Standardization and validation of the body weight adjustment regression equations in Olympic weightlifting

The problems in comparing the performances of Olympic weightlifters arise from the fact that the relationship between body weight and weightlifting results is not linear. In the present study, this relationship was examined by using a nonparametric curve fitting technique of robust locally weighted regression (LOWESS) on relatively large data sets of the weightlifting results made in top international competitions. Power function formulas were derived from the fitted LOWESS values to represent the relationship between the 2 variables in a way that directly compares the snatch, clean-and-jerk, and total weightlifting results of a given athlete with those of the world-class weightlifters (golden standards). A residual analysis of several other parametric models derived from the initial results showed that they all experience inconsistencies, yielding either underestimation or overestimation of certain body weights. In addition, the existing handicapping formulas commonly used in normalizing the performances of Olympic weightlifters did not yield satisfactory results when applied to the present data. It was concluded that the devised formulas may provide objective means for the evaluation of the performances of male weightlifters, regardless of their body weights, ages, or performance levels.     

The effects of amino acid supplementation on muscular performance during resistance training overreaching

The purpose of this study was to examine the effects of amino acid supplementation on muscular strength, power, and high-intensity endurance during short-term resistance training overreaching. Seventeen resistance-trained men were randomly assigned to either an amino acid (AA) or placebo (P) group and underwent 4 weeks of total-body resistance training consisting of two 2-week phases of overreaching (phase 1: 3 x 8-12 repetitions maximum [RM], 8 exercises; phase 2: 5 x 3-5 RM, 5 exercises). Muscle strength, power, and high-intensity endurance were determined before (T1) and at the end of each training week (T2-T5). One repetition maximum squat and bench press decreased at T2 in P (5.2 and 3.4 kg, respectively) but not in AA, and significant increases in 1 RM squat and bench press were observed at T3-T5 in both groups. A decrease in the ballistic bench press peak power was observed at T3 in P but not AA. The fatigue index during the 20-repetition jump squat assessment did not change in the P group at T3 and T5 (fatigue index = 18.6 and 18.3%, respectively) whereas a trend for reduction was observed in the AA group (p = 0.06) at T3 (12.8%) but not T5 (15.2%; p = 0.12). These results indicate that the initial impact of high-volume resistance training overreaching reduces muscle strength and power, and it appears that these reductions are attenuated with amino acid supplementation. In addition, an initial high-volume, moderate-intensity phase of overreaching followed by a higher intensity, moderate-volume phase appears to be very effective for enhancing muscle strength in resistance-trained men.     

Saccharomyces cerevisiae engineered to produce D-xylonate

Saccharomyces cerevisiae was engineered to produce D-xylonate by introducing the Trichoderma reesei xyd1 gene, encoding a D-xylose dehydrogenase. D-xylonate was not toxic to S. cerevisiae, and the cells were able to export D-xylonate produced in the cytoplasm to the supernatant. Up to 3.8 g of D-xylonate per litre, at rates of 25–36 mg of D-xylonate per litre per hour, was produced. Up to 4.8 g of xylitol per litre was also produced. The yield of D-xylonate from D-xylose was approximately 0.4 g of D-xylonate per gramme of D-xylose consumed. Deletion of the aldose reductase encoding gene GRE3 in S. cerevisiae strains expressing xyd1 reduced xylitol production by 67%, increasing the yield of D-xylonate from D-xylose. However, D-xylose uptake was reduced compared to strains containing GRE3, and the total amount of D-xylonate produced was reduced. To determine whether the co-factor NADP⁺ was limiting for D-xylonate production the Escherichia coli transhydrogenase encoded by udhA, the Bacillus subtilis glyceraldehyde 3-phosphate dehydrogenase encoded by gapB or the S. cerevisiae glutamate dehydrogenase encoded by GDH2 was co-expressed with xyd1 in the parent and GRE3 deficient strains. Although each of these enzymes enhanced NADPH consumption on D-glucose, they did not enhance D-xylonate production, suggesting that NADP⁺ was not the main limitation in the current D-xylonate producing strains.     

