Elevated cfDNA after exercise is derived primarily from mature polymorphonuclear neutrophils, with a minor contribution of cardiomyocytes.

Strenuous physical exercise causes a massive elevation in the concentration of circulating cell-free DNA (cfDNA), which correlates with effort intensity and duration. The cellular sources and physiological drivers of this phenomenon are unknown. Using methylation patterns of cfDNA and associated histones, we show that cfDNA in exercise originates mostly in extramedullary polymorphonuclear neutrophils. Strikingly, cardiomyocyte cfDNA concentration increases after a marathon, consistent with elevated troponin levels and indicating low-level, delayed cardiac cell death. Physical impact, low oxygen levels, and elevated core body temperature contribute to neutrophil cfDNA release, while muscle contraction, increased heart rate, ß-adrenergic signaling, or steroid treatment fail to cause elevation of cfDNA. Physical training reduces neutrophil cfDNA release after a standard exercise, revealing an inverse relationship between exercise-induced cfDNA release and training level. We speculate that the release of cfDNA from neutrophils in exercise relates to the activation of neutrophils in the context of exercise-induced muscle damage.

Myokine levels after resistance exercise in young adults with Prader-Willi syndrome (PWS).

Individuals with PWS require marked caloric restriction and daily exercise to prevent morbid obesity. Lower energy expenditure, hypotonia, decreased muscle mass, and cognitive impairment make exercise challenging for this population. Exercise guidelines include resistance training as an important component. Myokine responses to resistance exercise may mediate beneficial metabolic effects. We aimed to determine if young PWS adults can perform a resistance exercise program and to measure myokine responses in PWS versus age- and BMI-matched controls. Each group included 11 participants (7M/4F). Ages and BMI for PWS and controls were 30.7 ± 4.6 versus 30.1 ± 4.3 years and 28.3 ± 4.3 versus 28.2 ± 4.2 kg/m2 , respectively. Glucose, creatine kinase (CK), lactate, and myokines were measured before, after, 30, and 60 min after completing eight resistance exercises. Myokines were assayed using a multiplex myokine panel (Merck Millipore). CK was lower in PWS versus controls (62 ± 16 vs.322 ± 100 U/L, p < .04). Peak lactate was 3.7 ± 0.7 in PWS versus 7.3 ± 0.7 mmol/Lin controls (p < .001). The increase in interleukin-6 was similar in PWS and controls (41 ± 16% and 35 ± 10%, respectively). Pre- and post-exercise levels of the six myokines assayed showed no consistent differences between the PWS and control participants. PWS young adults are capable of performing resistance/strength-building exercise. The lower CK and peak lactate levels in PWS may reflect decreased muscle mass in this population. Further studies are needed to determine optimal exercise regimens and assess the role of myokines incontributing to the metabolic phenotype of PWS.

Physical activity and maximal oxygen uptake in adults with Prader-Willi syndrome.

BACKGROUND: Prader-Willi Syndrome (PWS) is the most common genetic syndrome causing life-threatening obesity. Strict adherence to a low-calorie diet and regular physical activity are needed to prevent weight gain. Direct measurement of maximal oxygen uptake (VO2 max), the "gold standard" for assessing aerobic exercise capacity, has not been previously described in PWS. OBJECTIVES: Assess aerobic capacity by direct measurement of VO2 max in adults with PWS, and in age and BMI-matched controls (OC), and compare the results with values obtained by indirect prediction methods. METHODS AND PATIENTS: Seventeen individuals (12 males) age: 19-35 (28.6 ± 4.9) years, BMI: 19.4-38.1 (27.8 ± 5) kg/m2 with genetically confirmed PWS who exercise daily, and 32 matched OC (22 males) age: 19-36 (29.3 ± 5.2) years, BMI: 21.1-48.1 (26.3 ± 4.9) kg/m2. All completed a medical questionnaire and performed strength and flexibility tests. VO2 max was determined by measuring oxygen consumption during a graded exercise test on a treadmill. RESULTS: VO2 max (24.6 ± 3.4 vs 46.5 ± 12.2 ml/kg/min, p < 0.001) and ventilatory threshold (20 ± 2 and 36.2 ± 10.5 ml/kg/min, p < 0.001), maximal strength of both hands (36 ± 4 vs 91.4 ± 21.2 kg, p < 0.001), and flexibility (15.2 ± 9.5 vs 26 ± 11.1 cm, p = 0.001) were all significantly lower for PWS compared to OC. Predicted estimates and direct measurements of VO2 max were almost identical for the OC group (p = 0.995), for the PWS group, both methods for estimating VO2 max gave values which were significantly greater (p < 0.001) than results obtained by direct measurements. CONCLUSIONS: Aerobic capacity, assessed by direct measurement of VO2 max, is significantly lower in PWS adults, even in those who exercise daily, compared to OCs. Indirect estimates of VO2 max are accurate for OC, but unreliable in PWS. Direct measurement of VO2 should be used for designing personal training programs and in clinical studies of exercise in PWS.

