Applied Sports Science newsletter, February 7, 2015

Background: By maintaining phosphate and calcium homeostasis, vitamin D is critical for bone health and possibly physical performance. Hence, vitamin D is important to athletes. Few studies have investigated vitamin D levels in relation to fractures and performance in athletes, and no published study has included a multiracial sample of professional American football players.

Purpose: To assess vitamin D levels, including the prevalence of vitamin D deficiency/insufficiency, in professional American football players and to evaluate the association of vitamin D levels with race, fracture history, and the ability to obtain a contract position, which may be a marker for athletic performance.

… Results: Mean vitamin D level was 27.4 ± 11.7 ng/mL, with significantly lower levels for black players (25.6 ± 11.3 ng/mL) versus white players (37.4 ± 8.6 ng/mL; F 1,78 = 13.00, P = .001). All athletes who were vitamin D deficient were black. When controlling for number of professional years played, vitamin D levels were significantly lower in players with at least 1 bone fracture when compared with no fractures. Players who were released during the preseason because of either injury or poor performance had significantly lower vitamin D levels than did players who played in the regular season.

Conclusion: Black professional football players have a higher rate of vitamin D deficiency than do white players. Furthermore, professional football players with higher vitamin D levels were more likely to obtain a contract position in the National Football League. Professional football players deficient in vitamin D levels may be at greater risk of bone fractures.

On the day after the transfer window closed in England and Scotland, Portuguese football agent Jorge Mendes has defended the amount of money in the game.

Mendes, who is reported to have brokered more than £1bn worth of transfers, has been described as the most powerful figure in the game.

… While in Memphis recently, Bleacher Report organized an exclusive film session with Allen, who broke down his defensive development and skills while guarding the NBA’s most lethal scorers. Below is a rare look inside the mind of arguably the league’s best perimeter defender, presented from Allen’s perspective and edited for clarity and length.

… OlympicTalk: You’ve talked about moving up to the marathon at some point. Did watching Mo’s adversity in trying a marathon last year affect you?

Rupp: Nah. In all honesty, I’m really excited for whenever it is that I choose to move up. Right now, my focus is on the track through the Olympics. After 2016, I’ll be able to start looking at when a marathon might fit in. It was a good reminder how tough it is [seeing Farah]. A lot of times, you just think about something going really, really well. It’s a big jump. It’s a big change. It’s so different training from 10K to a marathon. I’ll be the beneficiary from him, learning what worked and what didn’t, advice he might have for whenever I choose to move up. But I’m still excited for it. The marathon, there’s something special about it. That, the mile and the 100 meters are the three biggest events.

Heavy snow and freezing conditions did not stop QPR making full use of the facilities at St. George’s Park on Friday.

Harry Redknapp’s side took full advantage of The FA’s national football centre facilities ahead of their trip to the Britannia Stadium to take on Stoke City on Saturday.

PURPOSE:

The aim of this study was to compare morning and evening time-trial performance, RPE and mood state of trained swimmers, taking into account chronotype, habitual training time-of-day and PERIOD3 (PER3) variable number tandem repeat genotype.
METHODS:

Twenty-six swimmers (18 males, age: 32.6 ± 5.7 years) swam 200 m time trials (TT) at 06h30 and 18h30 in a randomised order.
RESULTS:

There was no difference between morning and evening performance when the swimmers were considered as a single group (06h30: 158.8 ± 22.7 s, 18h30: 158.5 ± 22.0 s, p = 0.611). However, grouping swimmers by chronotype and habitual training time-of-day allowed us to detect significant diurnal variation in performance, such that morning-type swimmers and those who habitually train in the morning were faster in the 06h30 TT (p = 0.036 and p = 0.011, respectively). This was accompanied by lower ratings of perceived exertion (RPE) scores post-warm-up, higher vigour and lower fatigues scores prior to the 06h30 TT in morning-type swimmers or those who trained in the morning. Similarly, neither types and those who trained in the evenings had lower fatigue and higher vigour prior to the 18h30 TT.
CONCLUSIONS:

It appears that both chronotype and habitual training time-of-day need to be considered when assessing diurnal variation in performance. From a practical point of view, athletes and coaches should be aware of the potentially powerful effect of training time on shifting time-of-day variation in performance.

