Comparison of body composition techniques before and after a 161-km ultramarathon using DXA, BIS and BIA.

The low cost, ease of application and portability of bioelectrical impedance analysis (BIA) and spectroscopy (BIS) devices make them attractive tools for measuring acute changes in body composition before and after exercise, despite potential limitations from active compartmental fluid shifts. The primary study aim was to evaluate use of dual energy x-ray absorptiometry (DXA) against BIA and BIS in measurements of percent body fat (%BF) and percent total body water (%TBW) before and after prolonged endurance exercise. 10 runners were measured pre-race and at race finish. Significant linear relationships were noted pre-race between DXA vs. BIS for %BF (r(2)=0.76; p<0.01) and %TBW (r(2)=0.74; p<0.01). Significant correlations were noted at race finish between DXA vs. BIS for %BF (r(2)=0.64; p<0.01) and %TBW (r(2)=0.66; p<0.05), but only when one outlier was removed. Limits of agreement (LOA) between DXA vs. BIS were wide for both %BF (mean difference of -3.6, LOA between 5.4 and -12.6) and %TBW (mean difference 2.4, LOA between 0.4 and -4.6). LOA was closer between the DXA vs. BIA with DXA measuring slightly higher than BIA for %BF (mean difference of 0.5, LOA between 2.1 and -3.1) and slightly lower than BIA for %TBW (mean difference 0.3, LOA between 3.3 and -2.7). Linear correlations between DXA vs. BIA were not statistically significant for %BF or %TBW before or after the race. DXA measurement of acute changes in %BF and %TBW are not congruent with BIA or BIS measurements. These 3 techniques should not be utilized interchangeably after prolonged endurance running.

Bone: an acute buffer of plasma sodium during exhaustive exercise?

Both hyponatremia and osteopenia separately have been well documented in endurance athletes. Although bone has been shown to act as a "sodium reservoir" to buffer severe plasma sodium derangements in animals, recent data have suggested a similar function in humans. We aimed to explore if acute changes in bone mineral content were associated with changes in plasma sodium concentration in runners participating in a 161 km mountain footrace. Eighteen runners were recruited. Runners were tested immediately pre- and post-race for the following main outcome measures: bone mineral content (BMC) and density (BMD) via dual-energy X-ray absorptiometry (DEXA); plasma sodium concentration ([Na+]p), plasma arginine vasopressin ([AVP]p), serum aldosterone concentration ([aldosterone]s), and total sodium intake. Six subjects finished the race in a mean time of 27.0±2.3 h. All subjects started and finished the race with [Na+]p within the normal range (137.7±2.3 and 136.7±1.6 mEq/l, pre- and post-race, respectively). Positive correlations were noted between change (Δ; post-race minus pre-race) in total BMC (grams) and [Na+]p (mEq/l) (r=0.99; p<0.0001), and between total sodium intake (mEq/kg) and %Δ lumbar spine BMD (r=0.94; p<0.001). Change in [aldosterone]s was positively correlated with: rate of total sodium intake (r=0.84; p<0.05); Δ total BMC (r=0.82; p<0.05); and Δ [Na+]p (r=0.88; p<0.05). No significant pre- to post-race mean differences were noted in BMC or BMD. Robust associations between Δ BMC and Δ [Na+]p suggest that sodium status and bone density may be inter-related during endurance exercise and should be considered in future investigations of athletic osteopenia.

Mutations in the PSTPIP1 gene and aberrant splicing variants in patients with pyoderma gangrenosum.

