Prolonged Moderate-Intensity Exercise Does Not Increase Muscle Injury Markers in Symptomatic or Asymptomatic Statin Users.

BACKGROUND: Statin use may exacerbate exercise-induced skeletal muscle injury caused by reduced coenzyme Q10 (CoQ10) levels, which are postulated to produce mitochondrial dysfunction. OBJECTIVES: We determined the effect of prolonged moderate-intensity exercise on markers of muscle injury in statin users with and without statin-associated muscle symptoms. We also examined the association between leukocyte CoQ10 levels and muscle markers, muscle performance, and reported muscle symptoms. METHODS: Symptomatic (n = 35; age 62 ± 7 years) and asymptomatic statin users (n = 34; age 66 ± 7 years) and control subjects (n = 31; age 66 ± 5 years) walked 30, 40, or 50 km/d for 4 consecutive days. Muscle injury markers (lactate dehydrogenase, creatine kinase, myoglobin, cardiac troponin I, and N-terminal pro-brain natriuretic peptide), muscle performance, and reported muscle symptoms were assessed at baseline and after exercise. Leukocyte CoQ10 was measured at baseline. RESULTS: All muscle injury markers were comparable at baseline (P > 0.05) and increased following exercise (P < 0.001), with no differences in the magnitude of exercise-induced elevations among groups (P > 0.05). Muscle pain scores were higher at baseline in symptomatic statin users (P < 0.001) and increased similarly in all groups following exercise (P < 0.001). Muscle relaxation time increased more in symptomatic statin users than in control subjects following exercise (P = 0.035). CoQ10 levels did not differ among symptomatic (2.3 nmol/U; IQR: 1.8-2.9 nmol/U), asymptomatic statin users (2.1 nmol/U; IQR: 1.8-2.5 nmol/U), and control subjects (2.1 nmol/U; IQR: 1.8-2.3 nmol/U; P = 0.20), and did not relate to muscle injury markers, fatigue resistance, or reported muscle symptoms. CONCLUSIONS: Statin use and the presence of statin-associated muscle symptoms does not exacerbate exercise-induced muscle injury after moderate exercise. Muscle injury markers were not related to leukocyte CoQ10 levels. (Exercise-induced Muscle Damage in Statin Users; NCT05011643).

Impact of tyrosine kinase inhibitors on glucose control and insulin regulation in patients with chronic myeloid leukemia.

Treatment with tyrosine kinase inhibitors (TKIs), especially nilotinib, often results in hyperglycemia, which may further increase cardiovascular disease risk in patients with chronic myeloid leukemia (CML). The mechanism underlying the TKI-induced glucose dysregulation is not clear. TKIs are suggested to affect insulin secretion but also insulin sensitivity of peripheral tissue has been proposed to play a role in the pathogenesis of TKI-induced hyperglycemia. Here, we aimed to assess whether skeletal muscle glucose uptake and insulin responses are altered in nondiabetic patients with CML receiving TKI treatment. After a glycogen-depleted exercise bout, an intravenous glucose bolus (0.3 g/kg body weight) was administered to monitor 2-h glucose tolerance and insulin response in 14 patients with CML receiving nilotinib, 14 patients with CML receiving imatinib, and 14 non-CML age- and gender-matched controls. A dynamic [18F]-FDG PET scan during a hyperinsulinemic-euglycemic clamp was performed in a subgroup of 12 male patients with CML to assess m. quadriceps glucose uptake. We showed that patients with CML treated with nilotinib have an increased insulin response to intravenous glucose administration after muscle glycogen-depleted exercise. Despite the increased insulin response to glucose administration in patients with CML receiving nilotinib, glucose disappearance rates were significantly slower in nilotinib-treated patients when compared with controls in the first 15 min after glucose administration. Although [18F]-FDG uptake in m. quadriceps was not different, patients receiving nilotinib showed a trend toward decreased glucose infusion rates during euglycemic clamping when compared with patients receiving imatinib. Together, these findings indicate disturbed skeletal muscle glucose handling in patients with CML receiving nilotinib therapy.NEW & NOTEWORTHY In this study, we have shown that non-diabetic patients with CML receiving nilotinib therapy show early signs of disturbed skeletal muscle glucose handling, which was not observed in imatinib-treated patients. These observations in nilotinib users may reflect decreased muscle insulin sensitivity, which could serve as a potential target to counteract glycemic dysregulation, and is of clinical importance since these patients have an increased cardiovascular disease risk.

