Applied Sports Science newsletter – May 19, 2015

PURPOSE:
The aim of the present study was to investigate the role of central and peripheral factors in neuromuscular fatigue induced by repeated maximal contractions in children and adults.
… RESULTS:
Torque reached 60% of initial value after 49.5 ± 16.8 and 34.0 ± 19.6 repetitions in boys and men, respectively (p<0.05). Furthermore, men showed a significantly higher KE MVC decline than boys between 50 and 90% of total repetitions (p<0.05). VA remained unchanged in men whereas it decreased significantly in boys (p<0.05). In contrast, while Qtwpot remained unchanged in boys, Qtwpot decreased progressively up to 60% of total repetitions in men (p<0.001). Finally, Mmax remained unchanged for VL and RF muscles in both groups.
CONCLUSION:
Children experienced no apparent peripheral fatigue and a higher central fatigue than adults. The greater fatigue resistance in children could be related to a strategy of the central nervous system aimed at limiting the recruitment of motor units, in order to prevent any extensive peripheral fatigue.

This study examined the mechanomyographic (MMGRMS) amplitude–force relationships for 5 (age = 19.20 ± 0.45 years) aerobically trained (AT), 5 (age = 25 ± 4.53 years) resistance-trained (RT) and 5 (age = 21.20 ± 2.17 years) sedentary (SED) individuals. Participants performed an isometric trapezoidal muscle action at 60% maximal voluntary contraction of the leg extensors that included linearly increasing, steady force, and linearly decreasing muscle actions. MMG and skinfold thickness were recorded from the vastus lateralis. b and a terms were calculated from the natural log-transformed MMGRMS–force relationships (linearly increasing and decreasing segments) for each participant. An average of MMGRMS was calculated for the entire steady force segment. The b terms for the RT (0.727 ± 0.334) and SED (0.622 ± 0.281) were significantly greater (P < 0.05) than the AT (0.159 ± 0.223) and were greater during the linearly increasing (0.622 ± 0.426) than decreasing (0.383 ± 0.269) segments when collapsed across segments and training status, respectively. MMGRMS during the steady force segment and skinfold thicknesses were not different among training statuses (P = 0.106, P = 0.142). Motor unit (MU) activation strategies were influenced as a function of exercise training status and muscle action. Future research is needed to fully understand the implications of these changes in MU control strategies as a result of chronic exercise training on exercise and athletic performance.

… As a coach, we can exploit our natural tendencies and for lack of a better term, flaws. One such flaw is what I call recentcy. It’s a made up word as far as I know, but the general gist of it is simple. We tend to remember what occurred more recently. … And the story is no different in running. In a recent conversation with my buddy for random philosophical converations, Phoebe Wright, we got to talking about this phenomenon. I called it my coaching practice of “people remember the last interval.” Her response was pretty accurate “What a simple and accurate yet silly coaching tip. You always want to finish the workout well.”

… One solution is to delegate and to fight bias at the organizational level, using choice architecture to modify the environment in which decisions are made. (See “Leaders as Decision Architects,” in this issue.) Much of the time, though, delegation isn’t appropriate, and it’s all on you, the manager, to decide. When that’s the case, you can outsmart your own biases. You start by understanding where they’re coming from: excessive reliance on intuition, defective reasoning, or both. In this article, we describe some of the most stubborn biases out there: tunnel vision about future scenarios, about objectives, and about options. But awareness alone isn’t enough, as Kahneman, reflecting on his own experiences, has pointed out. So we also provide strategies for overcoming biases, gleaned from the latest research on the psychology of judgment and decision making.

… Recently, we chose to take a closer look at the impact external variables like youth specialization has on the careers of collegiate athletes. Over a four-year period, we collected comprehensive previous medical histories on all incoming student-athletes at Stanford University, a task designed to better understand and quantify the risk of continued sport participation. What we found was shocking. 78% of the 1,693 distinct medical histories examined reported a total of 3,126 injuries. These injuries resulted in over a combined 93,000 days of participation lost. Additionally, over 500 student-athletes reported having had a least one surgery due to a youth sports injury. Of the injuries reported, 20% indicated still having symptoms from the injury, despite continued participation in sport. Based on these findings (and others here), the extensive medical histories now commonplace in our youth athletes can now help us better correlate movement pattern deficiencies and lack of physical recovery with the risk equation investigated upon arrival to their college campuses.