BACKGROUND: Pyoderma gangrenosum (PG) is a rare, noninfectious form of skin ulceration, typically accompanied by neutrophilic infiltration. Several familial cases have been reported, suggesting the involvement of genetic factors in the aetiology of PG. Two mutations (A230T and E250Q) in the PSTPIP1 gene, encoding proline-serine-threonine phosphatase-interacting protein (PSTPIP)1 have been identified in patients with PAPA (pyogenic sterile arthritis with PG and acne) syndrome, a rare autoinflammatory disorder with autosomal dominant inheritance. AIM: The aim of this study was to sequence PSTPIP1 complementary cDNA and genomic DNA for mutations, and to identify genetic polymorphisms in the promoter region of PSTPIP1 in patients with PG. METHODS: The genomic region and cDNA of the PSTPIP1 gene were sequenced from peripheral blood leucocytes of 14 patients with PG and 20 healthy controls. RESULTS: One patient (PG1) had aberrant splicing variants of the PSTPIP1 transcript with deletions of exons 9, 11 and 12 and of exons 9-12 together, and all other patients with PG carried deletions of exon 11 and of 11-12. We also identified a novel mutation (G258A) in patient PG3, and novel polymorphisms [(CCTG)(6) and (CCTG)(8) tandem repeats] in the promoter region of the PSTPIP1 gene. CONCLUSION: All combinations of aberrant splicing variants had frame shifts and premature stop codons leading to truncated proteins and loss of function of PSTPIP1. The (CCTG)(n) tandem repeats in the promoter region of PSTPIP1 had no association with PG. The mutations G258A and R52Q are predicted by the improved prediction algorithm to have a possibly damaging effect on PSTPIP1 function.

Body composition of 161-km ultramarathoners.

This study compares body composition characteristics with performance among participants in a 161-km trail ultramarathon. Height, mass, and percent body fat from bioimpedance spectroscopy were measured on 72 starters (17 women, 55 men). Correlation analyses were used to compare body characteristics with finish time, and unpaired t-tests were used to compare characteristics of finishers with non-finishers. Mean (+/-SD) BMI (kg x m(-2)) was 24.8+/-2.7 (range 19.1-32.2) for the men and 21.2+/-2.1 (range 18.1-26.7) for the women. Among the three fastest runners, BMI values ranged from 22.1 to 23.4 for men and 21.5 to 22.9 for women. Mean (+/-SD) percent body fat values for men and women were 17+/-5 (range 5-35) and 21+/-6 (range 10-29) , and ranged from 6 to 14 and 14 to 27 among the fastest three men and women. There was a significant positive correlation (r(2)=0.23; p=0.0025) between percent body fat and finish time for men but not for women, and percent body fat values were lower for finishers than non-finishers for men (p=0.03) and women (p=0.04). We conclude that despite wide variations in BMI and percent body fat among ultramarathon participants, the faster men have lower percent body fat values than the slower men, and finishers have lower percent body fat values than non-finishers.

Performance trends in 161-km ultramarathons.

This report documents performance-related trends in 100-mile (161-km) ultramarathon running competitions in North America. A retrospective analysis of results from 1977 through 2008 revealed that annual finish rates increased initially and then plateaued by the early 1990s at nearly 60%. The fastest times were produced by the 30-39 year age group among the men and the 40-49 year age group for the women. Finish times of women improved relative to men through the 1980s, but were then stable over the past two decades with the fastest women running about 20% slower than the fastest men. Additionally, the average times of the fastest runners did not change over the past two decades for any age group for either sex. The percentage difference in finish times between the first and fifth place runners has remained lower (p<0.0001) for men than women, and has shown an upward trend (p=0.003) across time for men. It is concluded that increasing participation in 161-km ultramarathons in North America has not been associated with improvements in performance or depth of competition with the exception of the relative improvements in finish times for women compared with men that was evident through the 1980s.

Anthropometric characteristics of ultramarathoners.

Little is known about the anthropometric characteristics of ultramarathon runners. The present work reports on the physical characteristics of the 392 (310 males, 82 females) starters and 270 (216 males, 54 females) finishers of the 2007 Western States Endurance Run, one of the largest 161-km trail runs in North America. Among the starters, mean (and 25th to 75th percentiles) body mass index (BMI) values were 23.2 (21.6 - 24.6) and 20.6 (19.4 - 21.9) kg . m (-2) for the men and women, respectively. Men were significantly taller, heavier and had greater BMI's across all age groups compared with the women. Among the top-5 overall finishers, mean BMI values were 23.2 (range 22.4 - 24.7) for the men and 19.8 (range 17.3 - 21.1) for the women. Average running speed and BMI were negatively correlated for both men (r (2) = 0.11, p < 0.0001) and women (r (2) = 0.10, p = 0.02). From this analysis, it is concluded that those participating in ultramarathon runs can vary widely in physical characteristics with BMI values that would classify some individuals as underweight and others as overweight. BMI varied considerably even among the top finishers, but lower BMI values were associated with faster running times.

