Distribution of naturally occurring radionuclides activity concentration in East Malaysian marine sediment

Studies of naturally occurring radioactive materials (NORM) distribution of ²²⁶Ra, ²²⁸Ra and ⁴⁰K in East Malaysia were carried out as part of a marine coastal environment project. The results of measurements will serve as baseline data and background reference level for Malaysia coastlines. Sediments from 21 coastal locations and 10 near shore locations were collected for analyses. The samples were dried, finely ground, sealed in a container and stored for a minimum of 30 days to establish secular equilibrium between ²²⁶Ra and ²²⁸Ra and their respective radioactive progenies. They were counted using a high-purity germanium (HPGe) spectrometer covering the respective progeny energy peak. For ⁴⁰K, the presence of this was measured directly via its 1460 keV energy peak. The concentration of ²²⁶Ra, ²²⁸Ra and ⁴⁰K in samples obtained from coastal Sarawak ranged between 23 and 41 (mean 30±2) Bq/kg, 27 and 45 (mean 39±4) Bq/kg and 142 and 680 (mean 462±59) Bq/kg, respectively. Meanwhile, the concentration of ²²⁶Ra, ²²⁸Ra and ⁴⁰K for samples obtained from coastal Sabah ranged between 16 and 30 (mean 23±2) Bq/kg, 23 and 45 (mean 35±4) Bq/kg and 402 and 842 (mean 577±75) Bq/kg, respectively. For the Sarawak near shore stations, the concentration of ²²⁶Ra, ²²⁸Ra and ⁴⁰K ranged between 11 and 36 (mean 22±2) Bq/kg, 21 and 65 (mean 39±5) Bq/kg and 149 and 517 (mean 309±41) Bq/kg, respectively. Meanwhile, the concentration of ²²⁶Ra, ²²⁸Ra and ⁴⁰K for samples obtained from Sabah ranged between 9 and 31 (mean 14±2) Bq/kg, 10 and 48 (mean 21±3) Bq/kg and 140 and 580 (mean 269±36) Bq/kg, respectively. The calculated external hazard values of between 0.17 and 0.33 (less than unity) showed that there is little risk of external hazard to the workers handling the sediments.     

Natural radioactivity in underground water from the Outer Carpathians in Poland with the use of nuclear spectrometry techniques

The investigations of natural radioactivity in underground mineral water and spring water in health resorts in the Outer Carpathians were performed. Samples from 40 water springs were collected 3–4 times over a period of 10 years (1997–2007). In order to obtain necessary data, two different nuclear spectrometry techniques were applied: WinSpectral α?β 1414 liquid scintillation counter from Wallac and α-spectrometer 7401 VR from Canberra–Packard, USA with the silicon surface barrier detector. The activity concentrations of ²²²Rn in the investigated samples varied from below 1 to 50 Bq/l. For radium isotopes the concentrations were in a range from below 10 to 490 mBq/l for ²²⁶Ra and from 29 to 397 mBq/l for ²²⁸Ra. The highest concentrations for both radium isotopes were obtained for medicinal water Zuber III from Krynica spa. The activity concentrations for uranium isotopes varied from below 0.5 to 16 mBq/l for ²³⁸U and from below 0.5 to 162 mBq/l for ²³⁴U with the highest values obtained for water Zuber IV. The highest annual effective dose arising from mainly radium isotopes was obtained for Zuber III water and was equal to 75 μSv/yr. Additionally, the annual effective doses due to ²²²Rn consumed with water were also estimated. The isotopic ratios between isotopes originating from the same decay chain (²³⁴U/²³⁸U, ²²⁶Ra/²³⁸U) and from different radioactive decay chains (²²⁶Ra/²²⁸Ra) were determined. The correlations between different isotopes were presented.     

