Variation vs. specialization: the dose-time-effect of technical and physiological variety in the development of elite swimmers

OBJECTIVE

It is heavily discussed whether larger variety or specialization benefit elite performance at peak age. Therefore, this study aimed to determine technical (number of different swimming strokes) and physiological (number of different race distances) variety required to become an international-class swimmer (> 750 swimming points) based on 1'522'803 race results.

RESULTS

Correlation analyses showed lower technical variety in higher ranked swimmers (P < 0.001), yet with small effects (0.11-0.30). However, Poisson distribution revealed dose-time-effects and specified number of swimming strokes required during each age group. Specifically, freestyle swimmers showed highest chances when starting to compete in three to four swimming strokes but reduced their variety to three swimming strokes at the ages of 12/13yrs with another transition to two swimming strokes at the ages of 19/21yrs (female/male swimmers, respectively). Although both sexes showed similar specialization pattern throughout their career, earlier specialization was generally evident in female compared to male swimmers. At peak performance age, freestyle was most frequently combined with butterfly. Swimmers who either kept competing in all five swimming strokes or focused on only one at the beginning of their careers showed lowest probability of becoming an international-class swimmer. Physiological variety increased during junior age but declined again to three race distances towards elite age.

Specialize Early and Select Late: Performance Trajectories of World-Class Finalists and International- and National-Class Swimmers

PURPOSE

To investigate performance progression from early-junior to peak performance age and compare variety in race distances and swimming strokes between swimmers of various performance levels.

METHODS

Using a longitudinal data analysis and between-groups comparisons 306,165 annual best times of male swimmers (N = 3897) were used to establish a ranking based on annual best times at peak performance age. Individual performance trajectories were retrospectively analyzed to compare distance and stroke variety. Performances of world-class finalists and international- and national-class swimmers (swimming points: 886 [30], 793 [28], and 698 [28], respectively) were compared across 5 age groups-13-14, 15-16, 17-18, 19-20, and 21+ years-using a 2-way analysis of variance with repeated measures.

RESULTS

World-class finalists are not significantly faster than international-class swimmers up to the 17- to 18-year age group (F2|774 = 65, P < .001, ηp2=.14) but specialize in short- or long-distance races at a younger age. World-class breaststroke finalists show faster breaststroke times compared to their performance in other swimming strokes from an early age (P < .05), while world-class freestyle and individual medley finalists show less significant differences to their performance in other swimming strokes.

CONCLUSIONS

While federation officials should aim for late talent selection, that is, not before the 17- to 18-year age group, coaches should aim to identify swimmers' preferred race distances early on. However, the required stroke variety seems to be specific for each swimming stroke. Breaststroke swimmers could aim for early and strong specialization, while freestyle and individual medley swimmers could maintain large and very large stroke variety, respectively.

Predicting future stars: Probability and performance corridors for elite swimmers

OBJECTIVES

To evaluate the new age groups of the World Junior Championships in swimming from a scientific perspective, establish benchmarks and performance corridors that predict success at peak performance age and compare performance corridors between men and women and short-, middle-, and long-distance freestyle races.

DESIGN

Longitudinal big data analysis.

METHODS

In total, 347,186 annual best times of male (n = 3360, 561 ± 177 Swimming Points) and female freestyle swimmers (n = 2570, 553 ± 183 Swimming Points) were collected across all race distances at peak performance age and retrospectively analyzed throughout adolescence. Cumulative Poisson distribution was used to calculate probabilities of becoming world-class finalist, international-class, or national-class swimmer for each age group. Performance corridors were expressed relative to the World Record and compared between performance levels, sex, race distances, and age groups with a 2-way analysis of variance.

RESULTS

Females are required to swim faster relative to the World Record at a younger age and show earlier performance plateaus than males at national and international levels. Additionally, world-class long-distance finalists show higher Swimming Points earlier in their career compared to short-distance swimmers. This effect is more distinctive in females than males.

CONCLUSIONS

Based on the sex-specific performance corridors and developments, the newly aligned age groups for the World Junior Championships are questionable regarding long-term athlete development. Based on race times from 131 nations, the present benchmarks provide valid international normative values to predict success chances at peak performance age and guide young swimmers along their talent pathway.

Two-dimensional plasmonic grating for increased quantum efficiency in midwave infrared nBn detectors with thin absorbers

We demonstrate a strategy for increasing the operating temperatures of nBn midwave infrared (MWIR) focal plane arrays, based on the use of two-dimensional plasmonic gratings to enhance the quantum efficiency (QE) of structures with very thin absorbers. Reducing the absorber volume correspondingly reduces the dark current in a diffusion-limited photodiode, while light trapping mediated by the plasmonic grating increases the net absorbance to maintain high QE. The plasmonically enhanced nBn MWIR sensors with absorber thicknesses of only 0.5 μm exhibit peak internal QEs as high as 57%, which enables a 5-fold reduction in dark current. Numerical simulations indicate the potential for further improvement.