Validation of a rating scale of perceived exertion in young children.

The aim of this study was to develop and validate a scale rating the perceived exertion of young children (RPE-C) who do not read. This scale presents seven pictures showing a man who becomes progressively fatigued. In order to evaluate this scale, we examined its reliability and sensitivity. Thirteen children (aged 5 to 6 years) completed two identical incremental maximal running trials during a period of one week. A group of 12 adolescents and a group of 12 adults also tested the RPE-C by performing one trial under the same experimental conditions as the child group. RPE-C was recorded at the end of each load level. Statistical analysis revealed significant effects for velocity (F = 23.98, p < 0.0001) with non-significant effects for the trials. Intraclass correlation coefficient (ICC) revealed an acceptable reliability of RPE-C at low and high exercise intensities but also showed a low reliability at intermediate load levels (0.17 < ICC < 0.77). A significant correlation between RPE-C and heart rate (r2 = 0.61, p < 0.0001) was observed in children. However, the r2 level was lower than that observed for the adolescent or adult groups. This finding demonstrates the sensitivity of RPE-C to discriminate the effects of age on perceived exertion. RPE-C seems to be a good tool which can be used in young children to monitor exercise performed at low and high intensities.

BRCA1 germline mutations in Cypriot breast cancer patients from 26 families with family history.

Germline mutations in the BRCA1 gene are causative for a variable number of hereditary breast/ovarian cancers. The data presented in this study are based on genetic analysis of the BRCA1 gene in 49 DNA samples from breast cancer patients with a positive family history. A combination of manual direct DNA sequencing and SSCP analysis was used to screen the entire coding region of BRCA1. Overall 13 variants were detected which included 5 missense mutations, 3 polymorphisms and 5 intronic changes. Further genetic analysis of the 13 variants was carried out using 50 control DNA samples. Our results showed that 12 out of the 13 variants detected in the DNA of the patients group, were also present in the control group. It appears that the Greek Cypriot families studied so far have an unexpectebly low frequency of deleterious mutations in the BRCA1 gene. This is the first report on BRCA1 mutation analysis in Cyprus.

Simplified deceleration method for assessment of resistive forces in cycling.

PURPOSE: The purpose of this study was to develop and test a simplified deceleration technique for measurement of aerodynamic and rolling resistances in cycling. METHODS: Coast-down tests were performed in level hallways with an experienced cyclist as the rider. Average initial velocities were 2.5-12.8 m x s(-1)) The deceleration technique was simplified by the use on only three switches and a derivation that did not require an assumption that deceleration is constant. The effective frontal area (AC(D)) and coefficient of rolling resistance (CR) were then calculated through a derivation from the equation for resistive forces opposing motion. Method reproducibility was tested by comparison of results for four tests of 30 trials under identical conditions. Method sensitivity was tested by performing 30 trials with three different rider head positions and four different transported mass conditions. RESULTS: Analysis of variance revealed that there were no differences among the results in the reproducibility study for either AC(D) or C(R). Furthermore, the reproducibility tests revealed mean errors of only 0.66% and 0.70% for AC(D) and CR, respectively. ANOVA identified a significant increase (P < 0.001) in rolling resistance with external loading and a significant effect (P < 0.001) of head position on AC(D). Mean (+/-SD) values for AC(D) and C(R) from tests in a racing aeroposture with the head up, the head in line with the trunk, and the head in an intermediate position were 0.304 +/- 0.011, 0.268 +/- 0.010, and 0.262 +/- 0.013 m2, respectively. C(R) averaged 0.00368 in the three head positions. CONCLUSIONS: The findings indicate that this simplified deceleration technique is satisfactorily reproducible and sensitive for measurement of aerodynamic and rolling resistances in cycling.

