Validity and reliability of linear encoder muscle power testing in persons with Parkinson's disease.

OBJECTIVE: To investigate the construct validity ON medication and the reliability both ON and OFF medication of linear encoder muscle power testing in persons with Parkinson's disease (pwPD). DESIGN: A study using baseline data from one randomized controlled trial (study 1) and one cohort study (study 2). SETTING: University exercise lab. PARTICIPANTS: Study 1: 35 healthy controls and 70 pwPD. Study 2: 20 pwPD. INTERVENTION: Study 1: baseline data. Study 2: 4 chair rise tests (2 ON and 2 OFF medication), in a randomized order, separated by 4 to 16 days. MAIN MEASURES: Linear encoder data were collected from a chair rise test. Known groups validity and convergent validity (i.e., construct validity) were assessed by comparing peak power between pwPD and healthy controls and associations between peak power and functional performance (i.e., 6-Min Walk Test, Timed Up and Go Test, Six-Spot Step Test), respectively. Reliability was assessed as day-to-day variation and by intraclass correlation coefficients. RESULTS: Peak power was comparable between pwPD and healthy controls (-7.2%, p = 0.17), but lower in moderately impaired pwPD compared to mildly impaired pwPD (-27%, p < 0.01) and healthy controls (-23%, p < 0.01). Moderate to strong associations were observed between peak power and functional performance (r2 = 0.44-0.51). Day-to-day variation ON and OFF medication were 1.0 and 1.3 W/kg, respectively, while intraclass correlation coefficients were 0.95 (0.87;0.98) and 0.93 (0.82;0.97), respectively. CONCLUSION: Linear encoder muscle power testing shows inconsistent known groups validity, acceptable convergent validity ON medication, and excellent day-to-day reliability ON and OFF medication in pwPD.

Muscle Strength and Power in People With Parkinson Disease: A Systematic Review and Meta-analysis.

BACKGROUND AND PURPOSE: No studies have synthesized the literature regarding mechanical muscle function (ie, strength, power, rate of force development [RFD]) in people with Parkinson disease (PD). Here, we aimed to expand our understanding of mechanical muscle function in people with PD (PwPD) by systematically reviewing (1) the psychometric properties of isokinetic/isometric dynamometry in PD, (2) the literature comparing mechanical muscle function in PwPD with healthy controls (HC), and (3) reported associations between muscle mechanical muscle function and functional capacity and/or disease severity. METHODS: Systematic literature search in 6 databases. Included studies had to (1) enroll and report data on PwPD, (2) include assessment(s) of psychometric properties (ie, validity, reliability, responsiveness) of isokinetic/isometric dynamometry in PD, and/or (3) assess mechanical muscle function in both PwPD and HC using isokinetic/isometric dynamometry. RESULTS: A total of 40 studies were included. Aim 1 studies (n = 2) showed high reliability for isometric dynamometry (hip-abductor/dorsiflexor/trunk flexor-extensor/handgrip: intraclass correlations coefficients range = 0.92-0.98). Aim 2 studies (n = 40) showed impaired mechanical muscle function (ie, strength, power, RFD) in PwPD compared with HC (effect sizes range = 0.52-1.89). Aim 3 studies (n = 11) showed weak-to-strong associations between overall and lower extremities muscle strength and functional capacity and/or disease severity outcomes (ie, Unified Parkinson Disease Rating Scale). DISCUSSION AND CONCLUSIONS: Sparse methodological evidence suggests high reliability when using dynamometry in PwPD. Muscle strength, power, and RFD are impaired in PwPD compared with HC. Muscle strength is associated with functional capacity and disease severity.Video Abstract available for more insights from the authors (see the Video, Supplemental Digital Content 1, available at: http://links.lww.com/JNPT/A403 ).

Efficacy of high-intensity aerobic exercise on common multiple sclerosis symptoms.

OBJECTIVES: Fatigue and walking impairment are disabling symptoms of multiple sclerosis (MS). We investigated the effects of progressive aerobic exercise (PAE) on fatigue, walking, cardiorespiratory fitness (VO2 max), and quality of life in people with MS (pwMS). MATERIALS & METHODS: Randomized controlled trial (1:1 ratio, stratified by sex) with a 24-week crossover follow-up and intention-to-treat analysis. Allocation to an exercise (24 weeks of PAE followed by self-guided physical activity) and a waitlist (24 weeks of habitual lifestyle followed by PAE) group. PAE comprised two supervised sessions per week; 30-60 min, 65-95% of maximum heart rate. Fatigue impact (Modified Fatigue Impact Scale; MFIS) and severity (Fatigue Severity Scale; FSS), walking ability (12-item MS Walking Scale; MSWS-12) and capacity (Six-Minute Walk Test; 6MWT, Six Spot Step Test; SSST), quality of life (Short Form 36 health survey; SF-36), and VO2 max were measured at baseline, 24 weeks, and 48 weeks. RESULTS: Eighty-six pwMS were enrolled. Following PAE between-group differences showed reductions in MFIStotal (-5.3 [95% CI: -10.9;0.4], point estimate >clinical relevance), MFISphysical subscore (-2.8 [-5.6;-0.1]), and MFISpsychosocial subscore (-0.9 [-1.6;-0.2]), and an increase in VO2 max (+3.5 ml O2 /min/kg [2.0;5.1]). MSWS-12 (-5.9 [-11.9; 0.2]) and 6MWT (+14 m [-5;33]) differences suggested potential small walking improvements. No changes observed in FSS, SSST, or SF-36. CONCLUSIONS: In a representative sample of pwMS, PAE induced a clinically relevant reduction in fatigue impact, whereas small and no effects were seen for walking and quality of life, respectively. The results need confirmation in a future trial due to the study limitations.

