Portrait of Glen Davison

Glen Davison

Director of Research
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About

Dr Glen Davison attained his first degree in Sport and Exercise Sciences at Sheffield Hallam University in 2001 and MSc in Exercise Physiology in September 2002. 

He commenced his PhD on “Nutrition and Exercise Immunology” in October 2002 at Loughborough University. Whilst at Loughborough Glen also worked as a Teaching Assistant in Exercise Physiology. He worked as a lecturer in Sports Nutrition and Exercise Physiology at Aberystwyth University for just over 5 years before joining the SSES, University of Kent, in September 2011. Dr Davison is also a BASES Accredited sport and exercise scientist (Physiology) and a Chartered Scientist (CSci). He has worked with amateur, elite and professional athletes from a range of sports, including Football, Rugby, Hockey, Athletics, Triathlon and Cycling.

His current interests include: Nutrition and Exercise Immunology; Interval training; Sport & Exercise Science support of athletes (i.e. maintaining optimal health and performance) in sports including Football, Rugby, Hockey, Athletics, Endurance/LD running, Triathlon and Cycling; Exercise Immunology in people with Diabetes. Exercise and Immune function in people with Chronic Obstructive Pulmonary Disease (COPD); Exercise in people with Parkinson's Disease.

Research interests

Immune System Function in athletes and how the human immune system responds to prolonged (endurance) exercise, as well as various types of training (including high-intensity interval training).

Immune System Function in athletes and how the human immune system responds to prolonged (endurance) exercise, as well as various types of training (including high-intensity interval training).

I am particularly interested:

  • The effects of nutrition on human immune function, physiological adaptation, and risk of upper respiratory tract infection (URTI) symptoms after exercise.
  • The effects of acute/short-term supplementation with commercially available supplements.
  • Immune function in people with Diabetes.

Teaching

Undergraduate

Postgraduate

Publications

Showing 50 of 63 total publications in the Kent Academic Repository. View all publications.

Article

  • Davison, G., Jones, A., Marchbank, T. and Playford, R. (2019). Oral bovine colostrum supplementation does not increase circulating insulin-like growth factor-1 concentration in healthy adults: results from short- and long-term administration studies. European Journal of Nutrition [Online]. Available at: http://dx.doi.org/10.1007/s00394-019-02004-6.
    Purpose
    Bovine colostrum is available in health food shops and as a sports food supplement and is rich in antibodies and growth factors including IGF-1. World Anti-Doping Agency advises athletes against taking colostrum for fear of causing increased plasma IGF-1. There are also concerns that colostrum may theoretically stimulate malignancy in organs which express IGF-1 receptors. We, therefore, determined changes in plasma IGF-1 levels in subjects taking colostrum or placebo for 1 day, 4 weeks, and 12 weeks.
    Methods
    Plasma IGF1 levels were determined in healthy males (n = 16) who ingested 40 g bovine colostrum or placebo along with undertaking moderate exercise for total period of 4.5 h. Two further studies followed changes in IGF1 using double-blind, parallel group, placebo-controlled, randomized trials of colostrum or placebo (N = 10 per arm, 20 g/day for 4 weeks and N = 25 colostrum, N = 29 placebo arm 20 g/day for 12 weeks).
    Results
    Baseline IGF1 levels 130 ± 36 ng/ml. 4.5 h protocol showed no effect of colostrum on plasma IGF1 (ANOVA, treatment group: p = 0.400, group × time: p = 0.498, time p = 0.602). Similarly, no effect of colostrum ingestion was seen following 4 week (ANOVA, group: p = 0.584, group × time interaction: p = 0.083, time p = 0.243) or 12 week (ANOVA, group: p = 0.400, group × time interaction: p = 0.498, time p = 0.602) protocol.
    Conclusions
    Ingestion of standard recommended doses of colostrum does not increase IGF-1 levels in healthy adults, providing additional support for the safety profile of colostrum ingestion.
  • Chou, C., Sung, Y., Davison, G., Chen, C. and Liao, Y. (2018). Short-Term High-Dose Vitamin C and E Supplementation Attenuates Muscle Damage and Inflammatory Responses to Repeated Taekwondo Competitions: A Randomized Placebo-Controlled Trial. International Journal of Medical Sciences [Online] 15:1217-1226. Available at: https://doi.org/10.7150/ijms.26340.
    Background: Exercise-induced muscle damage during intensive sport events is a very common
    issue in sport medicine. Therefore, the purpose is to investigate the effects of short-term high-dose
    vitamin C and E supplementation on muscle damage, hemolysis, and inflammatory responses to
    simulated competitive Olympic Taekwondo (TKD) matches in elite athletes.
    Methods: Using a randomized placebo-controlled and double-blind study design, eighteen elite
    male TKD athletes were weight-matched and randomly assigned into either a vitamin C and E group
    (Vit C+E; N = 9) or placebo group (PLA; N = 9). Vit C+E or PLA supplements were taken daily (Vit
    C+E: 2000 mg/d vitamin C; 1400 U/d vitamin E) for 4 days (3 days before and on competition day)
    before taking part in 4 consecutive TKD matches on a single day. Plasma samples were obtained
    before each match and 24-hours after the first match for determination of markers of muscle
    damage, hemolysis, and systemic inflammatory state.
    Results: Myoglobin was lower in the Vit C+E group, compared to PLA, during the match day (area
    under curve, AUC -47.0% vs. PLA, p = 0.021). Plasma creatine kinase was lower in the Vit C+E
    group (AUC -57.5% vs. PLA, p = 0.017) and hemolysis was lower in the Vit C+E group (AUC -40.5%
    vs. PLA, p = 0.034).
    Conclusions: We demonstrated that short-term (4-days) vitamin C and E supplementation
    effectively attenuated exercise-induced tissue damage and inflammatory response during and after
    successive TKD matches.
  • March, D., Jones, A., Thatcher, R. and Davison, G. (2018). The effect of bovine colostrum supplementation on intestinal injury and circulating intestinal bacterial DNA following exercise in the heat. European Journal of Nutrition [Online]. Available at: https://doi.org/10.1007/s00394-018-1670-9.
    Purpose
    Exercise-induced changes in intestinal permeability are exacerbated in the heat. The aim of this study was to
    determine the effect of 14 days of bovine colostrum (Col) supplementation on intestinal cell damage (plasma intestinal fatty
    acid-binding protein, I-FABP) and bacterial translocation (plasma bacterial DNA) following exercise in the heat.

    Methods
    In a double-blind, placebo-controlled, crossover design, 12 males completed two experimental arms (14 days of
    20 g/day supplementation with Col or placebo, Plac) consisting of 60 min treadmill running at 70% maximal aerobic capacity
    (30 °C, 60% relative humidity). Blood samples were collected pre-exercise (Pre-Ex), post-exercise (Post-Ex) and 1 h
    post-exercise (1 h Post-Ex) to determine plasma I-FABP concentration, and bacterial DNA (for an abundant gut species,
    Bacteroides).

