44 research outputs found
The Impact of Monetary Policy on Homeownership
From a theoretical perspective, monetary policy has an ambiguous impact on homeownership. For instance, contractionary monetary policy leads to higher interest rates and lower incomes making housing more unaffordable, but counteracting this is lower house prices. I build a heterogeneous agent overlapping generations model of the Australian housing market parameterising these three key transmission channels to study the sign and magnitude of the response of homeownership to monetary policy. I find there is a small positive effect of homeownership to a one standard deviation unanticipated contractionary monetary policy shock, with the shift in house prices explaining much of the movement in the homeownership rate
Differences in power output between national and club level cyclists during a new variable power cycling test
Accuracy in measurement of elevation gain in road cycling
Purpose
Accurate measures of elevation gain are important for monitoring energy expenditure and physical load. The aim of this study was to determine the accuracy of barometric devices used for measuring elevation gain.
Methods
Observational validation study. Twenty-eight barometric altimeter devices (SRM and Garmin) were used to measure total elevation gain during cycling over three different climbs (length range: 3.2-18.4 km), giving a total of 216 climbs. An online mapping tool (http://www.freemaptools.com/elevation-finder.htm) was used to calculate the criterion measure of total elevation gain. Data were categorised into two weather conditions: dry and wet.
Results
The standard errors of the estimate for total elevation gain measured by SRM and Garmin devices were 1.5% and 1.9%, respectively. In dry conditions, SRM devices underestimated the total elevation gain by an on average by of ~ 5% while the Garmin devices underestimated it by ~ 2%. In wet weather conditions the bias worsened to - 25%.
Conclusions
Measurements of total elevation gain recorded with devices of differed brands were similarly accurate in dry weather conditions. Wet weather conditions significantly decreased the accuracy of total elevation gain measurements
Six days of low carbohydrate, not energy availability, alters the iron and immune response to exercise in elite athletes
Purpose
To quantify the effects of a short-term (6-d) low carbohydrate (CHO) high fat (LCHF), and low energy availability (LEA) diet on immune, inflammatory, and iron-regulatory responses to exercise in endurance athletes.
Methods
Twenty-eight elite male race walkers completed two 6-d diet/training phases. During phase 1 (Baseline), all athletes consumed a high CHO/energy availability (CON) diet (65% CHO and ~40 kcal·kg−1 fat-free mass (FFM)·d−1). In phase 2 (Adaptation), athletes were allocated to either a CON (n = 10), LCHF (n = 8; <50 g·d−1 CHO and ~40 kcal·kg−1·FFM−1·d−1), or LEA diet (n = 10; 60% CHO and 15 kcal·kg−1·FFM−1·d−1). At the end of each phase, athletes completed a 25-km race walk protocol at ~75% V˙O2max. On each occasion, venous blood was collected before and after exercise for interleukin-6, hepcidin, cortisol, and glucose concentrations, as well as white blood cell counts.
Results
The LCHF athletes displayed a greater IL-6 (P = 0.019) and hepcidin (P = 0.011) response to exercise after Adaptation, compared with Baseline. Similarly, postexercise increases in total white blood cell counts (P = 0.026) and cortisol levels (P 0.05). No differences between CON and LEA were evident for any of the measured biological markers (all P > 0.05).
Conclusions
Short-term adherence to a LCHF diet elicited small yet unfavorable iron, immune, and stress responses to exercise. In contrast, no substantial alterations to athlete health were observed when athletes restricted energy availability compared with athletes with adequate energy availability. Therefore, short-term restriction of CHO, rather than energy, may have greater negative impacts on athlete health
Short severe energy restriction with refueling reduces body mass without altering training-associated performance improvement
Purpose
We investigated short-term (9 d) exposure to low energy availability (LEA) in elite endurance athletes during a block of intensified training on self-reported well-being, body composition, and performance.
Methods
Twenty-three highly trained race walkers undertook an ~3-wk research-embedded training camp during which they undertook baseline testing and 6 d of high energy/carbohydrate (HCHO) availability (40 kcal·kg FFM−1·d−1) before being allocated to 9 d continuation of this diet (n = 10 M, 2 F) or a significant decrease in energy availability to 15 kcal·kg FFM−1·d−1 (LEA: n = 10 M, 1 F). A real-world 10,000-m race walking event was undertaken before (baseline) and after (adaptation) these phases, with races being preceded by standardized carbohydrate fueling (8 g·kg body mass [BM]−1 for 24 h and 2 g·kg BM−1 prerace meal).
Results
Dual-energy x-ray absorptiometry–assessed body composition showed BM loss (2.0 kg, P < 0.001), primarily due to a 1.6-kg fat mass reduction (P < 0.001) in LEA, with smaller losses (BM = 0.9 kg, P = 0.008; fat mass = 0.9 kg, P < 0.001) in HCHO. The 76-item Recovery–Stress Questionnaire for Athletes, undertaken at the end of each dietary phase, showed significant diet–trial effects for overall stress (P = 0.021), overall recovery (P = 0.024), sport-specific stress (P = 0.003), and sport-specific recovery (P = 0.012). However, improvements in race performance were similar: 4.5% ± 4.1% and 3.5% ± 1.8% for HCHO and LEA, respectively (P < 0.001). The relationship between changes in performance and prerace BM was not significant (r = −0.08 [−0.49 to 0.35], P = 0.717).
