Predicting middle-distance track and cross-country performances of national and international level adolescent runners

This study evaluated the contribution of physiological data collected during laboratory testing in predicting race performances of trained junior middle-distance track (TK) and cross-country (XC) athletes. Participants performed a submaximal incremental ramp test, followed by an incremental test to exhaustion in a laboratory, with the results used to predict either 800 m TK, 1500 m TK or 4000-6000 m XC race performance. Twenty-eight participants (male (M), 15; female (F), 13) were analysed (age = 17 ± 2 years, height = 1.72 ± 0.08 m, body mass = 58.9 ± 8.9 kg). Performance times (min:s) for 800 m were: M, 1:56.55 ± 0:05.55 and F, 2:14.21 ± 0:03.89; 1500 m: M, 3:51.98 ± 0:07.35 and F 4:36.71 ± 0:16.58; XC: M (4900 ± 741 m), 16:00 ± 01:53; F (4628 ± 670 m), 17:41 ± 02:09. Stepwise regression analysis indicated significant contributions of speed at V̇O2max (sV̇O2max), and heart rate maximum (HRmax) to the prediction of 800 m TK (F(2,15) = 22.51, p <0.001, adjusted R2 = 0.72), sV̇O2max for 1500 m TK (F(1,13) = 36.65, p <0.001, adjusted R2 = 0.72) and V̇O2max, allometrically scaled to body mass and speed at lactate threshold (sLT) for XC (F(2,17) = 25.1, p <0.001, adjusted R2 = 0.72). Laboratory-based physiological measures can explain 72% of the variance in junior TK and XC events, although factors that explain performance alter depending on the race distance and tactics. The factors determining performance in TK and XC events are not interchangeable

Field-based and overspeed potentiated warm-ups increase clubhead speed and drive carry distance in skilled collegiate golfers

Warm-ups utilising post-activation performance enhancement (PAPE) strategies have been shown to increase clubhead speed (CHS) in golfers. However, the effectiveness of overspeed training using weighted clubs to elicit PAPE in CHS is unknown. The purpose of this investigation was to compare traditional, field-based warm-up activities with no potentiation activity (CON), against a field-based potentiated warm-up using high rate of force development bodyweight movements (BWP), and an overspeed warm-up using speed sticks (SSP) as the potentiation method. Thirteen skilled adult male golfers (handicap 1.0 ± 2.1) completed three testing sessions, separated by seven days. The CON, BWP and SSP warm-ups were identical, except for the potentiation method. After each warm-up condition, ten shots, separated by one minute, were recorded using a doppler rader launch monitor (Trackman 4) with CHS, ball speed (BS), carry distance (CD) and total distance (TD) recorded. A repeated measures one-way ANOVA with Bonferroni post hoc pairwise comparisons revealed increases in CHS in the BWP (p= 0.004) and SSP (p= 0.003) groups against CON, with no difference between BWP and SSP. Increased CD was observed for BWP (p= 0.034) and SWP (p= 0.030) against CON with no differences between BWP and SSP. No differences for BS or TD were observed. Warm-ups with BWP or SSP activities should be considered if players are attempting to increase CHS or CD of drives, although utilising overspeed potentiation methods appear to confer no additional benefit to bodyweight PAPE exercises in skilled collegiate golfers

Spectral changes of solar simulator xenon flash bulbs over lifetime and its effects on measurement uncertainty

The effects of lamp age on the spectral output of solar simulator xenon flash lamps and spectral output measurement uncertainty on the spectral mismatch are investigated. It is demonstrated that the spectrum of an older lamp set has a relatively lower blue and larger red content compared to a new set of bulbs. Measurements over the life-time of several sets of bulbs showed large unexpected variations due measurement uncertainty in spectral measurements themselves. The main influencing factors are investigated and a faulty temperature control is found to be the main source of uncertainty. It is shown that this alone can affect the mismatch calculation to a larger degree than the MMF would correct in itself

Variability and physical demands of international seam bowlers in one-day and Twenty20 international matches across five years