The effect of uranium migration on radionuclide distributions for soil samples at the El-Gor area,Sinai, Egypt

The concentrations and distributions of the activity of natural radionuclides in soil samples were investigated in fifteen soil samples at El-Gor area representing two profiles (A and B) using a HP–Ge detector and alpha counting by SSNTD (CR-39), respectively. The average concentrations of the radionuclides ²³⁸U, ²²⁶Ra, ²³⁵U, ²³²Th and ⁴⁰K are 203.4, 177.23, 9.77, 43.33 and 386.22 Bq kg⁻¹ (dry weight), respectively, and profile A and ²³⁸U, ²²⁶Ra, ²³⁵U, ²³²Th and ⁴⁰K have average concentrations of 232.58, 246, 11.7, 31.7, and 277.07 Bq kg⁻¹ for profile B, respectively. The eTh and eU were estimated to detect the migration process of uranium into or out of an area or uranium to or from the studied profiles. The results indicate a migration of uranium by 29% for profile A and 65.37% for profile B. The activity ratio (²³⁸U/²²⁶Ra) was found to be 0.9 in profile A and 1.15 in profile B. These ratios coincide with the uranium migration processes. The responsible mass corresponding to the measured ²²⁶Ra activity was also calculated. The radon activity concentrations for the two profiles are nearly 300 Bq m⁻³. The emanation coefficient (η) was calculated from the ratio of the expected radon activity to the measured radon for the studied soil samples. The value of η was found to depend only on the radium activity regardless to soil formation.     

Temporal variations of 7Be, 210Pb and 137Cs in moss samples over 14 month period

Concentrations of ²¹⁰Pb, ⁷Be and ¹³⁷Cs in moss samples were continuously measured, using low-background HPGe spectrometer at Novi Sad, Serbia (45°14′45″N, 19°51′35″E). Weekly data collected over 14 month period from January 2007 to March 2008 are presented and discussed. Measured values of ⁷Be activity concentrations in dry moss samples are ranged from 201 to 920 Bq/kg showing prominent increase in summer and autumn season. Data for ²¹⁰Pb, ranged from 347 to 885 Bq/kg do not show such trend. The average concentration of ¹³⁷Cs is 8.9 Bq/kg. It is shown that yield of ⁷Be can be estimated using average values of activity concentrations. Precipitation amount and duration of precipitation are measured and their possible influence on activity concentrations measured in moss samples was considered.     

222Rn, 226Ra and hydrochemistry in the Bauru Aquifer System,São José do Rio Preto (SP), Brazil

In this paper, the ²²²Rn and ²²⁶Ra activity concentration was measured in groundwater samples collected from the Bauru Aquifer System, São José do Rio Preto city, São Paulo State, Brazil. The site has been selected for a detailed radiometric survey due to the large number of tubular wells drilled in the aquifer there, which provide water for ~70% of the local population. Despite the importance of groundwater for the local water-supply system, there is a lack of both ²²²Rn and ²²⁶Ra data in the municipality. Establishment of these data is relevant to assure that the water quality from a radiological point of view, is not health threat. São José do Rio Preto city is geologically situated in Bauru Group that is located within the Paraná sedimentary basin. The monitoring program involved the collection of 50 groundwater samples from deep tubular wells during three field campaigns held from 17th to 19th January 2011, from 2nd to 3rd August 2011 and in 30th November 2011. Temperature and pH readings were realized in the field, whereas ²²²Rn and ²²⁶Ra analysis were performed at the laboratory using the Alpha Guard-Aquakit analytical protocol, which allowed us to obtain ²²²Rn activity concentration ranging from 0.69 to 14.95 Bq/L. These data indicate that the abundances of ²²²Rn and ²²⁶Ra in the groundwater system of Bauru Group is below the WHO guideline limit of 100 Bq/L. Chemical analysis has been also realized for major cations and anions in order to better understand the water features in the municipality.     

