Michael K. Baker

Obesity effects on depression: systematic review of epidemiological studies

Background:Obesity is a well-known cause of cardiovascular disease burden and premature death, but effects on psychological morbidity remain uncertain. This article reports findings following a systematic review of epidemiological studies to determine whether obesity causes depression.Methods:Multiple databases were searched for English-language studies of etiology of obesity (exposure variable, analyzed as an ordered category) on depression outcomes (dependent variables, continuous or categorical). Studies in children and in women during pregnancy or postpartum were excluded, as were nonrepresentative cross-sectional studies. Searches and identification of studies for inclusion were performed by EA, whereas a descriptive synthesis of important study characteristics was undertaken independently by us.Results:We reviewed 24 out of approximately 4500 potentially relevant studies; 4 were prospective cohort studies and 20 were cross-sectional studies (10 from the United States). Effect measures reported in all prospective cohort studies were consistent and suggested that obesity may increase the odds of future depression outcomes (symptoms or nonclinical diagnosis of depression). Effect measures reported in most cross-sectional studies from the United States supported the hypothesized association between obesity and prevalence of depression outcomes for women but not men, in contrast most cross-sectional studies from populations other than the United States consistently failed to find such associations.Conclusions:Overall, there is a weak level of evidence supporting the hypothesis that obesity increases the incidence of depression outcomes. Few high-quality prospective cohort studies exist, and cross-sectional studies account for the vast body of published evidence, and therefore firm conclusions for causality cannot yet be drawn. Our finding warrants additional high-quality etiological research on this topic.

A systematic review and meta-analysis of the effect of aerobic vs. resistance exercise training on visceral fat

It is increasingly recognized that the location of excess adiposity, particularly increased deposition of visceral adipose tissue (VAT), is important when determining the adverse health effects of overweight and obesity. Exercise therapy is an integral component of obesity management, but the most potent exercise prescription for VAT benefit is unclear. We aimed to evaluate the independent and synergistic effects of aerobic exercise (AEx) and progressive resistance training (PRT) and to directly compare the efficacy of AEx and PRT for beneficial VAT modulation. A systematic review and meta‐analysis was performed to assess the efficacy of exercise interventions on VAT content/volume in overweight and obese adults. Relevant databases were searched to November 2010. Included studies were randomized controlled designs in which AEx or PRT in isolation or combination were employed for 4 weeks or more in adult humans, where computed tomography (CT) or magnetic resonance imaging (MRI) was used for quantification of VAT pre‐ and post‐intervention. Of the 12196 studies from the initial search, 35 were included. After removal of outliers, there was a significant pooled effect size (ES) for the comparison between AEx therapy and control (−0.33, 95% CI: −0.52 to −0.14; P < 0.01) but not for the comparison between PRT therapy and control (0.09, 95% CI: −0.17 to −0.36; P = 0.49). Of the available nine studies which directly compared AEx with PRT, the pooled ES did not reach statistical significance (ES = 0.23, 95% CI: −0.02 to 0.50; P = 0.07 favouring AEx). The pooled ES did not reach statistical significance for interventions that combined AEx and PRT therapy vs. control (−0.28, 95% CI: −0.69 to 0.14; P = 0.19), for which only seven studies were available. These data suggest that aerobic exercise is central for exercise programmes aimed at reducing VAT, and that aerobic exercise below current recommendations for overweight/obesity management may be sufficient for beneficial VAT modification. Further investigation is needed regarding the efficacy and feasibility of multi‐modal training as a means of reducing VAT.

Exercise prescription for patients with type 2 diabetes and pre-diabetes: A position statement from Exercise and Sport Science Australia

Type 2 diabetes mellitus (T2DM) and pre-diabetic conditions such as impaired fasting glucose (IFG) and/or impaired glucose tolerance (IGT) are rapidly increasing in prevalence. There is compelling evidence that T2DM is more likely to develop in individuals who are insufficiently active. Exercise training, often in combination with other lifestyle strategies, has beneficial effects on preventing the onset of T2DM and improving glycaemic control in those with pre-diabetes. In addition, exercise training improves cardiovascular risk profile, body composition and cardiorespiratory fitness, all strongly related to better health outcomes. Based on the evidence, it is recommended that patients with T2DM or pre-diabetes accumulate a minimum of 210 min per week of moderate-intensity exercise or 125 min per week of vigorous intensity exercise with no more than two consecutive days without training. Vigorous intensity exercise is more time efficient and may also result in greater benefits in appropriate individuals with consideration of complications and contraindications. It is further recommended that two or more resistance training sessions per week (2-4 sets of 8-10 repetitions) should be included in the total 210 or 125 min of moderate or vigorous exercise, respectively. It is also recommended that, due to the high prevalence and incidence of comorbid conditions in patients with T2DM, exercise training programs should be written and delivered by individuals with appropriate qualifications and experience to recognise and accommodate comorbidities and complications.

The Study of Mental and Resistance Training (SMART) study—resistance training and/or cognitive training in mild cognitive impairment: a randomized, double-blind, double-sham controlled trial.

