Sjoerd Stevens

Many critically ill patients infected with SARS-CoV-2 have been submitted to an intensive care unit (ICU). Patients with a SARS-CoV-2 infection that survive critical illness are confronted with months of physical impairments. To maximize recovery, it is important to understand the musculoskeletal involvement in critically ill patients infected with SARS-CoV-2. The aim of the present study was to assess the myocellular changes in SARS-CoV-2 patients that occur throughout the first week of ICU admission. In n = 22 critically ill patients infected with SARS-CoV-2, a biopsy sample from the vastus lateralis muscle was obtained at day 1–3 and day 5–8 following ICU admission. Fluorescence microscopy was used to assess type I and type II muscle fiber size and distribution, myonuclear content, and muscle tissue capillarization. Transmission electron microscopy was used to support quantitative data at an ultrastructural level. Changes in type I and type II muscle fiber size showed large inter-individual variation. The average change in type I fiber size was +309 ± 1834 µm², ranging from −2129 µm² (−31%) to +3375 µm² (+73%). The average change in type II fiber size was −224 ± 1256 µm², ranging from −1410 µm² (−36%) to +2592 µm² (+48%). Ultrastructural observations showed myofibrillar and hydropic degeneration, and fiber necrosis. This study shows that ICU patients admitted with SARS-CoV-2 suffer from substantial muscle fiber damage during ICU admission. These results are a call for action towards more specialized rehabilitation programs for patients admitted to the ICU with SARS-CoV-2 infection.

Low back pain is a prevalent musculoskeletal disorder with high disability. Although exercise therapy is an important part of the multidisciplinary treatment of non-specific chronic low back pain (NSCLBP), the impact of exercise therapy on muscle morphology of the paraspinal muscles is largely unknown. The main aim of this study is to evaluate the effects of a high intensity training (HIT) program on muscle fiber characteristics of the multifidus (MF) and the erector spinae (ES) musculature in persons with NSCLBP and to compare these results with the effects of a moderate intensity training (MIT) program, which is used as a control group. In total, 38 participants with NSCLBP were randomly assigned to a HIT or MIT intervention group. Participants performed a 12-week training program. At baseline and after the training program, biopsy samples from the lumbar MF and ES were obtained. Muscle fiber characteristics were analyzed by immunofluorescence. For the ES, no significant changes were found in muscle fiber CSA and distribution of muscle fiber types in response to a training program at moderate or at high intensity. For the MF, a significant higher muscle area occupied by type II muscle fibers, referred to as the relative cross-sectional area (RCSA), was found in the HIT group. Based on muscle fiber characteristics in biopsy samples, a HIT program of 12 weeks seems to result in a more glycolytic profile in the MF.

High-intensity training (HIT) improves rehabilitation outcomes such as functional disability and physical performance in several chronic disorders. Promising results were also found in chronic nonspecific low back pain (CNSLBP). However, the impact of different exercise modes on HIT effectiveness in CNSLBP remains unclear. Therefore, this study evaluated the effectiveness of various HIT exercise modes and compared differences between these modes, on pain intensity, disability, and physical performance, as a therapeutic intervention for persons with CNSLBP. In a randomized comparative trial, consisting of a 12-week program, persons with CNSLBP were divided into four HIT groups, i.e., cardiorespiratory interval training coupled with either general resistance training, core strength training, combined general resistance and core strength training, or mobility exercises. Before and after the program, the Numeric Pain Rating Scale (NPRS), Modified Oswestry Disability Index (MODI), and Patient Specific Functioning Scale (PSFS) were recorded, and a cardiopulmonary exercise test (VO₂max, cycling time) and isometric trunk strength test (maximum muscle torque) were performed. Eighty participants (mean age: 44.0 y, 34 males) were included. Improvements were found within all groups after the HIT programs and ranged from −39 to −57% on the NPRS, +27 to +64% on the MODI, +38 to +89% on the PSFS, +7 to +14% on VO₂max, and +11 to +18% on cycling time. No differences between groups were found. High-intensity cardiorespiratory interval training improves CNSLBP rehabilitation outcomes when performed with other HIT exercise modes or mobility exercises. Hence, when setting up an exercise therapy program in CNSLBP rehabilitation, various HIT modes can be considered as therapy modalities.

Agten A, et al. Anat Cell Biol. 2020 Jan;53:e14. https://doi.org/10.5115/acb.20.009

Introduction: Exercise therapy (ET) is advocated as a treatment for chronic nonspecific low back pain (CNSLBP). However, therapy effect sizes remain low. In other chronic disorders, training at higher intensity has resulted in greater improvements on both general health related and disease specific outcomes compared to lower-intensity ET. Possibly, high-intensity training also improves effect sizes in CNSLBP. Objective: To compare the effects of a high-intensity ET program with a similar moderate-intensity ET program on disability, pain, function, exercise capacity, and abdominal/back muscle strength in persons with CNSLBP. Methods: In a randomized controlled trial, persons with CNSLBP performed a 12-wk ET program (24 sessions, 1.5 h per session, twice per week) at high-intensity training (HIT) or moderate-intensity training (MIT). Questionnaires to assess disability (Modified Oswestry Index [MODI]), pain intensity (Numeric Pain Rating Scale), and function (Patient Specific Functioning Scale), a cardiopulmonary exercise test to assess exercise capacity (V˙O_2max, cycling time), and a maximum isometric muscle strength test to assess abdominal/back muscle strength (maximum muscle torque) were administered at baseline and after the training program. Results: Thirty-eight participants (HIT: n = 19, MIT: n = 19) were included (mean age, 44.1 yr, SD = 9.8, 12 males). Groups did not differ at baseline. Between group differences (P < 0.01) in favor of HIT were found for MODI, V˙O_2max, and cycling time. Within group improvements (P < 0.01) were found in both groups on MODI (HIT:−64%, MIT:−33%), Numeric Pain Rating Scale (HIT, −56%; MIT, −39%), Patient-Specific Functioning Scale (HIT:+37%, MIT:+39%), V˙O_2max (HIT:+14, MIT:+4%), cycling time (HIT:+18%, MIT:+13%), and back muscle strength (HIT:+10%, MIT:+14%). Conclusions: High-intensity training proved to be a feasible, well tolerated, and effective therapy modality in CNSLBP. Moreover, it shows greater improvements on disability and exercise capacity than a similar ET performed at moderate intensity.

A 51-year-old male was routinely biopsied during a paraspinal muscle study. The biopsy sample was taken from the right erector spinae muscle at the fourth lumbar vertebra. The patient had no history of (diagnosed) major back trauma. The obtained sample was histologically analyzed (hematoxylin and eosin, safranin O), and complementary magnetic resonance imaging was performed. The biopsied sample contained chondroid tissue. Based on its location, the biopsy sample was appointed as chondroid metaplasia. Although chondroid metaplasia is not uncommon in humans, this is the first report of chondroid metaplasia within the paraspinal connective tissue. We propose a novel mechanism to explain the paraspinal chrondrogenic changes, related to spinal degeneration.