Aerobic capacity in speed-power athletes aged 20-90 years vs endurance runners and untrained participants.

We studied relationships between age and aerobic capacity in three groups of subjects adhering to different exercise modalities. A total of 203 men aged 20-90 years were examined: 52 speed-power track and field athletes (SP), 89 endurance runners (ER) and 62 untrained individuals (UT). Maximal exercise characteristics were obtained during a graded treadmill test until exhaustion: oxygen uptake (VO2max), heart rate (HRmax), oxygen pulse (O2 Pulsemax) and maximal distance (Distmax). Information about training history and weekly training amount was collected. A linear model of regression was adopted. VO2max in SP was lower than in ER, but significantly higher than in UT. The cross-sectional rates of decline in body mass-adjusted VO2max and Distmax were significantly smaller in SP than in ER and UT. About 80 years of age, the levels of VO2max and Distmax reached similar values in SP and ER. The decline in HRmax, but not in O2 Pulsemax was suggested as a cardiac adaptation accounting for between-group differences in VO2max loss. Weekly training volume was a significant positive predictor of age-related changes in aerobic capacity. In conclusion, not only endurance, but also speed-power exercise appears adequate to ensure an elevated aerobic capacity at old age.

Hypoxanthine as a predictor of performance in highly trained athletes.

Purine metabolism reflects the exercise-induced muscle adaptations and training status. This study evaluated the utility of plasma hypoxanthine in the prediction of actual sport performance. We studied male athletes: 28 triathletes (21.4±2.9 years), 12 long-distance runners (23.2±1.9 years), 13 middle-distance runners (22.9±1.8 years) and 18 sprinters (22.0±2.7 years). Season-best race times were considered, achieved over standard triathlon, 5 000 m, 1 500 m and 100 m, respectively. Incremental treadmill test was administered to determine maximum and "threshold" oxygen uptake. Resting and post-exercise plasma concentrations of hypoxanthine, xanthine, uric acid and lactate were measured as well as resting erythrocyte hypoxanthine-guanine phosphoribosyltransferase activity. Simple and multiple regression analyses were used to identify significant contributors to the variance in performance. Hypoxanthine considered alone explained more variance in triathletes, long-distance runners, middle-distance runners and sprinters (r 2=0.81, 0.81, 0.88 and 0.78, respectively) than models based on aerobic capacity and lactate (R 2=0.51, 0.37, 0.59 and 0.31, respectively). Combining purine metabolites and cardiorespiratory variables resulted in the best prediction (R 2=0.86, 0.93, 0.93 and 0.91; r=0.93, 0.96, 0.96 and 0.95, respectively). In summary, hypoxanthine is a strong predictor of performance in highly trained athletes and its prediction ability is very high regardless of sport specialization, spanning the continuum from speed-power to endurance disciplines.

Bone density and neuromuscular function in older competitive athletes depend on running distance.

UNLABELLED: Individuals who are involved in explosive sport types, such as 100-m sprints and long jump, have greater bone density, leg muscle size, jumping height and grip strength than individuals involved in long-distance running. INTRODUCTION: The purpose of this study is to examine the relationship between different types of physical activity with bone, lean mass and neuromuscular performance in older individuals. METHODS: We examined short- (n = 50), middle- (n = 19) and long-distance (n = 109) athletes at the 15th European Masters Championships in Poznan, Poland. Dual X-ray absorptiometry was used to measure areal bone mineral density (aBMD) and lean tissue mass. Maximal countermovement jump, multiple one-leg hopping and maximal grip force tests were performed. RESULTS: Short-distance athletes showed significantly higher aBMD at the legs, hip, lumbar spine and trunk compared to long-distance athletes (p ≤ 0.0012). Countermovement jump performance, hop force, grip force, leg lean mass and arm lean mass were greater in short-distance athletes (p ≤ 0.027). A similar pattern was seen in middle-distance athletes who typically showed higher aBMD and better neuromuscular performance than long-distance athletes, but lower in magnitude than short-distance athletes. In all athletes, aBMD was the same or higher than the expected age-adjusted population mean at the lumbar spine, hip and whole body. This effect was greater in the short- and middle-distance athletes. CONCLUSIONS: The stepwise relation between short-, middle- and long-distance athletes on bone suggests that the higher-impact loading protocols in short-distance disciplines are more effective in promoting aBMD. The regional effect on bone, with the differences between the groups being most marked at load-bearing regions (legs, hip, spine and trunk) rather than non-load-bearing regions, is further evidence in support of the idea that bone adaptation to exercise is dependent upon the local loading environment, rather than as part of a systemic effect.