    Results
    Two-way repeated measures ANOVA revealed an arm×time interaction for I-FABP (P=0.005, with greater PostEx
    increase in Plac than Col, P=0.01: Plac 407±194% of Pre-Ex vs Col, 311±134%) and 1 h Post-Ex (P=0.036: Plac
    265±80% of Pre-Ex vs Col, 229±56%). There was no interaction (P=0.904) but there was a main effect of arm (P=0.046)
    for plasma Bacteroides/total bacterial DNA, with lower overall levels evident in Col.

    Conclusion
    This is the first investigation to demonstrate that Col can be effective at reducing intestinal injury following
    exercise in the heat, but exercise responses (temporal pattern) of bacterial DNA were not influenced by Col (although overall
    levels may be lower).
  • Stimpson, N., Davison, G. and Javadi, A. (2018). Joggin’ the Noggin: Towards a Physiological Understanding of Exercise-Induced Cognitive Benefits. Neuroscience & Biobehavioral Reviews [Online] 88:177-186. Available at: https://doi.org/10.1016/j.neubiorev.2018.03.018.
  • March, D., Marchbank, T., Playford, R., Jones, A., Thatcher, R. and Davison, G. (2017). Intestinal fatty acid-binding protein and gut permeability responses to exercise. European Journal of Applied Physiology [Online] 117:931-941. Available at: http://dx.doi.org/10.1007/s00421-017-3582-4.
    Purpose

    Intestinal cell damage due to physiological stressors (e.g. heat, oxidative, hypoperfusion/ischaemic) may contribute to increased intestinal permeability. The aim of this study was to assess changes in plasma intestinal fatty acid-binding protein (I-FABP) in response to exercise (with bovine colostrum supplementation, Col, positive control) and compare this to intestinal barrier integrity/permeability (5 h urinary lactulose/rhamnose ratio, L/R).


    Methods

    In a double-blind, placebo-controlled, crossover design, 18 males completed two experimental arms (14 days of 20 g/day supplementation with Col or placebo, Plac). For each arm participants performed two baseline (resting) intestinal permeability assessments (L/R) pre-supplementation and one post-exercise following supplementation. Blood samples were collected pre- and post-exercise to determine I-FABP concentration.


    Results

    Two-way repeated measures ANOVA revealed an arm?×?time interaction for L/R and I-FABP (P?<?0.001). Post hoc analyses showed urinary L/R increased post-exercise in Plac (273% of pre, P?<?0.001) and Col (148% of pre, P?<?0.001) with post-exercise values significantly lower with Col (P?<?0.001). Plasma I-FABP increased post-exercise in Plac (191% of pre-exercise, P?=?0.002) but not in the Col arm (107%, P?=?0.862) with post-exercise values significantly lower with Col (P?=?0.013). Correlations between the increase in I-FABP and L/R were evident for visit one (P?=?0.044) but not visit two (P?=?0.200) although overall plots/patterns do appear similar for each.


    Conclusion

    These findings suggest that exercise-induced intestinal cellular damage/injury is partly implicated in changes in permeability but other factors must also contribute.
  • Chidley, C. and Davison, G. (2017). The effect of Chlorella pyrenoidosa supplementation on immune responses to 2 days of intensified training. European Journal of Nutrition [Online]. Available at: http://dx.doi.org/10.1007%2Fs00394-017-1525-9.
    Purpose: Periods of intensified training are associated with immune disturbances, The aim was to investigate the effects of supplementation with Chlorella pyrenoidosa (Chlorella) on secretory IgA (sIgA) responses to 2 days intensified training.
    Methods: Twenty-six subjects (age 29.1 ± 8.7 years; VO2max 53.7 ± 11.7 ml kg min?1) provided resting saliva samples for determination of sIgA, at baseline (week-0) and following 4, 5, and 6 weeks (weeks-4, -5, -6) of daily supplementation with 6 g/day Chlorella (n = 13) or placebo (PLA, n = 13). During week-4 a 2-day intensified training period was undertaken [morning and afternoon sessions each day, respectively: VO2max test; high-intensity interval training (HIIT, 3 × 30 s Wingate sprints); 90 min at ~60% VO2max; 3 × 30 s HIIT].
    Results: Chlorella increased resting sIgA secretion rate (trial × time, P = 0.016: no change with PLA but increases with Chlorella at week-4, week-5 and week-6, P = 0.020, <0.001, and 0.016). PLA vs Chlorella: week-0 = 54 ± 33 vs 57 ± 37 µg/min; week-4 = 54 ± 35 vs 83 ± 57 µg/min; week-5 = 63 ± 46 vs 98 ± 47 µg/min; week-6 = 58 ± 35 vs 85 ± 59 µg/min. Minimal acute changes in sIgA were seen in response to individual exercise bouts, but it was higher at some times in the Chlorella group (for bouts 2 and 3).
    Conclusion: Supplementation with Chlorella has beneficial effects on resting sIgA, which might be beneficial during periods of intensified training.
  • Jones, A., March, D., Thatcher, R., Diment, B., Walsh, N. and Davison, G. (2017). The effects of bovine colostrum supplementation on in vivo immunity following prolonged exercise: a randomised controlled trial. European Journal of Nutrition [Online]. Available at: https://doi.org/10.1007/s00394-017-1597-6.
    Background Bovine colostrum (COL) has been advocated as a nutritional countermeasure to exercise-induced immune dysfunction but there is a lack of research with clinically relevant in vivo measures. Aim To investigate the effects of COL supplementation on in vivo immunity following prolonged exercise using experimental contact hypersensitivity (CHS) with the novel antigen Diphenylcyclopropenone (DPCP). Methods In a double-blind design, 31 men were randomly assigned to COL (20 g/day) or placebo (PLA) for 58 days. Participants ran for 2 h at 60% maximal aerobic capacity on day 28 and received a primary DPCP exposure (sensitisation) 20 min after. On day 56, participants received a low dose-series DPCP challenge to elicit recall of in vivo immune-specific memory (quantified by skinfold thickness 24 h and 48 h later). Analysis of the dose response curves allowed determination of the minimum dose required to elicit a positive response (i.e. sensitivity). Results There was no difference in summed skinfold thickness responses between COL and PLA at 24 h (p = 0.124) and 48 h (p = 0.405). However, sensitivity of in vivo immune responsiveness was greater with COL at 24 h (p < 0.001) and 48 h (p = 0.023) with doses ~2-fold greater required to elicit a positive response in PLA. Conclusions COL blunts the prolonged exercise-induced decrease in clinically relevant in vivo immune responsiveness to a novel antigen, which may be a mechanism for reduced illness reports observed in previous studies. These findings also suggest that CHS sensitivity is highly relevant to host defence.
  • Jones, A., Robinson, R., Mohamed, P., Davison, G., Izzat, H. and Lewis, K. (2016). Impaired Blood Neutrophil Function in the Frequent Exacerbator of Chronic Obstructive Pulmonary Disease: A Proof-of-Concept Study. Lung [Online] 194:881-887. Available at: http://dx.doi.org/10.1007/s00408-016-9930-z.
    Purpose
    The underlying biological mechanisms of the frequent exacerbator phenotype of COPD remain unclear. We compared systemic neutrophil function in COPD patients with or without frequent exacerbations.

