Point Revolution.
      In addition to optimizing team strategy, advanced analytics have been developed to better measure the individual performance of a player.
      FanGraphs. Getting Started.
      Basketball’s Adjusted Plus-Minus statistic measures a player’s impact on the team scoring margin while controlling for the strength of the opponent as well as the player’s teammates.
      • Adjusted NBAstuffer.
      In baseball, Fielding Independent Pitching (FIP), expected FIP, and Skill-Interactive ERA have been developed to quantify a pitcher’s independent ability to prevent runs by using metrics that remove the role of the surrounding defense.
      FanGraphs. FanGraphs Baseball.
      Given the improved ability to measure individual player performance, recent studies have begun to include advanced statistics while reporting surgical outcomes.
      • Erickson B.J.
      • Chalmers P.N.
      • D’Angelo J.
      • Ma K.
      • Dines J.S.
      • Romeo A.A.
      Do outcomes or subsequent injuries differ after ulnar collateral ligament reconstruction with palmaris versus hamstring autograft?.
      • Marshall N.E.
      • Keller R.
      • Limpisvasti O.
      • Schulz B.
      • ElAttrache N.
      Major League Baseball pitching performance after Tommy John surgery and the effect of tear characteristics, technique, and graft type.
      • Erickson B.J.
      • Chalmers P.N.
      • D’Angelo J.
      • et al.
      Side of hamstring harvest does not affect performance, return-to-sport rate, or future hamstring injuries after ulnar collateral ligament reconstruction among professional baseball pitchers.
      • Fury M.S.
      • Oh L.S.
      • Linderman S.E.
      • et al.
      Return to performance after ulnar collateral ligament reconstruction in Major League Baseball pitchers: A case-control assessment of advanced analytics, velocity, spin rates, and pitch movement.
      John Smoltz, a Major League Baseball pitcher whose career lasted from 1988 to 2009, serves as an interesting case example in the assessment of postinjury performance. Before undergoing ulnar collateral ligament (UCL) reconstruction in 2000, he was a starting pitcher who had averaged 29.6 games started, 13.1 wins, 181.1 innings pitched (IP), and 174.8 strikeouts (K) per year. In the 4 seasons after returning from surgery, he averaged 1.25 games started, 1.5 wins, 71.1 IP, and 75 K per year. Table 1 illustrates his statistics for the 8 seasons occurring around his surgery in 2000.
      FanGraphs. FanGraphs Baseball.
      Table 1John Smoltz’s Season-Ending Statistics From 1996 to 2004
      YearGames StartedWinsInnings PitchedStrikeoutsWins Above Replacement (WAR)
      19963524253.32768.4
      199735152562416.7
      19982617167.21735.2
      19992911186.11565.4
      20015359571.3
      20020380.1852.5
      20030064.1732.9
      20040081.2852.1
      By cursory examination of Table 1, Smoltz had a statistical decline in the 4 seasons after surgery. The synthesis and subsequent analysis of these statistics for the sports medicine literature regarding return from UCL reconstruction would possibly report declines in “performance” of 57% to 96%. However, Smoltz had transitioned to the bullpen in 2001 to fill the team need at the closer position while also attempting to extend his career after early setbacks in his return from surgery.
      • Stephenson C.
      John Smoltz: 10 memorable moments in a Hall of Fame career for Atlanta Braves pitcher.
      ,
      • Mangin B.
      Smoltz, John | Baseball Hall of Fame.
      In his new closer role, Smoltz would impact games in high-leverage situations, but he would be unable to match the workload of innings pitched from his time as a starting pitcher. By using analytics that control for the disparity in IP, a different conclusion on performance can be made (Table 2). Smoltz’s average K/9 increased from 8.82 to 9.46, walks/9 decreased from 2.1 to 1.73, home runs/9 decreased from 0.67 to 0.66, and FIP decreased from 2.88 to 2.47. Therefore, he struck out batters at a higher rate while giving up a lower rate of walks and home runs. This improvement in performance is reflected by his decreased FIP, a metric that attempts to measure a pitcher’s performance independent of factors outside of his control.
      FanGraphs. FanGraphs Baseball.
      Although demonstrating a decline in many traditional statistics, John Smoltz was arguably one of the best relievers in professional baseball from the 2001 to 2004 seasons, and many statistics over this period compared favorably to Mariano Rivera, the New York Yankees closer considered by many to be the greatest closer of all-time.
      FanGraphs. FanGraphs Baseball.
      ,
      • Yankee Mariano Rivera Shapiro B.
      John Smoltz returned to his former role as a starting pitcher in 2005, and he would subsequently become the first pitcher to be elected into the Hall of Fame after undergoing UCL reconstruction.
      • Mangin B.
      Smoltz, John | Baseball Hall of Fame.
      Table 2Further Statistical Analysis of John Smoltz’s 1996-2004 Seasons
      YearK/9BB/9HR/9Fielding Independent Pitching (FIP)
      19969.791.950.672.64
      19978.472.210.743.04
      19989.292.360.542.71
      19997.531.930.683.14
      20018.691.531.073.27
      20029.522.690.452.39
      200310.211.120.281.54
      20049.371.430.882.72
      BB, walks; HR, home run; K, strikeout.
      However, understanding advanced analytics is critical to their interpretation. For example, Wins Above Replacement (WAR) quantifies the contribution of an individual’s performance to the team relative to a replacement-level player.
      FanGraphs. FanGraphs Baseball.
      In Table 1, Smoltz’s WAR averaged 2.2 during the postoperative years of 2001-2004—a decrease from an average 6.4 WAR from 1996-1999. This decline in value starkly contrasts the improvement in many other important pitching metrics. The formula for calculating WAR differs by position, and Smoltz’s transition into the closer role affected how his WAR was calculated. As a closer, he produced high-quality work in high- leverage situations, but the quantity of overall work was low.
      • Cameron D.
      WAR and Relievers.
      In addition, WAR is measured relative to a “replacement-level player.” Due to the relative importance of preserving the final few innings to secure a win, the role of closer is often replaced by the next-best relief pitcher on the major league team in the case of an injury. Although a highly useful analytic, these calculation differences limit the ability for comparison of WAR between starting pitchers and relievers.
      As professional sports become increasingly data-driven and their assessments of player performance continue to evolve, sports medicine researchers should further their understanding and utilization of advanced analytics to better assess individual performance in the elite athlete population.
      • Lewis M.
      Moneyball: The Art of Winning an Unfair Game. New York.
      ,
      • Elitzur R.
      Data analytics effects in Major League Baseball.

