Vitamin D status and skin cancer risk independent of time outdoors : 11-year prospective study in and Australian community

Vitamin D may have anti-skin cancer effects, but population-based evidence is lacking. We therefore assessed associations between vitamin D status and skin cancer risk in an Australian subtropical community. We analyzed prospective skin cancer incidence for 11 years following baseline assessment of serum 25(OH)-vitamin D in 1,191 adults (average age 54 years) and used multivariable logistic regression analysis to adjust risk estimates for age, sex, detailed assessments of usual time spent outdoors, phenotypic characteristics, and other possible confounders. Participants with serum 25(OH)-vitamin D concentrations above 75 nmol  l(-1) versus those below 75 nmol  l(-1) more often developed basal cell carcinoma (odds ratio (OR)=1.51 (95% confidence interval (CI): 1.10-2.07, P=0.01) and melanoma (OR=2.71 (95% CI: 0.98-7.48, P=0.05)). Squamous cell carcinoma incidence tended to be lower in persons with serum 25(OH)-vitamin D concentrations above 75 nmol  l(-1) compared with those below 75 nmol  l(-1) (OR=0.67 (95% CI: 0.44-1.03, P=0.07)). Vitamin D status was not associated with skin cancer incidence when participants were classified as above or below 50 nmol  l(-1) 25(OH)-vitamin D. Our findings do not indicate that the carcinogenicity of high sun exposure can be counteracted by high vitamin D status. High sun exposure is to be avoided as a means to achieve high vitamin D status.

Changes in inflammatory mediators following eccentric exercise of the elbow flexors

The aims of this study were to examine the plasma concentrations of inflammatory mediators including cytokines induced by a single bout of eccentric exercise and again 4 weeks later by a second bout of eccentric exercise of the same muscle group. Ten untrained male subjects performed two bouts of the eccentric exercise involving the elbow flexors (6 sets of 5 repetitions) separated by four weeks. Changes in muscle soreness, swelling, and function following exercise were compared between the bouts. Blood was sampled before, immediately after, 1 h, 3 h, 6 h, 24 h (1 d), 48 h (2 d), 72 h (3 d), 96 h (4 d) following exercise bout to measure plasma creatine kinase (CK) activity, plasma concentrations of myoglobin (Mb), interleukin (IL)-1beta, IL-1 receptor antagonist (IL-1ra), IL-4, IL-6, IL-8, IL-10, IL-12p40, tumor necrosis factor (TNF)-alpha, granulocyte colony-stimulating factor (G-CSF), myeloperoxidase (MPO), prostaglandin E2 (PGE2), heat shock protein (HSP) 60 and 70. After the first bout, muscle soreness increased significantly, and there was also significant increase in upper arm circumference; muscle function decreased and plasma CK activity and Mb concentration increased significantly. These changes were significantly smaller after the second bout compared to the first bout, indicating muscle adaptation to the repeated bouts of the eccentric exercise. Despite the evidence of greater muscle damage after the first bout, the changes in cytokines and other inflammatory mediators were quite minor, and considerably smaller than that following endurance exercise. These results suggest that eccentric exercise-induced muscle damage is not associated with the significant release of cytokines into the systemic circulation. After the first bout, plasma G-CSF concentration showed a small but significant increase, whereas TNF-alpha and IL-8 showed significant decreases compared to the pre-exercise values. After the second bout, there was a significant increase in IL-10, and a significant decrease in IL-8. In conclusion, although there was evidence of severe muscle damage after the eccentric exercise, this muscle damage was not accompanied by any large changes in plasma cytokine concentrations. The minor changes in systemic cytokine concentration found in this study might reflect more rapid clearance from the circulation, or a lack of any significant metabolic or oxidative demands during this particular mode of exercise. In relation to the adaptation to the muscle damage, the anti-inflammatory cytokine IL-10 might work as one of the underlying mechanisms of action.