… In a complex environment, experts are up against two main difficulties. The first is the fallibility of human memory and attention, especially when it comes to mundane, routine matters that are easily overlooked under the strain of more pressing events. (When you’ve got a patient throwing up and an upset family member asking you what’s going on, it can be easy to forget that you have not checked her pulse.) Faulty memory and distraction are a particular danger in what engineers call all-or-none processes: whether running to the store to buy ingredients for a cake, preparing an airplane for takeoff, or evaluating a sick person in the hospital, if you miss just one key thing, you might as well not have made the effort at all.

The purpose of this investigation was to estimate the test-retest cross-reliability of peripheral and central changes with respect to nonlinear and linear measures of a surface electromyography (EMG) signal measured during isometric maximal voluntary contraction (MVC) combined with superimposed electrical stimulation during a brief and fatiguing task involving the ankle plantar flexors over a two follicular phases of menstrual cycle. Ten healthy female adults underwent one familiarisation session and 5 identical test-retest sessions. The results showed that the decrease in plantar flexor EMG components (root mean square (RMS), mean frequency (MnF), wavelet packet entropy (WPE) for soleus and gastrocnemius muscles, central activation ratio (CAR) and MVC, and contractile properties (P20, P100, PTT-100 and HRT) of the plantar flexor muscles at the end of 2-min MVC were similar (time effect; p < 0.001, ηp > 0.7, SP > 99%) and exhibited high stability over five trials (trial effect; p > 0.05; ηp < 0.2, SP < 30%). High reliability between-trials were found for 5-s MVC (ICC > 0.82, p < 0.001) and meaningful reliability for 2-min MVC (ICC > 0.66, p < 0.01). In conclusion, in young healthy women, measurements of neuromuscular function, such as RMS, MnF and WPE of a surface EMG signal, MVC, CAR from a brief and sustained MVC of the ankle plantar flexors, are reliable and multidimensional stability were found with respect to both high and low correlation outcomes across the five identical test-retest trials of any two properties measured during brief and sustained MVC.

Design for Lasting Change and the Fogg Behavior Model

Thursday, February 05, 2015 | 3:00pm – 4:30pm | Location:
MIT Media Lab, E14-633

The Fogg Behavior Model states that for any behavior to occur, three factors must converge at the same moment: motivation, ability, and a trigger. Today’s technology can leverage these factors in new ways, creating potentials for new products that influence people. In this talk, Dr. BJ Fogg will emphasize that technology is not a magic bullet. It’s simply a channel. Designers must create the right psychological experience in order to achieve the outcome they want. The Fogg Behavior Grid can be a guide. It maps out 15 ways behaviors can change. Each has its own psychology and its own set of solutions.

This past weekend, January 30th to February 1st 2015, was the 5th annual National Soccer Coaching Conference at the University of Toronto. This year’s conference featured several excellent presenters, including coaches from the CIS, Major League Soccer, and the Canadian National Teams. In this blog post, I will be discussing the one lecture from the conference that was the most interesting to me. Raymond Verheijen, a coach and fitness coach who has worked with several different professional clubs and national teams from all over the world (most recently with the Argentinian Men’s National Team at the 2014 World Cup) gave a lecture titled “Always Play with your Best 11″, centred around proper periodization in top level soccer.

This tone of this lecture was serious right from the start. One of the points Mr. Verheijen made right in the beginning of his presentation was that coaches, in their work, and in their coaching/education courses, are too comfortable, and without being mad to feel uncomfortable (by being challenged) they will never learn, develop and improve themselves. He was also very critical of the “subjective” approach that he says most coaches take to their profession, whereby they use a philosophy and training methodology based on their own opinions (subjective) rather than based on facts (or an objective approach).

