Applied Sports Science newsletter – July 28, 2015

Ryan Kerrigan, recovering from arthroscopic knee surgery, preps for training camp with Explosive Performance.

… So much has happened the last few years, so little of it positive. Vitti even called it “a nightmare.” Few would disagree, the Lakers continually losing Bryant and Steve Nash to injury, along with a slew of games.

“When somebody gets hurt, I blame myself. That’s the Laker way — you’ve got a problem, you go in the bathroom, you look in the mirror, you start with that person,” Vitti said. “The one that really affected me and maybe even affected this decision [to retire] was Julius Randle. All of his doctors and his surgeon are saying that nothing was missed, but the guy goes out there and breaks his leg the first game [last season]. That one really bothered me.”

NFL restrictions on the amount of contact allowed have forced coaches to improvise, which means using everything from drones to remote-control cars.

The greatest anxiety troubling workers today is embodied in a simple question: How will we humans add value? … The big idea is always the same: For good or ill, machines become just like people—only better.

The aim of the present study was to examine the ability of a GPS-imbedded accelerometer to assess stride variables and vertical stiffness (K), which are directly related to neuromuscular fatigue during field-based high-intensity runs. The ability to detect stride imbalances was also examined. A team sport player performed a series of 30-s runs on an instrumented treadmill (6 runs at 10, 17 and 24 km/h) with or without his right ankle tapped (aimed at creating a stride imbalance), while wearing on his back a commercially-available GPS unit with an embedded 100-Hz tri-axial accelerometer. Contact (CT) and flying (FT) time, and K were computed from both treadmill and accelerometers (Athletic Data Innovations) data. The agreement between treadmill (criterion measure) and accelerometer-derived data was examined. We also compared the ability of the different systems to detect the stride imbalance. Biases were small (CT and K) and moderate (FT). The typical error of the estimate was trivial (CT), small (K) and moderate (FT), with nearly perfect (CT and K) and large (FT) correlations for treadmill vs. accelerometer. The tape induced very large increase in the right – left foot ? in CT, FT and K measured by the treadmill. The tape effect on CT and K ? measured with the accelerometers were also very large, but of lower magnitude than with the treadmill. The tape effect on accelerometer-derived ? FT was unclear. Present data highlight the potential of a GPS-embedded accelerometer to assess CT and K during ground running.

This study investigated the relationship between GPS variables measured in training and gameplay and injury occurrences in professional soccer. Nineteen professional soccer players competing in the Australian Hyundai A-League were monitored for one entire season using 5Hz Global Positioning System (GPS) units (SPI-Pro GPSports, Canberra, Australia) in training sessions and pre-season games. The measurements obtained were Total Distance, High Intensity Running Distance, Very High Intensity Running Distance, New Body Load and Metres per Minute. Non-contact soft tissue injuries were documented throughout the season. Players’ seasons were averaged over one and four week blocks according to when injuries occurred. These blocks were compared to each other and to players’ seasonal averages. Players performed significantly higher Metres per Minute in the weeks preceding an injury compared to their seasonal averages (+9.6 % and +7.4 % for one and four week blocks respectively) (p<0.01), indicating an increase in training and gameplay intensity leading up to injuries. Furthermore, injury blocks showed significantly lower average New Body Load compared to seasonal averages (-15.4 % and -9.0 % for one and four week blocks respectively) (p<0.01 and p=0.01). Periods of relative under-preparedness could potentially leave players unable to cope with intense bouts of high intensity efforts during competitive matches. Although limited by FIFA regulations, the results of this study isolated two variables predicting soft tissue injuries for coaches and sports scientist to consider when planning and monitoring training.

In last night’s Gold Cup semi-final between Mexico and Panama, Mexico escaped with a 2-1 extra-time victory. Like many recent CONCACAF games, a few judgmental calls more or less decided the outcome. This game included an early red card to a Panama player, and a late penalty kick awarded to Mexico. See Deadspin for highlights here.

Much of the commentary after the game ripped the game’s referee, American Mark Geiger. However, I’m not quite sure Geiger’s to blame. Specifically, while I’m not smart enough to get into the technicalities of any soccer call, I did notice that Geiger was forced to make a red call decision from at least 40 yards away. This seems absurd.

Using the dimensions from each of the fields/rinks in the NFL, NBA, NHL, and FIFA, as well as each organizations respective number of officials, I estimated the amount of square footage that each ref is responsible for. For example, three NBA referees cover 4,700 square-feet, or about 1,600 per ref.

… There has been rampant speculation as to the power-to-mass ratio that Froome achieved on La Pierre-Saint-Martin. Pierre Sallet, a French exercise physiologist, recently estimated Froome’s power-to-mass for the La Pierre-Saint-Martin climb to be an astounding 7.04 watts per kilogram (W/kg), a circa 2000 Armstrong-ian figure. Sallet, however, has not divulged the methodology of his calculation, and we’re only left to speculate that he used back-of-the-envelope calculations based on having precise knowledge of the road gradient, air density, cross-sectional area, and wind speed for all points on the climb. This is an extremely sensitive calculation, and minor misestimations of the highly variable parameters can and does lead to large errors. … Froome averaged 6.06 W/kg over the penultimate 14.4 km of La Pierre-Saint-Martin. At a recently reported mass of 68 kg, this amounts to 412 W over 38:15.

