Size-adjusted muscle power and muscle metabolism in patients with cystic fibrosis are equal to healthy controls - a case control study

Skeletal muscle contributions to reduced fitness in cystic fibrosis youth

Background

Increased maximal oxygen uptake (V̇O_2max) is beneficial in children with cystic fibrosis (CF) but remains lower compared to healthy peers. Intrinsic metabolic deficiencies within skeletal muscle (muscle "quality") and skeletal muscle size (muscle "quantity") are both proposed as potential causes for the lower V̇O_2max, although exact mechanisms remain unknown. This study utilises gold-standard methodologies to control for the residual effects of muscle size from V̇O_2max to address this "quality" vs. "quantity" debate.

Methods

Fourteen children (7 CF vs. 7 age- and sex-matched controls) were recruited. Parameters of muscle size - muscle cross-sectional area (mCSA) and thigh muscle volume (TMV) were derived from magnetic resonance imaging, and V̇O_2max obtained via cardiopulmonary exercise testing. Allometric scaling removed residual effects of muscle size, and independent samples t-tests and effect sizes (ES) identified differences between groups in V̇O_2max, once mCSA and TMV were controlled for.

Results

V̇O_2max was shown to be lower in the CF group, relative to controls, with large ES being identified when allometrically scaled to mCSA (ES = 1.76) and TMV (ES = 0.92). Reduced peak work rate was also identified in the CF group when allometrically controlled for mCSA (ES = 1.18) and TMV (ES = 0.45).

Conclusions

A lower V̇O_2max was still observed in children with CF after allometrically scaling for muscle size, suggesting reduced muscle "quality" in CF (as muscle "quantity" is fully controlled for). This observation likely reflects intrinsic metabolic defects within CF skeletal muscle.

Relationship of muscle thickness, strength, and diaphragm function in adults with cystic fibrosis

Objectives

This study aimed to evaluate the muscle thickness, strength, and diaphragmatic function and relate them with clinical findings.

Patients and methods

The cross-sectional study was conducted with 54 participants (27 males, 27 females; mean age; 24.5±5.3 years; range, 18 to 45 years) between January 2017 and October 2017. Of the participants, 31 were adult CF patients, and 23 were age-and sex-matched controls. Patient demographics, 6-min walk distance, body mass index (BMI), and fat-free mass index (FFMI) were evaluated. Each patient underwent pulmonary function tests. Quadriceps femoris thickness and diaphragm thickening fraction were assessed by ultrasonography. Upper extremity strength was measured with a handheld dynamometer.

Results

There was no difference between the patients' and controls' BMI (p=0.052). However, patients' FFMI was lower than the controls' (p=0.010). The FFMI correlated with pulmonary function tests. Patients' both right and left quadriceps femoris muscles were thinner than the controls (p=0.001 and p=0.001, respectively). Patients with pancreatic insufficiency had thinner muscles than patients without pancreatic insufficiency. The control group had a stronger handgrip than CF patients (33.5±10.1 vs. 24.5±9.2 kg, p=0.003).

Conclusion

Peripheral muscle wasting and weakness and lower functional capacity are highly prevalent in CF patients.

Effects of Exercise Training on Peripheral Muscle Strength in Children and Adolescents with Cystic Fibrosis: A Meta-Analysis

Background: Exercise training is a cornerstone of care for people with cystic fibrosis (pwCF); it improves exercise capacity and health-related physical fitness, but no meta-analysis has investigated its effects on muscle function in young pwCF. The objective of this meta-analysis was to assess the effects of exercise on peripheral muscle strength in young pwCF. Methods: An electronic search was conducted in four databases (Pubmed, Science Direct, CENTRAL, and PEDRO) from their inception to July 2022. Grey literature databases (OpenGrey, the European Respiratory Society, the American Thoracic Society, and the European Cystic Fibrosis Society) were also consulted. Randomized controlled trials comparing any type of exercise with standard care in young pwCF (5 to 19 years old) were included. Two authors independently selected the relevant studies, extracted the data, assessed the risk of bias (using the Rob2 tool), and rated the quality of the evidence. Results: Ten studies met the inclusion criteria, involving 359 pwCF. Exercise training improved both lower and upper limb muscle strength (SMD 1.67 (95%CI 0.80 to 2.53), I2 = 76%, p < 0.001 and SMD 1.30 (95%CI 0.66 to 1.93), I2 = 62%, p < 0.001, respectively). Improvements were also reported in muscle mass and maximal oxygen consumption. Results regarding physical activity levels were inconclusive. The overall risk of bias for the primary outcome was high. Conclusions: Exercise training may have a positive effect on peripheral muscle strength in young pwCF. The evidence quality is very low and the level of certainty is poor. There is a need for high-quality randomized controlled studies to confirm these results.