The choice of freely preferred cadence by trained nonprofessional cyclists may not be characterized by mechanical efficiency.

BACKGROUND: Most cycling studies involve professional cyclists. Because training may affect riding style, it is of interest to determine the physiological basis for the personal choice of cycling cadence in nonprofessional cyclists. METHODS: Eleven nonprofessional (5.2±1.7-year-riding experience) male road cyclists, aged 35.0±11.0 years, underwent four separate laboratory test sessions. The first two sessions included habituation, anthropometry, V˙O2max,$\dot V{{\text{O}}_{\text{2}}}{\text{max}},$ and lactate threshold (LaTH) measurements. Freely preferred cadence at LaTH was determined during the second session (mean±SD=94.7±2.9 rev·min-1). During the third and fourth sessions participants performed LaTH tests at 60 and 95 rev·min-1 in a randomized order, with power output (PO) increments of 25 W every 4 min, up to ~90% of V˙O2max.$\dot V{{\text{O}}_{\text{2}}}{\text{max}}{\text{.}}$ Results: V˙O2,$\dot V{{\text{O}}_{\text{2}}},$ expired ventilation (V˙E),$({\dot V_E}),$ blood lactate (La), and calculated net mechanical efficiency (MEnet) rose with increased PO. At 95 rev·min-1, V˙O2, V˙E,$\dot V{{\text{O}}_2},{\text{ }}{\dot V_{\text{E}}},$ and La were significantly higher than at 60 rev·min-1 at all POs. MEnet at 95 rev·min-1 was lower than at 60 rev·min-1. Mean PO attained at LaTh did not differ significantly between 60 and 95 rev·min-1 (220.9±29.0 and 214.5±9.2 W, respectively). La values at LaTH were higher at 95 rev·min-1 than at 60 rev·min-1 (3.01±0.17 vs. 2.10±0.13 mM, p<0.05, respectively). CONCLUSIONS: Our findings indicate that mechanical and physiological efficiencies may not determine the choice of cycling cadence by nonprofessional cyclists. This choice may reflect the need to maintain endurance at the expense of riding at a lower than optimal riding efficiency.

[EXERCISE CAPACITY AND AEROBIC PHYSICAL FITNESS ASSESSMENT AMONG ADOLESCENTS AND ADULTS WITH CYSTIC FIBROSIS BY A QUESTIONNAIRE AND EXERCISE TESTS].

BACKGROUND: Physical exercise has been shown to improve lung condition or to slow deterioration in patients with cystic fibrosis (CF) and improves their quality of life. This study analyzes the physical exercise capacity and the level of aerobic fitness of adolescents and adults with CF who are patients at the CF Center at Hadassah Medical Center Mount Scopus in Jerusalem, Israel. OBJECTIVES: To assess physical exercise capacity and aerobic capacity levels among CF patients by a physical activity questionnaire in comparison to assessment by exercise tests. METHODS: The participants completed a physical activity questionnaire, performed the "6 minute walk test" and a cardio-pulmonary test on a treadmill. RESULTS: The study group included 36 patients, ages 12-43 years, who completed a physical activity questionnaire. Most patients (92%) reported engaging in physical exercise. Most of those who exercised (61%) did so at a low intensity, as described in CF research literature. The average weekly exercise time was 177 minutes; 35 patients completed a cardio-pulmonary exercise test and a "6 minute walk test". The cardio-pulmonary exercise tests showed that 34% of the participants had 'good to excellent' aerobic fitness, 26% had 'moderate' aerobic fitness and 40% had "poor to very poor" fitness. Males achieved significantly higher maximal oxygen uptake than females, even when there were no differences in the severity of disease. Similar to the differences in the general population, these differences showed that male patients had higher aerobic fitness and exercise capacities than female CF patients. A significant correlation was found between self-reported exercise time and exercise intensity in the questionnaire and maximal oxygen uptake in the cardio-pulmonary test (r = 0.5, P < 0.01). The physical activity questionnaire had 85% sensitivity for the identification of patients with low aerobic exercise capacity and specificity of only 50%. CONCLUSION: The physical activity questionnaire showed a good correlation with the exercise tests results. This questionnaire should be used as a health promotion tool to adapt exercise programs for each patient.