Radium content in ground water from a granitic batholith of the metamorphic basement,eastern São Paulo State,Brazil

The radon emanation method was applied to measure the activity of ²²⁶Ra, dissolved and associated with suspended solids, in the ground waters from two wells drilled in the Morungaba Batholith fractured granites, intruded in the metamorphic basement, eastern border of the Paraná basin in São Paulo State, Brazil. The water samples were collected from March 2003,to April 2004, with a time interval of about one month between sampling campaigns. The mean observed dissolved ²²⁶Ra activity concentrations in the two wells were 47.9±7.1 and 51.6±8.8 mBq/L. No systematic time dependence of the ²²⁶Ra activity concentration was clearly identified. The activity of ²²⁶Ra associated with suspended solids contained in 1 L of ground water fell, during the sampling period, from 13±1 to 0.8±0.1 mBq in one well and from 4.9±0.3 to 0.6±0.1 mBq in the second well.     

Determination of the four natural Ra isotopes in thermal waters by gamma-ray spectrometry

Our method for the simultaneous determination of the four natural Ra isotopes (²²⁶Ra, ²²⁸Ra, ²²⁴Ra and ²²³Ra) in thermal waters involves a separation of Ra on a selective filter (3 M EMPORE? Radium Rad disk), and a single counting using a broad-energy HPGe detector (BE Ge manufactured by CANBERRA?). The calculation of ²²³Ra and ²²⁸Ra activities requires interference and cascade summing corrections. The ²²⁶Ra activities in CO₂-rich thermal waters of the Lodève Basin (South of France) range from 530 to 2240 mBq/l. The low (²²⁸Ra/²²⁶Ra) activity ratios (0.19–0.29) suggest that Ra is mostly derived from the aquifer carbonates. The short-lived ²²⁴Ra and ²²³Ra are probably added to the water through recoil or desorption processes from Th-enriched coatings on the fracture walls.     

Is the gut microbiota bacterial abundance and composition associated with intestinal epithelial injury,systemic inflammatory profile,and gastrointestinal symptoms in response to exertional-heat stress?

ObjectivesThe study aimed to examine if the α-diversity and relative abundance of the gastrointestinal bacterial taxa is associated with the response magnitude of markers characteristic of exercise-induced gastrointestinal syndrome in response to exertional-heat stress.DesignCross-sectional.MethodsTwenty-two endurance-trained athletes completed 2 h running at 60% $\stackrel{.}{V}$O_2max in hot ambient conditions (35.2 °C, 25% relative humidity). Faecal samples were collected pre-exercise to determine bacterial taxonomy by 16S rRNA amplicon sequencing (Illumina MiSeq platform). Data were processed using the QIIME2 pipeline (v2019.1) establishing taxonomic classification with >95% confidence using SILVA. Pre- and post-exercise blood samples were used to determine plasma I-FABP and cortisol concentrations, and systemic inflammatory response profile. Markers of physiological and thermoregulatory strain, and gastrointestinal symptoms were measured every 10 min during exercise. Associations were determined by partial correlation controlled for body mass variables.ResultsPositive associations between Tenericutes (r₍₁₈₎ = 0.446, p = 0.049) and Verrucomicrobia (r₍₁₈₎ = 0.450, p = 0.046) phylum, Akkermansiaceae (r₍₁₈₎ = 0.486, p = 0.030) and Ruminococcaceae (r₍₁₈₎ = 0.449, p = 0.047) family and aligned genus groups with I-FABP were observed. Whilst, associations between Faecalibacterium (r₍₁₂₎ = 0.668, p = 0.009) and Ruminoclostridium-9 (r₍₁₂₎ = −0.577, p = 0.031) genus with systemic inflammatory profile were observed. Association between bacterial phyla, family, and genus groups were also observed for gastrointestinal symptoms and markers of thermoregulatory strain (r₍₁₈₎ >0.400, p < 0.05).ConclusionsThe relative abundance of several commensal bacterial groups showed modest favourable (i.e., low perturbations) or detrimental associations with the magnitude of gastrointestinal integrity perturbations and symptoms, and potentially influences body temperature change, in response to exertional-heat stress.     