Moderate Intensity Exercise Training Improves Skeletal Muscle Performance in Symptomatic and Asymptomatic Statin Users.

BACKGROUND: The combination of statin therapy and physical activity reduces cardiovascular disease risk in patients with hyperlipidemia more than either treatment alone. However, mitochondrial dysfunction associated with statin treatment could attenuate training adaptations. OBJECTIVES: This study determined whether moderate intensity exercise training improved muscle and exercise performance, muscle mitochondrial function, and fiber capillarization in symptomatic and asymptomatic statin users. METHODS: Symptomatic (n = 16; age 64 ± 4 years) and asymptomatic statin users (n = 16; age 64 ± 4 years) and nonstatin using control subjects (n = 20; age 63 ± 5 years) completed a 12-week endurance and resistance exercise training program. Maximal exercise performance (peak oxygen consumption), muscle performance and muscle symptoms were determined before and after training. Muscle biopsies were collected to assess citrate synthase activity, adenosine triphosphate (ATP) production capacity, muscle fiber type distribution, fiber size, and capillarization. RESULTS: Type I muscle fibers were less prevalent in symptomatic statin users than control subjects at baseline (P = 0.06). Exercise training improved muscle strength (P < 0.001), resistance to fatigue (P = 0.01), and muscle fiber capillarization (P < 0.01), with no differences between groups. Exercise training improved citrate synthase activity in the total group (P < 0.01), with asymptomatic statin users showing less improvement than control subjects (P = 0.02). Peak oxygen consumption, ATP production capacity, fiber size, and muscle symptoms remained unchanged in all groups following training. Quality-of-life scores improved only in symptomatic statin users following exercise training (P < 0.01). CONCLUSIONS: A moderate intensity endurance and resistance exercise training program improves muscle performance, capillarization, and mitochondrial content in both asymptomatic and symptomatic statin users without exacerbating muscle complaints. Exercise training may even increase quality of life in symptomatic statin users. (The Effects of Cholesterol-Lowering Medication on Exercise Performance [STATEX]; NL5972/NTR6346).

Fatigue in chronic myeloid leukemia patients on tyrosine kinase inhibitor therapy: predictors and the relationship with physical activity.

Fatigue is a common side effect of tyrosine kinase inhibitor (TKI) therapy in chronic myeloid leukemia (CML) patients. However, the prevalence of TKI-induced fatigue remains uncertain and little is known about predictors of fatigue and its relationship with physical activity. In this study, 220 CML patients receiving TKI therapy and 110 gender- and age-matched controls completed an online questionnaire to assess fatigue severity and fatigue predictors (Part 1). In addition, physical activity levels were objectively assessed for 7 consecutive days in 138 severely fatigued and non-fatigued CML patients using an activity monitor (Part 2). We demonstrated that the prevalence of severe fatigue was 55.5% in CML patients and 10.9% in controls (P<0.001). We identified five predictors of fatigue in our CML population: age (OR 0.96, 95% CI 0.93-0.99), female gender (OR 1.76, 95% CI 0.92-3.34), Charlson Comorbidity Index (OR 1.91, 95% CI 1.16-3.13), the use of comedication known to cause fatigue (OR 3.43, 95% CI 1.58-7.44), and physical inactivity (OR of moderately active, vigorously active and very vigorously active compared to inactivity 0.43 (95% CI 0.12-1.52), 0.22 (95% CI 0.06-0.74), and 0.08 (95% CI 0.02-0.26), respectively). Objective monitoring of activity patterns confirmed that fatigued CML patients performed less physical activity on both light (P=0.017) and moderate to vigorous intensity (P=0.009). In fact, compared to the non-fatigued patients, fatigued CML patients performed 1 hour less of physical activity per day and took 2000 fewer steps per day. Our findings facilitate the identification of patients at risk of severe fatigue and highlight the importance to set the reduction of fatigue as a treatment goal in CML care. This study was registered at The Netherlands Trial Registry, NTR7308 (Part 1) and NTR7309 (Part 2).