    Methods
    Whole blood from COPD frequent exacerbators (defined as ?2 moderate–severe exacerbations in the previous 2 years) and non-exacerbators (no exacerbations in the preceding 2 years) was assayed for neutrophil function. Neutrophil function in healthy ex-smoking volunteers was also measured as a control (reference) group.

    Results
    A total of 52 subjects were included in this study: 26 frequent exacerbators, 18 non-exacerbators and 8 healthy controls. COPD frequent exacerbators had blunted blood neutrophil fMLP-stimulated oxidative burst compared to both non-exacerbators (p < 0.01) and healthy controls (p < 0.001). There were no differences between COPD frequent exacerbators and non-exacerbators in blood neutrophil PMA-stimulated oxidative burst, but both COPD groups had reduced responses compared to healthy controls (p < 0.001). Bacterial-stimulated neutrophil degranulation was greater in frequent exacerbators than non-exacerbators (p < 0.05).

    Conclusion
    This study is the first to report aberrant receptor-mediated blood neutrophil function in the frequent exacerbator of COPD.
  • Davison, G., Marchbank, T., March, D., Thatcher, R. and Playford, R. (2016). Zinc carnosine works with bovine colostrum in truncating heavy exercise–induced increase in gut permeability in healthy volunteers. American Journal of Clinical Nutrition [Online] 104. Available at: http://dx.doi.org/10.3945/?ajcn.116.134403.
    Background: Heavy exercise causes gut symptoms and, in extreme cases, heat stroke that is due to the increased intestinal permeability of luminal toxins.

    Objective: We examined whether zinc carnosine (ZnC), a health-food product taken alone or in combination with bovine colostrum (a natural source of growth factors), would moderate such effects.

    Design: Eight volunteers completed a 4-arm, double-blind, placebo-controlled crossover protocol (14 d of placebo, ZnC, colostrum, or ZnC plus colostrum) before undertaking standardized exercise 2 and 14 d after the start of treatment. Changes in epithelial resistance, apoptosis signaling molecules, and tight junction (TJ) protein phosphorylation in response to a 2°C rise in body temperature were determined with the use of Caco-2 and HT29 intestinal cells.

    Results: Body temperature increased 2°C, and gut permeability (5-h urinary lactulose:rhamnose ratios) increased 3-fold after exercise (from 0.32 ± 0.016 baseline to 1.0 ± 0.017 at 14 d; P < 0.01). ZnC or colostrum truncated the rise by 70% after 14 d of treatment. The combination treatment gave an additional benefit, and truncated exercise induced increase at 2 d (30% reduction; P < 0.01). A 2°C temperature rise in in vitro studies caused the doubling of apoptosis and reduced epithelial resistance 3–4-fold. ZnC or colostrum truncated these effects (35–50%) with the greatest response seen with the combination treatment (all P < 0.01). Mechanisms of action included increasing heat shock protein 70 and truncating temperature-induced changes in B cell leukemia/lymphoma-2 associated X protein ? and B cell lymphoma 2. ZnC also increased total occludin and reduced phosphorylated tyrosine claudin, phosphorylated tyrosine occludin, and phosphorylated serine occludin, thereby enhancing the TJ formation and stabilization.

    Conclusion: ZnC, taken alone or with colostrum, increased epithelial resistance and the TJ structure and may have value for athletes and in the prevention of heat stroke in military personnel. This trial was registered at www.isrctn.com as ISRCTN51159138.
  • Dyer, J., Davison, G., Marcora, S. and Mauger, A. (2016). Effect of a Mediterranean type diet on inflammatory and cartilage degradation biomarkers in patients with osteoarthritis. The Journal of Nutrition, Health and Aging [Online]. Available at: http://link.springer.com/article/10.1007/s12603-016-0806-y.
    Objectives: To investigate the effects of a Mediterranean type diet on patients with osteoarthritis (OA). Participants: Ninety-nine volunteers with OA (aged 31 - 90 years) completed the study (83% female). Setting: Southeast of England, UK. Design: Participants were randomly allocated to the dietary intervention (DIET, n = 50) or control (CON, n = 49). The DIET group were asked to follow a Mediterranean type diet for 16 weeks whereas the CON group were asked to follow their normal diet. Measurements: All participants completed an Arthritis Impact Measurement Scale (AIMS2) pre-, mid- and post- study period. A subset of participants attended a clinic at the start and end of the study for assessment of joint range of motion, ROM (DIET = 33, CON = 28), and to provide blood samples (DIET = 29, CON = 25) for biomarker analysis (including serum cartilage oligomeric matrix protein (sCOMP) (a marker of cartilage degradation) and a panel of other relevant biomarkers including pro- and anti-inflammatory cytokines). Results: There were no differences between groups in the response of any AIMS2 components and most biomarkers (p > 0.05), except the pro-inflammatory cytokine IL-1?, which decreased in the DIET group (~47%, p = 0.010). sCOMP decreased in the DIET group by 1 U/L (~8%, p = 0.014). There was a significant improvement in knee flexion and hip rotation ROM in the DIET group (p < 0.05). Conclusions: The average reduction in sCOMP in the DIET group (1 U/L) represents a meaningful change, but the longer term effects require further study.
  • Davison, G., Kehaya, C. and Jones, A. (2015). Nutritional and Physical Activity Interventions to Improve Immunity. American Journal of Lifestyle Medicine [Online]. Available at: http://dx.doi.org/10.1177/1559827614557773.
    Physical activity and nutrition are important in a healthy lifestyle with potential benefits to immunity often overlooked. Infection of the upper respiratory tract, and the associated symptoms, are the most frequent presentations to general practitioners and may have significant economic and social impact. In this review, we consider the role of physical activity and nutrition in improving immunity. Evidence suggests that regular moderate activity is particularly beneficial for immune enhancement and reducing the risk of infection. We also discuss some nutritional strategies. Unfortunately, the evidence for many is weak. Avoiding nutritional deficiencies seems the most pragmatic recommendation. This can be achieved with a balanced diet. Including a variety of fruits and vegetables may help ensure adequate intake of essential nutrients with little risk of excess intake of any single nutrient. Supplementation with individual nutrients is generally not recommended. Multinutrients may be beneficial for those with a preexisting deficiency but not if normal dietary intake is sufficient. Further benefit may be gained from some supplements including probiotics, bovine colostrum, and some plant-derived products (Echinacea, black elderberry, and some polyphenols) but only in specific situations/contexts. Individuals should consider their personal needs, use caution, and avoid the indiscriminate use of supplements.
  • Davison, G. (2015). Carbohydrate supplementation does not blunt the prolonged exercise-induced reduction of in vivo immunity. European Journal of Nutrition [Online] 55:1583-1593. Available at: http://dx.doi.org/10.1007%2Fs00394-015-0977-z.
    Background