BACKGROUND Mild cognitive impairment (MCI) increases dementia risk with no pharmacologic treatment available. METHODS The Study of Mental and Resistance Training was a randomized, double-blind, double-sham controlled trial of adults with MCI. Participants were randomized to 2 supervised interventions: active or sham physical training (high intensity progressive resistance training vs seated calisthenics) plus active or sham cognitive training (computerized, multidomain cognitive training vs watching videos/quizzes), 2-3 days/week for 6 months with 18-month follow-up. Primary outcomes were global cognitive function (Alzheimers Disease Assessment Scale-cognitive subscale; ADAS-Cog) and functional independence (Bayer Activities of Daily Living). Secondary outcomes included executive function, memory, and speed/attention tests, and cognitive domain scores. RESULTS One hundred adults with MCI [70.1 (6.7) years; 68% women] were enrolled and analyzed. Resistance training significantly improved the primary outcome ADAS-Cog; [relative effect size (95% confidence interval) -0.33 (-0.73, 0.06); P < .05] at 6 months and executive function (Wechsler Adult Intelligence Scale Matrices; P = .016) across 18 months. Normal ADAS-Cog scores occurred in 48% (24/49) after resistance training vs 27% (14/51) without resistance training [P < .03; odds ratio (95% confidence interval) 3.50 (1.18, 10.48)]. Cognitive training only attenuated decline in Memory Domain at 6 months (P < .02). Resistance training 18-month benefit was 74% higher (P = .02) for Executive Domain compared with combined training [z-score change = 0.42 (0.22, 0.63) resistance training vs 0.11 (-0.60, 0.28) combined] and 48% higher (P < .04) for Global Domain [z-score change = .0.45 (0.29, 0.61) resistance training vs 0.23 (0.10, 0.36) combined]. CONCLUSIONS Resistance training significantly improved global cognitive function, with maintenance of executive and global benefits over 18 months.

Effect of aerobic exercise training dose on liver fat and visceral adiposity

BACKGROUND & AIMS Aerobic exercise reduces liver fat and visceral adipose tissue (VAT). However, there is limited data from randomized trials to inform exercise programming recommendations. This study examined the efficacy of commonly prescribed exercise doses for reducing liver fat and VAT using a randomized placebo-controlled design. METHODS Inactive and overweight/obese adults received 8 weeks of either; i) low to moderate intensity, high volume aerobic exercise (LO:HI, 50% VO 2peak, 60 min, 4d/week); ii) high intensity, low volume aerobic exercise (HI:LO, 70% VO 2peak, 45 min, 3d/week); iii) low to moderate intensity, low volume aerobic exercise (LO:LO, 50% VO 2peak, 45 min, 3d/week); or iv) placebo (PLA). Liver fat (spectroscopy) and VAT (magnetic resonance imaging) were measured before and after intervention. RESULTS Forty-seven of the 48 (n = 12 in each group) participants completed the trial. There were no serious adverse events. There was a significant change in group × time interaction in liver fat, which reduced in HI:LO by 2.38 ± 0.73%, in LO:HI by 2.62 ± 1.00%, and in LO:LO by 0.84 ± 0.47% but not in PLA (increase of 1.10 ± 0.62%) (p = 0.04). There was a significant reduction in VAT in HI:LO (-258.38 ± 87.78 cm(3)), in LO:HI (-386.80 ± 119.5 cm(3)), and in LO:LO (-212.96 ± 105.54 cm(3)), but not in PLA (92.64 ± 83.46 cm(3)) (p = 0.03). There were no significant differences between the dose or intensity of the exercise regimen and reductions in liver fat or VAT (p > 0.05). CONCLUSION The study found no difference in efficacy of liver fat reduction by either aerobic exercise dose or intensity. All of the aerobic exercise regimens employed reduced liver fat and VAT by a small amount without clinically significant weight loss.

Lower limb muscle strengthening does not change frontal plane moments in women with knee osteoarthritis: A randomized controlled trial

BACKGROUND Osteoarthritis is a common musculo-skeletal problem accompanied with muscle weakness. Muscle weakness may be readily improved by resistance training. Greater muscle strength has been associated with a lower knee joint loading rate. METHODS We conducted a single-blind randomized controlled trial of 54 female patients with osteoarthritis in at least one knee, according to the American College of Rheumatology clinical criteria. Patients were randomized into a 6-month high intensity progressive resistance training or a sham-exercise program. The primary outcomes were first peak knee and hip adduction moment measured using three-dimensional gait analysis at self-selected habitual and maximal speeds. Secondary outcomes were sagittal plane knee and hip moments, peak muscle strength, gait speed, and self-reported knee osteoarthritis symptoms measured by the Western Ontario and McMaster Osteoarthritis Index (WOMAC). FINDINGS Six months of high intensity resistance training did not change the first peak knee or hip adduction moment at either habitual or maximum walking speeds (P>0.413) compared to the sham-exercise. However, the second peak hip adduction moment (P=0.025) and WOMAC pain score (P<0.001) were reduced significantly in both groups over time, but there was no group effect. The changes in the second peak hip adduction moment were inversely related to the changes in the WOMAC pain score (r=-0.394, P=0.009). INTERPRETATIONS Muscle strength training in women with osteoarthritis, while effective for reducing osteoarthritis symptoms, appeared to operate through mechanisms other than improved knee or hip joint loading, as paradoxically, improved symptoms were related to decreases of hip adduction moment in late stance.