Separation of 90Sr from radioactive waste matrices—Microwave versus fusion decomposition

Radioactive waste (slurry) from a detention pond deriving from two research reactors and several inactive and active drain outlets at the Paul Scherrer Institute are the basis for the current ⁹⁰Sr investigation. For decomposition, a microwave method was applied, where 1 g of dry-ashed slurry was partially dissolved (HNO₃ (65%)/H₂O₂ (30%); v:v=8:2). In this slurry we obtained an ⁹⁰Sr activity of 5.3±0.2 Bq/g in solution. In a second run, we applied a borate-fusion (Li metaborate/Li tetraborate (80:20 w/w%) dissolving 1 g of dry-ashed “Si-free” slurry at 1100 °C in a muffle furnace. We achieved an ⁹⁰Sr activity of (7.8±0.3) Bq/g, yet observing BaSO₄ precipitation during the chromatographical separation of Sr. An alkali fusion using Na₂CO₃ was done using the Bunsen burner and the muffle furnace for 20 min at 1000 °C, in combination. During formation of the hot glass, the surplus of Na₂CO₃, produced Na₂SO₄ and BaCO₃ in solid form. The hot glass was dissolved in deionised water, removing thus the SO₄²⁻ ions. Dissolving the residue directly in HNO₃, solves Ba as Ba(NO₃)₂ and thus we achieved over 80% of the ¹³³Ba activity in the solution, as measured by γ-spectrometry. ⁸⁵Sr tracer of 88.0%±3.3% was recovered, yielding on average in (7.4±0.3) Bq/g of ⁹⁰Sr activity. The increase of 2.1–2.5 Bq/g of ⁹⁰Sr activity achieved with the alkali fusion, and the Li metaborate/Li tetraborate 80:20 w/w% fusion, respectively, clearly shows that some Sr must have been present as SrSO₄ in the slurry.     

Foot-related pain and disability and spatiotemporal parameters of gait during self-selected and fast walking speeds in people with gout: A two-arm cross sectional study

ObjectivesTo examine gait parameters in people with gout during different walking speeds while adjusting for body mass index (BMI) and foot-pain, and to determine the relationship between gait parameters and foot-pain and disability.MethodGait parameters were measured using the GAITRite™ walkway in 20 gout participants and 20 age- and sex-matched controls during self-selected and fast walking speeds. Foot-pain and disability was measured using the Manchester Foot Pain and Disability Index (MFPDI) which contains four domains relating to function, physical appearance, pain and work/leisure.ResultsAt the self-selected speed, gout participants demonstrated increased step time (p = 0.017), and stance time (p = 0.012), and reduced velocity (p = 0.031) and cadence (p = 0.013). At the fast speed, gout participants demonstrated increased step time (p = 0.007), swing time (p = 0.005) and stance time (p = 0.019) and reduced velocity (p = 0.036) and cadence (p = 0.009). For participants with gout, step length was correlated with total MFPDI (r = −0.62, p = 0.008), function (r = −0.65, p = 0.005) and physical appearance (r = −0.50, p = 0.041); stride length was correlated with total MFPDI (r = −0.62, p = 0.008), function (r = −0.65, p = 0.005) and physical appearance (r = −0.50, p = 0.041); and velocity was correlated with total MFPDI (r = −0.60, p = 0.011), function (r = −0.63, p = 0.007) and work/leisure (r = −0.53, p = 0.030).ConclusionGait patterns exhibited by people with gout are different from controls during both self-selected and fast walking speeds, even after adjusting for BMI and foot-pain. Additionally, gait parameters were strongly correlated with patient-reported functional limitation, physical appearance and work/leisure difficulties, while pain did not significantly influence gait in people with gout.     