Exercise intolerance in cystic fibrosis-the role of CFTR modulator therapies

Exercise intolerance is common in people with CF (pwCF), but not universal among all individuals. While associated with disease prognosis, exercise intolerance is not simply a reflection of the degree of lung disease. In people with severe CF, respiratory limitations may contribute more significantly to impaired exercise capacity than in those with mild-moderate CF. At all levels of disease severity, there are peripheral factors e.g., abnormal macro- and micro-vascular function that impair blood flow and reduce oxygen extraction, and mitochondrial defects that diminish metabolic efficiency. We discuss advances in understanding the central and peripheral mechanisms underlying exercise intolerance in pwCF. Exploring both the central and peripheral factors that contribute to exercise intolerance in CF can help inform the development of new therapeutic targets, as well as help define prognostic criteria.

Does allogeneic stem cell transplantation in survivors of pediatric leukemia impact regular physical activity, pulmonary function, and exercise capacity?

BACKGROUND

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) has improved survival in high-risk childhood leukemia but is associated with long-term sequelae such as impaired pulmonary function and reduced exercise capacity impacting quality of life.

METHODS

A convenience sample of 17 patients after allo-HSCT (HSCT-12 male, age 15.7±6.7 years, time after HSCT 5.3±2.8 years) underwent pulmonary function testing, echocardiography, and an incremental exercise test on a bike. Physical activity and health-related quality of life were assessed by questionnaires (7-day physical activity recall, PEDS-QL). Seventeen healthy age- and gender-matched controls served as control group (CG) for results of pulmonary function and exercise testing.

RESULTS

HSCT showed reduced pulmonary function (HSCT vs. CG: FEV1 90.5±14.0 vs. 108.0±8.7%pred; FVC 88.4±19.3 vs. 107.6±6.9%pred, DLCO 75.3±23.6 vs. 104.9±12.8%pred) and exercise capacity (VO₂peak 89±30.8%pred, CG 98±17.5%pred; Wmax 84±21.7%pred, CG 115±22.8%pred), but no relevant cardiac dysfunction and a good quality of life (PEDS-QL mean overall score 83.3±10.7). Differences in peak oxygen uptake between groups were mostly explained by 5 adolescent patients who underwent total body irradiation for conditioning. They showed significantly reduced diffusion capacity and reduced peak oxygen uptake. Patients reported a mean time of inactivity of 777±159min/day, moderate activity of 110±107 min/day, hard activity of 35±36 min/day, and very hard activity of 23±22 min/day. A higher amount of inactivity was associated with a lower peak oxygen uptake (correlation coefficient tau -0.48, p=0.023).

CONCLUSIONS

This pilot study shows that although patients after allo-HSCT reported a good quality of life, regular physical activity and exercise capacity are reduced in survivors of stem cell transplantation, especially in adolescents who are treated with total body irradiation for conditioning. Factors hindering regular physical activity need to be identified and exercise counseling should be part of follow-up visits in these patients.

Sex-Based Performance Responses to an Acute Sprint Interval Cycling Training Session in Collegiate Athletes

There are limited data pertaining to the effects of sex on sprint interval cycling (SIC) training session performance. Purpose: We investigated sex-based differences on sprint interval cycling (SIC) performance in collegiate soccer players. Methods: Twelve men and twelve women completed two identical lab trials, 7-14 days apart. The first lab session served as familiarization, "dry run," trial. Reported data were collected and analyzed during the second, "testing" SIC training trial. Each SIC training session was comprised of a warm-up, at 50 revolutions per min (RPM) with no resistance, and six repeated 30-s Wingate Anaerobic Tests (WAnT) separated by a 4-min recovery period between each sprint. Results: Significant (P ≤ .05) sex differences were observed in peak power (PP), peak power relative to body mass (RPP), mean power (MP), mean power relative to body mass (RMP) but not in peak power relative to fat free mass (FFMPP). When WAnT bouts 2-6 were expressed as %Δ of WAnT1, there were no significant (P > .05) differences between the sexes across all performance variables. Further, Cohen's d statistics demonstrated only trivial and small effect size between the groups. Average HR and RPE were not significantly (P > .05) different between the sexes. Correlational analysis revealed a significant (P ≤ .05) relationship between FFM, and PP and MP. Conclusion: Although overall performance may be affected by a number of physiological mechanisms, the results of the current study indicate that differences between men and women soccer players performing SIC training, are likely attributed to differences in body composition.