Efficacy and feasibility of a novel tri-modal robust exercise prescription in a retirement community: a randomized, controlled trial

OBJECTIVES: To test the feasibility and efficacy of current guidelines for multimodal exercise programs in older adults.

A Randomized Controlled Trial of Whole Body Vibration Exposure on Markers of Bone Turnover in Postmenopausal Women

Purpose. To examine the effects of two doses of low-frequency (12 Hz), low-magnitude (0.3 g), whole body vibration on markers of bone formation and resorption in postmenopausal women. Methods. Women were recruited and randomized into a sham vibration control group, one time per week vibration group (1×/week), or three times per week vibration group (3×/week). Vibration exposure consisted of 20 minutes of intermittent vibration for the 1×/week and 3×/week groups, and sham vibration (<0.1 g) for the control group for eight weeks. Double-blinded primary outcome measures were urine markers of bone resorption: N-telopeptide X normalised to creatinine (NTx/Cr) and bone formation: bone-specific alkaline phosphatase (ALP). Results. Forty-six women (59.8 ± 6.2 years, median 7.3 years since menopause) were enrolled. NTx/Cr was significantly reduced (34.6%) in the 3×/wk vibration group but not in the 1×/wk vibration group compared with sham control (P < .01) group. No effect of time or group allocation was observed on the bone formation marker ALP (P = .27). Conclusion. We have shown for the first time that low-frequency, low-magnitude vibration 3×/week for eight weeks in postmenopausal women results in a significant reduction in NTx/Cr, a marker of bone resorption, when compared with sham vibration exposure.

The relationship between knee adduction moment and cartilage and meniscus morphology in women with osteoarthritis

OBJECTIVE The aim of this cross-sectional study is to investigate the relationship between knee adduction moment and knee adduction angular impulse and meniscus, cartilage and bone morphology in women with knee osteoarthritis (OA). METHOD Forty-five women aged >40 years with OA in at least one knee, according to American College of Rheumatology clinical criteria were studied. The knee joint loading was assessed by three-dimensional motion analysis system during gait. Three Tesla magnetic resonance imaging (MRI) with a coronal T2-weighted spin echo sequence was used for evaluating meniscus pathology, and a coronal T1-weighted gradient echo sequence for quantifying cartilage morphology and bone surface size. Cartilage thickness, denuded area and subchondral area in the femorotibial joint was measured using custom software. RESULTS A higher peak knee adduction moment was observed in participants with medial compared to those with lateral tears (2.92+/-1.06 vs -0.46+/-1.7, P<0.001). Participants with a higher knee adduction moment displayed a larger medial meniscus extrusion (r=0.532, P<0.001) and a lower medial meniscus height (r=-0.395, P=0.010). The inverse relationship was observed for the lateral meniscus. A higher knee adduction moment was also associated with a higher ratio of the medial to lateral tibial subchondral bone area (r=0.270, P=0.035). By contrast, cartilage thickness and denuded areas in the femur and tibia were not related to the knee adduction moment. Similar results were found for the relationship between knee adduction angular impulse and meniscus, cartilage and bone morphology. CONCLUSIONS Dynamic knee joint loading is significantly related to meniscus pathology and bone size, but not to cartilage thickness in women with OA.

Dynamic alignment and its association with knee adduction moment in medial knee osteoarthritis

Lower limb dynamic alignment represents the limb position during functional loading conditions and obtains valuable information throughout the gait cycle rather than a single instant in time. This study aims to determine whether dynamic alignment is altered in medial knee osteoarthritis (OA) and how dynamic alignment is related to knee adduction moment (KAM). Community-dwelling women (n=17) with medial OA in at least one knee, according to the American College of Rheumatology criteria and 17 body mass index-matched women without OA were recruited. A three-dimensional motion analysis system was used to collect the gait data at self-selected habitual and maximal speeds. Clinical evaluation of lower extremities, physical function, pain, habitual level of physical activity, quality of life and physical self-efficacy were assessed. Shank adduction angle and shank mean angular velocity were significantly greater in the OA group compared to the controls from heel strike to 30% stance. KAM was not different between the groups (p=0.542). Dynamic alignment variables were the best predictors of KAM. Health-related quality of life, habitual level of physical activity, lower extremity muscle strength and balance performance were impaired in the OA group compared to the controls. The importance of variables that contribute to dynamic alignment and the contribution of limb alignment to KAM were highlighted in this study. Detection of postural changes such as altered dynamic alignment in early stages of OA will lead to the institution of joint-protective measures including changes in footwear, orthotics, gait re-training, use of assistive devices to reduce weight-bearing loads, strengthening and balance enhancing exercises, better analgesia, or cartilage-preserving pharmacotherapy.