Estimating the effects of ambient temperature on mortality : methodological challenges and proposed solutions

The health impacts of exposure to ambient temperature have been drawing increasing attention from the environmental health research community, government, society, industries, and the public. Case-crossover and time series models are most commonly used to examine the effects of ambient temperature on mortality. However, some key methodological issues remain to be addressed. For example, few studies have used spatiotemporal models to assess the effects of spatial temperatures on mortality. Few studies have used a case-crossover design to examine the delayed (distributed lag) and non-linear relationship between temperature and mortality. Also, little evidence is available on the effects of temperature changes on mortality, and on differences in heat-related mortality over time. This thesis aimed to address the following research questions: 1. How to combine case-crossover design and distributed lag non-linear models? 2. Is there any significant difference in effect estimates between time series and spatiotemporal models? 3. How to assess the effects of temperature changes between neighbouring days on mortality? 4. Is there any change in temperature effects on mortality over time? To combine the case-crossover design and distributed lag non-linear model, datasets including deaths, and weather conditions (minimum temperature, mean temperature, maximum temperature, and relative humidity), and air pollution were acquired from Tianjin China, for the years 2005 to 2007. I demonstrated how to combine the case-crossover design with a distributed lag non-linear model. This allows the case-crossover design to estimate the non-linear and delayed effects of temperature whilst controlling for seasonality. There was consistent U-shaped relationship between temperature and mortality. Cold effects were delayed by 3 days, and persisted for 10 days. Hot effects were acute and lasted for three days, and were followed by mortality displacement for non-accidental, cardiopulmonary, and cardiovascular deaths. Mean temperature was a better predictor of mortality (based on model fit) than maximum or minimum temperature. It is still unclear whether spatiotemporal models using spatial temperature exposure produce better estimates of mortality risk compared with time series models that use a single site’s temperature or averaged temperature from a network of sites. Daily mortality data were obtained from 163 locations across Brisbane city, Australia from 2000 to 2004. Ordinary kriging was used to interpolate spatial temperatures across the city based on 19 monitoring sites. A spatiotemporal model was used to examine the impact of spatial temperature on mortality. A time series model was used to assess the effects of single site’s temperature, and averaged temperature from 3 monitoring sites on mortality. Squared Pearson scaled residuals were used to check the model fit. The results of this study show that even though spatiotemporal models gave a better model fit than time series models, spatiotemporal and time series models gave similar effect estimates. Time series analyses using temperature recorded from a single monitoring site or average temperature of multiple sites were equally good at estimating the association between temperature and mortality as compared with a spatiotemporal model. A time series Poisson regression model was used to estimate the association between temperature change and mortality in summer in Brisbane, Australia during 1996–2004 and Los Angeles, United States during 1987–2000. Temperature change was calculated by the current day's mean temperature minus the previous day's mean. In Brisbane, a drop of more than 3 �C in temperature between days was associated with relative risks (RRs) of 1.16 (95% confidence interval (CI): 1.02, 1.31) for non-external mortality (NEM), 1.19 (95% CI: 1.00, 1.41) for NEM in females, and 1.44 (95% CI: 1.10, 1.89) for NEM aged 65.74 years. An increase of more than 3 �C was associated with RRs of 1.35 (95% CI: 1.03, 1.77) for cardiovascular mortality and 1.67 (95% CI: 1.15, 2.43) for people aged < 65 years. In Los Angeles, only a drop of more than 3 �C was significantly associated with RRs of 1.13 (95% CI: 1.05, 1.22) for total NEM, 1.25 (95% CI: 1.13, 1.39) for cardiovascular mortality, and 1.25 (95% CI: 1.14, 1.39) for people aged . 75 years. In both cities, there were joint effects of temperature change and mean temperature on NEM. A change in temperature of more than 3 �C, whether positive or negative, has an adverse impact on mortality even after controlling for mean temperature. I examined the variation in the effects of high temperatures on elderly mortality (age . 75 years) by year, city and region for 83 large US cities between 1987 and 2000. High temperature days were defined as two or more consecutive days with temperatures above the 90th percentile for each city during each warm season (May 1 to September 30). The mortality risk for high temperatures was decomposed into: a "main effect" due to high temperatures using a distributed lag non-linear function, and an "added effect" due to consecutive high temperature days. I pooled yearly effects across regions and overall effects at both regional and national levels. The effects of high temperature (both main and added effects) on elderly mortality varied greatly by year, city and region. The years with higher heat-related mortality were often followed by those with relatively lower mortality. Understanding this variability in the effects of high temperatures is important for the development of heat-warning systems. In conclusion, this thesis makes contribution in several aspects. Case-crossover design was combined with distribute lag non-linear model to assess the effects of temperature on mortality in Tianjin. This makes the case-crossover design flexibly estimate the non-linear and delayed effects of temperature. Both extreme cold and high temperatures increased the risk of mortality in Tianjin. Time series model using single site’s temperature or averaged temperature from some sites can be used to examine the effects of temperature on mortality. Temperature change (no matter significant temperature drop or great temperature increase) increases the risk of mortality. The high temperature effect on mortality is highly variable from year to year.