Influence of ceramic and stainless steel brackets on the notching of archwires during clinical treatment.

The surface topography of 100 clinically used archwires of stainless steel, beta-, or nickel-titanium were investigated that had contacted either ceramic or stainless steel brackets. One group consisted of two sets: 60 wires with no treatment records accessed to bias analyses, and 40 wires for which extensive clinical records were available, half of which were used with ceramic or stainless steel brackets. A control group consisted of two sets: 30 unused wires comprised of five round and rectangular wires of each alloy, and four wires that were ligated and immediately removed from patients' mouths. After ultrasonic cleaning, each wire was inspected under an optical and/or a scanning electron microscope. Notches were categorized with regard to frequency, patterns, and severity, and mapped as a function of wire aspect (lingual, facial, and occlusal/gingival) and anatomical regions (molar, premolar, canine, and incisor). From these data the average severity of notch patterns and a notching index were derived. Although no recognizable defect patterns were observed in the control group, seven basic patterns were recognized for each wire cross-sectional shape in the clinically used wires. These wires appeared most damaged on their lingual aspect and least damaged on their facial aspect. With regard to anatomical regions, notching was prevalent in the anterior regions and sparse in the molar regions. The notch activity and the severity were nearly three times greater from ceramic brackets than from stainless steel brackets. Over one-third of all notches documented in ceramic bracket cases had severity numbers of 3 and penetrated at least one-quarter of each wire's dimension, However, over two-thirds of all notches documented in stainless steel bracket cases had severity numbers of 1. From these tabulations a theory of notch formation was proposed in which vertical movement from tooth or wire during mastication caused fretting wear, and horizontal movement during orthodontic procedures such as space closure, tipping, or bodily movement caused sliding wear.

Relationship between glycosyl hydrolase inventory and growth physiology of the hyperthermophile Pyrococcus furiosus on carbohydrate-based media.

Utilization of a range of carbohydrates for growth by the hyperthermophile Pyrococcus furiosus was investigated by examining the spectrum of glycosyl hydrolases produced by this microorganism and the thermal labilities of various saccharides. Previously, P. furiosus had been found to grow in batch cultures on several alpha-linked carbohydrates and cellobiose but not on glucose or other beta-linked sugars. Although P. furiosus was not able to grow on any nonglucan carbohydrate or any form of cellulose in this study (growth on oat spelt arabinoxylan was attributed to glucan contamination of this substrate), significant growth at 98 degrees C occurred on beta-1,3- and beta-1,3-beta-1,4-linked glucans. Oligosaccharides generated by digestion with a recombinant laminarinase derived from P. furiosus were the compounds that were most effective in stimulating growth of the microorganism. In several cases, periodic addition of beta-glucan substrates to fed-batch cultures limited adverse thermochemical modifications of the carbohydrates (i.e., Maillard reactions and caramelization) and led to significant increases (as much as two- to threefold) in the cell yields. While glucose had only a marginally positive effect on growth in batch culture, the final cell densities nearly tripled when glucose was added by the fed-batch procedure. Nonenzymatic browning reactions were found to be significant at 98 degrees C for saccharides with degrees of polymerization (DP) ranging from 1 to 6; glucose was the most labile compound on a mass basis and the least labile compound on a molar basis. This suggests that for DP of 2 or greater protection of the nonreducing monosaccharide component may be a factor in substrate availability. For P. furiosus, carbohydrate utilization patterns were found to reflect the distribution of the glycosyl hydrolases which are known to be produced by this microorganism.