      Motion Analysis and Wearable Technology

      As far back as the 19th century, observers have attempted to discretely measure sport performance.
      The Stopwatch and the Chronograph Part 1 | THE SEIKO MUSEUM.
      In 1822, Nicolas Mathieu Rieussec presented King Louis XVIII with a new invention—the stopwatch—to record and report the winning times of horseraces.
      The Stopwatch and the Chronograph Part 1 | THE SEIKO MUSEUM.
      In 1878, photographer Eadweard Muybridge developed a 12-camera system to determine whether a sprinting horse was ever fully airborne. The groundbreaking series of photographs, The Horse in Motion, captured evidence of the aloft horse with all 4 hooves tucked underneath. This accomplishment unveiled the new possibility of assessing athletic motion through photography.
      The Horse in Motion | 100 Photographs | The Most Influential Images of All Time.
      In modern sport, technological advancements continue to allow for further analysis of athletic movement. Optoelectronic marker–based motion capture systems have largely been considered the gold standard for motion analysis, but the technology is expensive, difficult to interpret, and limited to controlled laboratory settings.
      • Wirth M.A.
      • Fischer G.
      • Verdú J.
      • Reissner L.
      • Balocco S.
      • Calcagni M.
      Comparison of a new inertial sensor based system with an optoelectronic motion capture system for motion analysis of healthy human wrist joints.
      ,
      • Lapinski M.
      • Medeiros C.B.
      • Scarborough D.M.
      • et al.
      A Wide-Range, Wireless Wearable Inertial Motion Sensing System for Capturing Fast Athletic Biomechanics in Overhead Pitching.
      These systems also may be limited in their ability to provide accurate accelerations, forces, and torques during high-speed motions of many sports.
      • Lapinski M.
      • Medeiros C.B.
      • Scarborough D.M.
      • et al.
      A Wide-Range, Wireless Wearable Inertial Motion Sensing System for Capturing Fast Athletic Biomechanics in Overhead Pitching.
      Due to these constraints as well as the desire to directly measure forces that were specific to certain athletic movements, wearable inertial measurement units were developed. The use of wearable technology has rapidly expanded, and this technology has been explored in recent health care and sports medicine research.
      • Lapinski M.
      • Medeiros C.B.
      • Scarborough D.M.
      • et al.
      A Wide-Range, Wireless Wearable Inertial Motion Sensing System for Capturing Fast Athletic Biomechanics in Overhead Pitching.
      • Sajeev J.K.
      • Koshy A.N.
      • Teh A.W.
      Wearable devices for cardiac arrhythmia detection: A new contender?.
      • Rose M.
      • Curtze C.
      • O’Sullivan J.
      • et al.
      Wearable inertial sensors allow for quantitative assessment of shoulder and elbow kinematics in a cadaveric knee arthroscopy model.
      • De Zambotti M.
      • Cellini N.
      • Goldstone A.
      • Colrain I.M.
      • Baker F.C.
      Wearable sleep technology in clinical and research settings.
      • Harper D.J.
      • Carling C.
      • Kiely J.
      High-intensity acceleration and deceleration demands in elite team sports competitive match play: A systematic review and meta-analysis of observational studies.
      • Cummins C.
      • Orr R.
      • O’Connor H.
      • West C.
      Global positioning systems (GPS) and microtechnology sensors in team sports: A systematic review.
      • Li R.T.
      • Kling S.R.
      • Salata M.J.
      • Cupp S.A.
      • Sheehan J.
      • Voos J.E.
      Wearable performance devices in sports medicine.
      motusBASEBALL (Motus Global, Inc., Massapequa, NY) developed an arm sleeve for baseball players that houses an inertial measurement unit over the medial elbow to measure throw counts, peak elbow varus torque, arm speed, arm slot, maximum shoulder rotation, and workload, and this technology has been used in numerous recent studies on training and rehabilitation programs.
      • Melugin H.P.
      • Larson D.R.
      • Fleisig G.S.
      • et al.
      Baseball pitchers’ perceived effort does not match actual measured effort during a structured long-toss throwing program.
      • Leafblad N.D.
      • Larson D.R.
      • Fleisig G.S.
      • et al.
      Variability in baseball throwing metrics during a structured long-toss program: Does one size fit all or should programs be individualized?.
      • Reinold M.M.
      • Macrina L.C.
      • Fleisig G.S.
      • Aune K.
