1.The results of studies during simple progressive exercise to exhaustion and steady-state submaximal exercise in 117 boys and girls aged 6-16 years are presented.2. In the simple progressive exercise test, the highest work load achieved and the submaximal heart rate were related to size and sex. The maximum heart rate and submaximal ventilation were largely independent of size and sex.3. Steady-state exercise was performed at one-third and two-thirds of the maximum work load achieved in the simple progressive test. The Indirect (CO,) Fick method was used to measure cardiac output. 4. At any given level of steady-state work, tidal volume, dead space, heart rate and stroke volume were closely related to size, with girls having higher heart rates and smaller stroke volumes than boys. Minute ventilation and cardiac output were virtually independent of size and sex. The cardiac output in children was the same as that in the adult for any given oxygen consumption. Blood lactate was related to size at any given work load, but was independent of size at any given fraction of the maximum working capacity.

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Introduction: Type 1 neurofibromatosis (NF1) belongs to the group of phacomatoses characterised by the formation of neurofibromas in the course of the nerves. In some cases, it may also lead to lesser known skeletal symptoms such as disturbances in calcium-phosphate metabolism and decreased bone mineral density. Aim of the study: The purpose of this work is to analyse possible skeletal complications in the course of neurofibromatosis, based on presentation of patients with NF1. Material and methods: The study included 10 children diagnosed with NF1 (seven girls and three boys), aged four to 17 years. Medical examinations including evaluation of any motor system abnormalities, anthropometric measurements of body height and weight (to evaluate the respective parameters, centile charts were used from the OLAF project), and bone densitometry using dual-energy X-ray absorptiometry (DXA) were performed. Calcium and phosphate metabolisms were assessed based on laboratory tests (concentration of vitamin D-25(OH)D, parathormone and alkaline phosphatase levels, and bone turnover markers). Results: Decreased body height was found in half of the patients (5/10). Typical dysplastic bone lesions were observed in 3/10 children. On densitometry, in nine out of 10 examined children a Z-score decrease to <-1.0 was observed, and in five children this value was ≤-2.0. Decreased 25(OH)D concentration was found in 7/10 examined children. In three out of 10 patients the osteocalcin level was increased. Conclusions: NF1 may jeopardise normal development and function of the skeletal system in children-both of the mineral and bone metabolism. Assessment of the motor system and of the calcium and phosphate metabolism should be part of extended diagnosis and monitoring of this disease. Risk factors for bone fractures in children with NF1 are low bone mass and decreased vitamin D concentration.