Nutrition and indoor cycling : A cross-sectional analysis of carbohydrate intake for online racing and training

Cycling is a sport characterised by high training load, and adequate nutrition is essential for training and race performance. With the increased popularity of indoor trainers, cyclists have a unique opportunity to practice and implement key nutritional strategies. This study aimed to assess carbohydrate (CHO) intake of cyclists training or racing in this unique scenario for optimising exercise nutrition. A mixed-methods approach consisting of a multiple-pass self-report food recall and questionnaire was used to determine total CHO intake pre, during and post-training or racing using a stationary trainer and compared with current guidelines for endurance exercise. Sub-analyses were also made for higher ability cyclists (>4 W/kg functional threshold power), races v. non-races and ‘key’ training sessions. Mean CHO intake pre and post-ride was 0·7 (SD 0·6) and 1·0 (SD 0·8) g kg/BM and 39·3 (SD 27·5) g/h during training. CHO intake was not different for races (pre/during/post, P = 0·31, 0·23, 0·18, respectively), ‘key sessions’ (P = 0·26, 0·89, 0·98) or higher ability cyclists (P = 0·26, 0·76, 0·45). The total proportion of cyclists who failed to meet CHO recommendations was higher than those who met guidelines (pre = 79 %, during = 86 %, post = 89 %). Cyclists training or racing indoors do not meet current CHO recommendations for cycling performance. Due to the short and frequently high-intensity nature of some sessions, opportunity for during exercise feeding may be limited or unnecessary

Two-versus one photon excitation laser scanning microscopy: Critical importance of excitation wavelength

It is often anticipated that two-photon excitation (TPE) laser scanning microscopy should improve cell survival and tissue penetration relative to conventional one-photon excitation (OPE) confocal scanning laser microscopy (CLSM). However few studies have directly compared live cell imaging using one- vs two-photon laser scanning microscopy. We have used calcein-loaded in situ chondrocytes within cartilage as a model for quantitatively comparing these techniques. TPE reduced photo-bleaching and improved cell viability compared to OPE. Using improved detection sensitivity coupled with increased tissue penetration of the near infra-red TPE laser, it was possible to capture images deeper within the cartilage. However, the advantages of TPE vs OPE were strongly dependent on excitation wavelength. We conclude that optimising TPE conditions is essential if the full benefits of this approach are to be realised

Functional independence of circadian clocks that regulate plant gene expression

AbstractBackground: Circadian clocks regulate the gene expression, metabolism and behaviour of most eukaryotes, controlling an orderly succession of physiological processes that are synchronised with the environmental day/night cycle. Central circadian pacemakers that control animal behaviour are located in the brains of insects and rodents, but the location of such a pacemaker has not been determined in plants. Peripheral plant and animal tissues also maintain circadian rhythms when isolated in culture, indicating that these tissues contain circadian clocks. The degree of autonomy that the multiple, peripheral circadian clocks have in the intact organism is unclear.Results: We used the bioluminescent luciferase reporter gene to monitor rhythmic expression from three promoters in transgenic Arabidopsis and tobacco plants. The rhythmic expression of a single gene could be set at up to three phases in different anatomical locations of a single plant, by applying light/dark treatments to restricted tissue areas. The initial phases were stably maintained after the entraining treatments ended, indicating that the circadian oscillators in intact plants are autonomous. This result held for all the vegetative plant organs and for promoters expressed in all major cell types. The rhythms of one organ were unaffected by entrainment of the rest of the plant, indicating that phase-resetting signals are also autonomous.Conclusions: Higher plants contain a spatial array of autonomous circadian clocks that regulate gene expression without a localised pacemaker. Circadian timing in plants might be less accurate but more flexible than the vertebrate circadian system

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No abstract.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/58017/1/23350_ftp.pd

Comment on "Local accumulation times for source, diffusion, and degradation models in two and three dimensions" [J. Chem. Phys. 138, 104121 (2013)]

In a recent paper, Gordon, Muratov, and Shvartsman studied a partial differential equation (PDE) model describing radially symmetric diffusion and degradation in two and three dimensions. They paid particular attention to the local accumulation time (LAT), also known in the literature as the mean action time, which is a spatially dependent timescale that can be used to provide an estimate of the time required for the transient solution to effectively reach steady state. They presented exact results for three-dimensional applications and gave approximate results for the two-dimensional analogue. Here we make two generalizations of Gordon, Muratov, and Shvartsman’s work: (i) we present an exact expression for the LAT in any dimension and (ii) we present an exact expression for the variance of the distribution. The variance provides useful information regarding the spread about the mean that is not captured by the LAT. We conclude by describing further extensions of the model that were not considered by Gordon,Muratov, and Shvartsman. We have found that exact expressions for the LAT can also be derived for these important extensions..

Optimization and Validation of a Human <i>Ex Vivo</i> Femoral Head Model for Preclinical Cartilage Research and Regenerative Therapies

OBJECTIVE: Articular cartilage is incapable of effective repair following injury or during osteoarthritis. While there have been developments in cartilage repair technologies, there is a need to advance biologically relevant models for preclinical testing of biomaterial and regenerative therapies. This study describes conditions for the effective ex vivo culture of the whole human femoral head. DESIGN: Fresh, viable femoral heads were obtained from femoral neck fractures and cultured for up to 10 weeks in (a) Dulbecco’s modified Eagle’s medium (DMEM); (b) DMEM + mixing; (c) DMEM + 10% human serum (HS); (d) DMEM + 10% HS + mixing. The viability, morphology, volume, and density of fluorescently labelled in situ chondrocytes and cartilage surface roughness were assessed by confocal microscopy. Cartilage histology was studied for glycosaminoglycan content using Alcian blue and collagen content using picrosirius red. RESULTS: Chondrocyte viability remained at >95% in DMEM + 10% HS. In DMEM alone, viability remained high for ~4 weeks and then declined. For the other conditions, superficial zone chondrocyte viability fell to 0.05). CONCLUSIONS: In this ex vivo model, chondrocyte viability was maintained in human femoral heads for up to 10 weeks in culture, a novel finding not previously reported. This human model could prove invaluable for the exploration, development, and assessment of preclinical cartilage repair and regenerative therapies