    Carbohydrate (CHO) supplementation during prolonged exercise is widely acknowledged to blunt in vitro immunoendocrine responses, but no study has investigated in vivo immunity.
    Purpose

    To determine the effect of CHO supplementation during prolonged exercise on in vivo immune induction using experimental contact hypersensitivity with the novel antigen diphenylcyclopropenone (DPCP).
    Methods

    In a double-blind design, 32 subjects were randomly assigned to 120 min of treadmill exercise at 60 % V?O2max

    with CHO (Ex-CHO) or placebo (Ex-PLA) supplementation. Responses were also compared to 16 resting control (CON) subjects from a previous study (for additional comparison with a resting non-exercise condition). Standardised diets (24 h pre-trial) and breakfasts (3.5 h pre-trial) were provided. Subjects received a primary DPCP exposure (sensitisation) 20 min after trial completion, and exactly 28 days later the strength of immune reactivity was quantified by magnitude of the cutaneous response (skin-fold thickness and erythema) to a low dose-series DPCP challenge. Stress hormones and leucocyte trafficking were also monitored.
    Results

    CHO supplementation blunted the cortisol and leucocyte trafficking responses, but there was no difference (P > 0.05) between Ex-CHO and Ex-PLA in the in vivo immune responses (e.g. both ~46 % lower than CON for skin-fold response).
    Conclusions

    CHO supplementation does not influence the decrease in in vivo immunity seen after prolonged exercise. The effects with more stressful (or fasted) exercise remain to be determined. However, there appears to be no benefit under the conditions of the present study, which have practical relevance to what many athletes do in training or competition.
  • Jones, A., Cameron, S., Thatcher, R., Beecroft, M., Mur, L. and Davison, G. (2014). Effects of bovine colostrum supplementation on upper respiratory illness in active males. Brain, behavior, and immunity [Online] 39:194-203. Available at: http://dx.doi.org/10.1016/j.bbi.2013.10.032.
    Bovine colostrum (COL) has been advocated as a nutritional countermeasure to exercise-induced immune dysfunction and increased risk of upper respiratory illness (URI) in athletic populations, however, the mechanisms remain unclear. During winter months, under double-blind procedures, 53 males (mean training load±SD, 50.5±28.9 MET-hweek(-1)) were randomized to daily supplementation of 20g of COL (N=25) or an isoenergetic/isomacronutrient placebo (PLA) (N=28) for 12weeks. Venous blood was collected at baseline and at 12weeks and unstimulated saliva samples at 4 weeks intervals. There was a significantly lower proportion of URI days and number of URI episodes with COL compared to PLA over the 12weeks (p<0.05). There was no effect of COL on in vitro neutrophil oxidative burst, salivary secretory IgA or salivary antimicrobial peptides (p>0.05), which does not support previously suggested mechanisms. In a subset of participants (COL=14, PLA=17), real-time quantitative PCR, targeting the 16S rRNA gene showed there was an increase in salivary bacterial load over the 12 weeks period with PLA (p<0.05) which was not as evident with COL. Discriminant function analysis of outputs received from serum metabolomics showed changes across time but not between groups. This is the first study to demonstrate that COL limits the increased salivary bacterial load in physically active males during the winter months which may provide a novel mechanism of immune-modulation with COL and a relevant marker of in vivo (innate) immunity and risk of URI.
  • Tumilty, L., Davison, G., Beckmann, M. and Thatcher, R. (2014). Failure of oral tyrosine supplementation to improve exercise performance in the heat. Medicine and science in sports and exercise [Online] 46:1417-1425. Available at: http://dx.doi.org/10.1249/MSS.0000000000000243.
    PURPOSE

    Acute oral tyrosine administration has been associated with increased constant-load, submaximal exercise capacity in the heat. This study sought to determine whether self-paced exercise performance in the heat is enhanced with the same tyrosine dosage.

    METHODS

    After familiarization, seven male endurance-trained volunteers, unacclimated to exercise in the heat, performed two experimental trials in 30°C (60% relative humidity) in a crossover fashion separated by at least 7 d. Subjects ingested 150 mg·kg(-1) body mass tyrosine (TYR) or an isocaloric quantity of whey powder (PLA) in 500 mL of sugar-free flavored water in a randomized, double-blind fashion. Sixty minutes after drink ingestion, the subjects cycled for 60 min at 57% ± 4% peak oxygen uptake (VO2peak) and then performed a simulated cycling time trial requiring completion of an individualized target work quantity (393.1 ± 39.8 kJ).

    RESULTS

    The ratio of plasma tyrosine plus phenylalanine (tyrosine precursor) to amino acids competing for brain uptake (free-tryptophan, leucine, isoleucine, valine, methionine, threonine, and lysine) increased 2.5-fold from rest in TYR and remained elevated throughout exercise (P < 0.001), whereas it declined in PLA from rest to preexercise (P = 0.004). Time-trial power output (P = 0.869) and performance (34.8 ± 6.5 and 35.2 ± 8.3 min in TYR and PLA, respectively; P = 0.4167) were similar between trials. Thermal sensation (P > 0.05), RPE (P > 0.05), core temperature (P = 0.860), skin temperature (P = 0.822), and heart rate (P = 0.314) did not differ between trials.