The use of SMS messaging for physical activity promotion : preferences of Australian adolescents and their parents

OBJECTIVE: Recent increases in youth mobile phone ownership and usage may provide a unique and innovative opportunity for engagement by health promoters, via a familiar and immediately accessible medium. This study investigated adolescents’ and their parents’ preferences for promoting physical activity via means of SMS messaging. METHODS: Adolescents (36 males and 76 females) and their parents (37 males 75 females) were recruited from two non-denominational same-sex private schools, in Brisbane, Australia. The mean age and standard deviation (SD) for adolescents and parents was 14.03 (0.58) and 47.18 (4.65) respectively. Participants responded to a series of questions regarding mobile phone ownership, and preferences for physical activity, school-based physical activity programs, and programs invovling SMS messaging. Data analysis included descriptive statistics and frequency distributions. T-tests were employed to measure gender effect. RESULTS: Overall, 47 (42%) parents desired their child to be more physically active, and were interested for their child to participate in a school-based physical activity program. Of those parents, 16 (34%) parents were interested in their child participating in an SMS-based physical activity program, with 21 (45%) not interested, and 10 (21%) neutral. One hundred and four (95%) adolescents owned a mobile phone, with 84 (82%) of those adolescents wanting to be more physically active. Of those adolescents, 14 (17%) were interested in participating in an SMS-based physical activity program, with 40 (48%) not interested, and 30 (36%) neutral. There was no significant gender effect. CONCLUSIONS: Although SMS messaging may provide an innovative method for youth physical activity promotion, low levels of interest are concerning. These results differ from other studies utilising SMS messaging for the purpose of health promotion, where more positive feedback from participants were reported. A screening process to gauge interest prior to the implementation of any SMS-based health promotion program may prove invaluable toward the success of the program.

Physical performance profile of sub-elite juvenile Gaelic Games players and the prevalence of a Relative Age Effect (RAE)