Radium-226 concentration in spring water sampled in high radon regions

Water ²²⁶Ra concentration in springs was measured in regions with high indoor radon: Ural, North Caucasus (Russia), Niska Banja (Serbia), Piestany (Slovakia), and Issyk-Kul (Kyrgyzstan). This paper presents the results for ²²⁶Ra concentration above 0.03 Bq l^–1. Radium in water could indicate indoor radon problem in the region and water investigation is useful at the initial stage of radon survey. Even low ²²⁶Ra concentration in water (0.1–0.6 Bq l^–1) caused high ²²⁶Ra activity in travertine (up to 1500 Bq kg^?1), which resulted in indoor radon concentration above 2000 Bq m^?3 (Niska Banja).     

Potential moderators and mediators of intervention effects in an obesity prevention program for adolescent boys from disadvantaged schools

ObjectivesThe purpose of this study was to explore potential moderators and mediators of intervention effects in the Physical Activity Leaders (PALs) obesity prevention program for adolescent boys from disadvantaged secondary schools.DesignGroup randomized controlled trial.MethodsOne hundred adolescent boys (mean age = 14.3 (0.6) years) from four schools were randomized to the PALs intervention or a control group for the 6-month study period. The primary outcome was change in BMI and secondary outcomes were physical activity assessed using pedometers and constructs from Social Cognitive Theory (SCT) assessed using a questionnaire.ResultsModeration analyses revealed a significant weight status interaction for BMI (p = 0.04), indicating stronger intervention effects for youth classified as overweight/obese at baseline. The intervention had a significant effect on resistance training self-efficacy (p < 0.001), but none of the SCT constructs satisfied the criteria for mediation. The number of intervention sessions attended was associated with changes in BMI (r = ?0.38, p = 0.001), resistance training self-efficacy (r = 0.42, p < 0.001) and physical activity behavioral strategies (r = 0.26, p = 0.018). Changes in BMI were also associated with changes in resistance training self-efficacy (r = ?0.21, p = 0.06) and physical activity behavioral strategies (r = ?0.29, p = 0.009).ConclusionsA school-based intervention incorporating student leadership increased adolescent boys’ resistance training self-efficacy, but changes in physical activity were not detected and none of the SCT constructs satisfied the criteria for mediation. Baseline weight status was a moderator of intervention effect with the strongest intervention effects observed among overweight and obese adolescent boys.     

Body mass index,dose to organs at risk during vaginal brachytherapy,and the role of three-dimensional CT-based treatment planning

PurposeTo assess the effect of body mass index (BMI) on dose to organs at risk (OARs) during high-dose-rate vaginal brachytherapy and evaluate the role of three-dimensional dose evaluation during treatment planning.Methods and MaterialsThree-dimensional dosimetric data for rectum, bladder, sigmoid colon, and small bowel for 125 high-dose-rate vaginal brachytherapy fractions were analyzed. Dose–volume histograms were generated for D_{0.1 cc} and D_{2 cc} of each OAR. Contributing factors including the use of urinary catheter and cylinder size were also recorded. As different dose fractionations were used, the OAR doses were tabulated as a percent dose prescribed to 0.5 cm. All patients were treated to 4 cm of the vaginal length.ResultsMedian BMI in this cohort was 31.7 kg/m². The BMI values had a weak inverse correlation with D_{0.1 cc} to sigmoid colon (r_s = −0.18, p = 0.047) and D_{0.1 cc} to bladder (r_s = −0.19, p = 0.038). There was a strong inverse correlation of D_{2 cc} and increasing BMI (r_s = −0.64, p = 0.003). The median D_{2 cc} was 25.1% for BMI higher than 31 and 61.9% for BMI of 31 or lower. For D_{0.1 cc}, there was also a strong inverse correlation with increasing BMI (r_s = −0.57, p < 0.001). Median D_{1 cc} was 33.5% for BMI >31 and 84.4% for BMI ≤ 31. On multivariate analysis higher BMI remained a significant predictor of lower small bowel D_{2 cc} (p < 0.001) and D_{0.1 cc} (p < 0.001).ConclusionsWomen with a lower BMI receive higher doses to the bladder and small bowel compared with those with a higher BMI. Three-dimensional dose evaluation should be considered in patients with low BMI, particularly when combined with external beam radiation.     