The impact of cold-water immersion on power production in the vertical jump and the benefits of a dynamic exercise warm-up

The purpose of this study was to examine the influence of a cold treatment and a dynamic warm-up on lower body power in the form of a countermovement vertical jump (CMVJ). Nine physically active men, who were either current or ex-National Collegiate Athletic Association (NCAA) Division 1 athletes, consented to participate in the study. Using a balanced, randomized presentation and a within-subject design, each subject performed 4 environmental and warm-up protocols (i.e., ambient temperature without warm-up, ambient temperature with warm-up, cold without warm-up, or cold with warm-up). Two sets of 3 maximal effort CMVJs were performed on a force plate at each testing time point. For each protocol, the subjects completed a pretest set of CMVJ (pretreatment [PRE]), were then exposed to 1 of the 2 temperature treatments, completed another set of CMVJ (initial [IT]), then either went through a 15-minute warm-up, or were asked to sit in place. Then a final set of CMVJs was completed (posttreatment [PT]). The primary finding in this study was that warm-up was effective in offsetting the negative effects of cold exposure on CMVJ power. There was a significant main effect for Time (PRE > PT > IT), and there was a significant (p ≤ 0.05) main effect for Trial (AMB = AMBWU > COLDWU > COLD). Because athletic competitions happen in various colder climates, it is important to make sure that a proper warm-up be completed to maximize the athlete's power output. The results of this study demonstrate that when athletes are exposed to cold conditions, it is recommended that before practice or play, a dynamic warm-up be employed to optimize performance.     

Nonlinear time series analysis of food intake in the dab and the rainbow trout

Evidence suggests that dab and rainbow trout are able to quickly adjust their food intake to an appropriate level when offered novel diets. In addition day-to-day and meal-to-meal food intake varies greatly and meal timing is plastic. Why this is the case is not clear: Food intake in fish is influenced by many factors, however the hierarchy and mechanisms by which these interact is not yet fully understood. A model of food intake may be helpful to understand these phenomena; to determine model type it is necessary to understand the qualitative nature of food intake. Food intake can be regarded as an autoregressive (AR) time series, as the amount of food eaten at time t will be influenced by previous meals, and this allows food intake to be considered using time series analyses. Here, time series data were analysed using nonlinear techniques to obtain qualitative information from which evidence for the hierarchy of mechanisms controlling food intake may be drawn. Time series were obtained for a group of dab and individuals and a group of rainbow trout for analysis. Surrogate data sets were generated to test several null hypotheses describing linear processes and all proved significantly different to the real data, suggesting nonlinear dynamics. Examination of topography and recurrence diagrams suggested that all series were deterministic and non-stationary. The point correlation dimension (PD2i) suggested low-dimensional dynamics. Our findings suggest therefore that any model of appetite should create output that is deterministic, non-stationary, low-dimensional and having nonlinear dynamics.     

Serum lipidomics meets cardiac magnetic resonance imaging: profiling of subjects at risk of dilated cardiomyopathy

Dilated cardiomyopathy (DCM), characterized by left ventricular dilatation and systolic dysfunction, constitutes a significant cause for heart failure, sudden cardiac death or need for heart transplantation. Lamin A/C gene (LMNA) on chromosome 1p12 is the most significant disease gene causing DCM and has been reported to cause 7-9% of DCM leading to cardiac transplantation. We have previously performed cardiac magnetic resonance imaging (MRI) to LMNA carriers to describe the early phenotype. Clinically, early recognition of subjects at risk of developing DCM would be important but is often difficult. Thus we have earlier used the MRI findings of these LMNA carriers for creating a model by which LMNA carriers could be identified from the controls at an asymptomatic stage. Some LMNA mutations may cause lipodystrophy. To characterize possible effects of LMNA mutations on lipid profile, we set out to apply global serum lipidomics using Ultra Performance Liquid Chromatography coupled to mass spectrometry in the same LMNA carriers, DCM patients without LMNA mutation and controls. All DCM patients, with or without LMNA mutation, differed from controls in regard to distinct serum lipidomic profile dominated by diminished odd-chain triglycerides and lipid ratios related to desaturation. Furthermore, we introduce a novel approach to identify associations between the molecular lipids from serum and the MR images from the LMNA carriers. The association analysis using dependency network and regression approaches also helped us to obtain novel insights into how the affected lipids might relate to cardiac shape and volume changes. Our study provides a framework for linking serum derived molecular markers not only with clinical endpoints, but also with the more subtle intermediate phenotypes, as derived from medical imaging, of potential pathophysiological relevance.     