    CONCLUSIONS

    These data indicate that acute tyrosine administration did not influence self-paced endurance exercise performance in the heat. Plasma tyrosine availability is apparently not a key determinant of fatigue processes under these conditions.
  • Davison, G. and Jones, A. (2014). Oral neutrophil responses to acute prolonged exercise may not be representative of blood neutrophil responses. Applied Physiology, Nutrition and Metabolism [Online]. Available at: http://dx.doi.org/10.1139/apnm-2014-0396.
  • Hudson, J., Davison, G. and Robinson, P. (2013). Psychophysiological and stress responses to competition in team sport coaches: an exploratory study. Scandinavian journal of medicine & science in sports [Online] 23:e279-85. Available at: http://onlinelibrary.wiley.com/doi/10.1111/sms.12075/suppinfo.
    Examinations of stress in coaches have mainly been qualitative and focused on chronic stressors. This exploratory study examined stress responses in coaches during competition, including psychological and physiological indices. Using reversal theory, we examined metamotivational state profiles during competition. Ten male team sport coaches (mean age 39.8 ± 13.12 years) reported levels of subjective stress, pleasant and unpleasant emotions, metamotivational state, and provided saliva samples, on a competition day: 15 min prior to the pre-match team talk; start of the match; end of the first half; start of the second half, and end of the match, then at equivalent times on a noncompetition day. Saliva samples were assayed for alpha-amylase activity. On competition day, alpha-amylase activity was significantly higher, as were subjective stress, arousal, and unpleasant emotions. Prior to and during active play, participants were mainly in the conformist, alloic (other-oriented), and mastery states, and at the end of the match, in the telic and sympathy states. Only 22 metamotivational state reversals were observed, mostly at the start and end of the match. The elevated levels of subjective stress, alpha-amylase activity, and unpleasant emotions suggest that educational programs may be useful for some coaches to manage psychological states during competition.
  • Tumilty, L., Davison, G., Beckmann, M. and Thatcher, R. (2013). Acute oral administration of a tyrosine and phenylalanine-free amino acid mixture reduces exercise capacity in the heat. European journal of applied physiology [Online] 113:1511-22. Available at: http://dx.doi.org/10.1007/s00421-012-2577-4.
    Acute tyrosine administration is associated with increased exercise capacity in the heat. To explore whether reduced plasma tyrosine and phenylalanine (tyrosine precursor) is associated with impaired exercise capacity in the heat, eight healthy, moderately trained male volunteers, unacclimated to exercise in the heat, performed two tests in a crossover design separated by at least 7 days. In a randomised, double-blind fashion, subjects ingested 500 mL flavoured, sugar-free water containing amino acids [(TYR-free; isoleucine 15 g, leucine 22.5 g, valine 17.5 g, lysine 17.5 g, methionine 5 g, threonine 10 g, tryptophan 2.5 g)] to lower the ratio of plasma tyrosine plus phenylalanine:amino acids competing for blood-brain barrier uptake (CAA), a key determinant of brain uptake, or a balanced mixture (BAL; TYR-free plus 12.5 g tyrosine and 12.5 g phenylalanine). One hour later, subjects cycled to exhaustion at 63 ± 5 % [Formula: see text]O2peak in 30 °C and 60 % relative humidity. Pre-exercise ratio of plasma tyrosine plus phenylalanine:?CAA declined 75 ± 5 % from rest in TYR-free (P < 0.001), but was unchanged in BAL (P = 0.061). Exercise time was shorter in TYR-free (59.8 ± 19.0 min vs. 66.2 ± 16.9 min in TYR-free and BAL respectively; P = 0.036). Heart rate (P = 0.298), core (P = 0.134) and skin (P = 0.384) temperature, RPE (P > 0.05) and thermal sensation (P > 0.05) were similar at exhaustion in both trials. These data indicate that acutely depleting plasma catecholamine precursors:?CAA is associated with reduced submaximal exercise capacity in the heat.
  • Wright, B. and Davison, G. (2013). Carbohydrate Mouth Rinse Improves 1.5 h Run Performance: Is There a Dose-Effect?. International Journal of Exercise Science [Online] 6:328-340. Available at: http://digitalcommons.wku.edu/ijes/vol6/iss4/8/.
    There is a substantial body of recent evidence showing ergogenic effects of carbohydrate (CHO) mouth rinsing on endurance performance. However, there is a lack of research on the dose-effect and the aim of this study was to investigate the effect of two different concentrations (6% and 12% weight/volume, w/v) on 90 minute treadmill running performance. Seven active males took part in one familiarization trial and three experimental trials (90-minute self-paced performance trials). Solutions (placebo, 6% or 12% CHO-electrolyte solution, CHO-E) were rinsed in the mouth at the beginning, and at 15, 30 and 45 minutes during the run. The total distance covered was greater during the CHO-E trials (6%, 14.6 ± 1.7 km; 12%, 14.9 ± 1.6 km) compared to the placebo trial (13.9 ± 1.7 km, P < 0.05). There was no significant difference between the 6% and 12% trials (P > 0.05). There were no between trial differences (P > 0.05) in ratings of perceived exertion (RPE) and feeling or arousal ratings suggesting that the same subjective ratings were associated with higher speeds in the CHO-E trials. Enhanced performance in the CHO-E trials was due to higher speeds in the last 30 minutes even though rinses were not provided during the final 45 minutes, suggesting the effects persist for at least 20-45 minutes after rinsing. In conclusion, mouth rinsing with a CHO-E solution enhanced endurance running performance but there does not appear to be a dose-response effect with the higher concentration (12%) compared to a standard 6% solution.
  • Davison, G. (2013). Bovine colostrum and immune function after exercise. Medicine and sport science [Online] 59:62-69. Available at: http://dx.doi.org/10.1159/000341966.
    Strenuous and/or prolonged exercise causes transient perturbations in immune function. It is well accepted that this is one mechanism contributing to the higher occurrence of infection (e.g. upper respiratory tract infection (URTI)) in athletes, especially endurance athletes. URTI or upper respiratory tract (URT) symptoms can negatively affect training and competition performance but athletes must train intensively to be successful. Therefore, interventions that can legitimately enhance immune function and reduce URTI risk can be of benefit to athletes. Bovine colostrum supplementation has been investigated as a possible nutritional countermeasure to enhance (or maintain) immune function, and reduce URTI risk, following strenuous or prolonged exercise and during intensive training periods. There is convincing evidence that daily supplementation with bovine colostrum, for a number of weeks (and preliminary evidence for acute effects after a single dose), can maintain intestinal barrier integrity, immune function and reduce the chances of suffering URTI or URT symptoms in athletes or those undertaking heavy training. The mechanisms are not fully understood at present but there is preliminary evidence suggesting that the effects on immune function are attributable, at least in part, to small bioactive components that survive digestion and are biologically available after consumption, but further work is required. In summary, the balance of existing evidence does support the notion that bovine colostrum is beneficial for certain groups of athletes, such as those involved in strenuous training (e.g. endurance athletes), in terms of immunity and resistance to infection.
  • Davison, G., Callister, R., Williamson, G., Cooper, K. and Gleeson, M. (2012). The effect of acute pre-exercise dark chocolate consumption on plasma antioxidant status, oxidative stress and immunoendocrine responses to prolonged exercise. European Journal of Nutrition [Online] 51:69-79. Available at: http://dx.doi.org/10.1007/s00394-011-0193-4.
    Purpose Acute antioxidant supplementation may modulate oxidative stress and some immune perturbations that typically occur following prolonged exercise. The aims of the present study were to examine the effects of acutely consuming dark chocolate (high polyphenol content) on plasma antioxidant capacity, markers of oxidative stress and immunoendocrine responses to prolonged exercise. Methods Fourteen healthy men cycled for 2.5 h at ~60% maximal oxygen uptake 2 h after consuming 100 g dark chocolate (DC), an isomacronutrient control bar (CC) or neither (BL) in a randomised-counterbalanced design. Results DC enhanced pre-exercise antioxidant status (P = 0.003) and reduced by trend (P = 0.088) 1 h post-exercise plasma free F2-isoprostane compared with CC (also, F2-isoprostane increased post-exercise in CC and BL but not DC trials). Plasma insulin concentration was significantly higher pre-exercise (P = 0.012) and 1 h post-exercise (P = 0.026) in the DC compared with the CC trial. There was a better maintenance of plasma glucose concentration on the DC trial (2-way ANOVA trial {$\times$} time interaction P = 0.001), which decreased post-exercise in all trials but was significantly higher 1 h post-exercise (P = 0.039) in the DC trial. There were no between trial differences in the temporal responses (trial {$\times$} time interactions all P {\ensuremath{>}} 0.05) of hypothalamic?pituitary?adrenal axis stress hormones, plasma interleukin-6, the magnitude of leukocytosis and neutrophilia and changes in neutrophil function. Conclusion Acute DC consumption may affect insulin, glucose, antioxidant status and oxidative stress responses, but has minimal effects on immunoendocrine responses, to prolonged exercise.
  • Burnley, M., Davison, G. and Baker, J. (2011). Effects of priming exercise on VO2 kinetics and the power-duration relationship. Medicine and science in sports and exercise [Online] 43:2171-9. Available at: http://dx.doi.org/10.1249/MSS.0b013e31821ff26d.
    PURPOSE