RGMA and IL21R show association with experimental inflammation and multiple sclerosis

Rat chromosome 1 harbors overlapping quantitative trait loci (QTL) for cytokine production and experimental models of inflammatory diseases. We fine-dissected this region that regulated cytokine production, myelin oligodendrocyte glycoprotein (MOG)-induced experimental autoimmune encephalomyelitis (EAE), anti-MOG antibodies and pristane-induced arthritis (PIA) in advanced intercross lines (AILs). Analysis in the tenth and twelfth generation of AILs resolved the region in two narrow QTL, Eae30 and Eae31. Eae30 showed linkage to MOG-EAE, anti-MOG antibodies and levels of interleukin-6 (IL-6). Eae31 showed linkage to EAE, PIA, anti-MOG antibodies and levels of tumor necrosis factor (TNF) and IL-6. Confidence intervals defined a limited set of potential candidate genes, with the most interesting being RGMA, IL21R and IL4R. We tested the association with multiple sclerosis (MS) in a Nordic case-control material. A single nucleotide polymorphism in RGMA associated with MS in males (odds ratio (OR)=1.33). Polymorphisms of RGMA also correlated with changes in the expression of interferon-gamma (IFN-gamma) and TNF in cerebrospinal fluid of MS patients. In IL21R, there was one positively associated (OR=1.14) and two protective (OR=0.87 and 0.68) haplotypes. One of the protective haplotypes correlated to lower IFN-gamma expression in peripheral blood mononuclear cells of MS patients. We conclude that RGMA and IL21R and their pathways are crucial in MS pathogenesis and warrant further studies as potential biomarkers and therapeutic targets.

MHC haplotype-dependent regulation of MOG-induced EAE in rats

Experimental autoimmune encephalomyelitis (EAE) induced in the rat by active immunization with myelin-oligodendrocyte-glycoprotein (MOG) is mediated by synergy between MOG-specific T cells and demyelinating MOG-specific antibody responses. The resulting disease is chronic and displays demyelinating central nervous system (CNS) pathology that closely resembles multiple sclerosis. We analyzed major histocompatibility complex (MHC) haplotype influences on this disease. The MHC haplotype does not exert an all-or-none effect on disease susceptibility. Rather, it determines the degree of disease susceptibility, recruitment of MOG-specific immunocompetent cells, clinical course, and CNS pathology in a hierarchical and allele-specific manner. Major haplotype-specific effects on MOG-EAE map to the MHC class II gene region, but this effect is modified by other MHC genes. In addition, non-MHC genes directly influence both disease and T cell functions, such as the secretion of IFN-gamma. Thus, in MOG-EAE, allelic MHC class II effects are graded, strongly modified by other MHC genes, and overcome by effects of non-MHC genes and environment.

Amelioration of collagen II-induced arthritis in rats by the type IV phosphodiesterase inhibitor Rolipram

The effect of Rolipram, a selective inhibitor of the cyclic AMP specific phosphodiesterase (PDE IV) was evaluated in the rat collagen type II (RCII)-induced arthritis model in the DA rat. Rolipram was given either shortly before expected onset of disease (days 10-14) or shortly after the onset of clinically evident arthritis (days 15-19 after immunization). Administration at days 10-14 delayed the onset of arthritis for approximately 5 days, but the severity of arthritis was thereafter comparable to that seen in a non-treated control group. Rolipram treatment of animals with manifest arthritis inhibited further arthritis development and also tended to diminish its severity at a phase of disease where non-treated control animals showed a rapidly progressing disease development. Serum levels of antibodies to RCII were in all experiments similar between Rolipram-treated and control animals. An in situ hybridization method for determining cytokine mRNA synthesis in regional lymph nodes, after administration of Rolipram (at days 2-7), demonstrated a strong inhibitory effect on tumour necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma) mRNA expression, whereas no effects were seen on IL-2 mRNA synthesis after in vivo challenge with native RCII emulsified in Freund's incomplete adjuvant. The results thus demonstrate strong preventive as well as therapeutic effects of Rolipram in a model for arthritis that is very similar to human rheumatoid arthritis with respect to cytokine regulation, and suggest that Rolipram has its major effects in the effector stage of the arthritogenic immune response.

Role of adjuvants in turning autoimmunity into autoimmune disease

Autoreactive B- as well as T-lymphocytes are often integral parts of the normal immune system and are not per se pathogenic. Also activation of these autoreactive lymphocytes may in many cases occur without ensuing pathology. In the current paper is discussed two situations whereby unspecific inflammatory stimuli in the form of immunological adjuvants may either by themselves cause arthritis, or may change a non-pathogenetic to a destructive and chronic inflammatory disease.

