Purpose: Training with low carbohydrate (CHO) availability is suggested to enhance the adaptation to exercise, but no studies have investigated this within an elite population. Therefore, this study aimed to determine whether periodic CHO restricted training in elite athletes would increase fibre type-specific mitochondrial content and capillarisation. Methods: In a previous study (Gejl et al. 2017), 19 male elite triathletes (VO2max 65.0 mL.kg-1.min-1) took part in 4 weeks of training supplemented with either low CHO (three days per week) (LOW, n = 12) or energy-matched CHO enriched training (HIGH, n = 7). The CHO manipulation days consisted of a morning high intensity interval cycling session to deplete muscle glycogen followed by 7 h of recovery in which subjects consumed energy-matched diets containing either high (6 g CHO.kg bm-1) or low CHO (1 g CHO.kg bm-1). Subjects then completed a 2 h moderate-intensity cycle either with low or high CHO availability. Muscle biopsies obtained pre and post-training were used to determine fibre type-specific mitochondrial content (COXIV) and capillarisation using immunofluorescence microscopy. Statistical significance was set at 0.05 confidence level and parameters were assessed using two-way mixed design ANOVAs. Results. Training increased COXIV expression in both type I (LOW +22%, HIGH +20%) and type II (LOW +22%, HIGH +21%; P < 0.001), with no difference between groups. Training also increased capillary density (LOW +9%, HIGH +14%; P = 0.001) with no difference between groups. Capillary-fibre perimeter exchange ratio (CFPER) also significantly increased with training in both type I (LOW +14%, HIGH +14%) and type II (LOW +9%, HIGH +11%; P = 0.006) with no difference between groups. Conclusion. These results demonstrate for the first time that periodically training with low CHO availability has no additional benefits to fibre type-specific training adaptations in elite triathletes. Interestingly though, the training intervention induced significant increases to both mitochondrial content and capillarisation even within highly-trained endurance athletes. Future studies should aim to determine whether exercising with low CHO availability can enhance the adaptive response to training and expand health-span in older less trained populations.