Changes in muscle activation patterns and subjective low back pain ratings during prolonged standing in response to an exercise intervention.

Regis University, School of Physical Therapy, Denver, CO, USA.
Journal of electromyography and kinesiology: official journal of the International Society of Electrophysiological Kinesiology (Impact Factor: 1.73). 12/2010; 20(6):1125-33. DOI: 10.1016/j.jelekin.2010.07.007
Source: PubMed

ABSTRACT Low back pain (LBP) development has been associated with occupational standing. Increased hip and trunk muscle co-activation is considered to be predisposing for LBP development during standing in previously asymptomatic individuals. The purpose of this work was to investigate muscle activation and LBP responses to a prescribed exercise program. Pain-developing (PD) individuals were expected to have decreased LBP and muscle co-activation following exercise intervention.
Electromyography (EMG) data were recorded from trunk and hip muscle groups during 2-h of standing. An increase of >10mm on visual analog scale (VAS) during standing was threshold for PD categorization. Participants were assigned to progressive exercise program with weekly supervision or control (usual activity) for 4 weeks then re-tested.
Forty percent were categorized as PD on day 1, VAS=24.2 (±4.0)mm. PD exercisers (PDEX) had lower VAS scores (8.93±3.66 mm) than PD control (PDCON) (16.5±6.3 mm) on day 2 (p=0.007). Male PDEX had decreased gluteus medius co-activation levels (p<0.05) on day 2.
The exercise program proved beneficial in reducing LBP during standing. There were changes in muscle activation patterns previously associated with LBP. Predisposing factors for LBP during standing were shown to change positively with appropriate exercise intervention.

Download full-text


Available from: Erika Nelson-Wong, Apr 24, 2015
1 Follower
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: A major research focus is optimization of interventions for low back pain (LBP). Predisposing factors for LBP development have been previously identified. To differentiate changes in these factors with intervention, factor stability over time must be determined. Twenty-three volunteers without LBP participated in a LBP-inducing standing protocol on two separate days. Outcome measures included visual analog scale (VAS) for LBP and trunk/hip muscle coactivation patterns. Intraclass correlation coefficients (ICCs) were used to examine repeatability. Between-day repeatability of outcome measures was excellent (ICCs >0.80). Individuals were consistent in subjective LBP, with 83% reporting similar day-to-day VAS levels. Muscle co-activation patterns and LBP reports are stable measures over time for this LBP-inducing protocol. Changes in these measures following intervention can be considered to be treatment effects and are not due to natural variability. This provides support for use of this protocol in studying interventions for standing-induced LBP.
    07/2010; 2010:289278. DOI:10.1155/2010/289278
  • [Show abstract] [Hide abstract]
    ABSTRACT: This paper presents a robust control system design for a nonlinear multivariable paper machine benchmark problem. The aim is to control the output variables basis weight and ash contents with the control inputs thickstock and filler flow, such that reference steps in basis weight and ash contents yield closed loop time responses within specifications for a given set of retention parameter values, with specified minimal cross influence on the other controlled variable. A static nondiagonal nonlinear precompensator is designed to minimize steady state cross coupling, then a set of equivalent linear transfer functions are identified by least squares. The time domain specifications are then translated to approximate frequency domain specifications using an assumption that the closed loop is essentially similar to a third order system. Based on the frequency domain specifications, and the set of equivalent transfer functions, a diagonal dynamic feedback controller and a diagonal dynamic prefilter are designed according to the quantitative feedback theory (QFT). This involves the computation of frequency domain constraints (Horowitz bounds) for the nominal open loops, and manual loop shaping of the latter. The main design constraint is plant delay
    Proceedings of the IEEE Conference on Decision and Control 01/1995; 4. DOI:10.1109/CDC.1995.479254
  • [Show abstract] [Hide abstract]
    ABSTRACT: Previous literature has shown that individuals can develop transient low back pain (LBP) during a 2-h bout of unconstrained prolonged standing. The purpose of this study was to investigate the postural changes of individuals who develop LBP during standing (PD) and those who do not (NPD). Forty-one subjects (20 male, 21 female) participated in a 2-h prolonged standing occupational simulation and recorded their ratings of perceived LBP on a visual analog scale (VAS). Center of pressure changes (shifts, drifts, and fidgets) and body weight shifts were determined for each subject. All subjects showed an increase in the BW shift frequency and a decrease in average shift duration over the 2-h protocol. All NPD and female PD were consistent for many of the variables; however, male PD did not show similar patterns to the other groups, especially for anterior-posterior (AP) shift amplitude and total body weight asymmetry. Although gender differences between the pain groups were found, PD and NPD do not use different postural changes during unconstrained standing, showing that changes to postural control may be an "adaptive", rather than "causative" response to their LBP development. Future works should concentrate on bridging the literature seen in quiet standing before and after prolonged standing and the response of PD, as well as the effect of an exercise intervention on postural control, especially for male PD.
    Gait & posture 07/2011; 34(4):490-5. DOI:10.1016/j.gaitpost.2011.06.025 · 2.30 Impact Factor