Circulating angiogenic cell response to sprint interval and continuous exercise.

INTRODUCTION: 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 ± 2 years, BMI 25.5 ± 0.9 kg m- 2, [Formula: see text]peak 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 6 × 20 s sprints on a cycle ergometer, in a counterbalanced design. Blood was sampled pre-, post-, 2 h and 24 h post-exercise 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 24 h. Tie2-expressing classical (CD14++CD16-), intermediate (CD14++CD16+) and non-classical (CD14+CD16++) monocytes and circulating CD34+CD45dim 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 2 h and 24 h. 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.

Keto-adaptation enhances exercise performance and body composition responses to training in endurance athletes.

BACKGROUND: Low-carbohydrate diets have recently grown in popularity among endurance athletes, yet little is known about the long-term (>4wk) performance implications of consuming a low-carbohydrate high fat ketogenic diet (LCKD) in well-trained athletes. METHODS: Twenty male endurance-trained athletes (age 33±11y, body mass 80±11kg; BMI 24.7±3.1kg/m2) who habitually consumed a carbohydrate-based diet, self-selected into a high-carbohydrate (HC) group (n=11, %carbohydrate:protein:fat=65:14:20), or a LCKD group (n=9, 6:17:77). Both groups performed the same training intervention (endurance, strength and high intensity interval training (HIIT)). Prior to and following successful completion of 12-weeks of diet and training, participants had their body composition assessed, and completed a 100km time trial (TT), six second (SS) sprint, and a critical power test (CPT). During post-intervention testing the HC group consumed 30-60g/h carbohydrate, whereas the LCKD group consumed water, and electrolytes. RESULTS: The LCKD group experienced a significantly greater decrease in body mass (HC -0.8kg, LCKD -5.9kg; P=0.006, effect size (ES): 0.338) and percentage body fat percentage (HC -0.7%, LCKD -5.2%; P=0.008, ES: 0.346). Fasting serum beta-hydroxybutyrate (ßHB) significantly increased from 0.1 at baseline to 0.5mmol/L in the LCKD group (P=0.011, ES: 0.403) in week 12. There was no significant change in performance of the 100km TT between groups (HC -1.13min·s, LCKD -4.07min·s, P=0.057, ES: 0.196). SS sprint peak power increased by 0.8 watts per kilogram bodyweight (w/kg) in the LCKD group, versus a -0.1w/kg reduction in the HC group (P=0.025, ES: 0.263). CPT peak power decreased by -0.7w/kg in the HC group, and increased by 1.4w/kg in the LCKD group (P=0.047, ES: 0.212). Fat oxidation in the LCKD group was significantly greater throughout the 100km TT. CONCLUSIONS: Compared to a HC comparison group, a 12-week period of keto-adaptation and exercise training, enhanced body composition, fat oxidation during exercise, and specific measures of performance relevant to competitive endurance athletes.