Gaelic Games are the indigenous sports played in Ireland, the most popular being Gaelic football and hurling. The games are contact sports and the physical demands are thought to be similar to those of Australian Rules football, rugby union, rugby league, field hockey, and lacrosse (Delahunt et al., 2011). The difference in chronological age between children in a single age group is known as relative age and its consequences as the RAE, whereby younger players are disadvantaged (Del Campo et al., 2010). The purpose of this study was to describe the physical and performance profile of sub-elite juvenile Gaelic Games players and to establish if a RAE is present in this cohort and any influence physiological moderator variables may have on this. Following receipt of ethical approval (EHSREC11-45), six sub-elite county development squads (Under-14/15/16 age groups, male, n=115) volunteered to partake in the study. Anthropometric data including skin folds and girths were collected. A number of field tests of physical performance including 5 and 20m speed, vertical and broad jump distance, and an estimate of VO2max were carried out. Descriptive data are presented as Mean SD. Juvenile sub-elite Gaelic Games players aged 14.53 0.82 y were 172.87 7.63 cm tall, had a mass of 64.74 11.06 kg, a BMI of 21.57 2.82 kg.m-2 and 9.22 4.78 % body fat. Flexibility, measured by sit and reach was 33.62 6.86 cm and lower limb power measured by vertical and broad jump were 42.19 5.73 and 191.16 25.26 cm, respectively. Participant time to complete 5m, 20m and an agility test (T-Test) was 1.12 0.07, 3.31 0.30 and 9.31 0.55 s respectively. Participant’s estimated VO2max was 48.23 5.05 ml.kg.min-1. Chi-Square analysis of birth month by quartile (Q1 = January-March) revealed that a RAE was present in this cohort, whereby an over-representation of players born in Q1 compared with Q2, Q3 and Q4 was evident (2 = 14.078, df = 3, p = 0.003). Kruskal-Wallis analysis of the data revealed no significant difference in any of the performance parameters based on quartile of birth (Alpha level = 0.05).This study provides a physical performance profile of juvenile sub-elite Gaelic Games players, comparable with those of other sports such as soccer and rugby. This novel data can inform us of the physical requirements of the sport. The evidence of a RAE is similar to that observed in other contact sports such as soccer and rugby league (Carling et al, 2009; Till et al, 2010). Although a RAE exists in this cohort, this cannot be explained by any physical/physiological moderator variables. Carling C et al. (2009). Scandinavian Journal of Medicine and Science in Sport 19, 3-9. Delahunt E et al. (2011). Journal of Athletic Training 46, 241-5. Del Campo DG et al. (2010). Journal of Sport Science and Medicine 9, 190-198. Delorme N et al. (2010). European Journal of Sport Science 10, 91-96. Till K et al. (2010). Scandinavian Journal of Medicine and Science in Sports 20, 320-329.

Mortality and cost outcomes of elderly trauma patients admitted to intensive care and the general wards of an Australian tertiary referral hospital

Mortality and cost outcomes of elderly intensive care unit (ICU) trauma patients were characterised in a retrospective cohort study from an Australian tertiary ICU. Trauma patients admitted between January 2000 and December 2005 were grouped into three major age categories: aged ≥65 years admitted into ICU (n=272); aged ≥65 years admitted into general ward (n=610) and aged <65 years admitted into ICU (n=1617). Hospital mortality predictors were characterised as odds ratios (OR) using logistic regression. The impact of predictor variables on (log) total hospital-stay costs was determined using least squares regression. An alternate treatment-effects regression model estimated the mortality cost-effect as an endogenous variable. Mortality predictors (P ≤0.0001, comparator: ICU ≥65 years, ventilated) were: ICU <65 not-ventilated (OR 0.014); ICU <65 ventilated (OR 0.090); ICU age ≥65 not-ventilated (OR 0.061) and ward ≥65 (OR 0.086); increasing injury severity score and increased Charlson comorbidity index of 1 and 2, compared with zero (OR 2.21 [1.40 to 3.48] and OR 2.57 [1.45 to 4.55]). The raw mean daily ICU and hospital costs in A$ 2005 (US$) for age <65 and ≥65 to ICU, and ≥65 to the ward were; for year 2000: ICU, $2717 (1462) and $2777 (1494); hospital, $1837 (988) and $1590 (855); ward $933 (502); for year 2005: ICU, $3202 (2393) and $3086 (2307); hospital, $1938 (1449) and $1914 (1431); ward $1180 (882). Cost increments were predicted by age ≥65 and ICU admission, increasing injury severity score, mechanical ventilation, Charlson comorbidity index increments and hospital survival. Mortalitycost-effect was estimated at -63% by least squares regression and -82% by treatment-effects regression model. Patient demographic factors, injury severity and its consequences predict both cost and survival in trauma. The cost mortality effect was biased upwards by conventional least squares regression estimation.

Network governance in US airport taxicab planning activities

This thesis examines the use of network governance in US airport transportation planning activities involving taxicab services for airport patrons. The research provides US airports with new insights whereby they can successfully engage with both transportation regulatory agencies and taxicab service providers in developing mutually agreeable policies that foster the development of supply-side taxicab service improvements. A mix of quantitative and qualitative research methods is used to unearth how US airports interact with these actors, and to identify attitudes held by airport staff in their engagements involving airport taxicab planning matters. The research may ultimately lead to the achievement of sustainable increases in the air passenger ground transportation modal share at US airports, resulting in both desirable long-term operational and environmental benefits for airport management, those involved with the provision of airport taxicab services, and the traveling public.