Objectives: To quantify and compare the match demands and variability of international One4 Day (ODI) with Twenty20 (T20) cricket matches and to compare ODI match demands when5 competing home and away. Design: Single cohort, longitudinal observation. Methods: Thirteen international male seam bowlers across 204 matches (ODI= 160; T20= 44) were investigated over five-years (2015-2019). Using global positioning sensors and accelerometers, physical demands were quantified using distance covered at different velocities and the number of entries into high and low intensity acceleration and deceleration bands. Variability was quantified using coefficient of variation (CV) and smallest worthwhile change. Results: Significantly greater (p4 m∙s2 19 (within-player ODI CV= 79.2%. T20 CV= 77.2%. Between-player ODI CV= 84.7%. T20= 38.8%) and distance covered >25 km∙h-1 20 (within-player ODI CV = 65.5%. T20= 64.1%) showed the greatest variability. Conclusions: Players are exposed to different physical demands in ODI Vs T20 matches, but not for home Vs away ODI matches. Practitioners should be aware of the large variability in high-speed/intensity accelerations and decelerations across matches

Exploring metastable defect behavior in solution-processed antimony doped CIGS thin film solar cells

This study investigates the metastable defect behavior from temperature dependent current density-voltage (JVT) and capacitance spectroscopy measurements in solutionprocessed antimony (Sb) doped CIGS thin film solar cells. From the Voc(T) analysis, the main recombination mechanism is found to be Schottky-Read-Hall recombination in the bulk. A detailed study of the carrier concentration, defect density and energy level defects was performed using capacitance spectroscopy. Admittance spectroscopy measurements revealed an admittance step at low temperatures with an activation energy of 42 meV

Spectral response measurements of Perovskite solar cells

A new spectral response measurement routine is proposed that is universally applicable for all perovskite devices. It is aimed at improving measurement accuracy and repeatability of spectral response curves and current-voltage curve spectral mismatch factor corrections. Frequency response, effects of preconditioning as well as dependency on incident light intensity and voltage load on spectral response measurements are characterized on two differently structured perovskite device types. It is shown that device preconditioning affects the spectral response shape, causing errors in spectral mismatch factor corrections of up to 0.8% when using a reference cell with a good spectral match and a class A solar simulator. Wavelength dependent response to incident light intensity and voltage load is observed on both device types, which highlights the need to measure at short circuit current and maximum power point to correct spectral mismatch. The method with recommendations given ensures the correct measurement conditions are applied and measurements are corrected for instability in performance

I-V performance characterisation of perovskite solar cells

Interlaboratory comparisons of I-V performance measurements of perovskite solar cells have highlighted a clear need for development in application of measurement routines to deliver repeatable and comparable results. This work investigates the impact of applied measurement methodologies and conditions on I-V performance. Dependencies on light soaking, temperature effects and I-V curve trace speed are investigated. Furthermore, the problems faced with tracking the maximum power point are detailed. Measurement results on slow responding perovskite solar cells highlight the problems when tracing the I-V curve and show that maximum power point trackers can easily fail to track the real maximum output. Best practice advice is given with the aim to achieve realistic and reproducible characterisation results that are comparable among laboratories

Variability and physical demands of international seam bowlers in one-day and Twenty20 international matches across five years.

Objectives: To quantify and compare the match demands and variability of international One-Day (ODI) with Twenty20 (T20) cricket matches and to compare ODI match demands when competing home and away. Design: Single cohort, longitudinal observation. Methods: Thirteen international male seam bowlers across 204 matches (ODI= 160; T20= 44) were investigated over five-years (2015-2019). Using global positioning sensors and accelerometers, physical demands were quantified using distance covered at different velocities and the number of entries into high and low intensity acceleration and deceleration bands. Variability was quantified using coefficient of variation (CV) and smallest worthwhile change. Results: Significantly greater (p4 m∙s2 (within-player ODI CV= 79.2%. T20 CV= 77.2%. Between-player ODI CV= 84.7%. T20= 38.8%) and distance covered >25 km∙h-1 (within-player ODI CV= 65.5%. T20= 64.1%) showed the greatest variability. Conclusions: Players are exposed to different physical demands in ODI Vs T20 matches, but not for home Vs away ODI matches. Practitioners should be aware of the large variability in high-speed/intensity accelerations and decelerations across matches