Background:

To evaluate the effect of combined exercise training on metabolic control, physical fitness and quality of life in adolescents with type 1 diabetes. Design: A double-blind randomized controlled trial with patients receiving combined aerobic and strength or no training. Setting: University Hospital Ghent (Belgium). Subjects: Sixteen children with type 1 diabetes were randomized into a control group (n ¼ 8) and an intervention group (n ¼ 8). Interventions: Patients participated twice a week for 20 weeks in the combined aerobic and strength group. The control group continued their normal daily activities. Main measures: Before and after the intervention anthropometric variables (weight, length, BMI, body composition), metabolic control (glycaemia, HbA1c, daily insulin injected), aerobic capacity (peak Vo 2 , peak power, peak heart rate, 6-minute walk distance), strength (1 repetition maximum of upper and lower limb, hand grip strength, muscle fatigue resistance, sit-to-stand) and quality of life (SF-36) were assessed. Results: At baseline, none of the measured parameters differed significantly between the two groups. There was no significant evolution in the groups concerning anthropometric indices, glycaemia and HbA1c. However, the daily doses of insulin injected were significantly lowered in the training group (0.96 IU/kg.day pre versus 0.90 IU/kg.day post; P50,05), while it was increased in the control group. Physical fitness increased significantly in the training group. General health, vitality and role emotional had a tendency to improve. Conclusion: Combined exercise training seemed to lower daily insulin requirement and improve physical fitness, together with better well-being.

Orally ingested SRBA has a very high whole body retention (97%-98%) that is not declining throughout the 5-wk supplementation period, nor is it influenced by the coingestion of macronutrients. Thus, a very small portion (1%-2%) is lost through urinary excretion, and equally only a small portion is incorporated into muscle carnosine (≈ 3%), indicating that most ingested BA is metabolized (possibly through oxidation). Second, in soleus muscles, the efficiency of carnosine loading is significantly higher when PBA is coingested with a meal (+64%) compared with in between the meals (+41%), suggesting that insulin stimulates muscle carnosine loading. Finally, the chronic supplementation of SRBA versus PBA seems equally effective.

We confirm that β-alanine, and not L-histidine, is the rate-limiting precursor for carnosine synthesis in human skeletal muscle. Yet, although L-histidine is not rate limiting, its availability is not unlimited and gradually declines upon chronic β-alanine supplementation. The significance of this decline still needs to be determined, but may affect physiological processes such as protein synthesis.