BackgroundExercise therapy is generally recommended for patients with osteoarthritis (OA) of the knee. Comorbidity, which is highly prevalent in OA, may interfere with exercise therapy. To date, there is no evidence-based protocol for the treatment of patients with knee OA and comorbidity. Special protocols adapted to the comorbidity may facilitate the application of exercise therapy in patients with knee OA and one or more comorbidities.PurposeThe purpose of this study was to develop comorbidity-adapted exercise protocols for patients with knee OA and comorbidity.MethodSeveral steps were undertaken to develop comorbidity-adapted protocols: selection of highly prevalent comorbidities in OA, a literature search to identify restrictions and contraindications for exercise therapy for the various comorbid diseases, consultation of experts on each comorbid disease, and field testing of the protocol in eleven patients with knee OA and comorbidity.ResultsBased on literature and expert opinion, comorbidity-adapted protocols were developed for highly prevalent comorbidities in OA. Field testing showed that the protocols provided guidance in clinical decision making in both the diagnostic and the treatment phase. Because of overlap, the number of exercise protocols could be reduced to three: one for physiological adaptations (coronary disease, heart failure, hypertension, diabetes type 2, chronic obstructive pulmonary diseases, obesity), one for behavioral adaptations (chronic a-specific pain, nonspecific low back pain, depression), and one for environmental adaptations (visual or hearing impairments). Evaluation of patient outcome after treatment showed significant (P<0.05) and clinically relevant improvements in activity limitations and pain.ConclusionComorbidity-adapted exercise protocols for patients with knee OA were developed, providing guidance in clinical reasoning with regard to diagnostics and treatment. To evaluate the effectiveness of treatment in line with our protocols, a randomized clinical trial should be performed.

Background: Osteoarthritis (OA) has a very high rate of comorbidity. Exercise therapy is recommended in current guidelines on the management of OA of the hip and knee. Unfortunately, current protocols and guidelines for exercise therapy in OA of the hip and knee do not offer advice concerning comorbidityassociated adaptations for exercise therapy in OA patients. Because of the high prevalence of comorbidity in OA, it is important to establish when exercise therapy for OA of the hip and knee should be adapted when patients have one or more comorbidities. Objective: To identify restrictions and contraindications for exercise therapy for common comorbidities (cardiac diseases, hypertension, type 2 diabetes, obesity, chronic obstructive pulmonary disease (COPD), depression, chronic pain, low back pain (LBP), visual or hearing impairments, and chronic cystitis) in hip and knee OA patients. Major findings: Cardiac diseases, hypertension, type 2 diabetes, COPD, and chronic cystitis are associated with restrictions resulting from physiological impairments. Conversely, LBP, chronic pain syndromes, and depression are associated with psychological and behavioural restrictions to exercise therapy. Visual and hearing impairments result predominantly in environmental restrictions to exercise. Obesity is associated with restrictions resulting from physiological and psychological impairments and behavioural barriers. Several absolute contraindications exist and patient safety cannot be guaranteed when these are not taken into account during exercise therapy. Conclusion: Restrictions and contraindications for exercise in patients with OA of the hip and knee and comorbidity have been identified. This overview is helpful in decisions on the treatment of patients and will be instrumental in the development of a protocol for comorbidity related adaptations in exercise therapy for OA patients.

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A single-center randomized, controlled cross-over exercise intervention in 20 women willing to reduce weight (20–40 y, BMI: 27.4 ± 2.1), with the aim to examine potential benefits for weight loss under normal (N-Ox: 20.9%) and mildly reduced (R-Ox: 17.0%) normobaric oxygen in an “Altitude Simulation Chamber”. O2 consumption (VO2), CO2 production (VCO2), blood oxygen saturation (SaO2), blood glucose and lactate (mM) were studied before, during and after cycling for 22 min at a mean personalized workload of 54.2 ± 11.7 watts, about 40% of VO2max. Despite lower absolute SaO2 values and a greater decline from rest to exercise under R-Ox (time x treatment interaction p < 0.01), VO2 did not differ from N-Ox (time x treatment interaction p = 0.178). Average net VO2, 13.8 mL O2 per watt, reflected fairly normal aerobic cycling, irrespective of O2 regime. The Respiratory Exchange Ratio (RER; VO2/VCO2), 0.83 at rest, increased for both treatments to a ratio close to or beyond unity during and directly after exercise (treatment effect p = 0.407). The tendency of cycling for weight loss to clear carbohydrates rather than fat, irrespective of normal or mildly reduced normobaric oxygen, is discussed as a lactate-mediated and phenotype-specific consequence of apparent anaerobic glycolysis with adverse perspectives for weight loss and metabolic health.

Endothelial cells play an important role in the autoregulation of the vascular diameter for maintaining physiological flow and shear stress. An increase in blood flow causes an increase in shear stress, which is sensed by the endothelial cells, resulting in the release of vasoactive substances. An impaired endothelial mediated vasomotive response seems reflective for several cardiovascular pathologies, such as failure of atherosclerosis and arterio-venous fistulas (AVF).