    This study aimed to investigate the influence of prior heavy- and severe-intensity exercise on the oxygen uptake (V·O?) kinetics and the power-duration relationship.

    METHODS

    Ten cyclists performed 13 exercise tests during a 4-wk period, consisting of a ramp test to determine the gas exchange threshold (GET) and the peak V·O?, followed by a series of square-wave tests to exhaustion under three conditions: no prior exercise (control), prior heavy exercise (6 min at a work rate above GET but below critical power [CP)], and prior severe exercise (6 min at a work rate above the CP). Pulmonary gas exchange was measured throughout the exhaustive exercise bouts and the parameters of the power-duration relationship (CP and the curvature constant, W') were determined from the linear work-time model.

    RESULTS

    Prior heavy exercise increased the amplitude of the primary V·O? response (by ? 0.19 ± 0.28 L·min(-1), P = 0.001), reduced the V·O? slow component trajectory (by 0.04 ± 0.09 L·min(-2), P = 0.002), and increased the time to exhaustion (by ? 52 ± 92 s, P = 0.005). The CP was unchanged (control vs prior heavy: 284 ± 47 vs 283 ± 44 W; 95% confidence interval, -7 to 5 W), whereas the W' was increased by heavy-intensity priming (16.0 ± 4.8 vs 18.7 ± 4.8 kJ; 95% confidence interval, 0.3-5.2 kJ). Severe-intensity exercise had a similar effect on the V·O? kinetics but had no effect on the time to exhaustion, the CP (275 ± 45 W), or the W' (16.7 ± 4.7 kJ).

