Systematic review of the methodological quality and outcome measures utilized in exercise interventions for adults with spinal cord injury.

STUDY DESIGN: Systematic literature review. OBJECTIVES: The primary aims of this study were to evaluate the methodological quality of exercise intervention studies in adults with spinal cord injuries (SCIs); and to classify the reported outcome measures according to the International Classification of Functioning, Disability and Health (ICF). METHODS: Electronic searches of PubMed, CINAHL, SPORTDiscus, PsychINFO, Scopus and the Cochrane Center Register of Controlled Trials from 2001 to 2011 were performed. Selected studies were evaluated for methodological quality using the Downs and Black checklist. Outcome measures were extracted and linked to categories of the ICF using standardized linking rules. RESULTS: Two-hundred forty abstracts were retrieved, 57 studies met eligibility criteria. The mean methodological quality score was 14.7 ± 3.2 out of 28 on the Downs and Black checklist. Three-hundred seventy four outcome measures were extracted with 333 concepts linked to 35 second-level ICF categories across the four components. CONCLUSION: Studies of exercise interventions for adults with SCI included in this review are generally low in methodological quality, primarily reporting outcomes related to the Body Functions and Body Structures components of the ICF. It is recommended that studies employ more vigorous methodological designs to reduce bias and confounding, and include outcome measures targeting more categories in the Activities and Participation component so as to reflect the potential benefits of exercise on health and functioning in this population.

Intramuscular fat and glucose tolerance after spinal cord injury--a cross-sectional study.

STUDY DESIGN: Survey. OBJECTIVE: Determine intramuscular fat (IMF) in affected skeletal muscle after complete spinal cord injury using a novel analysis method and determine the correlation of IMF to plasma glucose or plasma insulin during an oral glucose tolerance test. SETTING: General community of Athens, GA, USA. METHODS: A total of 12 nonexercise-trained complete spinal cord injured (SCI) persons (10 males and two females 40+/-12 years old (mean+/-SD), range 26-71 years, and 8+/-5 years post SCI) and nine nonexercise-trained nondisabled (ND) controls 29+/-9 years old, range 23-51 years, matched for height, weight, and BMI, had T(1) magnetic resonance images of their thighs taken and underwent an oral glucose tolerance test (OGTT) after giving consent. RESULTS: Average skeletal muscle cross-sectional area (CSA) (mean+/-SD) was 58.6+/-21.6 cm(2) in spinal cord subjects and 94.1+/-32.5 cm(2) in ND subjects. Average IMF CSA was 14.5+/-6.0 cm(2) in spinal cord subjects and 4.7+/-2.5 cm(2) in nondisabled subjects, resulting in an almost four-fold difference in IMF percentage of 17.3+/-4.4% in spinal cord subjects and 4.6+/-2.6% in nondisabled subjects. The 60, 90 and 120 min plasma glucose or plasma insulin were higher in the SCI group. IMF (absolute and %) was related to the 90 or 120 min plasma glucose or plasma insulin (r(2)=0.71-0.40). CONCLUSIONS: IMF is a good predictor of plasma glucose during an OGTT and may be a contributing factor to the onset of impaired glucose tolerance and type II diabetes, especially in SCI. In addition, reports of skeletal muscle CSA should be corrected for IMF.

The effect of a repeat bout of exercise on muscle injury in persons with spinal cord injury.

Following an initial bout of damaging exercise, a successive bout of similar exercise typically results in less injury, known as the "protective effect". Unloading due to spinal cord injury (SCI) increases the susceptibility to contraction-induced muscle injury. We tested the hypothesis that two bouts of isometric actions would evoke the same damage in the quadriceps femoris (QF) of patients with SCI. Six male subjects [32 (5) years old, 182 (9) cm, 81 (21) kg, injury level C6-T7, 6 (2) years post-injury, mean (SD)] were tested at two time points (Time1, Time2), separated by 8 weeks. Magnetic resonance images were taken of the QF prior to, immediately after, and 3 days after electromyostimulation (EMS) that evoked isometric knee extension. EMS (50 Hz) consisted of five sets of ten contractions (2 s on/6 s off, 1 min b/t sets) followed by three sets of ten contractions (1 s on/1 s off, 30 s b/t sets). Relative cross-sectional area of stimulated and injured skeletal muscle was obtained by quantifying pixels with an elevated T2. Relative area of stimulated QF was the same for both time points [92 (6)% and 89 (7)%] as was torque loss (approximately 55%). Three days post-EMS, the relative area of stimulated QF injured was not different between time points [30 (14)% vs 29 (17)%, P>0.05]. These results indicate an absence of a protective effective for repeat exercise bouts separated by 8 weeks in SCI patients using EMS.

Variable frequency trains enhance torque independent of stimulation amplitude.

AIM: Variable frequency trains have been reported to enhance force of fatigued human skeletal muscle. More rapid calcium turnover and/or enhanced stiffness may be responsible for the augmented torque-time integral during surface stimulation at moderate amplitude. In contrast, it has recently been suggested that variable frequency train enhancement occurs only at low forces as a result of preferential stimulation of fast fibres and/or altered motor unit recruitment. If correct, this would limit the practical benefit of variable frequency trains. Accordingly, we tested the hypothesis that torque augmentation by variable frequency trains in fatigued skeletal muscle was independent of stimulation amplitude. METHODS: The m. quadriceps femoris of six males was stimulated with constant frequency trains (six 200-micros square waves separated by 70 ms) or variable frequency trains (first interpulse interval 5 ms) at an amplitude that initially evoked approximately 25 or approximately 50% of maximal voluntary isometric torque. RESULTS: After 180 constant frequency trains (50% duty cycle), isometric peak torque decreased approximately 63%. In fatigued muscle, variable frequency trains enhanced the torque-time integral by approximately 23% over that for constant frequency trains and this effect was independent of stimulation amplitude. This was due to greater peak torque and less slowing of rise time. CONCLUSION: These responses show that the torque-time integral can be enhanced at both moderate and high stimulation amplitudes. As such, it is suggested that neither recruitment nor preferential activation of fast muscle is responsible for the "catch-like" property that can be demonstrated in fatigued human skeletal muscle.