Clinically-indicated replacement versus routine replacement of peripheral venous catheters

BACKGROUND: US Centers for Disease Control guidelines recommend replacement of peripheral intravenous (IV) catheters no more frequently than every 72 to 96 hours. Routine replacement is thought to reduce the risk of phlebitis and bloodstream infection. Catheter insertion is an unpleasant experience for patients and replacement may be unnecessary if the catheter remains functional and there are no signs of inflammation. Costs associated with routine replacement may be considerable. This is an update of a review first published in 2010. OBJECTIVES: To assess the effects of removing peripheral IV catheters when clinically indicated compared with removing and re-siting the catheter routinely. SEARCH METHODS: For this update the Cochrane Peripheral Vascular Diseases (PVD) Group Trials Search Co-ordinator searched the PVD Specialised Register (December 2012) and CENTRAL (2012, Issue 11). We also searched MEDLINE (last searched October 2012) and clinical trials registries. SELECTION CRITERIA: Randomised controlled trials that compared routine removal of peripheral IV catheters with removal only when clinically indicated in hospitalised or community dwelling patients receiving continuous or intermittent infusions. DATA COLLECTION AND ANALYSIS: Two review authors independently assessed trial quality and extracted data. MAIN RESULTS: Seven trials with a total of 4895 patients were included in the review. Catheter-related bloodstream infection (CRBSI) was assessed in five trials (4806 patients). There was no significant between group difference in the CRBSI rate (clinically-indicated 1/2365; routine change 2/2441). The risk ratio (RR) was 0.61 but the confidence interval (CI) was wide, creating uncertainty around the estimate (95% CI 0.08 to 4.68; P = 0.64). No difference in phlebitis rates was found whether catheters were changed according to clinical indications or routinely (clinically-indicated 186/2365; 3-day change 166/2441; RR 1.14, 95% CI 0.93 to 1.39). This result was unaffected by whether infusion through the catheter was continuous or intermittent. We also analysed the data by number of device days and again no differences between groups were observed (RR 1.03, 95% CI 0.84 to 1.27; P = 0.75). One trial assessed all-cause bloodstream infection. There was no difference in this outcome between the two groups (clinically-indicated 4/1593 (0.02%); routine change 9/1690 (0.05%); P = 0.21). Cannulation costs were lower by approximately AUD 7.00 in the clinically-indicated group (mean difference (MD) -6.96, 95% CI -9.05 to -4.86; P ≤ 0.00001). AUTHORS' CONCLUSIONS: The review found no evidence to support changing catheters every 72 to 96 hours. Consequently, healthcare organisations may consider changing to a policy whereby catheters are changed only if clinically indicated. This would provide significant cost savings and would spare patients the unnecessary pain of routine re-sites in the absence of clinical indications. To minimise peripheral catheter-related complications, the insertion site should be inspected at each shift change and the catheter removed if signs of inflammation, infiltration, or blockage are present. OBJECTIVES: To assess the effects of removing peripheral IV catheters when clinically indicated compared with removing and re-siting the catheter routinely. SEARCH METHODS: For this update the Cochrane Peripheral Vascular Diseases (PVD) Group Trials Search Co-ordinator searched the PVD Specialised Register (December 2012) and CENTRAL (2012, Issue 11). We also searched MEDLINE (last searched October 2012) and clinical trials registries. SELECTION CRITERIA: Randomised controlled trials that compared routine removal of peripheral IV catheters with removal only when clinically indicated in hospitalised or community dwelling patients receiving continuous or intermittent infusions. DATA COLLECTION AND ANALYSIS: Two review authors independently assessed trial quality and extracted data. MAIN RESULTS: Seven trials with a total of 4895 patients were included in the review. Catheter-related bloodstream infection (CRBSI) was assessed in five trials (4806 patients). There was no significant between group difference in the CRBSI rate (clinically-indicated 1/2365; routine change 2/2441). The risk ratio (RR) was 0.61 but the confidence interval (CI) was wide, creating uncertainty around the estimate (95% CI 0.08 to 4.68; P = 0.64). No difference in phlebitis rates was found whether catheters were changed according to clinical indications or routinely (clinically-indicated 186/2365; 3-day change 166/2441; RR 1.14, 95% CI 0.93 to 1.39). This result was unaffected by whether infusion through the catheter was continuous or intermittent. We also analysed the data by number of device days and again no differences between groups were observed (RR 1.03, 95% CI 0.84 to 1.27; P = 0.75). One trial assessed all-cause bloodstream infection. There was no difference in this outcome between the two groups (clinically-indicated 4/1593 (0.02%); routine change 9/1690 (0.05%); P = 0.21). Cannulation costs were lower by approximately AUD 7.00 in the clinically-indicated group (mean difference (MD) -6.96, 95% CI -9.05 to -4.86; P ≤ 0.00001). AUTHORS' CONCLUSIONS: The review found no evidence to support changing catheters every 72 to 96 hours. Consequently, healthcare organisations may consider changing to a policy whereby catheters are changed only if clinically indicated. This would provide significant cost savings and would spare patients the unnecessary pain of routine re-sites in the absence of clinical indications. To minimise peripheral catheter-related complications, the insertion site should be inspected at each shift change and the catheter removed if signs of inflammation, infiltration, or blockage are present.

