Reliability of Isometric Muscle Strength Measurement and Its Accuracy Prediction of Maximal Dynamic Force in People with Multiple Sclerosis.

Background and Objectives: Multiple sclerosis (MS) is a disease that manifests with varied neurological symptoms, including muscle weakness, especially in the lower extremities. Strength exercises play an important role in the rehabilitation and functional maintenance of these patients. The individualized prescription of strength exercises is recommended to be based on the maximum force determined by the one-repetition maximum (1RM), although to save time and because it requires less equipment, it is often determined by the maximum voluntary isometric contraction (MVIC). The purpose of this work was to study, in patients with MS (pwMS), the reliability of MVIC and the correlation between the MVIC and 1RM of the knee extensors and to predict the MVIC-based 1RM. Materials and Methods: A total of 328 pwMS participated. The study of the reliability of MVIC included all pwMS, for which MVIC was determined twice in one session. Their 1RM was also evaluated. The sample was randomized by MS type, sex, and neurological disability score into a training group and a testing group for the analysis of the correlation and prediction of MVIC-based 1RM. Results: MVIC repeatability (ICC, 2.1 = 0.973) was determined, along with a minimum detectable change of 13.2 kg. The correlation between MVIC and 1RM was R2 = 0.804, with a standard error estimate of 12.2 kg. The absolute percentage error of 1RM prediction based on MVIC in the test group was 12.7%, independent of MS type and with no correlation with neurological disability score. Conclusions: In patients with MS, MVIC presents very good intrasubject repeatability, and the difference between two measurements of the same subject must differ by 17% to be considered a true change in MVIC. There is a high correlation between MVIC and 1RM, which allows estimation of 1RM once MVIC is known, with an estimation error of about 12%, regardless of sex or type of MS, and regardless of the degree of neurological disability.

Muscle Quality of Knee Extensors Based on Several Types of Force in Multiple Sclerosis Patients with Varying Degrees of Disability.

Background and Objectives: Multiple sclerosis (MS) tends to affect muscle performance, mainly in the lower extremities. The degree of disability is associated with the loss of strength and muscle mass, to varying extents. Muscle quality (MQ) expresses the amount of force produced relative to the activated muscle mass. The purpose of this study was to compare the MQ of the knee extensors in the main manifestations of strength (isometric, dynamic strength, and power) among patients with differing degrees of neurological disability and evolutionary forms of the disease. We also establish reference values for MQ in MS patients (pwMS). Materials and Methods: In total, 250 pwMS were evaluated according to the Expanded Disability Status Scale (EDSS). The maximum dynamic and isometric forces and muscle power manifested a load of 60% of the maximum dynamics of the knee extensors. The lean mass of the thigh and hip was determined by densitometry, and the MQ was calculated for the three types of force evaluated. Results: The pwMS with relapsing remitting MS (RRMS) presented isometric MQ values that were 15.8% better than those of pwMS with primary progressive MS (PPMS) and 13.8% better than those of pwMS with secondary progressive MS (SPMS). For pwMS with SPMS, the dynamic MQ was 16.7% worse than that of patients with RRMS, while the power MQ was 29.5% worse. By degree of disability (<4 >7.5 EDSS score), patients with better MQ had mild EDSS scores, and patients with severe EDSS scores had 24.8%, 25.9%, and 40.3% worse isometric, dynamic, and power MQ scores, respectively, than those with RRMS. Based on these results, reference values for MQ in pwMS were established. Conclusions: The pwMS with different types of MS do not show differences in lean mass or strength but do show differences in MQ. In pwMS with different EDSS grades, there are no differences in lean mass, but there are differences in strength based on MQ, especially power MQ.

Reference Values for Isometric, Dynamic, and Asymmetry Leg Extension Strength in Patients with Multiple Sclerosis.

Having recognized the value of resistance training in patients with multiple sclerosis (PwMS), there are a lack of lower limb normative reference values for one repetition maximum (1RM) and maximal voluntary isometric contraction (MVIC) in this population. Hence, the purposes of this study were to provide reference values for 1RM and MVIC of knee extensors in PwMS across the disability spectrum and to examine knee extension strength asymmetry. Three hundred and ninety PwMS participated in the study, performing MVIC and 1RM tests of bilateral (both legs together at once) and unilateral (each leg singly) knee extensors. There was no difference in 1RM according to the disease course of MS, but there was according to the degree of neurological disability, being more preserved in those with a lower degree of disability. MVIC tends to be higher in patients with relapsing-remitting MS respect those with progressive MS, and in patients with lower levels of neurological disability. Asymmetry above the values considered normal in 1RM was present in 20-60% of patients and 56-79% in the MVIC test, depending on the type of MS and tended to be lower in those with less disability. Reference values are given by quartiles for 1RM, MVIC, and asymmetry.

Resistance Training in Breast Cancer Survivors: A Systematic Review of Exercise Programs.

The aim of this study was to identify the characteristics of resistance training (RT) programs for breast cancer survivors (BCS). A systematic review of the literature was performed using PubMed, Medline, Science Direct, the Cochrane Breast Cancer Specialised Register of the Cochrane Library, the Physiotherapy Evidence Database (PEDro), and Scopus, with the aim of identifying all published studies on RT and BCS from 1 January 1990 to 6 December 2019, using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The risk of bias in the studies was assessed using the revised Cochrane Risk of Bias tool (RoB 2.0). Sixteen trials were included for qualitative analysis. More than half of the trials do not adequately report the characteristics that make up the exercise program. The maximal strength was the most frequently monitored manifestation of strength, evaluated mainly as one-repetition maximum (1RM). Resistance training was performed on strength-training machines, twice a week, using a load between 50% and 80% of 1RM. The trials reported significant improvement in muscle strength, fatigue, pain, quality of life, and minor changes in aerobic capacity.