University of Toronto researchers show that engineered ‘hydrogels’ not only help with stem cell transplantation, but actually speed healing in both the eye and brain.

Purpose: Optimal high intensity interval training (HIIT) regimes for running performance are unknown, although most protocols result in some benefit to key performance factors (running economy (RE), anaerobic threshold (AT) or V[spacing dot above]O2max). Lower-body positive pressure (LBPP) treadmills offer the unique possibility to partially unload runners and reach supramaximal speeds. We studied the use LBPP to test an overspeed HIIT protocol in trained runners.

…

Results: Group by time effects were present for vV[spacing dot above]O2max (CON: 17.5 vs. 18.3, p=0.03; LBPP: 19.7 vs. 22.3 km[BULLET OPERATOR]h-1; p<0.001) and Tlim (CON: 307.0 vs. 404.4 s, p=0.28; LBPP: 444.5 vs. 855.5, p<0.001). Simple main effects for time were present for field performance (CON: -18, LBPP: -25 s, p=0.002), V[spacing dot above]O2max (CON: 57.6 vs. 59.6; LBPP 54.1 vs. 55.1 ml[middle dot]kg-1[middle dot]min-1; p=0.04) and submaximal heart rate (157.7 vs. 154.3 and 151.4 vs. 148.5 bpm; p=0.002). RE was unchanged.

Conclusions: A 4 week HIIT protocol at 100% vV[spacing dot above]O2max improves field performance, vV[spacing dot above]O2max, V[spacing dot above]O2max and submaximal heart rate in trained runners. Improvements are similar if intervals are run on a regular treadmill or at higher speeds on a LPBB treadmill with 10% BW reduction. LBPP could provide an alternative for taxing HIIT sessions.

To study spatial awareness, Darkball asks you to catch a ball you can’t see as many times in a row as possible.

Research firm Tractica predicts that worldwide unit shipments of clinical and non-clinical connected wearable patches will grow to 12.3 million per year by 2020. Last year, annual shipments were just 67,000. The market for such connected patches, Tractica predicts, will hit $3.3 billion per year.

Tractica describes the category as including “patches, tattoos, or small devices that are affixed to the skin and worn for a limited period of time, ranging from an hour to several weeks” and adds that “the patches also have an element of wireless connectivity, and have a medical, health, or wellness purpose that can range from monitoring physiological data to delivering medication.”

… Scientists love to study athletes, and have focused much effort in helping them train to be at their peak. No doubt important work that has allowed athletes to continually break world records in their efforts to go faster. But geneticist Euan Ashley at Stanford University and an international team of researchers, including Swedish exercise physiologist Mikael Mattsson, think that super athletes like Gregg can tell us more than the best way to train. They think the genomes of Gregg and others might just hold the secret to better health for everyone.

More than 25 million people rely on Adderall™ and other similar drugs to help treat narcolepsy, depression and attention deficit and hyperactivity disorder (ADHD). But how does amphetamine, the active ingredient in Adderall™, work? This week, Reactions explains how amphetamine helps you focus.

In February, Matthew Benham, the owner of the English club Brentford, did an astonishing thing. Even though Brentford had earned promotion to the second-tier Championship just last season, and even though the club was in fifth place in the league, Benham effectively fired the manager (Mark Warburton), assistant manager (David Weir) and sporting director (Frank McParland), announcing their contracts would not be renewed at season’s end.

Why on earth would he do a thing like that? The answer, Benham argues, lay in the data. His data. Benham, you see, is not your typical sports owner. Over the years, Benham made a fortune betting on soccer, more than enough to buy Brentford (his childhood team) in 2012 and a Danish club called Midtjylland last year. His betting success was based on a mathematical model that he believes is far more reflective of a team’s strength than the league table itself.

Course Description

Achieve an understanding of basic fluency, relevant industry applications, and the latest technological tools now being used in basketball.

Course instructor is Jason Rosenfeld, Director of Basketball Analytics at the National Basketball Association (NBA) League Office.

How do the different cell types in our bodies maintain their distinctive and characteristic sizes? Although much is known about the signaling networks that stimulate or suppress cell growth, such as the mammalian target of rapamycin (mTOR) pathway, this central question remains: How do a common set of pathways precisely specify the appropriate size for any given cell type and physiological condition? The precision with which size is controlled is demonstrated by the uniformity in cell size typically seen in tissues. Most epithelial tissues, for example, display a striking regularity in the size and morphology of cells, whereas size heterogeneity can be a sign of neoplastic growth.