Fabrication and in vitro characterisation of bioactive glass composite scaffolds for bone regeneration

Here we fabricate and characterise bioactive composite scaffolds for bone tissue engineering applications. 45S5 Bioglass® (45S5) or strontium-substituted bioactive glass (SrBG) were incorporated into polycaprolactone (PCL) and fabricated into 3D bioactive composite scaffolds utilising additive manufacturing technology. We show that composite scaffolds (PCL/45S5 and PCL/SrBG) can be reproducibly manufactured with a scaffold morphology highly resembling that of PCL scaffolds. Additionally, micro-CT analysis reveals BG particles were homogeneously distributed throughout the scaffolds. Mechanical data suggested that PCL/45S5 and PCL/SrBG composite scaffolds have higher compressive Young’s modulus compared to PCL scaffolds at similar porosity (~75%). After 1 day in accelerated degradation conditions using 5M NaOH, PCL/SrBG, PCL/45S5 and PCL lost 48.6 ±3.8%, 12.1 ±1% and 1.6 ±1% of its original mass, respectively. In vitro studies were conducted using MC3T3 cells under normal and osteogenic conditions. All scaffolds were shown to be non-cytotoxic, and supported cell attachment and proliferation. Our results also indicate that the inclusion of bioactive glass (BG) promotes precipitation of calcium phosphate on the scaffold surfaces which leads to earlier cell differentiation and matrix mineralisation when compared to PCL scaffolds. However, as indicated by ALP activity, no significant difference in osteoblast differentiation was found between PCL/45S5 and PCL/SrBG scaffolds. These results suggest that PCL/45S5 and PCL/SrBG composite scaffold shows potential as a next generation bone scaffold.

Modified alumina nanofiber membranes for protein separation

Large-scale purification/separation of bio-substances is a key technology required for rapid production of biological substances in bioengineering. Membrane filtration is a new separation process and has potential to be used for concentration (removal of solvent), desalting (removal of low molecular weight compounds), clarification (removal of particles), and fractionation (protein-protein separation). In this study, we developed an efficient membrane for protein separation based on ceramic nanofibers. Alumina nanofibers were prepared on a porous support and formed large flow passages. The radical changes in membrane structure provided new ceramic membranes with a large porosity (more than 70%) due to the replacement of bulk particles with fine fibers as building components. The pore size had an average of 11 nm and pure water flux was approximately 360 L•h-1•m-2•bar-1. Further surface modification with a self-assembled monolayer of (3-aminopropyl) triethoxysilane enhanced the membrane filtration properties. Characterization with SEM, FTIR, contact angle, and proteins separation tests indicated that the fibril layers uniformly spread on the surface of the porous support. Moreover, the membrane surface was changed from hydrophilic to hydrophobic after silane groups were grafted. It demonstrated that the silane-grafted alumina fiber membrane can reject 100% BSA protein and 92% cellulase protein. It was also able to retain 75% trypsin protein while maintaining a permeation flux of 48 L•h-1•m-2•bar-1.

