Can a fatigue test of the isolated lumbar extensor muscles of untrained young men predict strength progression in a resistance exercise program?

AIM: The aim of this exploratory study was to investigate the predictive value of a fatigue test of the lumbar extensor muscles for training progression in a group of 28 healthy but predominantly sedentary male students, in an 8-week resistance exercise program. METHODS: A three-phased fatigue test of the lumbar extensor muscles was designed, consisting of two consecutive measurements of full-range isometric back strength on a lumbar measurement device, separated by a dynamic back extension set to volitional fatigue. Differences between the strength values of the 1st and 3rd step is thought to reflect individual back muscle fatigue characteristics. The training program was primarily aimed at improving lumbar extensor endurance, by using a relative high number of repetition and low training loads. Linear regression analysis was used to evaluate the relationship between lumbar strength progression and several fatigue test parameters. RESULTS: The main fatigue indicator in our regression models (isometric strength decline between 1st and 3rd step) did not show predictive value in lumbar strength progression in training and testing, respectively. On the other hand, the work capacity that subjects delivered in the dynamic set (2nd step) had some predictive value. CONCLUSION: Based on the results, isometric strength decline measurement has no additional value to a standardized set of repetitions until failure in predicting future training performance. In practice, this means that a lower back training machine could be used at baseline to assist in tailoring individual lumbar training regimes, without the additional use of an isometric-strength testing module.

Evidence that MIG-6 is a tumor-suppressor gene.

Mitogen-inducible gene 6 (MIG-6) is located in human chromosome 1p36, a locus frequently associated with human lung cancer. MIG-6 is a negative regulator of epidermal growth factor (EGF) signaling, and we show that Mig-6 - like EGF - is induced by hepatocyte growth factor/scatter factor (HGF/SF) in human lung cancer cell lines. Frequently, the receptors for both factors, EGFR and Met, are expressed in same lung cancer cell line, and MIG-6 is induced by both factors in a mitogen-activated protein kinase-dependent fashion. However, not all tumor lines express MIG-6 in response to either EGF or HGF/SF. In these cases, we find missense and nonsense mutations in the MIG-6 coding region, as well as evidence for MIG-6 transcriptional silencing. Moreover, germline disruption of Mig-6 in mice leads to the development of animals with epithelial hyperplasia, adenoma, and adenocarcinoma in organs like the lung, gallbladder, and bile duct. These data suggests that MIG-6 is a tumor-suppressor gene and is therefore a candidate gene for the frequent 1p36 genetic alterations found in lung cancer.

Contribution of the polymer standards' polydispersity to the observed band broadening in size-exclusion chromatography.

The contribution of the polydispersity of polymer standards to the observed band broadening in size-exclusion chromatography was evaluated. Initially, theoretical predictions based on an equation by Knox et al. were found to overestimate this contribution, greatly due to the fact that the polydispersity values specified by the manufacturers are upper limits and therefore too high to be applied in this context. An improved estimate of the polydispersity values was obtained from the size-exclusion chromatography results and these new values were used to reassess the polydispersity contribution to band broadening. For two of three columns tested the best molar-mass-distribution parameters, i.e. those the least affected by extra-column and intra-column band broadening effects, can be obtained for polymers with a molar mass in the effective range of the given column and at rather low mobile-phase flow rates. At those conditions, for low-molar-mass polymers, the estimated polydispersity index values approach the theoretical ones derived from a Poisson distribution.

Tracking of lung function parameters and the longitudinal relationship with lifestyle.

The purpose of this study was to analyse tracking (i.e. relative stability over time/predictability of future values by early measurements) of lung function parameters and their longitudinal relationship with lifestyle (smoking, alcohol consumption, daily physical activity, neuromotor and cardiopulmonary fitness, and dietary intake of retinol and polyunsaturated fatty acids (PUFA)). Data were obtained from the observational Amsterdam Growth and Health Study, a longitudinal study with six repeated measurements between ages 13-27 yrs (n=167). The statistical analyses were carried out with generalized estimating equations. The following "stability" coefficients were found: for forced vital capacity (FVC) in males 0.66 (95% confidence interval (CI): 0.54-0.77) and in females 0.51 (95% CI: 0.43-0.60); for forced expiratory volume in one second (FEV1) in males 0.65 (95% CI: 0.50-0.80), in females 0.53 (95% CI 0.46-0.60); for peak expiratory flow (PEF) in both males and females 0.41 (95% CI: 0.31-0.51). Positive relationships were found between alcohol consumption and FVC and FEV1 and between neuromotor fitness and PEF and (only for males) with FVC and FEV1. Physical activity was inversely related to PEF and the intake of PUFA positively related to FVC and FEV1. Smoking was related to a decrease in FVC and FEV1; changes in physical activity positively correlated to changes in FVC. In conclusion, high to moderate stability/tracking was observed for forced vital capacity and forced expiratory volume in one second; for peak expiratory flow it was slightly lower. Preventive strategies regarding improvements of lung function should focus on smoking cessation and improving daily physical activity.