Previous studies have reported differences in muscle function and metabolism between patients with cystic fibrosis (CF) and healthy controls (HC), but it is currently unknown whether these abnormalities are specific to CF or also seen in other airway diseases. In this study, we used magnetic resonance spectroscopy (MRS) during exercise to assess muscle metabolism in CF patients. Twenty patients with CF and 20 age, gender, and habitual activity-matched HCs and a respiratory disease comparison group with primary ciliary dyskinesia (PCD; n ϭ 10) were studied.31 Phosphorus MRS ( 31 P-MRS) was used to characterize muscle bioenergetic metabolism at rest and after high-, moderate-, and low-intensity exercise. CF patients exhibited lower resting ATP/phosphocreatine (PCr) ratio and significantly higher end-exercise pH values compared with both HC and PCD patients. Both CF and PCD patients demonstrated significantly slower PCr recovery time constants after high-intensity exercise. Our results suggest that not only there are specific abnormalities of muscle metabolism in CF patients but also there is a nonspecific impact of respiratory disease on muscle function. (Pediatr Res 69: 40-45, 2011)

The study was undertaken to document cartilage and soft tissue changes/findings in ankles and knees of normal children of different age groups to be used for comparison in the assessment of children with haemophilia. Cartilage thickness and soft tissue changes were recorded at predetermined sites of ankles/knees on both US and MRI in healthy boys in three age groups: 7-9; 10-14; and 15-18 years. To assess the validity of the ultrasound and MRI measurements, an ex vivo study was done using agar phantoms with techniques and scanners similar to those applied in vivo. Twenty (48%) knees and 22 (52%) ankles of 42 boys, were evaluated. There was a reduction in the thickness of joint cartilage with age. A difference in cartilage measurements was noted in most sites between the age groups on both US and MRI (P < 0.05 each), but such difference was not noted for joint fluid in ankles or knees (P = 0.20, P = 0.68 or P = 0.75, P = 0.63 for US, MRI, respectively). Although cartilage measurements were smaller on US than on MRI for both ankles and knees (P < 0.05 each), this observation was not recorded for fluid in knees (P = 0.02). For diminutive measurements (2 mm) mean US measurements were smaller than corresponding phantom's measurements, P = 0.02. Age-related measurements were noted for cartilage thickness on US and MRI in ankles and knees. US measurements were smaller than corresponding MRI measurements at most joint sites, which were supported by results on small-diameter phantoms.

Context:Turner syndrome (TS) is a chromosomal disorder occurring in approximately 1 in 2500 live births. Individuals with TS report lower levels of physical activity than healthy control (HC) subjects. Cardiorespiratory limitations may contribute to the observed reduction in physical activity.Objective: The objective of this study was to compare muscle metabolism of patients with TS vs HC subjects before and after exercise using exercise testing, magnetic resonance imaging, and magnetic resonance spectroscopy techniques. Design:We hypothesized that girls and adolescents with TS would have muscle metabolic abnormalities not present in the HC population. Setting:The research was conducted at the Hospital for Sick Children in Toronto, Ontario, Canada.Participants: Fifteen participants with TS were age-, activity-, and body mass index Z-scorematched with 16 HC subjects. Main Outcome Measures:31 P magnetic resonance spectroscopy was used to characterize muscle metabolism at rest and after 30 seconds of high-intensity exercise, 60 seconds of moderate-intensity exercise, and 5 minutes of low-intensity exercise.Results: While achieving the same workloads, participants with TS exhibited a greater difference between rest and end-exercise pH compared with HC subjects after 30 seconds (TS, 0.29 Ϯ 0.04; HC, 0.21 Ϯ 0.08; P ϭ .03) and 90 seconds (TS, 0.47 Ϯ 0.22; HC, 0.32 Ϯ 0.13; P ϭ .02) of exercise. During the 5-minute exercise test, similar workloads were achieved between groups; however, ATP production was greater in participants with TS vs the HC subjects via all 3 bioenergetic pathways (total ATP: TS, 0.90 Ϯ 0.34; HC, 0.60 Ϯ 0.25; P ϭ .01). Conclusions:The results of this study suggest that patients with TS exhibit greater anaerobic stress during exercise than HC subjects, which may lead to symptoms of increased muscle fatigue with short bursts of activity. Recovery metabolism after exercise appears to be similar between participants with TS and HC subjects, which is suggestive of normal mitochondrial metabolism and oxygen transport. (J Clin Endocrinol Metab 98:

Results of this exploratory study suggest that MH-positive patients have impaired aerobic metabolism compared to healthy individuals. This could explain the exercise intolerance exhibited in MH-susceptible patient population.

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