Nutrient provision increases signalling and protein synthesis in human skeletal muscle after repeated sprints

The effect of nutrient availability on the acute molecular responses following repeated sprint exercise is unknown. The aim of this study was to determine skeletal muscle cellular and protein synthetic responses following repeated sprint exercise with nutrient provision. Eight healthy young male subjects undertook two sprint cycling sessions (10 × 6 s, 0.75 N m torque kg -1, 54 s recovery) with either pre-exercise nutrient (24 g whey, 4.8 g leucine, 50 g maltodextrin) or non-caloric placebo ingestion. Muscle biopsies were taken from vastus lateralis at rest, and after 15 and 240 min post-exercise recovery to determine muscle cell signalling responses and protein synthesis by primed constant infusion of L-[ring- 13C 6] phenylalanine. Peak and mean power outputs were similar between nutrient and placebo trials. Post-exercise myofibrillar protein synthetic rate was greater with nutrient ingestion compared with placebo ( ? 48%, P<0.05) but the rate of mitochondrial protein synthesis was similar between treatments. The increased myofibrillar protein synthesis following sprints with nutrient ingestion was associated with coordinated increases in Akt-mTOR-S6KrpS6 phosphorylation 15 min post-exercise (?200-600%, P<0.05), while there was no effect on these signalling molecules when exercise was undertaken in the fasted state. For the first time we report a beneficial effect of nutrient provision on anabolic signalling and muscle myofibrillar protein synthesis following repeated sprint exercise. Ingestion of protein/carbohydrate in close proximity to high-intensity sprint exercise provides an environment that increases cell signalling and protein synthesis.

High rates of muscle glycogen resynthesis after exhaustive exercise when carbohydrate is coingested with caffeine

We determined the effect of coingestion of caffeine (Caff) with carbohydrate (CHO) on rates of muscle glycogen resynthesis during recovery from exhaustive exercise in seven trained subjects who completed two experimental trials in a randomized, double-blind crossover design. The evening before an experiment subjects performed intermittent exhaustive cycling and then consumed a low-CHO meal. The next morning subjects rode until volitional fatigue. On completion of this ride subjects consumed either CHO [4 g/kg body mass (BM)] or the same amount of CHO + Caff (8 mg/kg BM) during 4 h of passive recovery. Muscle biopsies and blood samples were taken at regular intervals throughout recovery. Muscle glycogen levels were similar at exhaustion [?75 mmol/kg dry wt (dw)] and increased by a similar amount (?80%) after 1 h of recovery (133 ± 37.8 vs. 149 ± 48 mmol/kg dw for CHO and Caff, respectively). After 4 h of recovery Caff resulted in higher glycogen accumulation (313 ± 69 vs. 234 ± 50 mmol/kg dw, P < 0.001). Accordingly, the overall rate of resynthesis for the 4-h recovery period was 66% higher in Caff compared with CHO (57.7 ± 18.5 vs. 38.0 ± 7.7 mmol·kg dw-1·h-1, P < 0.05). After 1 h of recovery plasma Caff levels had increased to 31 ± 11 ?M (P < 0.001) and at the end of the recovery reached 77 ± 11 ?M (P < 0.001) with Caff. Phosphorylation of CaMKThr286 was similar after exercise and after 1 h of recovery, but after 4 h CaMKThr286 phosphorylation was higher in Caff than CHO (P < 0.05). Phosphorylation of AMP-activated protein kinase (AMPK)Thr172 and AktSer473 was similar for both treatments at all time points. We provide the first evidence that in trained subjects coingestion of large amounts of Caff (8 mg/kg BM) with CHO has an additive effect on rates of postexercise muscle glycogen accumulation compared with consumption of CHO alone.