    CONCLUSIONS

    Prior heavy-intensity exercise primes the V·O? kinetics and increases the amount of work that can be performed above the CP.
  • Davison, G. (2011). Innate immune responses to a single session of sprint interval training. Applied physiology, nutrition, and metabolism [Online] 36:395-404. Available at: http://dx.doi.org/10.1139/h11-033.
    Sprint interval training (SIT) is a potent stimulus for physiological and metabolic adaptations comparable with those induced by traditional "aerobic" endurance training. There has been a great deal of recent research on SIT, which may lead to increased use of this type of training. The purpose of the present study was to determine the acute effects of SIT on aspects of innate immunity not previously researched in this context. Nine males completed 1 SIT and 1 resting control trial in a crossover design. Blood and saliva samples were obtained at pre-, post-, and 30 min postexercise to measure blood neutrophil oxidative burst activity (OBA) in addition to saliva secretary IgA (s-IgA) and lysozyme. SIT induced a significant depression of neutrophil fMLP-stimulated OBA (-30% for the 30-min postexercise time point, p < 0.01), PMA-stimulated OBA (-14% for the postexercise time point, -21% for the 30-min postexercise time point, p < 0.01), and bacterial-stimulated degranulation (-23% for the postexercise time point, -32% for the 30-min postexercise time point, p < 0.01) but not fMLP-then-PMA-stimulated OBA, saliva lysozyme, or s-IgA concentrations or secretion rates (p > 0.05). The main novel finding of the present study is that a single session of SIT causes significant exercise-induced immunodepression of some neutrophil functions but mucosal immunity was not depressed.
  • Tumilty, L., Davison, G., Beckmann, M. and Thatcher, R. (2011). Oral tyrosine supplementation improves exercise capacity in the heat. European journal of applied physiology 111:2941-2950.
    Increased brain dopamine availability improves prolonged exercise tolerance in the heat. It is unclear whether supplementing the amino-acid precursor of dopamine increases exercise capacity in the heat. Eight healthy male volunteers [mean age 32 ± 11 (SD) years; body mass 75.3 ± 8.1 kg; peak oxygen uptake ([Formula: see text]) 3.5 ± 0.3 L min(-1)] performed two exercise trials separated by at least 7 days in a randomised, crossover design. Subjects consumed 500 mL of a flavoured sugar-free drink (PLA), or the same drink with 150 mg kg body mass(-1) tyrosine (TYR) in a double-blind manner 1 h before cycling to exhaustion at a constant exercise intensity equivalent to 68 ± 5% [Formula: see text] in 30°C and 60% relative humidity. Pre-exercise plasma tyrosine:large neutral amino acids increased 2.9-fold in TYR (P < 0.01), while there was no change in PLA (P > 0.05). Subjects cycled longer in TYR compared to PLA (80.3 ± 19.7 min vs. 69.2 ± 14.0 min; P < 0.01). Core temperature, mean weighted skin temperature, heart rate, ratings of perceived exertion and thermal sensation were similar in TYR and PLA during exercise and at exhaustion (P > 0.05) despite longer exercise time in TYR. The results show that acute tyrosine supplementation is associated with increased endurance capacity in the heat in moderately trained subjects. The results also suggest for the first time that the availability of tyrosine, a nutritional dopamine precursor, can influence the ability to subjectively tolerate prolonged submaximal constant-load exercise in the heat.
  • Marchbank, T., Davison, G., Oakes, J., Ghatei, M., Patterson, M., Moyer, M. and Playford, R. (2011). The nutriceutical bovine colostrum truncates the increase in gut permeability caused by heavy exercise in athletes. American Journal of Physiology: Gastrointestinal and liver physiology [Online] 300:G477-84. Available at: http://dx.doi.org/10.1152/ajpgi.00281.2010.
    Heavy exercise causes gut symptoms and, in extreme cases, "heat stroke" partially due to increased intestinal permeability of luminal toxins. We examined bovine colostrum, a natural source of growth factors, as a potential moderator of such effects. Twelve volunteers completed a double-blind, placebo-controlled, crossover protocol (14 days colostrum/placebo) prior to standardized exercise. Gut permeability utilized 5 h urinary lactulose-to-rhamnose ratios. In vitro studies (T84, HT29, NCM460 human colon cell lines) examined colostrum effects on temperature-induced apoptosis (active caspase-3 and 9, Bax?, Bcl-2), heat shock protein 70 (HSP70) expression and epithelial electrical resistance. In both study arms, exercise increased blood lactate, heart rate, core temperature (mean 1.4°C rise) by similar amounts. Gut hormone profiles were similar in both arms although GLP-1 levels rose following exercise in the placebo but not the colostrum arm (P = 0.026). Intestinal permeability in the placebo arm increased 2.5-fold following exercise (0.38 ± 0.012 baseline, to 0.92 ± 0.014, P < 0.01), whereas colostrum truncated rise by 80% (0.38 ± 0.012 baseline to 0.49 ± 0.017) following exercise. In vitro apoptosis increased by 47-65% in response to increasing temperature by 2°C. This effect was truncated by 60% if colostrum was present (all P < 0.01). Similar results were obtained examining epithelial resistance (colostrum truncated temperature-induced fall in resistance by 64%, P < 0.01). Colostrum increased HSP70 expression at both 37 and 39°C (P < 0.001) and was truncated by addition of an EGF receptor-neutralizing antibody. Temperature-induced increase in Bax? and reduction in Bcl-2 was partially reversed by presence of colostrum. Colostrum may have value in enhancing athletic performance and preventing heat stroke.
  • Davison, G. and Diment, B. (2010). Bovine colostrum supplementation attenuates the decrease of salivary lysozyme and enhances the recovery of neutrophil function after prolonged exercise. British journal of nutrition [Online] 103:1425-32. Available at: http://dx.doi.org/10.1017/S0007114509993503.
    Oral supplementation with bovine colostrum (COL) has been shown to enhance immunity in human subjects. However, there is limited research on the use of bovine COL supplementation to counter exercise-induced immunodepression, as a model of stress-induced immunodepression, and previous research has focused primarily on salivary IgA. The aim of the present study was to determine the effects of bovine COL supplementation on exercise-induced changes in innate immunity (neutrophil function and salivary lysozyme) in addition to salivary IgA. Twenty healthy, active men cycled for 2 h at approximately 64 % maximal oxygen uptake after 4 weeks of daily bovine COL (n 10) or placebo (PLA, n 10) supplementation. Blood and saliva samples were obtained before and after supplementation, before and after exercise. Exercise induced significant increases in markers of physiological stress and stress to the immune system (circulating neutrophils, neutrophil:lymphocyte ratio, immature granulocytes, atypical lymphocytes and plasma cortisol), but there were no differences between the COL and PLA groups. Significant group x time interactions (two-way mixed model ANOVA) were observed for neutrophil function (stimulated degranulation) and salivary lysozyme concentration and release (P < 0.05). Significant exercise-induced decreases were observed in these parameters, and bovine COL supplementation either speeded the recovery (neutrophil function) or prevented the decrease (salivary lysozyme) in these measures of innate immunity. These results suggest that 4 weeks of bovine COL supplementation limits the immunodepressive effects induced by an acute prolonged physical stressor, such as exercise, which may confer some benefits to host defence.
  • Davison, G., Allgrove, J. and Gleeson, M. (2009). Salivary antimicrobial peptides (LL-37 and alpha-defensins HNP1-3), antimicrobial and IgA responses to prolonged exercise. European journal of applied physiology [Online] 106:277-84. Available at: http://dx.doi.org/10.1007/s00421-009-1020-y.
    There are many factors in mucosal secretions that contribute to innate immunity and the 'first line of defence' at mucosal surfaces. Few studies, however, have investigated the effects of exercise on many of these 'defence' factors. The aim of the present study was to determine the acute effects of prolonged exercise on salivary levels of selected antimicrobial peptides (AMP) that have not yet been studied in response to exercise (HNP1-3 and LL-37) in addition to immunoglobulin A (IgA). A secondary objective was to assess the effects of exercise on saliva antibacterial capacity. Twelve active men exercised on a cycle ergometer for 2.5 h at approximately 60% of maximal oxygen uptake. Unstimulated whole saliva samples were obtained before and after exercise. There was a significant decrease (P < 0.05) in salivary IgA:osmolality ratio, following exercise, but IgA concentration and secretion rate were unaltered. Salivary HNP1-3 and LL-37 concentrations (P < 0.01 and P < 0.05, respectively), concentration:osmolality ratios (P < 0.01) and secretion rates (P < 0.01) all increased following exercise. Salivary antibacterial capacity (against E. coli) did not change. The increased concentration of AMPs in saliva may confer some benefit to the 'first line of defence' and could result from synergistic compensation within the mucosal immune system and/or airway inflammation and epithelial damage. Further study is required to determine the significance of such changes on the overall 'defence' capacity of saliva and how this influences the overall risk for infection.

Book section

  • Davison, G. (2014). Sports Nutrition and Dairy Products. In: Kanekanian, A. ed. Milk and Dairy Products As Functional Foods. Wiley-Blackwell, pp. 147-173.
  • Allgrove, J. and Davison, G. (2014). Dark Chocolate/Cocoa Polyphenols and Oxidative Stress. In: Watson, R. R., Preedy, V. R. and Zibadi, S. eds. Polyphenols in Human Health and Disease. Elsevier, pp. 241-251. Available at: http://www.sciencedirect.com/science/article/pii/B9780123984562000190.
  • Davison, G. and Simpson, R. (2011). Immunity. In: Lanham-New, S. A., Stear, S., Shirreffs, S. and Collins, A. eds. Sport and Exercise Nutrition. Wiley-Blackwell, pp. 281-303.

