Resistance training in women with myotonic dystrophy type 1: a multisystemic therapeutic avenue.

Myotonic dystrophy type 1 (DM1) is a hereditary disease characterized by muscular impairments. Fundamental and clinical positive effects of strength training have been reported in men with DM1, but its impact on women remains unknown. We evaluated the effects of a 12-week supervised strength training on physical and neuropsychiatric health. Women with DM1 performed a twice-weekly supervised resistance training program (3 series of 6-8 repetitions of squat, leg press, plantar flexion, knee extension, and hip abduction). Lower limb muscle strength, physical function, apathy, anxiety and depression, fatigue and excessive somnolence, pain, and patient-reported outcomes were assessed before and after the intervention, as well as three and six months after completion of the training program. Muscle biopsies of the vastus lateralis were also taken before and after the training program to assess muscle fiber growth. Eleven participants completed the program (attendance: 98.5 %). Maximal hip and knee extension strength (p < 0.006), all One-Repetition Maximum strength measures (p < 0.001), apathy (p = 0.0005), depression (p = 0.02), pain interference (p = 0.01) and perception of the lower limb function (p = 0.003) were significantly improved by training. Some of these gains were maintained up to six months after the training program. Strength training is a good therapeutic strategy for women with DM1.

Psychometric properties of a standardized protocol of muscle strength assessment by hand-held dynamometry in healthy adults: a reliability study.

BACKGROUND: Maximal isometric muscle strength (MIMS) assessment is a key component of physiotherapists' work. Hand-held dynamometry (HHD) is a simple and quick method to obtain quantified MIMS values that have been shown to be valid, reliable, and more responsive than manual muscle testing. However, the lack of MIMS reference values for several muscle groups in healthy adults with well-known psychometric properties limits the use and the interpretation of these measures obtained with HHD in clinic. OBJECTIVE: To determine the intra- and inter-rater reliability, standard error of measurement (SEM) and minimal detectable change (MDC) of MIMS torque values obtained with HHD. METHODS: Intra and Inter-rater Reliability Study. The MIMS torque of 17 muscle groups was assessed by two independent raters at three different times in 30 healthy adults using a standardized HHD protocol using the MEDup™ (Atlas Medic, Québec, Canada). Participants were excluded if they presented any of the following criteria: 1) participation in sport at a competitive level; 2) degenerative or neuromusculoskeletal disease that could affect torque measurements; 3) traumatic experience or disease in the previous years that could affect their muscle function; and 4) use of medication that could impact muscle strength (e.g., muscle relaxants, analgesics, opioids) at the time of the evaluation. Intra- and inter-rater reliability were determined using two-way mixed (intra) and random effects (inter) absolute agreement intraclass correlation coefficients (ICC: 95% confidence interval) models. SEM and MDC were calculated from these data. RESULTS: Intra- and inter-rater reliability were excellent with ICC (95% confidence interval) varying from 0.90 to 0.99 (0.85-0.99) and 0.89 to 0.99 (0.55-0.995), respectively. Absolute SEM and MDC for intra-rater reliability ranged from 0.14 to 3.20 Nm and 0.38 to 8.87 Nm, respectively, and from 0.17 to 5.80 Nm and 0.47 to 16.06 Nm for inter-rater reliability, respectively. CONCLUSIONS: The excellent reliability obtained in this study suggest that the use of such a standardized HHD protocol is a method of choice for MIMS torque measurements in both clinical and research settings. And the identification of the now known metrological qualities of such a protocol should encourage and promote the optimal use of manual dynamometry.

What is Known About Muscle Strength Reference Values for Adults Measured by Hand-Held Dynamometry: A Scoping Review.

Objective: To map the body of existing literature regarding reference values of maximal isometric muscle strength (MIMS) of upper and lower limbs obtained with handheld dynamometers (HHD) in healthy adults to identify potential gaps in the literature and specify future research needs. Data Sources: A scoping review in which PubMed, EMBASE, CINAHL plus, PEDRO, and Cochrane databases were searched before May 1, 2020. Study Selection: All studies using standardized HHD protocols for the purpose of establishing reference values in healthy adult population were included. Two independent reviewers completed an initial screening of article titles and abstracts, and the remaining articles were read in their entirety and screened according to the inclusion and exclusion criteria. Disagreements were discussed, with recourse to a third reviewer when needed. Data Extraction: Data of the selected studies were extracted and charted by 2 independent reviewers using a tested data extraction grid to ensure method standardization. Data were subsequently merged to produce the complete final extracted data. Data Synthesis: Titles and abstracts of 4015 studies were screened, 46 articles were fully reviewed, and 9 manuscripts were selected for the final analysis. A large variability exists between protocols used for muscle testing in terms of type of device, measurement units, subject positioning, and muscle groups tested. Conclusion: The existing literature regarding HHD reference values of MIMS is scarce and presents gaps notably relating to strength units and well-described protocols with known psychometric properties, despite the development and increased availability of high quality HHD. This observation emphasizes the critical need to develop reference values in manual dynamometry in adults to optimize the use of manual dynamometry for diagnostic and prognostic decisions.

tDCS Task-Oriented Approach Improves Function in Individuals With Fibromyalgia Pain. A Pilot Study.