A Trypanosoma brucei brucei-derived factor that triggers CD8+ lymphocytes to interferon-gamma secretion: purification, characterization and protective effects in vivo by treatment with a monoclonal antibody against the factor

A protein factor that stimulates CD8+ lymphocytes to produce and secrete IFN-gamma has been purified from Trypanosoma brucei brucei (T.b. brucei). This was accomplished by raising monoclonal antibodies (MoAbs) against a fraction of T.b. brucei obtained by gel filtration, which contained high levels of material inducing rat mononuclear cells (MNC) to IFN-gamma production. MoAbs from four hybridomas strongly inhibited trypanosome-induced IFN-gamma production. One of them (MO1) was used for purification of the trypanosome-derived lymphocyte triggering factor (TLTF) by affinity chromatography. SDS electrophoresis of the purified TLTF displayed a band of 42-45 kDa MW. Gel filtration of homogenates of whole parasites yielded several peaks of IFN-gamma-inducing activity with a lowest MW of 41-46 kDa. Bioactivity of all peaks was blocked by MO1, suggesting that a single molecule, or a single epitope of additional molecules, is responsible for the different peaks with IFN-gamma-inducing activity. IFN-gamma released from MNC stimulates T.b. brucei growth. Blocking of TLTF in vitro with MO1 inhibited MNC-supported growth of the parasites. To study the in vivo relevance of TLTF in the course of experimental African trypanosomiasis, MO1 was used to treat rats and mice at different times after infection. Treatments instituted at different time-points after infection suppressed parasite growth, abrogated the IFN-gamma production by splenocytes induced by the infection and prolonged survival of the animals. The data support the hypothesis that TLTF and IFN-gamma have a crucial regulatory function in the parasite-host interactions and that these molecules influence the disease course during experimental African trypanosomiasis.

500-Kilodalton calcium sensor regulating cytoplasmic Ca2+ in cytotrophoblast cells of human placenta

Two monoclonal IgG antibodies E11 and G11, which react with parathyroid and kidney tubule cells, are in the present communication demonstrated to immunostain the surface of cytotrophoblast cells in human placenta. The G11 but not the E11 antibody has earlier been found to interfere with the sensing and gating of extracellular calcium in parathyroid cells. Microfluorometric measurement of the cytoplasmic calcium (Ca2+i) concentration was performed on suspended placental cells loaded with fura-2. The E11-positive placental cells displayed biphasic and parathyroid-like increases in Ca2+i in response to extracellular Ca2+. This increase was blocked by the G11 antibody and absent in the E11-negative placental cells. A sandwich enzyme-linked immunosorbent assay was constructed in which the G11 and E11 antibodies were shown to react with the same molecule. This calcium sensor was isolated and found to consist of a single, glycosylated polypeptide of approximately 500 kDa.

In vivo flux of plasma cholesterol into human abdominal aorta with advanced atherosclerosis

To measure the flux of free and esterified cholesterol from plasma into abdominal aortic tissue that had severe atherosclerotic lesions, we intravenously injected two autologous plasma samples containing radioactive cholesterol into patients scheduled for reconstructive arterial surgery. After the injections, blood samples were collected for calculation of the exposure of arterial tissue to labeled free and esterified plasma cholesterol. When tissue specimens were removed a few days after the injection, the aortic influx was determined by the simultaneous use of two differently labeled species of cholesterol. The flux of free and esterified cholesterol into 51 tissue specimens from the abdominal aorta of 12 normocholesterolemic patients was 41 +/- 3 and 45 +/- 3 nmol X cm-2 X day-1 (mean +/- SE), respectively, with 7% to 30% hydrolysis and 8% to 24% esterification of the labeled sterols in the atherosclerotic tissue. The influx was up to 100 times greater than the influx into nonatherosclerotic ascending aorta previously measured in other patients. The cholesterol content of the atherosclerotic tissue corresponded to 16 +/- 3 months (mean +/- SE) of continuous cholesteryl ester influx. Unless counteracted by cholesteryl ester efflux from the plaque, this influx provides enough cholesteryl ester from plasma to cause rapid lesion progression.

Ischemic colitis complicating reconstruction of the abdominal aorta

A review of 23 patients with ischemic colitis after surgical treatment of the abdominal aorta disclosed a pathogenetic heterogeneous finding. Ligation of the inferior mesenteric artery, abolished collateral blood supply or nonocclusive low flow state, or both, was a common feature. An incidence of 0.5 per cent was revealed for full-thickness necrosis. The mortality was 70 per cent since diagnosis was made first since perforation and peritonitis had occurred. On the basis of these findings vital prophylactic measures and diagnostic possibilities are discussed herein.

Fracture of the body of the talus

Fifty-one patients with fracture of the body of the talus were seen at follow-up examination an average of 23 months after treatment. Osteonecrosis had developed in 8 out of 17 patients with displaced shearing or crush fractures of the trochlea. Malunion as well as subluxation predisposed to osteoarthrosis in the subtalar and talocrural joints. Thus, osteoarthrosis was present in 9 out of 21 patients without malunion, in 8 out of 16 patients with malunion, and in 11 out of 14 with malunion as well as subluxation. Judging from the nature of the complaints, the difficulties in rehabilitation, and the disability assessment, the prognosis was fairly grave, also after the small, usually non-displaced fractures of the posterior and lateral tubercles. Out of 20 patients with fractures of this type only 6 obtained almost complete relief from their symptoms, only 8 could go back to their previous work on a full-time basis, and 11 were assessed to be 10 per cent or more disabled. Fractures in the posterior and lateral tubercles must therefore be interpreted as links in more extensive injuries involving the subtalar joint and possibly the talocrural joint with associated injuries to articular cartilage, joint capsules, and ligaments.