Obstructive sleep apnea in professional rugby league athletes: An exploratory study

ObjectivesTo explore the prevalence of obstructive sleep apnea (OSA) within a professional rugby league team and determine associations of OSA with ethnicity, positional group, and physical characteristics.DesignObservational prospective cohort study.MethodsTwenty-two professional rugby league athletes underwent one night of home-based polysomnography with apnea-hypopnea index (AHI), rapid eye movement (REM)_AHI, non-REM_AHI and supine_AHI determined to indicate OSA. Linear models were used to assess if playing position (back or forward) or ethnicity (European-Australian or Polynesian) influenced AHI, REM_AHI, non-REM_AHI and supine_AHI. Models were also built to determine differences according to body composition.ResultsSeven athletes were classified with mild OSA (6 forwards and 1 back, 3 European-Australians, and 4 Polynesians) and three with moderate OSA (2 forwards and 1 back, 3 Polynesians). When considering ethnicity, differences were observed between Polynesians and European-Australians for REM_AHI (ES = 0.90, p = 0.02). Increased body mass index (BMI) was associated with a moderate increase in AHI (r = 0.38, p = 0.04) and non-REM_AHI (r = 0.36, p = 0.05), while higher skinfold thickness moderately related to a higher AHI (r = 0.40, p = 0.05) non-REM_AHI (r = 0.47, p = 0.02), and supine_AHI (r = 0.41, p = 0.04).ConclusionsThis exploratory study found 10 cases of OSA. Polynesian athletes and athletes classified as forwards constituted the majority of reported cases, suggesting their susceptibility to OSA. Furthermore, the data suggests that athletes with greater BMI and skinfold thickness may be predisposed to OSA.     

Yo-Yo intermittent recovery test versus the Université de Montréal Track Test: Relation with a high-intensity intermittent exercise

The first purpose of this study was to determine whether the peak velocity (V_Yo-Yo) achieved during the Yo-Yo intermittent recovery test (Yo-Yo) and the maximal aerobic velocity (MAV) determined from the Université de Montréal Track Test (UMTT) could be used interchangeably. The second purpose was to check that the V_Yo-Yo is related to the intermittent exercise performance, which consisted of repeated 90 m distance runs in 15 s performed until exhaustion, alternated with 15 s of passive recovery (15/15). Fourteen amateur soccer players performed, in a random order, the 15/15 and two incremental field-tests: the Yo-Yo and the UMTT. The results of this study showed that MAV was significantly correlated to the V_Yo-Yo (r = 0.79, p < 0.01). However, the error was not constant, when the V_Yo-Yo and the MAV values were higher than 16.3 km h^?1, the MAV values tends to be higher than the V_Yo-Yo, while when the V_Yo-Yo and the MAV values were lower than 16.3 km h^?1, the MAV values tends to be lower than the V_Yo-Yo. MAV and V_Yo-Yo were significantly correlated to the time to exhaustion of the 15/15 (r = 0.74 and r = 0.72, respectively) and show that both tests are similarly related to the high-intensity intermittent exercise performance.     

