The impact of obesity on skeletal muscle strength and structure through adolescence to old age

Obesity is associated with functional limitations in muscle performance and increased likelihood of developing a functional disability such as mobility, strength, postural and dynamic balance limitations. The consensus is that obese individuals, regardless of age, have a greater absolute maximum muscle strength compared to non-obese persons, suggesting that increased adiposity acts as a chronic overload stimulus on the antigravity muscles (e.g., quadriceps and calf), thus increasing muscle size and strength. However, when maximum muscular strength is normalised to body mass, obese individuals appear weaker. This relative weakness may be caused by reduced mobility, neural adaptations and changes in muscle morphology. Discrepancies in the literature remain for maximal strength normalised to muscle mass (muscle quality) and can potentially be explained through accounting for the measurement protocol contributing to muscle strength capacity that need to be explored in more depth such as antagonist muscle co-activation, muscle architecture, a criterion valid measurement of muscle size and an accurate measurement of physical activity levels. Current evidence demonstrating the effect of obesity on muscle quality is limited. These factors not being recorded in some of the existing literature suggest a potential underestimation of muscle force either in terms of absolute force production or relative to muscle mass; thus the true effect of obesity upon skeletal muscle size, structure and function, including any interactions with ageing effects, remains to be elucidated.     

A review of the assessment and prevalence of sedentarism in older adults,its physiology/health impact and non-exercise mobility counter-measures

This literature review focuses on aspects of sedentary behaviour (SB) in elderly. Since it has been identified as a distinct health risk, independent of physical activity, SB is a significant issue. This is particularly true for an ageing population as evidence shows that older adults (aged ≥65 years) are the most sedentary age group (on average 8.5–9.6 h daily sitting time). Accurate SB assessment is important for understanding this habitual behaviour and its impact. However, SB measurement is challenging, regardless of the method used. Although negative associations of SB in elderly have been reported for several health outcomes, evidence is inconclusive, apart from the evidence on the adverse SB effect on the all-cause mortality rate. Generally, strategies have been proposed to counteract SB, of which breaking prolonged sedentary bouts with at least light-intensity physical activity seems to be the most promising. Overall, further research in elderly is required to increase the evidence and to either support or refute the current findings. Moreover, further research will help to develop informed SB guidelines for an optimal strategy to counteract SB and its health effects in older adults.     

Testing a Path-Analytic Mediation Model of How Motivational Enhancement Physiotherapy Improves Physical Functioning in Pain Patients

Purpose Pain is a complex phenomenon not easily discerned from psychological, social, and environmental characteristics and is an oft cited barrier to return to work for people experiencing low back pain (LBP). The purpose of this study was to evaluate a path-analytic mediation model to examine how motivational enhancement physiotherapy, which incorporates tenets of motivational interviewing, improves physical functioning of patients with chronic LBP. Methods Seventy-six patients with chronic LBP were recruited from the outpatient physiotherapy department of a government hospital in Hong Kong. Results The re-specified path-analytic model fit the data very well, χ ²(3, N = 76) = 3.86, p = .57; comparative fit index = 1.00; and the root mean square error of approximation = 0.00. Specifically, results indicated that (a) using motivational interviewing techniques in physiotherapy was associated with increased working alliance with patients, (b) working alliance increased patients’ outcome expectancy and (c) greater outcome expectancy resulted in a reduction of subjective pain intensity and improvement in physical functioning. Change in pain intensity also directly influenced improvement in physical functioning. Conclusions The effect of motivational enhancement therapy on physical functioning can be explained by social–cognitive factors such as motivation, outcome expectancy, and working alliance. The use of motivational interviewing techniques to increase outcome expectancy of patients and improve working alliance could further strengthen the impact of physiotherapy on rehabilitation outcomes of patients with chronic LBP.     