Efficacy of high-intensity aerobic exercise on cognitive performance in people with multiple sclerosis: A randomized controlled trial.

BACKGROUND: Cognitive impairment is highly prevalent in multiple sclerosis (MS). Progressive aerobic exercise (PAE) represents a promising approach toward preservation or even improvement of cognitive performance in people with MS (pwMS). OBJECTIVE: To investigate the effects of PAE on the cognitive domains of information processing, learning and memory, and verbal fluency in pwMS. METHODS: This randomized controlled trial included an exercise (n = 43, 24 weeks of supervised PAE, followed by self-guided physical activity) and a waitlist group (n = 43, 24 weeks of habitual lifestyle, followed by supervised PAE). Assessments included the Brief Repeatable Battery of Neuropsychological tests (BRB-N), self-reported mood, and cardiorespiratory fitness. Published reference data were used to compute Z-scores for BRB-N scores. Cognitive impairment was defined as one or more Z-scores ⩽ -1.5SD. RESULTS: No between-group changes in the total group were observed in BRB-N scores following PAE. In the cognitively impaired subgroup (43% of the total group) the between-group point estimate suggested a potential clinical relevant improvement in the Symbol Digit Modalities Test (95% CI overlapping zero). Cardiorespiratory fitness increased in the total group and the cognitively impaired subgroup. CONCLUSION: In the present representative MS group, 24 weeks of supervised PAE had no effect on any cognitive domain in the total group but potentially improved processing speed in the cognitively impaired subgroup.

Effects of Autograft Types on Muscle Strength and Functional Capacity in Patients Having Anterior Cruciate Ligament Reconstruction: A Randomized Controlled Trial.

BACKGROUND: The effects of different autograft types for anterior cruciate ligament reconstruction (ACL-R) on muscle function are sparsely investigated in randomized controlled trials. Our aim was to investigate the effects of quadriceps tendon autograft (QTB) vs. semitendinosus-gracilis autograft (StG) on thigh muscle strength and functional capacity, and a patient-reported outcome 1 year after ACL-R, and to compare the results to healthy controls. METHODS: ACL-R patients (n = 100) and matched controls (CON, n = 50) were recruited, with patients being randomly assigned to QTB (n = 50) or StG (n = 50) ACL-R. One year after ACL-R, bilateral knee extensor (KE) and flexor (KF) muscle strength (isometric, dynamic, explosive, limb symmetry index [LSI], hamstring:quadriceps ratio [HQ ratio]) were assessed by isokinetic dynamometry, along with functional capacity (single leg hop distance [SHD]) and a patient-reported outcome (International Knee Documentation Committee [IKDC] score). RESULTS: KE muscle strength of the operated leg was lower (9-11%) in QTB vs. StG as was KE LSI, while KF muscle strength was lower (12-17%) in StG vs. QTB as was KF LSI. HQ ratios were lower in StG vs. QTB. Compared with the controls, KE and KF muscle strength were lower in StG (10-22%), while KE muscle strength only was lower in QTB (16-25%). Muscle strength in the StG, QTB, and CON groups was identical in the non-operated leg. While SHD and IKDC did not differ between StG and QTB, SHD in both StG and QTB was lower than CON. The IKDC scores improved significantly 1 year following ACL-R for both graft types. CONCLUSION: One year after ACL-R, muscle strength is affected by autograft type, with StG leading to impairments of KE and KF muscle strength, while QTB results in more pronounced impairments of KE only. Functional capacity and patient-reported outcome were unaffected by autograft type, with the former showing impairment compared to healthy controls. CLINICAL TRIALS REGISTRATION NUMBER: NCT02173483.

Correction: Langeskov-Christensen, M., et al. Aerobic Capacity Is Not Associated with Most Cognitive Domains in Patients with Multiple Sclerosis-A Cross-Sectional Investigation. Journal of Clinical Medicine 2018, 7, 272.

The authors wish to make the following corrections to this paper [...].

Can we trust self-reported walking distance when determining EDSS scores in patients with multiple sclerosis? The Danish MS hospitals rehabilitation study.