Conclusions
A series of strategically timed but brief phases of substantially restricted energy availability might achieve ideal race weight as part of a long-term periodization of physique by high-performance athletes, but the relationship between BM, training quality, and performance in weight-dependent endurance sports is complicated
Short-Term Very High Carbohydrate Diet and Gut-Training Have Minor Effects on Gastrointestinal Status and Performance in Highly Trained Endurance Athletes
We implemented a multi-pronged strategy (MAX) involving chronic (2 weeks high carbohydrate [CHO] diet + gut-training) and acute (CHO loading + 90 g·h(−1) CHO during exercise) strategies to promote endogenous and exogenous CHO availability, compared with strategies reflecting lower ranges of current guidelines (CON) in two groups of athletes. Nineteen elite male race walkers (MAX: 9; CON:10) undertook a 26 km race-walking session before and after the respective interventions to investigate gastrointestinal function (absorption capacity), integrity (epithelial injury), and symptoms (GIS). We observed considerable individual variability in responses, resulting in a statistically significant (p < 0.001) yet likely clinically insignificant increase (Δ 736 pg·mL(−1)) in I-FABP after exercise across all trials, with no significant differences in breath H(2) across exercise (p = 0.970). MAX was associated with increased GIS in the second half of the exercise, especially in upper GIS (p < 0.01). Eighteen highly trained male and female distance runners (MAX: 10; CON: 8) then completed a 35 km run (28 km steady-state + 7 km time-trial) supported by either a slightly modified MAX or CON strategy. Inter-individual variability was observed, without major differences in epithelial cell intestinal fatty acid binding protein (I-FABP) or GIS, due to exercise, trial, or group, despite the 3-fold increase in exercise CHO intake in MAX post-intervention. The tight-junction (claudin-3) response decreased in both groups from pre- to post-intervention. Groups achieved a similar performance improvement from pre- to post-intervention (CON = 39 s [95 CI 15–63 s]; MAX = 36 s [13–59 s]; p = 0.002). Although this suggests that further increases in CHO availability above current guidelines do not confer additional advantages, limitations in our study execution (e.g., confounding loss of BM in several individuals despite a live-in training camp environment and significant increases in aerobic capacity due to intensified training) may have masked small differences. Therefore, athletes should meet the minimum CHO guidelines for training and competition goals, noting that, with practice, increased CHO intake can be tolerated, and may contribute to performance outcomes
Short-term very high carbohydrate diet and gut-training have minor effects on gastrointestinal status and performance in highly trained endurance athletes
We implemented a multi-pronged strategy (MAX) involving chronic (2 weeks high carbohydrate [CHO] diet + gut-training) and acute (CHO loading + 90 g·h−1 CHO during exercise) strategies to promote endogenous and exogenous CHO availability, compared with strategies reflecting lower ranges of current guidelines (CON) in two groups of athletes. Nineteen elite male race walkers (MAX: 9; CON:10) undertook a 26 km race-walking session before and after the respective interventions to investigate gastrointestinal function (absorption capacity), integrity (epithelial injury), and symptoms (GIS). We observed considerable individual variability in responses, resulting in a statistically significant (p < 0.001) yet likely clinically insignificant increase (Δ 736 pg·mL−1) in I-FABP after exercise across all trials, with no significant differences in breath H2 across exercise (p = 0.970). MAX was associated with increased GIS in the second half of the exercise, especially in upper GIS (p < 0.01). Eighteen highly trained male and female distance runners (MAX: 10; CON: 8) then completed a 35 km run (28 km steady-state + 7 km time-trial) supported by either a slightly modified MAX or CON strategy. Inter-individual variability was observed, without major differences in epithelial cell intestinal fatty acid binding protein (I-FABP) or GIS, due to exercise, trial, or group, despite the 3-fold increase in exercise CHO intake in MAX post-intervention. The tight-junction (claudin-3) response decreased in both groups from pre- to post-intervention. Groups achieved a similar performance improvement from pre- to post-intervention (CON = 39 s [95 CI 15–63 s]; MAX = 36 s [13–59 s]; p = 0.002). Although this suggests that further increases in CHO availability above current guidelines do not confer additional advantages, limitations in our study execution (e.g., confounding loss of BM in several individuals despite a live-in training camp environment and significant increases in aerobic capacity due to intensified training) may have masked small differences. Therefore, athletes should meet the minimum CHO guidelines for training and competition goals, noting that, with practice, increased CHO intake can be tolerated, and may contribute to performance outcomes
Inter and intra-examiner reliability of ultrasound elastography for assessment of the anterior thigh in healthy adults
BACKGROUND:
To date there are few studies of acceptable methodological quality investigating the reliability of elastography ultrasound use in the lower limb. The aim of the study was to investigate the inter and intra-reliability of EUS assessment of anterior thigh soft-tissues.
METHODS:
Twelve healthy subjects (9 females, 3 males, mean ± SD age=28.9 ± 5.8 years, height = 169.6 ± 9.2cm, weight 69.6 ± 13.4kg) were recruited using convenience sampling. A repeated measures test retest design was used to compare EUS measures between (inter) and within (intra) 3 examiners (2 novices, 1 expert) using acoustic radiation force impulse elastography. The subjects attended one session where each examiner collected measures from each subject two times. Colour hue histograms were derived from elastogram images.
RESULTS:
Extraction reliability for images was excellent with ICC of 0.99 (95% CI= 0.99 – 1.00). The intra-examiner reliability was ‘fair to good’ for the experienced examiner and mostly ‘excellent’ for the novices. The inter-examiner reliability ranged between ‘fair to good’ and ‘excellent’.
CONCLUSIONS:
There was acceptable reliability for both inter and intra-examiner reliability for EUS assessment of anterior thigh soft-tissue stiffness. However, the small number of examiners may limit the generalisability of these findings