Validation of simple tests of biathlon shooting ability.

The aim of this study was to validate three simple tests of biathlon shooting abilities. Twelve expert biathletes performed visual reaction time tests adapted for the rifle in the standing (RT-S) and prone positions (RT-P), and a tremometer test adapted for the rifle in the standing position (TT-S). Six consecutive days' measurements showed an acceptable reproducibility for these tests (coefficient of variation = 1.2% for RT-S, 1.1% for RT-P and 6.5% for TT-S). A significant difference was observed between TT-S at rest and after roller skiing 2.1 km at 90 % of maximal heart rate. This finding demonstrates the sensitivity of TT-S to discriminate the effects of fatigue on postural control. Among 24 biathletes of regional to expert level, significant correlations were observed between resting RT-P and prone shooting performance after roller skiing (r2 = 0.23; p = 0.01) and between resting TT-S and shooting performance in the standing position after roller skiing (r2 = 0.68; p = 0.0001), demonstrating the specificity of these tests. From these results, we conclude that TT-S is a valid field test of biathlon shooting performance.

A genome-wide search for type 2 diabetes susceptibility genes in Utah Caucasians.

Considerable evidence supports a major inherited component of type 2 diabetes. We initially conducted a genome-wide scan with 440 microsatellite markers at 10-cM intervals in 19 multigenerational families of Northern European ancestry with at least two diabetic siblings. Initial two-point analyses of these families directed marker typing of 23 additional families. Subsequently, all available marker data on the total of 42 families were analyzed using both parametric and nonparametric multipoint methods to test for linkage to type 2 diabetes. One locus on chromosome 1q21-1q23 met genome-wide criteria for significant linkage under a model of recessive inheritance with a common diabetes allele (logarithm of odds [LOD] = 4.295). Both pedigree-based nonparametric linkage (NPL) analysis and affected sib pair (MAPMAKER/SIBS) nonparametric methods also showed the highest genome-wide scores at this region, near markers CRP and APOA2, but failed to meet levels of genome-wide significance. The risk of type 2 diabetes to siblings of a diabetic person when compared with the population (lambdaS) was estimated from MAPMAKER/SIBS to be 2.8 in these 42 families. Simulation studies using study data confirmed a genome-wide significance level of P<0.05 (95% CI 0.005-0.0466). However, analysis of 20 similarly ascertained but smaller families failed to confirm this linkage. The LOD score with 50% heterogeneity for all 62 families considered together was only 2.25, with an estimated lambdaS of 1.87. Our data suggest a novel diabetes susceptibility locus near APOA2 on chromosome 1 in a region with many transcribed genes.

Poling forces during roller skiing: effects of grade.

PURPOSE: A substantial proportion of the propulsive forces required for uphill skiing are generated from the upper body, but no study has systematically examined poling forces at different slopes. In the present experiment, poling forces and timing were examined during roller skiing on 2.1% and 5.1% uphills. METHODS: Nine highly skilled cross-country skiers roller skied at paced submaximal and at maximal speeds using the V1 skate (V1) and double pole (DP) techniques. Poling forces and timing were measured with piezoelectric transducers. RESULTS: Peak force (PF), average force (AF) and average force over the entire cycle (ACF) were significantly greater (P < 0.01) at the steeper grade with both techniques. Values for the ratio of V1 to DP did not differ between the two grades for PF, AF, and ACF but tended to increase with velocity for both techniques. With both V1 and DP, upper body recovery time was shorter (P < 0.01) at the steeper grade, and cycle rate was greater (P < 0.01) at the steeper grade. CONCLUSIONS: We conclude that 1) the relative demands on the upper body with V1 compared with DP were similar between the two grades, and 2) the responses to an elevation in grade of increased poling forces, shortened poling recovery times, and increased cycle rate are comparable to the responses to an increase in speed.

Poling forces during roller skiing: effects of technique and speed.