Characterization and functional analysis of the MAL and MPH Loci for maltose utilization in some ale and lager yeast strains

Maltose and maltotriose are the major sugars in brewer's wort. Brewer's yeasts contain multiple genes for maltose transporters. It is not known which of these express functional transporters. We correlated maltose transport kinetics with the genotypes of some ale and lager yeasts. Maltose transport by two ale strains was strongly inhibited by other alpha-glucosides, suggesting the use of broad substrate specificity transporters, such as Agt1p. Maltose transport by three lager strains was weakly inhibited by other alpha-glucosides, suggesting the use of narrow substrate specificity transporters. Hybridization studies showed that all five strains contained complete MAL1, MAL2, MAL3, and MAL4 loci, except for one ale strain, which lacked a MAL2 locus. All five strains also contained both AGT1 (coding a broad specificity alpha-glucoside transporter) and MAL11 alleles. MPH genes (maltose permease homologues) were present in the lager but not in the ale strains. During growth on maltose, the lager strains expressed AGT1 at low levels and MALx1 genes at high levels, whereas the ale strains expressed AGT1 at high levels and MALx1 genes at low levels. MPHx expression was negligible in all strains. The AGT1 sequences from the ale strains encoded full-length (616 amino acid) polypeptides, but those from both sequenced lager strains encoded truncated (394 amino acid) polypeptides that are unlikely to be functional transporters. Thus, despite the apparently similar genotypes of these ale and lager strains revealed by hybridization, maltose is predominantly carried by AGT1-encoded transporters in the ale strains and by MALx1-encoded transporters in the lager strains.     

Differential effects of strength training leading to failure versus not to failure on hormonal responses, strength, and muscle power gains.

The purpose of this study was to examine the efficacy of 11 wk of resistance training to failure vs. nonfailure, followed by an identical 5-wk peaking period of maximal strength and power training for both groups as well as to examine the underlying physiological changes in basal circulating anabolic and catabolic hormones. Forty-two physically active men were matched and then randomly assigned to either a training to failure (RF; n = 14), nonfailure (NRF; n = 15), or control groups (C; n = 13). Muscular and power testing and blood draws to determine basal hormonal concentrations were conducted before the initiation of training (T0), after 6 wk of training (T1), after 11 wk of training (T2), and after 16 wk of training (T3). Both RF and NRF resulted in similar gains in 1-repetition maximum bench press (23 and 23%) and parallel squat (22 and 23%), muscle power output of the arm (27 and 28%) and leg extensor muscles (26 and 29%), and maximal number of repetitions performed during parallel squat (66 and 69%). RF group experienced larger gains in the maximal number of repetitions performed during the bench press. The peaking phase (T2 to T3) after NRF resulted in larger gains in muscle power output of the lower extremities, whereas after RF it resulted in larger gains in the maximal number of repetitions performed during the bench press. Strength training leading to RF resulted in reductions in resting concentrations of IGF-1 and elevations in IGFBP-3, whereas NRF resulted in reduced resting cortisol concentrations and an elevation in resting serum total testosterone concentration. This investigation demonstrated a potential beneficial stimulus of NRF for improving strength and power, especially during the subsequent peaking training period, whereas performing sets to failure resulted in greater gains in local muscular endurance. Elevation in IGFBP-3 after resistance training may have been compensatory to accommodate the reduction in IGF-1 to preserve IGF availability.