β‐globin gene cluster haplotypes in sickle cell patients from Panamá

Objective: To analyze the frequency of the haplotypes of β‐globin gene cluster in randomly selected patients withsickle cell disease (SCD), attended in the Children's Hospital of Panama. Methods: Five polymorphic sites in the β‐globin gene cluster were analyzed by polymerase chain reaction (PCR) followed by restriction digestion and agarose gel electrophoresis in a total of 100 patients, including 95 homozygous for HbS (sickle cell anemia) and 5 compound heterozygotes for HbS and HbC genes (HbSC disease). Results: The Bantu haplotype was predominant with a frequency of 51%, followed by the Benin (30%), Senegal (8.5%), and Cameroon (4%); other haplotypes were also identified. Genotype was CAR/CAR in 39 patients, BEN/BEN in 22, SEN/SEN in 6, CAM/CAM in 4, ARB/ARB in 1, CAR/BEN in 15, CAR/SEN in 5, CAR/Hp5 in 3, CAR/Hp1 in 1, BEN/Hp11 in 1, Atp Hp1/Hp1 in 2, and Atp Hp5/Hp5 in 1 individual. Hemoglobin concentrations, hematocrit, and mean corpuscular hemoglobin concentration values did not differ among homozygous forms of haplotypes. The mean HbF in all patients was 15.39 ± 1.21, whereas SEN/SEN patients had higher HbF than BEN/BEN patients (24.26 ± 4.18 vs. 13.17 ± 2.39, respectively, P < 0.05). The percentage of reticulocytes was highest in BEN/BEN and CAR/CAR, and it was associated with worst prognosis. Conclusion: The results show the presence of common β^S haplotypes in Panama; the prevalence of African origin, and the similarity in the Panamanian and Colombian distribution of haplotypes. Am. J. Hum. Biol. 2011. © 2011 Wiley‐Liss, Inc.     

Comparison of fat-free mass in super obesity (BMI ≥ 50 kg/m2) and morbid obesity (BMI <50 kg/m2) in response to different weight loss surgeries

BackgroundDifferences in excess weight loss, body mass index (BMI) change, and body composition have been related to different types of bariatric procedures. Our objective was to explore these alterations related to body mass in superobese (SO) and morbidly obese (MO) patients in a university hospital setting.MethodsPatients provided written informed consent and had their body composition measured before and after surgery using bioimpedance (Tanita 310). The t test was used to compare MO and SO. Pearson's correlations were used to examine the BMI, excessive BMI loss, percentage of body fat (BF) change, and fat-free mass.ResultsA total of 133 MO patients had a BMI of 43.3 kg/m² and 88 SO patients had a BMI of 59.4 kg/m². The percentage of BF was 46.7% and 51.9% (P < .0001). The differences in the follow-up period after surgery (21.5 and 20.6 months; P = .62) and patient age (43.4 and 42.5 yr) were not significant, but the gender distribution was significant (P = .003). After surgery, the MO patients had a BMI of 30.9 ± 5.7 kg/m² and the SO patients had a BMI of 37.3 ± 9.0 kg/m². The percentage of BF was not different between the 2 groups (MO, 33.1% ± 9.6% and SO, 35.0% ± 12.4%; P = .21). Gender differences in the percentage of BF were present before surgery; however, after surgery, these were absent for the men in the 2 groups (24.8% and 26.6%; P = .51). The change in the BMI and the change in the BF had a stronger correlation for the MO patients (r = .83 versus r = .53) than for the SO patients. The fat-free mass loss correlated with the change in BMI without regard to procedure. The percentage of excessive BMI loss was 65.1% for the MO and 63.4% for the SO patients (P = .64).ConclusionsThe SO patients achieved excessive BMI loss similar to that of the MO patients, with more SO men choosing biliopancreatic diversion/duodenal switch. At a BMI of 37.3 kg/m², the SO patients had a percentage of BF that was not different from that of the MO patients at 30.9 kg/m². The fat-free mass losses correlated with the change in BMI.     

Medical versus surgical treatment of type 2 diabetes: the search for level 1 evidence

Data from observational and nonrandomized comparative studies have shown a dramatic effect of bariatric surgery on type 2 diabetes mellitus (T2DM), including in nonobese patients. However, a relative paucity of level 1 evidence is available to define the exact role of surgery as a treatment modality for T2DM, especially in less obese subjects. Performing randomized clinical trials in this field, however, poses significant and specific challenges for the study design. We have addressed such challenges in a carefully designed randomized controlled trial comparing glycemic control with optimal medical management versus Roux-en-Y gastric bypass in overweight to mildly obese patients with T2DM mellitus (body mass index 26-35 kg/m(2)). The present report describes the rationale and design of the Weill Cornell Medical College study. In addition to glycemic endpoints, however, clinical trials should also investigate the effect of surgery on cardiovascular risk or T2DM-specific morbidity. Addressing these endpoints would entail large, randomized clinical trials with prolonged period of observation and ideally a multicenter study design. Such a multisite trial poses substantial logistical and financial challenges, which would predictably delay rather than accelerate progress of research in this field. A consortium of centers performing independent small and medium size randomized clinical trials may provide a more realistic and feasible approach. In this paper, we present an overview of on-going randomized clinical trials in this field and propose a worldwide consortium of randomized controlled trials (WORLDCoRDS) using the Weill Cornell Medical College protocol. The aim of this consortium is to standardize research in T2DM surgery and timely accumulate homogeneous data that can help assess the effects of GI surgery on cardiovascular risk and T2DM-related mortality and morbidity.