      • Andrews J.R.
      Effect of a 6-week weighted baseball throwing program on pitch velocity, pitching arm biomechanics, passive range of motion, and injury rates.
      • Camp C.L.
      • Tubbs T.G.
      • Fleisig G.S.
      • et al.
      The relationship of throwing arm mechanics and elbow varus torque: Within-subject variation for professional baseball pitchers across 82,000 throws.
      A previous study has questioned the validity of reported magnitudes when compared with marker-based motion capture but found acceptable reliability.
      • Boddy K.J.
      • Marsh J.A.
      • Caravan A.
      • Lindley K.E.
      • Scheffey J.O.
      • O’Connell M.E.
      Exploring wearable sensors as an alternative to marker-based motion capture in the pitching delivery.
      Future studies should continue to assess the validity and reliability of similar devices, but there remains potential for using inertial measurement unit technology to assess the recovery of preinjury or surgery benchmarks in throwing athletes.
      Professional sports organizations also have embraced wearable technology to monitor players under both game and practice environments.
      • Newcomb T.
      Catapult data takes next generation leap for NFL, NBA.
      Used by more than 2,000 sports teams, Catapult Sports (Catapult Innovations, Canberra Australia) developed a platform incorporating Global Positioning System technology, accelerometers, gyroscopes, and magnetometers that allow for workload monitoring as well as recording of maximal and average player velocities and acceleration.
      Catapult Sports. Vector.
      Previous studies have assessed the validity and reliability of these systems.
      • Musahl V.
      • Karlsson J.
      • Krutsch W.
      • Mandelbaum B.R.
      • Espregueira-Mendes J.
      • D’Hooghe P.
      Return to Play in Football: An Evidence-Based Approach. Berlin.
      • Johnston R.J.
      • Watsford M.L.
      • Kelly S.J.
      • Pine M.J.
      • Spurrs R.W.
      Validity and interunit reliability of 10 Hz and 15 Hz GPS units for assessing athlete movement demands.
      • Scott M.T.U.
      • Scott T.J.
      • Kelly V.G.
      The validity and reliability of global positioning systems in team sport.
      Although recent literature has used Global Positioning System to study athlete workloads for injury prevention, there has been a paucity of literature on recovery from injury or surgery.
      • Duhig S.
      • Shield A.J.
      • Opar D.
      • Gabbett T.J.
      • Ferguson C.
      • Williams M.
      Effect of high-speed running on hamstring strain injury risk.
      • Ruddy J.D.
      • Pollard C.W.
      • Timmins R.G.
      • Williams M.D.
      • Shield A.J.
      • Opar D.A.
      Running exposure is associated with the risk of hamstring strain injury in elite Australian footballers.
      • Sanders G.J.
      • Roll B.
      • Peacock C.A.
      • Kollock R.O.
      Maximum movement workloads and high-intensity workload demands by position in NCAA Division I collegiate football.
      Future studies on the recovery of sprint speed or change of direction after anterior cruciate ligament reconstruction, for example, would be of interest to athletes whose sports require these skills.
      The National Football League has recently partnered with Zebra Technologies to implement Next Gen Stats, a player and ball tracking system that uses radio-frequency identification chips that are embedded in every player and referee’s uniform, game footballs, endzone pylons, and first-down markers.
      NFL Football Operations. NFL Next Gen Stats.
      The system captures speed, acceleration, distance traveled, and location within inches, and the resulting data have allowed for the generation of new performance measures and proprietary statistics.
      NFL Football Operations. NFL Next Gen Stats.
      NFL teams have adjusted draft grades and made decisions about free agency acquisitions based on on-field speed measurements that have differed from the traditional combine or pro day assessments of speed.
      • Clark K.
      The NFL’s Analytics Revolution Has Arrived - The Ringer.
      Although the NFL keeps the Next Gen Stats raw data private among the league and its organizations, statisticians and sports scientists have been able to use the limited publicly available data to measure passing game performance.
      • Mallepalle S.
      • Yurko R.
      • Pelechrinis K
      • Ventura S
      Extracting NFL tracking data from images to evaluate quarterbacks and pass defenses.