Correlation between enhancement characteristics of MR mammography and capillary density of breast lesions

ObjectiveTo correlate capillary density of breast lesions using the markers D2-40, CD31, and CD34 with early and late enhancement of magnetic resonance mammography (MRM).Materials and methodsThe local ethics committee approved this study, and informed consent was available from all patients. The study included 64 women with 66 histologically proven breast lesions (41 malignant, 25 benign). MR-enhancement 1 min after contrast medium administration was determined in the tumor (I_t1/I_t0 ratio) and in comparison to the surrounding tissue (I_t1/I_t1-fat ratio). Capillary density was quantified based on immunohistological staining with D2-40, CD31, and CD34 in breast tumors and surrounding breast tissue. Mean capillary densities were correlated with contrast enhancement in the tumor and surrounding breast tissue. The Kruskal–Wallis test was used to test whether lesions with different MR enhancement patterns differed in terms of capillary density.ResultsFor CD34, there was statistically significant correlation between capillary density and tumor enhancement (r = 0.329, p = 0.012), however not for the malignant or benign groups separately. Mean vessel number identified by staining with D2-40 and CD31 did not correlate significantly with tumor enhancement (D2-40: r = −0.188, p = 0.130; CD31: r = 0.095, p = 0.448). There were no statistically significant differences in capillary density between breast lesions with delayed enhancement or a plateau and lesions showing washout (Kruskal–Wallis test. D2-40: p = 0.173; CD31: p = 0.647; CD34: p = 0.515).ConclusionOf the three markers tested, CD34 showed best correlation between early contrast enhancement on MRM and capillary density. Further studies are necessary to clearly demonstrate an association between capillary density and contrast enhancement in breast tumors and surrounding tissue.     

Radiological impact assessment to the environment due to waste from disposal of porcelain

The present study aimed to assess the radiological parameters from gamma rays due to the uncontrolled disposal of porcelain waste to the environment. Qualitative and quantitative identification of radionuclides in the investigated samples was carried out by means of a high-purity germanium (HPGe) detector. The average activity concentrations of the local porcelain samples were measured as 208.28?Bq/kg for ²²⁶Ra, 125.73?Bq/kg for ²³⁸U, 84.94?Bq/kg for ²³²Th and 1033.61?Bq/kg for ⁴⁰K, respectively. The imported samples had an average activity of 240.57?Bq/kg for ²²⁶Ra, 135.56?Bq/kg for ²³⁸U, 115.74?Bq/kg for ²³²Th and 1312.49?Bq/kg for ⁴⁰K, respectively. Radiological parameters and the radium equivalent Ra_eq for the investigated samples were calculated. The external and internal hazard indices, representative level index (I_γ), alpha index (I_α), and the exemption level (I_x), were estimated to be higher than the recommended value (unity), while the average activity concentrations for the studied samples were higher than recommended levels. In conclusion, we are concerned that disposal of porcelain in the environment might be a significant hazard.     

Vastus intermedius muscle architecture predicts the late phase of the knee extension rate of force development in recreationally resistance-trained men

ObjectivesThe current study investigated the correlation between quadriceps muscle architecture and the knee extension rate of force development (RFD).Designcross-sectional study.MethodsMuscle thickness, pennation angle and fascicle length normalized per the thigh-length were measured via ultrasound in vastus lateralis, rectus femoris, vastus intermedius and vastus medialis. The knee extension rate of force was assessed isometrically at 90° knee angle and calculated in different 50-ms epochs (0−50, 50−100, 100−150, 150−200 and 200−250 ms). The maximum voluntary contraction was also recorded.ResultsLarge correlations were observed between vastus intermedius muscle thickness and the 100−150 ms (r = 0.694, p = 0.004), 150−200 ms (r = 0.597, p = 0.019) and 200−250 ms (r = 0.546, p = 0.045) epochs. Large correlation was observed between vastus intermedius normalized fascicle length and 100−150 ms (r = 0.570, p = 0.043) and large correlations with 150−200 ms (r = 0.643, p = 0.010) and 200−250 ms (r = 0.629, p = 0.012) epochs. Additionally, large correlations were observed between vastus lateralis normalized fascicle length and the 100−150 ms (r = 0.535, p = 0.049), 150−200 ms (r = 0.629, p = 0.016) and 200−250 ms (r = 0.563, p = 0.046) epochs. Vastus intermedius muscle thickness predicted 59% (R² = 0.581, p = 0.002) of the RFD of the 100−150 ms epoch; vastus intermedius muscle thickness and fascicle length predicted 51% (R² = 0.506, p = 0.029) of the 150−200 ms epoch; vastus intermedius and vastus lateralis fascicle length predicted 48% (R² = 0.483, p = 0.037) of the 200−250 ms epoch. No further correlation was observed.ConclusionsFascicle length and muscle thickness were observed as predictive of the late phase of the rate of force development. Vastus intermedius muscle architecture has a primary role in the knee extension RFD.     

