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 ).

Aerobic capacity in persons with Parkinson's disease: a systematic review.

PURPOSE: To systematically review studies assessing (1) psychometric properties of the maximal oxygen uptake (VO2max) test in PD, (2) VO2max levels in persons with PD (pwPD) compared to healthy controls (HCs), and (3) reported VO2max associations in PD. MATERIALS AND METHODS: Six databases were searched. Descriptive data synthesis was used to summarize psychometric properties and reported VO2max associations. The VO2max means and test end-criteria were calculated using linear mixed models. Simple linear regression was used for associations. RESULTS: The review included 25 studies. Psychometric properties of the VO2max test, reported in one study, showed intraclass correlations of 0.90-0.94 for VO2max. Thirteen studies reported test end-criteria, with only mean respiratory exchange ratio (on medication) and percentage of predicted maximal heart rate (off medication) fulfilling standardized minimum values for the VO2max test. The VO2max was comparable between pwPD and HC as well as between different PD-medication states. Associations between VO2max and age, sex, and fatigue were reported. CONCLUSIONS: In mildly to moderately affected pwPD, limited evidence exists on the psychometric properties of the VO2max test and end-criteria were sparsely reported. Surprisingly, VO2max was comparable between pwPD and HC as well as between different PD-medication states, and only age, sex, and fatigue were associated with VO2max. Implications for rehabilitationIn mildly to moderately affected persons with PD (pwPD), only one study has examined psychometric properties of the VO2max test, reporting excellent test-retest reliability.A general lack of consistency on how to measure and report VO2max end-criteria was observed, but when reported, the end-criteria were most often not met.No difference was found in VO2max between mildly to moderately affected pwPD and HC, or between pwPD across different medication states.The identified negative association between VO2max and fatigue suggests aerobic exercise as a potential symptomatic treatment of fatigue when rehabilitation professionals are treating pwPD.

Lower extremity muscle power - A critical determinant of physical function in aging and multiple sclerosis.

BACKGROUND AND PURPOSE: In aging, lower extremity muscle power is undoubtedly one of the most important parameters of neuromuscular function implicating lower extremity physical function (e.g. walking capacity). However, no previous studies have examined the combined effects of aging and multiple sclerosis (MS) on lower extremity muscle power concomitant with lower extremity physical function. The aim of this cross-sectional study was to examine potential decrements in pwMS vs. healthy controls (HC) across the adult lifespan in these outcomes. METHODS: In the present explorative cross-sectional study, n = 42 pwMS (females n = 29 (69%); age = 53 ± 12 years (mean ± SD), range 31-78; patient determined disease steps score = 3.7 ± 1.7, range 0-7) and n = 49 age-matched HC (females n = 34 (69%); age = 56 ± 16 years, range 24-78) were enrolled, and divided into groups of young (≤ 44 years), middle-aged (45-59 years), and old (≥ 60 years). Muscle power was obtained from bilateral leg press (PowerLegPressPeak) and maximal chair rise (PowerChairRise) using a linear encoder. Associations were assessed between muscle power and measurements of lower extremity physical function (5 x sit-to-stand (5STS); timed 25-foot-walk-test (T25FWT)). RESULTS: Muscle power was reduced in pwMS vs. HC (PowerLegPressPeak -23[-34:-12]% (mean[95%CI]); PowerChairRise -26[-35:-17]%) and was negatively associated with advanced age in both pwMS (decline per decade -0.40 W.kg-1 and -2.53 W.kg-1, respectively) and HC (decline per decade -0.42 W.kg-1 and -2.03 W.kg-1, respectively). Muscle power was strongly associated with physical function in pwMS (r2range = 0.45-0.61, p < 0.01) yet only moderately associated in HC (r2range = 0.18-0.39, p < 0.01). CONCLUSION: The combined effects of MS and aging reveal substantial decrements in lower extremity muscle power that is accompanied by (and strongly associated with) decrements in lower extremity physical function. Consequently, lower extremity muscle power should be viewed as a clinically important factor (i.e. a critical determinant of lower extremity physical function) in pwMS. We propose that lower extremity muscle power should be specifically targeted by preventive and rehabilitative exercise strategies, especially in older pwMS.