      Player-Tracking Systems

      The recent development of optical player-tracking systems allows for real-time measurements of performance in competition environments. The NBA became the first American sports league to implement league-wide player tracking systems in 2013. Currently, an optical tracking system provided by Second Spectrum (Second Spectrum Inc, Los Angeles, CA) provides data on player speed, distance traveled, defensive impact, shooting and scoring efficiency, and rebounding.
      • Communications N.B.A.
      NBA announces multiyear partnership with Sportradar and Second Spectrum.
      These data are readily available for fans and scientists to analyze, and recent sports medicine literature has used this data to assess player performance.
      • Sampaio J.
      • McGarry T.
      • Calleja-González J.
      • Jiménez Sáiz S.
      • Schelling I Del Alcázar X.
      • Balciunas M.
      Exploring game performance in the National Basketball Association using player tracking data.
      Similar to the NBA, Major League Baseball introduced StatCast in 2015, a spatiotemporal tracking system using a standardized optical camera system as well as radar technology to track player and ball movement.
      • Lage M.
      • Ono J.P.
      • Cervone D.
      • Chiang J.
      • Dietrich C.
      • Silva C.T.
      StatCast Dashboard: Exploration of spatiotemporal baseball data.
      This measurement system provides data on player positioning, sprinting speed, reaction time, hitting distance, launch angle, batted ball exit velocity, as well as various pitching metrics including velocity, pitch movement, and ball spin rate. Recent publications on pitching mechanics have begun to utilize this technology.
      • Fury M.S.
      • Oh L.S.
      • Linderman S.E.
      • et al.
      Return to performance after ulnar collateral ligament reconstruction in Major League Baseball pitchers: A case-control assessment of advanced analytics, velocity, spin rates, and pitch movement.
      ,
      • Portney D.A.
      • Buchler L.T.
      • Lazaroff J.M.
      • Gryzlo S.M.
      • Saltzman M.D.
      Influence of pitching release location on ulnar collateral ligament reconstruction risk among Major League Baseball pitchers.
      The vast datasets that are available provide sports scientists and researchers with the possibilities of exploring new questions regarding injury and performance. For example, a recent study demonstrated that professional baseball hitters miss an average of 21 games after suffering an abdominal oblique injury.
      • Camp C.L.
      • Conte S.
      • Cohen S.B.
      • et al.
      Epidemiology and impact of abdominal oblique injuries in major and minor league baseball.
      Although this provides teams and players with valuable information regarding expected recovery timelines, little remains known about postinjury performance or risk factors for reinjury. StatCast data now allow researchers to investigate the relationship of injury to exit velocity, a critical marker of rotational performance that is dependent on the generated bat speed, pitch speed, and collision efficiency.
      • Nathan A.M.
      Regulating the performance of baseball bats.
      This information would serve important to professional baseball players, as 1-mph increases in exit velocity may correlate to 13% increases in home runs.
      • Nathan A.M.
      Exit speed and home runs. April 2.
      Yankees outfielder Aaron Judge was placed on the injured list on April 20, 2019, with an oblique injury. From the start of season until the time of injury, his average batted ball exit velocity was 98.4 mph. After returning from injury, his average exit velocity was 95.2 mph.
      baseballsavant.com. Aaron Judge Statcast, Visuals & Advanced Metrics.
      Whether an increased exit velocity raises the risk of subsequent oblique injury or exit velocity decreases after return from injury has yet to be studied. Regardless, access to these detailed performance data open new avenues in sports medicine research.

      Conclusions

      Advancements in sport analytics, wearable technology, and player-tracking systems have improved our understanding of performance in the elite athlete. Sports medicine researchers should collaborate with sports science teams to continue investigating the validity and reliability of emerging technology, assist in interpreting big data, and remain accountable to the goals of our athletic population. Future studies in sports medicine should consider using these detailed, granular assessments to address the demands of the elite athlete population.

      Supplementary Data

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