PURPOSE: Although it has been reported that the majority of propulsive forces are generated through the poles with ski skating, no study has systematically examined poling forces among different skating techniques. The objective of the present study was to examine poling forces and timing during roller skiing on a 2.1% uphill. METHODS: Nine highly skilled cross-country skiers roller skied at three paced speeds and maximal speed using the V1 skate (V1), V2-alternate (V2A), V2 skate (V2), and double pole (DP) techniques while poling forces and timing were measured with piezoelectric transducers. RESULTS: Peak force (PF) values with the skating techniques were significantly lower than with DP and ranged from 18.9 +/- 3.1% of body weight (BW) to 31.5 +/- 5.6% BW across the speeds of the study. Average force over the entire cycle (ACF) increased with speed with DP, V2A and V1 (P < 0.01) but not with V2. PF and ACF were higher (P < 0.01) with V2 than V1 and V2A. Poling time was longer (P < 0.01) with V2A compared with V1 and V2. CONCLUSIONS: The results of this study suggest that 1) the use of the upper body is greater with V2 than with other skating techniques while there is a relatively greater reliance on the lower body for generation of the additional propulsive forces required to increase velocity, and (2) poling forces do not appear to be as effectively applied with V2 as with V2A.

Effect of rolling resistance on poling forces and metabolic demands of roller skiing.

OBJECTIVE: To examine the effect of an increase in roller ski rolling resistance on the physiological and upper body demands of roller skiing with the V2-alternate technique. METHODS: Nine highly skilled cross-country skiers roller skied at three paced speeds on a flat oval loop using roller skis with high (HiR) and low (LowR) rolling resistance. Oxygen uptake (VO2), heart rate, and poling forces were measured during the last 30 s and rating of perceived exertion (RPE) was requested immediately after each 4-min bout of roller skiing. RESULTS: VO2 and all force-related variables increased significantly with speed and were higher (P < 0.01) for HiR at given speeds. Poling time was similar between HiR and LowR, whereas poling recovery time was shorter (P = 0.0002) and cycle rate was higher (P = 0.002) for HiR. For given VO2 levels, peak and average forces, heart rates, and RPE values were similar between HiR and LowR, whereas average poling force across the cycle was greater (P = 0.006) and duty cycle (i.e., percentage of cycle when poling forces were applied) was higher (P = 0.0001) with HiR. CONCLUSIONS: 1) The decrease in poling recovery time and increase in cycle rate associated with an increase in roller ski rolling resistance is comparable to the effect previously observed from increasing grade and probably occurs as a means of limiting deceleration. 2) Since changes in rolling resistance do not alter the relationships of RPE and heart rate with VO2, the central cardiovascular adaptations from roller ski training should not be affected by the rolling resistance of the roller skis. 3) Higher resistance roller skis are likely to induce greater upper body aerobic adaptations than lower resistance roller skis.

Physiological effects of technique and rolling resistance in uphill roller skiing.

OBJECTIVE: The double pole technique (DP) has been shown to be more economical than the V1 skate technique (V1 ) on flat terrain. The objective of the present study was to compare these two techniques during uphill roller skiing. In addition, the physiological effects of changing roller ski rolling resistance was examined for V1. METHODS: Five female and five male competitive cross-country skiers roller skied 4-min bouts on a 5.2% incline while physiological measurements were made. RESULTS: Oxygen uptake (VO2) values averaged 8% greater (P = 0.0004) with V1, whereas rating of perceived exertion (RPE) and blood lactate concentrations were higher (P < or = 0.002) with DP. Doubling the dynamic friction coefficient of the roller skis, which increased external power output by 16-17%, resulted in VO2 values with V1 that averaged 13% higher (P = 0.0006). This magnitude of change in roller ski rolling resistance did not cause a statistical change in the relationship of VO2 with RPE. CONCLUSIONS: These findings suggest that 1) grade has little effect on relative economies of DP and V1, possibly because of a lower effectiveness of force application with V1 when going uphill, and 2) large differences in roller ski rolling resistance should have no effect on the cardiovascular training adaptations that result from uphill roller skiing with V1.