BACKGROUND: In multiple sclerosis (MS), the Expanded Disability Status Scale (EDSS) reflects disease severity. Although parts of the EDSS are dependent on actual walking distance, self-reported statements are often applied. OBJECTIVES: The purpose of the present study was, therefore, to compare self-reported walking distance to actual walking distance to outline how this influences EDSS scoring. METHODS: MS patients with EDSS 4.0-7.5 (n = 273) were included from the Danish MS hospitals rehabilitation study (n = 427). All patients subjectively classified their maximal walking distance according to one of seven categories (>500; 300-499; 200-299; 100-199; 20-99; 5-19; 0-4 m). Subsequently, actual maximal walking distance was assessed and EDSS was determined from both self-reported walking distance (EDSSself-report) and actual walking distance (EDSSactual). RESULTS: In 145 patients (53%), self-reported walking distance was misclassified when compared to the actual walking distance. Misclassification was more frequent in patients using walking aids (64% vs. 44%, p < 0.05) and in patients with primary progressive MS (69%, p < 0.05). Misclassification of walking distance corresponded to incorrect EDSS scores (EDSSself-report vs EDSSactual) of ⩾0.5 point in 24%. CONCLUSION: In MS patients with EDSS 4.0-7.5, 53% misclassified their walking distance yielding incorrect EDSS scores in 24%. Therefore, correct EDSS determination must be based on measurement of actual walking distance.

Muscle glycogen content modifies SR Ca2+ release rate in elite endurance athletes.

PURPOSE: The aim of the present study was to investigate the influence of muscle glycogen content on sarcoplasmic reticulum (SR) function and peak power output (Wpeak) in elite endurance athletes. METHODS: Fourteen highly trained male triathletes (VO2max = 66.5 ± 1.3 mL O2·kg·min), performed 4 h of glycogen-depleting cycling exercise (HRmean = 73% ± 1% of maximum). During the first 4 h of recovery, athletes received either water (H2O) or carbohydrate (CHO), separating alterations in muscle glycogen content from acute changes affecting SR function and performance. Thereafter, all subjects received CHO-enriched food for the remaining 20-h recovery period. RESULTS: Immediately after exercise, muscle glycogen content and SR Ca release rate was reduced to 32% ± 4% (225 ± 28 mmol·kg dw) and 86% ± 2% of initial levels, respectively (P < 0.01). Glycogen markedly recovered after 4 h of recovery with CHO (61% ± 2% of preexercise) and SR Ca release rate returned to preexercise level. However, in the absence of CHO during the first 4 h of recovery, glycogen and SR Ca release rate remained depressed, with the normalization of both parameters at the end of the 24 h of recovery after receiving a CHO-enriched diet. Linear regression demonstrated a significant correlation between SR Ca release rate and muscle glycogen content (P < 0.01, r = 0.30). The 4 h of cycling exercise reduced Wpeak by 5.5%-8.9% at different cadences (P < 0.05), and Wpeak was normalized after 4 h of recovery with CHO, whereas Wpeak remained depressed (P < 0.05) after water provision. Wpeak was fully recovered after 24 h in both the H2O and the CHO group. CONCLUSION: In conclusion, the present results suggest that low muscle glycogen depresses muscle SR Ca release rate, which may contribute to fatigue and delayed recovery of Wpeak 4 h postexercise.

Proliferation of myogenic stem cells in human skeletal muscle in response to low-load resistance training with blood flow restriction.

Low-load resistance training with blood flow restriction has been shown to elicit substantial increases in muscle mass and muscle strength; however, the effect on myogenic stem cells (MSCs) and myonuclei number remains unexplored. Ten male subjects (22.8 ± 2.3 years)performed four sets of knee extensor exercise (20% 1RM) to concentric failure during bloodflow restriction (BFR) of the proximal thigh (100 mmHg), while eight work-matched controls(21.9 ± 3.0 years) trained without BFR (control, CON). Twenty-three training sessions were performed within 19 days. Maximal isometric knee extensor strength (MVC) was examined pre- and post-training, while muscle biopsies were obtained at baseline (Pre), after 8 days intervention(Mid8) and 3 (Post3) and 10 days (Post10) post training to examine changes in myofibre area (MFA), MSC and myonuclei number. MVC increased by 7.1% (Post5) and 10.6% (Post12)(P <0.001) with BFR training, while type I and II MFA increased by 38% (Mid8), 35 ­ 37%(Post3) and 31 ­ 32% (Post10) (P <0.001). MSCs per myofibre increased with BFR training from 0.10 ± 0.01 (Pre) to 0.38 ± 0.02 (Mid8), 0.36 ± 0.04 (Post3) and 0.25 ± 0.02 (Post10) (P <0.001). Likewise, myonuclei per myofibre increased from 2.49 ± 0.07 (Pre) to 3.30 ± 0.22(Mid8), 3.20 ± 0.16 (Post3) and 3.11 ± 0.11 (Post10), (P<0.01). Although MFA increased in CON at Mid8, it returned to baseline at Post3. No changes in MSC or myonuclei number were observed in CON. This study is the first to show that short-term low-load resistance exercise performed with partial blood flow restriction leads to marked proliferation of myogenic stem cells and resulting myonuclei addition in human skeletal muscle, which is accompanied by substantial myofibre hypertrophy.