Fibromyalgia (FM) is a complex pain syndrome accompanied by physical disability and loss of daily life activities. Evidences suggest that modulation of the primary motor cortex (M1) by transcranial direct current stimulation (tDCS) improves functional physical capacity in chronic pain conditions. However, the gain on physical function in people living with FM receiving tDCS is still unclear. This study aimed to evaluate whether the tDCS task-oriented approach improves function and reduces pain in a single cohort of 10 FM. A total of 10 women with FM (60.4 ± 15.37 years old) were enrolled in an intervention including anodal tDCS delivered on M1 (2 mA from a constant stimulator for 20 min); simultaneously they performed a functional task. The anode was placed on the contralateral hemisphere of the dominant hand. Outcome assessments were done before the stimulation, immediately after stimulation and 30 min after the end of tDCS. The same protocol was applied in subsequent sessions. A total of five consecutive days of tDCS were completed. The main outcomes were the number of repetitions achieved and time in active practice to evaluate functional physical task performance such as intensity of the pain (visual analog scale) and level of fatigue (Borg scale). After 5 days of tDCS, the number of repetitions achieved significantly increased by 49% (p = 0.012). No change was observed in active practice time. No increase in pain was observed despite the mobility of the painful parts of the body. These results are encouraging since an increase in pain due to the mobilization of painful body parts could have been observed at the end of the 5th day of the experiment. These results support the use of tDCS in task-based rehabilitation.

Training program-induced skeletal muscle adaptations in two men with myotonic dystrophy type 1.

OBJECTIVE: The purpose of this side product of another unpublished research project, was to address the effects of a training program on skeletal muscle adaptations of people with myotonic dystrophy type 1 (DM1), under a multifaceted perspective. The objective of this study was to look at training induced muscular adaptations by evaluating changes in muscle strength, myofiber cross-sectional area (CSA), proportion of myofiber types and with indirect markers of muscle growth [proportion of centrally nucleated fibers (CNF) and density of neutrophils and macrophages]. Two men with DM1 underwent a 12-week strength/endurance training program (18 sessions). Two muscle biopsies were obtained pre- and post-training program. RESULTS: Muscular adaptations occurred only in Patient 1, who attended 72% of the training sessions compared to 39% for Patient 2. These adaptations included increase in the CSA of type I and II myofibers and changes in their proportion. No changes were observed in the percentage of CNF, infiltration of neutrophils and macrophages and muscle strength. These results illustrate the capacity of skeletal muscle cells to undergo adaptations linked to muscle growth in DM1 patients. Also, these adaptations seem to be dependent on the attendance. Trial registration Clinicaltrials.gov NCT04001920 retrospectively registered on June 26th, 2019.

Correction to: What is known about the effects of exercise or training to reduce skeletal muscle impairments of patients with myotonic dystrophy type 1? A scoping review.

An incorrect attribution of the first study regarding the effect of exercise in DM1 mouse models needs to be revised.

What is known about the effects of exercise or training to reduce skeletal muscle impairments of patients with myotonic dystrophy type 1? A scoping review.

BACKGROUND: Myotonic dystrophy type 1 (DM1) is a neuromuscular disease characterized by multisystemic involvements including a progressive loss of maximal muscle strength and muscle wasting. Poor lower-limb strength is an important factor explaining disrupted social participation of affected individuals. This review aims to map what is known about the effects of exercise and training programs undertaken to counteract skeletal muscle impairments in DM1 patients. METHODS: Medline, CINAHL and EMBASE databases were searched. Regarding study eligibility, title and abstract of 704 studies followed by 45 full articles were reviewed according to the following eligibility criteria. Inclusion: (1) humans with DM1 and (2) experimental protocol relying on exercise or training. Exclusion: (1) studies that do not evaluate skeletal muscle responses or adaptations, (2) reviews covering articles already included and (3) pharmacological intervention at the same time of exercise or training program. RESULTS: Twenty-one papers were selected for in-depth analysis. Different exercise or training protocols were found including: acute exercise, neuromuscular electric stimulation, strength training, aerobic training, balance training and multiple rehabilitation interventions. Seven studies reported clinical measurements only, five physiological parameters only and nine both types. CONCLUSION: This scoping review offers a complete summary of the current scientific literature on the effect of exercise and training in DM1 and a framework for future studies based on the concomitant evaluation of the several outcomes in present literature. Although there were a good number of studies focusing on clinical measurements, heterogeneity between studies does not allow to identify what are the adequate training parameters to obtain exercise or training-induced positive impacts on muscle function. Scientific literature is even more scarce regarding physiological parameters, where much more research is needed to understand the underlying mechanisms of exercise response in DM1.