Wideos from Analysis Marketing’s Analytics and Visualisation in Football event that took place on June 25 in London have been posted to YouTube.

Background Elite athletes should have little concern about meeting recommended guidelines on physical activity. However, sedentary behaviour is considered a health risk independent of physical activity, and is recognised in public health guidelines advising against prolonged sedentary time. There has been very little research on athletes’ physical activity behaviour outside elite sport.

Methods Given health and performance links, we investigated in-season post-training activity levels in 28 elite professional footballers during the English Premiership season. Players volunteered to wear a triaxial wrist accelerometer for 1?week, removing it only for training and matches. In total, 25 players met the inclusion criteria for analysis. Players recorded on average 632.6?min wear time p/day during the post-training period (SD±52.9) for a mean of 3.8?days (SD±1.5).

Results On average, players recorded 76.2?min p/day (SD±28.8) of moderate or vigorous activity post-training. The majority (79%) of post-training time was spent in sedentary activities (500.6?min per day±59.0).

Conclusions Professional footballers are alarmingly sedentary in their leisure time, and comparatively more so than non-athletic groups of a similar age and older. This raises questions over optimum recovery and performance, as well as long-term health and cardiovascular risk. Worryingly, retirement from elite sport is likely to further imbalance activity and sedentary behaviour. Promoting regular periodic light to moderate leisure time activity could be beneficial. Further research and provision of education and support for players is required in this area.

… Teams coming off of only one day of rest score an average 98.88 points per game; while teams coming off of 1+ days of rest score 100.36 points per game. Parsing that average beyond one day of rest, the points per game average stabilizes at 100.38, 100.56, 100.29 and so on. Consequently, teams on zero days of rest only win 46.55% of their games, compared to a 51.06% win percentage for 1+ days of rest.

Seeing these issues, I wanted to look for reasons beyond Krishna’s fatigue-confirming piece to find the answers for these downturns. Initially, looking at FGA and FTA per game showed no significant results, so I turned again to Krishna and his shot difficulty metric. I first looked at shot difficulty (measured as aXPPS) and the basic FG% against the league averages by days of rest (up to 3 days due to sample size).

Numerous studies have shown that increases in fitness (e.g., VO2max, MAS, Yo-Yo, etc.) are associated with increased cardiac-parasympathetic activity among healthy, athletic and clinical populations. This is one of the reasons why aerobic exercise is considered to be cardio-protective, due to enhanced resting vagal-modulation.

However, there is considerable inter-individual variation in how a given individual responds to an exercise program. Following a standardized endurance training program, some individuals will show significant improvements in aerobic fitness while others will show only small improvements. Some may even regress. Why this occurs is likely due to a variety of potential variables including genetic factors, appropriateness of training stimulus and life style factors (i.e., sufficient recovery, sleep quality, nutrition, stress, etc.). Given the association between fitness changes and HRV changes, monitoring HRV throughout training may be useful in evaluating individual adaptation to a training program.

In our latest study (in press with JSCR), we wanted to determine if changes in HRV mid-way through a training program related to eventual changes in intermittent running performance in a collegiate female soccer team.

… MLS remains a small feeder league – albeit one with an abnormal capacity for luring big, aging stars, relative to its size – where teams operate on extremely tight budgets in a vast, global, and almost psychotically competitive talent exchange. What’s more, that market is already incredibly efficient. You get more or less what you pay for. But if you can redefine what it is you are and are not, what you need and don’t, and how your thin wad of money is best spent, effective analytics can offer real advantages. Especially since everybody is working under the constraints of the same salary cap system – budgets for Designated Players excepted – evening the playing field and increasing the incentive to recruit better.

So what, then, were MLS teams doing about analytics?

Over a 90-minute soccer match, Sweden’s Zlatan Ibrahimovic makes dozens of feints, false starts, and other fine movements in an attempt to free himself from opposing defenders. Each motion requires Ibrahimovic to accelerate, and then decelerate, his 209-pound frame forward or backward, left or right. Each effort takes a toll on his body that Paul Balsom, the head of performance for the Swedish national team, cannot track.

“Really, football is all about those movements,” said Balsom, who is responsible for keeping Ibrahimovic on the field and out of the trainer’s room. “We’re not getting enough information.”

Soon, Balsom and other sports scientists will get the data they crave. On July 7, FIFA issued a memorandum announcing the approval of wearable electronic performance and tracking systems in matches. FIFA’s approval came two months after the International Football Association Board amended its laws to allow the use of the tracking devices, called EPTS, on principle — on the condition that they not endanger player safety and that information is not relayed to coaches during matches.