Muscle Toxicity of Drugs: When Drugs Turn Physiology into Pathophysiology.

Drugs are prescribed to manage or prevent symptoms and diseases, but may sometimes cause unexpected toxicity to muscles. The symptomatology and clinical manifestations of the myotoxic reaction can vary significantly between drugs and between patients on the same drug. This poses a challenge on how to recognize and prevent the occurrence of drug-induced muscle toxicity. The key to appropriate management of myotoxicity is prompt recognition that symptoms of patients may be drug related and to be aware that inter-individual differences in susceptibility to drug-induced toxicity exist. The most prevalent and well-documented drug class with unintended myotoxicity are the statins, but even today new classes of drugs with unintended myotoxicity are being discovered. This review will start off by explaining the principles of drug-induced myotoxicity and the different terminologies used to distinguish between grades of toxicity. The main part of the review will focus on the most important pathogenic mechanisms by which drugs can cause muscle toxicity, which will be exemplified by drugs with high risk of muscle toxicity. This will be done by providing information on key clinical and laboratory aspects, muscle electromyography patterns and biopsy results, and pathological mechanism and management for a specific drug from each pathogenic classification. In addition, rather new classes of drugs with unintended myotoxicity will be highlighted. Furthermore, we will explain why it is so difficult to diagnose drug-induced myotoxicity, and which tests can be used as a diagnostic aid. Lastly, a brief description will be given of how to manage and treat drug-induced myotoxicity.

First-Aid Treatment for Friction Blisters: "Walking Into the Right Direction?"

OBJECTIVE: Blisters are common foot injuries during and after prolonged walking. However, the best treatment remains unclear. The aim of the study was to compare the effect of 2 different friction blister treatment regimens, wide area fixation dressing versus adhesive tape. DESIGN: A prospective observational cohort study. SETTING: The 2015 Nijmegen Four Days Marches in the Netherlands. PARTICIPANTS: A total of 2907 participants (45 ± 16 years, 52% men) were included and received 4131 blister treatments. INTERVENTIONS: Blisters were treated with either a wide area fixation dressing or adhesive tape. MAIN OUTCOME MEASURES: Time of treatment application was our primary outcome. In addition, effectiveness and satisfaction were evaluated in a subgroup (n = 254). During a 1-month follow-up period, blister healing, infection and the need for additional medical treatment were assessed in the subgroup. RESULTS: Time of treatment application was lower (41.5 minutes; SD = 21.6 minutes) in the wide area fixation dressing group compared with the adhesive tape group (43.4 minutes; SD = 25.5 minutes; P = 0.02). Furthermore, the wide area fixation dressing group demonstrated a significantly higher drop-out rate (11.7% vs 4.0%, P = 0.048), delayed blister healing (51.9% vs 35.3%, P = 0.02), and a trend toward lower satisfaction (P = 0.054) when compared with the adhesive tape group. CONCLUSIONS: Wide area fixation dressing decreased time of treatment application by 2 minutes (4.5%) when compared with adhesive tape. However, because of lower effectiveness and a trend toward lower satisfaction, we do not recommend the use of wide area fixation dressing over adhesive tape in routine first-aid treatment for friction blisters.