Linzy Houchen

Ultrasound assessment of lower limb muscle mass in response to resistance training in COPD

BackgroundQuantifying the improvements in lower limb or quadriceps muscle mass following resistance training (RT), is an important outcome measure in COPD. Ultrasound is a portable, radiation free imaging technique that can measure the size of superficial muscles belonging to the quadriceps group such as the rectus femoris, but has not been previously used in COPD patients following RT. We compared the responsiveness of ultrasound derived measures of quadriceps mass against dual energy x-ray absorptiometry (DEXA), in patients with COPD and healthy controls following a programme of high intensity knee extensor RT.MethodsPortable ultrasound was used to assess the size of the dominant quadriceps in 45 COPD patients and 19 healthy controls-before, during, and after 8 weeks of bilateral high intensity isokinetic knee extensor RT. Scanning was performed at the mid-thigh region, and 2 indices of quadriceps mass were measured-rectus femoris cross-sectional area (RFcsa) and quadriceps muscle thickness (Qt). Thigh lean mass (Tdexa) was determined by DEXA.ResultsTraining resulted in a significant increase in Tdexa, RFcsa and Qt in COPD patients [5.7%, 21.8%, 12.1% respectively] and healthy controls [5.4%, 19.5%, 10.9 respectively]. The effect size for the changes in RFcsa (COPD= 0.77; Healthy=0.83) and Qt (COPD=0.36; Healthy=0.78) were greater than the changes in Tdexa (COPD=0.19; Healthy=0.26) following RT.ConclusionsSerial ultrasound measurements of the quadriceps can detect changes in muscle mass in response to RT in COPD. The technique has good reproducibility, and may be more sensitive to changes in muscle mass when compared to DEXA.Trial registrationhttp://www.controlled-trials.com (Identifier: ISRCTN22764439)

Inflammatory and Satellite Cells in the Quadriceps of Patients With COPD and Response to Resistance Training

BACKGROUND Quadriceps dysfunction in COPD may be mediated by inflammatory mechanisms or impaired satellite cell function. Resistance training is of proven efficacy in these patients, but data on muscle inflammatory and satellite cell response to resistance exercise in COPD are lacking.We aimed to examine the inflammatory and satellite cell profile of the quadriceps in patients with COPD and healthy control subjects at rest and after acute and chronic resistance exercise. METHODS Seventeen patients with COPD and 10 healthy control subjects underwent 8 weeks ofbilateral lower-limb, high-intensity resistance training, thrice weekly, on an isokinetic dynamometer.Quadriceps muscle biopsy specimens from the dominant thigh were obtained at baseline,24 h following the fi rst exercise bout, and after 8 weeks 24 h after the last exercise bout. Glycolmethacrylate-embedded muscle biopsy specimens were analyzed using immunohistochemistry to identify neutrophils, macrophages, and satellite cells. RESULTS Neutrophils were significantly elevated in the quadriceps of patients with COPD at baseline compared with healthy control subjects ( P 5 .03). Inflammatory cells were increased significantly at 24 h in both groups but were similar to baseline values at week 8, with no difference detectable between healthy control subjects and patients with COPD. Satellite cell numbers were comparable between patients and control subjects at baseline, tended to increase at 24 h, and remained elevated at week 8. CONCLUSIONS Inflammatory cells are elevated in the resting quadriceps of patients with COPD. Acute resistance exercise leads to an inflammatory myositis, which is attenuated with regular training. Satellite cells in patients and control subjects are comparable and are increased in response to exercise. TRIAL REGISTRY ISRCTN Register ; No.: ISRCTN22764439; URL: www.controlled-trials.com.

How sustainable is strength training in chronic obstructive pulmonary disease

OBJECTIVES To examine whether the benefits from strength training are sustained after an initial training period in patients with chronic obstructive pulmonary disease (COPD). DATA SOURCES MEDLINE (1966 to May 2008), CENTRAL (1948 to May 2008) and PEDro (1929 to May 2008). REVIEW METHODS Criteria for inclusion in this review were that study participants had COPD and undertook an intervention that included strength training. A period of follow-up (>/=12 weeks) after strength training and a measure of muscle strength taken at this time were required. All experimental study designs were accepted, and the publication language had to be English. Reviews were excluded. The PEDro scale was used to assess the methodological quality of studies. RESULTS Only three eligible studies were identified (PEDro scores ranged from 5 to 7). Two studies found that the benefits from strength training were still evidental at 12 weeks and 12 months after an initial 12-week and 6-month training period, respectively. The other study found no difference between the control and training groups 12 weeks after a 12-week training intervention. Only one study discussed continuation of strength training during the follow-up period. The results of these studies could not be pooled for meta-analysis, as the study interventions and assessments were heterogeneous. CONCLUSION Despite an extensive search of the literature, only three articles were identified. Therefore, the long-term effects of strength training remain unknown. Further trials examining the sustainability of strength training with homogeneous populations, training programmes and assessments are warranted. This would enable the pooling of results for meta-analysis, and provide clearer recommendations to pulmonary rehabilitation practitioners.