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Although commonly understood as immune cells, certain T lymphocyte and monocyte subsets have angiogenic potential, contributing to blood vessel growth and repair. These cells are highly exercise responsive and may contribute to the cardiovascular benefits seen with exercise. Purpose: To compare the effects of a single bout of continuous (CONTEX) and sprint interval exercise (SPRINT) on circulating angiogenic cells (CAC) in healthy recreationally active adults. Methods: Twelve participants (aged 29 ±2y, BMI 25.5±0.9 kg. m-2 , ̇O 2peak 44.3±1.8 ml. kg-1. min-1 ; mean±SEM) participated in the study. Participants completed a 45 min bout of CONTEX at 70% peak oxygen uptake and 6x20 sec sprints on a cycle ergometer, in a counterbalanced design. Blood was sampled pre-, post-, 2h and 24h postexercise for quantification of CAC subsets by whole blood flow cytometric analysis. Angiogenic T lymphocytes (TANG) and angiogenic Tie2-expressing monocytes (TEM) were identified by the expression of CD31 and Tie2 respectively. Results: Circulating (cells. µL-1) CD3 + CD31 + TANG increased immediately post-exercise in both trials (p<0.05), with a significantly greater increase (p<0.05) following SPRINT (+57%) compared to CONTEX (+14%). Exercise increased (p<0.05) the expression of the chemokine receptor CXCR4 on TANG at 24h. Tie2-expressing classical (CD14 ++ CD16-), intermediate (CD14 ++ CD16 +) and non-classical (CD14 + CD16 ++) monocytes and circulating CD34 + CD45 dim progenitor cells were higher post-exercise in SPRINT, but unchanged in CONTEX. All post-exercise increases in SPRINT were back to pre-exercise levels at 2h and 24h. Conclusion: Acute exercise transiently increases circulating TANG, TEM and progenitor cells with greater increases evident following very high intensity sprint exercise than following prolonged continuous paced endurance exercise.

Low carbohydrate ketogenic diets (LCKD) where carbohydrate intake is <50 g/d have become popular is many populations, including endurance athletes (1) . The complete effect of this diet on nutrient absorption and its potential to influence health has not been fully uncovered (2) . A 14 day ketogenic diet in females demonstrated no effect on RBC, Hb or Hct levels in healthy females (3) , but longer duration research in an athletic population is lacking. The aim of the current research is to examine the effect of a LCKD versus a high carbohydrate diet, on blood count indicators of iron status in endurance athletes.Following ethical approval 19 participants selected into a high carbohydrate (HC) (65 % kcal CHO, 20 % kcal fat, 14 % kcal protein) or LCKD (>75 % kcal fat, 10-15 % kcal protein and <50 g/d CHO) group for 12 weeks. Participants also completed an endurance training protocol during the trial. Whole blood samples were analysed using the haematology analyser before and after selection into each dietary group. RM ANOVA was used to assess changes in indicators of iron status in participants over time. Paired t-tests assessed changed within group over time. RBC, Hb, and Hct significantly decreased over time. Within group Hct decreased between weeks 1 and 12 in the HC participants and Hb, MCH and MCHC decreased within the LCKD participants.Endurance training has been associated with increased plasma volume with exercise induced inflammation also implicated as a possible cause for iron deficiency in athletes (4) . It is possible the endurance training added during this trial had a similar effect on iron status within these participants. However it does not explain the difference in Hb, MCH and MCHC between HC and LCKD participants. Due to the effect iron status has on oxygen transport to muscle, further research is warranted to investigate the effect of a ketogenic diet on iron status in endurance athletes.