Imagine tracking Sidney Crosby’s every move on the ice in real time.

It may not be far off.

The NHL is experimenting with player tracking technology that could be available as early as next season for broadcasters and fans.

Jersey cams will be worn by referees for first time in a professional basketball game, while tests continue to allow players to wear them in the near future.

An API to retrieve and read NFL Game Center JSON data.

Centre to be built in partnership with Manchester council will look after elite athletes – and the health local residents

An image kernel is a small matrix used to apply effects like the ones you might find in Photoshop or Gimp, such as blurring, sharpening, outlining or embossing. They’re also used in machine learning for ‘feature extraction’, a technique for determining the most important portions of an image. In this context the process is referred to more generally as “convolution” (see: convolutional neural networks.)

To see how they work, let’s start by inspecting a black and white image. The matrix on the left contains numbers, between 0 and 255, which each correspond to the brightness of one pixel in a picture of a face. The large, granulated picture has been blown up to make it easier to see; the last image is the “real” size.

The 2014-15 NBA season has reached its halfway point with every team logging 41 games played. An extended All-Star break will allow players to rest and recuperate, especially with injuries beginning to mount. Despite the number of games lost to injury rising during the second quarter, the league is on pace to finish below last season’s record setting total and below the league average over the last nine seasons. Some familiar franchises, including the Knicks and Timberwolves, were hit particularly hard with a massive amount of games and dollars lost.

The purpose of this study was to assess the test-retest reliability of postural balance in patients with anterior cruciate ligament reconstruction (ACL) and controls. Ten healthy subjects and 15 individuals with ACL reconstruction performed single-leg and double-leg balance tests. The center of pressure (COP) was recorded using a pressure platform. For the total COP path, the intraclass correlation coefficient (ICC) ranged from 0.79 to 0.91. For the COP standard deviation, the ICCs ranged from 0.68 to 0.94. For the COP velocity, the ICCs ranged from 0.72 to 0.91. The sway area and ellipse scores displayed ICCs values of 0.67 to 0.95 and 0.53 to 0.92, respectively. The ICCs were higher for double leg tests compared with single-stance ones. These results indicate that 30 s balance tests in double and single-leg stance are reliable tools to assess static balance. The use of such tests to monitor rehabilitation programs following ACL reconstruction is recommended.

Behaviours such as smoking, drinking, eating too much, and exercising too little impose a huge disease burden on individuals and societies. “Nudging” is a new approach that policy-makers and others can use to modify such behaviours, with the goal of improving quality of life and the sustainability of health care systems. Nudges are little cues that can help us make better decisions about our lifestyles. Rather than using coercion, prohibition, or large financial incentives to influence decision-making, nudges leverage the scientific insights of behavioural economics and cognitive psychology to influence conduct. Usually inexpensive and simple to implement, they are cost-effective and are intended to act as a supplement and occasionally an alternative to conventional mechanisms such as regulation and legislation. The Canadian government has recently expressed its interest in exploring the potential of nudging within the public service, and the nudge agenda has already been pursued by governments within the United Kingdom and the United States with positive results.

The European sports nutrition sector says the recent EFSA opinion that backed daily caffeine intakes up to 400 mg per day, will lift the sector – if it makes it into EU law books.

Have you ever wondered why it’s so tough to put down that last slice of bacon? Part of the answer is that humans are evolutionarily programmed to crave fatty foods, which offer the biggest bang for the buck, nutritionally speaking, with more than twice the calorie density of protein- or starch-rich food.

But a new Harvard study suggests that it’s a uniquely human practice — cooking — that allows humans to more fully access that energy.

Drug cheats will not be tackled properly until anti-doping agencies do more to assess the scale of the problem scientifically, says Roger Pielke Jr.