Conference or workshop item

  • Hynes, E. and Davison, G. (2017). MUCOSAL IMMUNE MARKERS IN PROFESSIONAL ENGLISH FOOTBALL PLAYERS. In: 13th Symposium of the International Society of Exercise Immunology (ISEI). Available at: http://isei.dk/index.php?pageid=21.
  • Jones, A., Mironas, A., Mur, L., Beckmann, M., Thatcher, R. and Davison, G. (2017). VITAMIN D STATUS MODULATES INNATE IMMUNE RESPONSES AND METABOLIC PROFILES FOLLOWING ACUTE PROLONGED CYCLING. In: 13th Symposium of the International Society of Exercise Immunology (ISEI). International Society of Exercise Immunology, pp. 100-102. Available at: http://isei.dk/index.php?pageid=21.
  • Hynes, E. and Davison, G. (2017). Reactivation of Epstein-Barr virus following prolonged cycling. In: 13th Symposium of the International Society of Exercise Immunology (ISEI). International Society of Exercise Immunology, pp. 152-153. Available at: http://isei.dk/index.php?pageid=21.
  • Jones, A. and Davison, G. (2017). NO EFFECT OF ACUTE OR CHRONIC BOVINE COLOSTRUM SUPPLEMENTATION ON CIRCULATING INSULIN-LIKE GROWTH FACTOR-I. In: 13th Symposium of the International Society of Exercise Immunology (ISEI). Available at: http://isei.dk/index.php?pageid=21.
  • Tumilty, L., Thatcher, R., Beckmann, M. and Davison, G. (2015). No effect of oral tyrosine administration on mood and motivation or heart rate variability during endurance performance in the heat. In: 20th Annual Congress of the European College of Sport Science. Available at: http://ecss-congress.eu/2015/15/.
  • Davison, G., Dyer, J., Marcora, S. and Mauger, A. (2015). Effect of a Mediterranean diet on inflammatory and cartilage degradation markers in osteoarthritis. In: 20th Annual Congress of the European College of Sport Science. Available at: http://ecss-congress.eu/2015/15/.
  • Curtis, F., Rice, S., Thatcher, R. and Davison, G. (2015). Associations between vitamin D status and measures of glycaemia in participants with normoglycaemia, impaired fasting glucose and type 2 diabetes. In: Diabetes UK Annual Conference. Available at: http://emjreviews.com/events/diabetes-uk-professional-conference-2015/.
  • March, D., Thatcher, R., Marchbank, T., Playford, R. and Davison, G. (2014). 2 days of bovine colostrum supplementation did not blunt the exercise induced increase in intestinal permeability. In: 19th Annual Congress of the European College of Sport Science.
  • Tumilty, L., Davison, G., Beckmann, M. and Thatcher, R. (2014). Acute oral tyrosine supplementation does not prevent the decline in maximal handgrip force in hyperthermic subjects. In: 19th Annual Congress of the European College of Sport Science.
  • Jones, A., Thatcher, R. and Davison, G. (2014). The effects of bovine colostrum supplementation on in vivo cell-mediated immune response following prolonged exercise. In: 19th Annual Congress of the European College of Sport Science.
  • Lewis, K., Robinson, R., Mohammed, P., Davison, G. and Jones, A. (2014). Neutrophil function in COPD. In: Cardiff Chest Federation/Welsh Thoracic Society Meeting.
  • March, D., Thatcher, R., Marchbank, T., Playford, R. and Davison, G. (2014). Two days of bovine colostrum supplementation did not blunt the exercise induced increase in intestinal permeability. In: Welsh Exercise Medicine Symposium.
  • Jones, A., Cameron, S., Thatcher, R., Beecroft, M., Mur, L. and Davison, G. (2013). Exploring the mechanisms behind the effects of chronic bovine colostrum supplementation on risk of upper respiratory tract infection. In: International Society of Exercise and Immunology Symposium.
  • Davison, G. and Jones, A. (2012). Effect of prolonged exercise on oral and blood neutrophil function. In: 17th Annual Congress of the European College of Sport Science.
  • Tumilty, L., Davison, G., Beckmann, M. and Thatcher, R. (2012). Acute oral tyrosine administration does not improve exercise performance in the heat in man. In: The Physiological Basis of Elite Performance: The Physiological Society.
  • Tumilty, L., Davison, G., Beckmann, M. and Thatcher, R. (2011). A tyrosine and phenylalanine-free amino acid mixture decreases exercise capacity in the heat. In: The British Association of Sport and Exercise Sciences Annual Conference.
  • Jones, A., Thatcher, R. and Davison, G. (2011). The effect of acute bovine colostrum supplementation on neutrophil responses to prolonged cycling. In: 10th Symposium of the International Society of Exercise and Immunology.
  • Davison, G., Thatcher, R. and Jones, A. (2011). Acute bovine colostrum supplementation enhances neutrophil oxidative burst at rest and following immunodepressive exercise: a pilot study. In: 10th Symposium of the International Society of Exercise and Immunology.
  • Davison, G., Thatcher, R. and Jones, A. (2011). Effect of prolonged exercise on oxidative burst function of peripheral blood and oral neutrophils: A pilot study. In: 10th Symposium of the International Society of Exercise and Immunology.
  • Marchbank, T., Davison, G., Oakes, J., Ghatei, M., Patterson, M., Rolfs, J. and Playford, R. (2010). Clinical trial: influence of bovine colostrum on intestinal permeability in healthy athletes after heavy exercise. In: British Society of Gastroenterology Annual General Meeting. Available at: http://gut.bmj.com/cgi/content/meeting_abstract/59/1_MeetingAbstracts/A34-a.
    Introduction: Heavy exercise results in gut symptoms and in extreme cases "heat stroke" due, in part, to increased intestinal permeability of luminal toxins. We examined if bovine colostrum a rich source of growth factors and immune modulators could prevent these permeability changes.

    Methods: Twelve healthy volunteers completed a double-blind, placebo-controlled, crossover protocol (14 days colostrum or placebo) prior to standardised exercise. Gut permeability utilised 5 h urinary lactulose: rhamnose ratios. In vitro studies (T84 cells) examined effects of colostrum on temperature-induced apoptosis (active caspase-3) and epithelial resistance.

    Results: For both arms of study, exercise increased the blood lactate, heart rate, core temperature (mean 2°C rise) and plasma VIP by similar amounts. However, GLP-1 plasma levels results were discordant; rising by 88.7 pmol/l in placebo arm but falling by 4.2 pmol/l in colostrum arm (p=0.026). Intestinal permeability in placebo arm increased 2.5-fold following exercise (0.38±0.012 baseline value, to 0.92±0.014, p<0.01), whereas colostrum truncated this rise by 80% (only rising from 0.38±0.012, initial baseline value, to 0.49±0.017) following exercise. In vitro apoptosis increased by 63% in response to increasing temperature by 2°C whereas this effect was truncated by 66% if colostrum was co-present (all p<0.01). Similar results were obtained when changes in epithelial resistance were assessed (colostrum truncating the fall in resistance by 64%, p<0.01).

    Conclusion: Bovine colostrum reduced exercise-induced increase in gut permeability, possibly through mechanisms including reducing temperature-induced apoptosis. This may have value in enhancing athletic performance and preventing heat stroke.
  • Davison, G. (2009). A single session of Sprint Interval Training impairs neutrophil function. In: 9th Symposium of the International Society of Exercise and Immunology.
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