Insights into gait disorders: Walking variability using phase plot analysis,Parkinson's disease

Gait variability may have greater utility than spatio-temporal parameters and can, be an indication for risk of falling in people with Parkinson's disease (PD). Current methods rely on prolonged data collection in order to obtain large datasets which may be demanding to obtain. We set out to explore a phase plot variability analysis to differentiate typically developed adults (TDAs) from PD obtained from two 10 m walks.Fourteen people with PD and good mobility (Rivermead Mobility Index ≥8) and ten aged matched TDA were recruited and walked over 10-m at self-selected walking speed. An inertial measurement unit was placed over the projected centre of mass (CoM) sampling at 100 Hz. Vertical CoM excursion was derived to determine modelled spatiotemporal data after which the phase plot analysis was applied producing a cloud of datapoints. SD_A described the spread and SD_B the width of the cloud with β the angular vector of the data points. The ratio (?) was defined as SD_A: SD_B.Cadence (p = .342) and stride length (p = .615) did not show a significance between TDA and PD. A difference was found for walking speed (p = .041). Furthermore a significant difference was found for β (p = .010), SD_A (p = .004) other than SD_B (p = .385) or ratio ? (p = .830).Two sequential 10-m walks showed no difference in PD for cadence (p = .193), stride length (p = .683), walking speed (p = .684) and β (p = .194), SD_A (p = .051), SD_B (p = .145) or ? (p = .226).The proposed phase plot analysis, performed on CoM motion could be used to reliably differentiate PD from TDA over a 10-m walk.     

Pedometer steps/min in physical education: Does the pedometer matter?

ObjectivesThe investigation sought to replicate previous Yamax physical education steps/min findings by quantifying physical activity via pedometry albeit with the Walk4Life (W4L) pedometer. Specifically, the objective was to determine steps/min cut point intervals for the 33% and 50% physical activity (i.e., percent of lesson time engaged in physical activity [%PA]) physical education guidelines via the W4L pedometer.DesignField-based criterion-referenced validation.MethodsData were collected from 75 lessons on 411 fifth- through twelfth-grade (M_age = 13.83 ± 2.17 y) participants who had concurrently measured pedometer and behavioural observation data. The W4L and Yamax pedometer outcome measure was steps/min, and observation measure was %PA. Pearson r correlation and diagnostic (i.e., sensitivity, specificity, and receiver-operating characteristic [ROC] curve) tests were conducted.Results(a) Steps/min and %PA demonstrated a strong relationship (W4L, r = 0.96, p = 0.0001; Yamax, r = 0.96, p = 0.0001), (b) W4L pedometer steps/min accurately discriminated (ROC area under curve ≥ 98%) between achievement or non-achievement of %PA guidelines, (c) the W4L steps/min cut point intervals for the 33%PA guideline (55.0–59.5) were significantly lower than those found for the Yamax pedometer (60.8–65.0), and (d) a borderline overlap was found between W4L (75.7–79.5) and Yamax (79.1–85.8) steps/min cut point intervals for the 50%PA guideline.ConclusionsW4L steps/min demonstrated a strong relationship with %PA, and outstanding accuracy for physical education physical activity guideline discrimination; however, steps/min values indicative of physical education physical activity guideline achievement is pedometer brand dependent, and should be considered for steps/min implementation and surveillance.