Hemoglobin is best known as red blood cells’ superstar protein—carrying oxygen and other gases on the erythrocytes as they zip throughout the bodies of nearly all vertebrates. Less well known is its presence in vegetables, including the sugar beet, in which Nélida Leiva-Eriksson recently discovered the protein while working on her doctoral thesis at Lund University in Sweden. In fact, many land plants—from barley to tomatoes—contain the protein, says Raúl Arredondo-Peter, an expert on the evolution of plant hemoglobins, or leghemoglobins, at the Autonomous University of the State of Morelos in Mexico. “Hemoglobins are very ancient proteins,” he notes. Scientists first discovered them in the bright-red nodules of soybean roots in 1939 but have yet to determine the proteins’ role in plants in most cases. One popular idea is that hemoglobin binds with and delivers nitric oxide to cells, sending signals to regulate growth.

… I built my data set using two sources. I used ratings created by Ken Massey, a statistician best known for his system of rating sports teams, to measure team success. The ratings take into account factors such as win-loss and strength of schedule, which allowed me to distinguish between two teams with an identical win-loss record. I then used recruiting data from Rivals to measure how well a team recruited in each year from 2002 to 2014.1 With that, I made a simple statistical model to predict where a team would finish in the ratings and compared the prediction to its actual 2014 rating.

The chart below shows how much better or worse each school fared in 2014 compared with how its recruiting predicts that it would finish.

… it makes sense that Park Tudor’s Cox, 30, is among a small but growing number of coaches using advanced statistics and video breakdown to gain an advantage — or, at least, attempt to — in high school basketball.

Park Tudor, the defending Class 2A state champion and ranked No. 1 again this season, pays $1,400 per season to use Krossover, a New York-based company that breaks down submitted game video and returns a detailed film breakdown and advanced team and individual statistics.

AIM:

To estimate the genetic and environmental contribution to the variation observed in the rate of torque development (RTD), which is considered an important determinant of sport performance.
METHODS:

Nine monozygotic (MZ) and seven dizygotic (DZ) twin pairs, of both sexes aged 19–26 years, performed three isometric maximal voluntary contractions with the knee at 70 degrees and 40 degrees of flexion (0 degrees = terminal extension) on a Contrex Isokinetic dynamometer. The RTD was extracted from the force time curves and calculated in two different ways, giving rise to two indices, the maximal rate of torque development (MRTD), and the torque at the first 100 msec (F 100msec ). Heritability estimates ( h 2 ) were derived on the basis of intrapair variances between MZ and DZ twin pairs.
RESULTS:

A significant genetic influence ( P <0.05) was found for both RTD indices (h2 = 0.99, and 0.93 for MRTD, and F 100msec respectively) at only 40 degrees of knee flexion, an angle associated with intensive neural activation. CONCLUSION:

The maximal rate of torque development of knee extensor muscles during the initial phase of their contraction and at enhanced neural activation, is under strong genetic influence.

… where do interested clubs even begin to start using analytics? How should they begin to go about collecting and managing performance data? To whom do they turn for help in analysing it? How do clubs tell the difference between statistical snake oil and statistical science?

For a club without a single analyst let alone an entire department, there is, thankfully, a very simple and effective answer to all of these questions: start small.

Many people think that sports analytics involves not only hiring an analyst but also compiling complex data sets, purchasing expensive monitoring equipment and elaborate software, etc. etc.. While these can all be effective tools over time, there is no need for a club with no history using data analysis to jump in whole hog in the first instance. In fact, any club can effectively use data even without necessarily using any higher math at all.

… The key insight of game theory for an N.F.L. coach is that when you think about what choice you should make, you need to also consider the response from the opposing coach, understanding that he is also thinking strategically. This line of thinking suggests that you should not necessarily call a run play, even if you’re blessed with a great running back. Likewise, it’s not clear that you should definitely pass. Rather, your choice should be somewhat random — a choice that game theorists call a “mixed strategy.”