Determination of the Minimum Detectable Change in the Total and Segmental Volumes of the Upper Limb, Evaluated by Perimeter Measurements.

Among female breast cancer survivors, there is a high prevalence of lymphedema subsequent to axillary lymph node dissection and axillary radiation therapy. There are many methodologies available for the screening, diagnosis and follow-up of breast cancer survivors with or without lymphedema, the most common of which is the measurement of patients' arm circumference. The purpose of this study was to determine the intra-rater minimal detectable change (MDC) in the volume of the upper limb, both segmentally and globally, using circumference measurements for the evaluation of upper limb volume. In this study, 25 women who had received a unilateral mastectomy for breast cancer stage II or III participated. On two occasions separated by 15 min, the same researcher determined 11 perimeters for each arm at 4 cm intervals from the distal crease of the wrist in the direction of the armpit. The MDC at the segmental level ranged from 3.37% to 7.57% (2.7 to 14.6 mL, respectively) and was 2.39% (42.9 mL) at the global level of the arm; thus, minor changes in this value result in a high level of uncertainty in the interpretation of the results associated with the diagnosis of lymphedema and follow-up for presenting patients.

Effects of Classic Progressive Resistance Training Versus Eccentric-Enhanced Resistance Training in People With Multiple Sclerosis.

OBJECTIVE: To compare the effects of classic progressive resistance training (PRT) versus eccentric strength-enhanced training (EST) on the performance of functional tests and different strength manifestations in the lower limb of people with multiple sclerosis (PwMS). DESIGN: Experimental trial. SETTING: Strength training program. PARTICIPANTS: PwMS (N=52; 19 men, 33 women) belonging to MS associations from the Castilla y León, Spain. INTERVENTIONS: Participants were assigned to 1 of 2 groups: a control group that performed PRT or an experimental group that performed EST. In both groups, the knee extensor muscles were trained for 12 weeks. MAIN OUTCOME MEASURES: Before and after 12 weeks of training, maximal voluntary isometric contraction and 1 repetition maximum (1RM) of the knee extensors were evaluated, as were the Chair Stand Test (CST) and Timed 8-Foot Up and Go (TUG) functional tests. RESULTS: No differences were found between the groups in the initial values for different tests. Intragroup comparisons found significant differences in CST (F=69.4; P<.001), TUG (F=40.0; P<.001), and 1RM (F=57.8; P<.001). For intergroup comparisons, EST presented better results than PRT in the CST (EST, 4.7%±2.8%; PRT, 1.9%±2.8%; F=13.1; P=.001) and TUG (EST, -2.9±4.7; PRT, -.41±5.6; F=5.6; P=.022). CONCLUSIONS: In PwMS, EST leads to improvements in 1RM, TUG, and CST that are similar to those of PRT. However, for patients who participated in this study, the EST seems to promote a better transfer of strength adaptations to the functional tests, which are closer to daily-living activities.

Effects of high-speed power training on muscle strength and power in patients with multiple sclerosis.

This study examined the effects of a high-speed power training program in peak muscle power and maximal voluntary isometric contraction (MVIC) of knee extensors in patients with relapsing-remitting multiple sclerosis (MS). Forty patients, 20 women (age 42.8 +/- 10.3 yr) and 20 men (age 44.0 +/- 8.7 yr) diagnosed with relapsing-remitting MS were randomly assigned, with respect to sex, to either an exercise group or a control group. Participants from the exercise group performed 12 wk of supervised muscle power training of knee extensors. All subjects were tested for MVIC and peak muscle power at baseline and after the training intervention. A strain gauge was used to measure the MVIC, and peak muscle power was assessed with a linear encoder at five relative loads. The training-related effects were assessed using a t-test. The results showed no significant changes in the control group from baseline to postintervention evaluation. In contrast, the exercise group significantly increased MVIC (10.8%; p < 0.05) and muscle power at 40, 50, 60, 70, and 80% of the MVIC by 21.8, 14.5, 17.3, 19.4, and 22.3%, respectively (p < 0.01), after the training. These findings suggest that 12 wk of high-speed power training improve both MVIC and muscle power at five different loads in patients with relapsing-remitting MS.

Effects of a resistance training program and subsequent detraining on muscle strength and muscle power in multiple sclerosis patients.

BACKGROUND: Although resistance training adaptations in multiple sclerosis (MS) patients have been described, the detraining response in this population is largely unknown. OBJECTIVE: [corrected] This study was designed to evaluate the effects of a 12-week detraining period on muscle strength (isometric and endurance) and muscle power of multiple sclerosis (MS) patients that had previously carried out a 12-week resistance training program (RTP). METHODS: Forty-two MS patients were randomly assigned into two groups: an exercise group (EG) that performed a 12-week RTP for the knee extensors muscles; and a control group (CG), that did not perform any specific training. Knee extension maximal voluntary isometric contraction (MVIC), muscle power and muscle endurance were evaluated before and after the RTP, as well as 12 weeks after training completion. A strain gauge was used to measure the maximal voluntary isometric contraction and muscle power was assessed with a linear encoder. Muscle endurance was interpreted as the number of repetitions that a patient could perform in a single set of knee extension exercise. RESULTS: The EG increased MVIC and muscle power after the training period, although the training did not affect muscle endurance. After 12 weeks of detraining, MVIC returned to pre-training values but muscle power was still greater than pre-training values in the EG. The CG did not present any change in the variables measured during the intervention. CONCLUSIONS: A 12-week RTP improved MVIC and muscle power in MS patients. Additionally, 12 weeks of detraining blunted strength training adaptations in MS patients, although muscle power training adaptations were still evident after the detraining period.