Effect of a weight-loss program on mental stress-induced cardiovascular responses and recovery

Objective: We assessed the effect of weight loss on blood pressure (BP) and pulse rate during rest, psychological stress, and recovery after stress.

Methods: Two groups of men completed two mental stress tests 12 wk apart. The control group continued their usual diet, whereas the weight-loss group underwent a dietary weight-loss program in which they were randomized to a high-fruit/vegetable and low-fat dairy diet or a low-fat diet.

Results: Fifty-five men with a baseline BP of 125.9 ± 6.9/83.6 ± 7.1 mmHg (mean ± SD) completed the study (weight-loss group, n = 28; control group, n = 27). The weight-loss group lost weight (mean ± SEM, −4.3 ± 0.3 versus +0.4 ± 0.4 kg, P = 0.001) compared with controls and had a significant decrease in resting systolic BP (SBP; −2.0 ± 1.1% versus +2.0 ± 1.1%, P < 0.05). There was a greater decrease in SBP (P < 0.05) and pulse rate (P < 0.05) at all time points during the stress test in the weight loss compared with the control group. At week 12, SBP in 23 (82%) subjects in the weight-loss group and 24 (89%) in the control group returned to resting levels, with recovering levels in the weight-loss group returning to resting levels 6.1 ± 2.6 min earlier than in the control group (P < 0.05). There was an overall greater decrease in diastolic BP (DBP; P < 0.05) and DBP during recovery up to 27 min after stress (P < 0.05) in the high-fruit/vegetable and low-fat dairy diet group (n = 14) compared with the low-fat diet group (n = 14).

Conclusion: A 5% loss of weight decreased BP during rest and returned SBP to resting levels faster, thus decreasing the period of increased BP as a result of mental stress, which is likely to lower the risk of cardiovascular disease in the long term.

An electromyographic comparison of neck conditioning exercises in healthy controls

The purpose of this study was to compare surface electromyography (EMG) activation levels of selected neck muscles for two common neck-training modalities (Thera-Band and Cybex). Seventeen asymptomatic subjects (eight men and nine women) with a mean age 23.4 years were recruited. EMG activation normalized to maximal voluntary isometric contraction (MVIC) was measured with subjects performing exercises with green, blue, and black Thera-Bands and 50%, 70%, and 90% of 3RM for the Cybex modality. Four variables were used to depict exercise intensity: average and peak EMG activation in the concentric and eccentric phases. Significant differences (P <= 0.05) in EMG activation were evident when comparing intensities of the Cybex modality with each other and when comparing the Cybex intensities with Thera-Band intensities in most cases. Minimal differences were found among differing intensities of Thera-Band. Thera-Band exercise resulted in low-level EMG activation (range, flexion 3.8-15.7% MVIC; range, extension 20.2-34.8% MVIC); therefore, such exercise may be useful in rehabilitation programs. Cybex exercise (range, flexion 20.9-83.5% MVIC; range, extension 40.6-95.8% MVIC) may be useful for occupation-related injury prevention. However, exercise prescription should be undertaken with care as the mechanical loading on passive spinal structures is unknown.

Maternal overnutrition programs changes in the expression of skeletal muscle genes that are associated with insulin resistance and defects of oxidative phosphorylation in adult male rat offspring.

Children of obese mothers have increased risk of metabolic syndrome as adults. Here we report the effects of a high-fat diet in the absence of maternal obesity at conception on skeletal muscle metabolic and transcriptional profiles of adult male offspring. Female Sprague Dawley rats were fed a diet rich in saturated fat and sucrose [high-fat diet (HFD): 23.5% total fat, 9.83% saturated fat, 20% sucrose wt:wt] or a normal control diet [(CD) 7% total fat, 0.5% saturated fat, 10% sucrose wt:wt] for the 3 wk prior to mating and throughout pregnancy and lactation. Maternal weights were not different at conception; however, HFD-fed dams were 22% heavier than controls during pregnancy. On a normal diet, the male offspring of HFD-fed dams were not heavier than controls but demonstrated features of insulin resistance, including elevated plasma insulin concentration [40.1 ± 2.5 (CD) vs 56.2 ± 6.1 (HFD) mU/L; P = 0.023]. Next-generation mRNA sequencing was used to identify differentially expressed genes in the offspring soleus muscle, and gene set enrichment analysis (GSEA) was used to detect coordinated changes that are characteristic of a biological function. GSEA identified 15 upregulated pathways, including cytokine signaling (P < 0.005), starch and sucrose metabolism (P < 0.017), inflammatory response (P < 0.024), and cytokine-cytokine receptor interaction (P < 0.037). A further 8 pathways were downregulated, including oxidative phosphorylation (P < 0.004), mitochondrial matrix (P < 0.006), and electron transport/uncoupling (P < 0.022). Phosphorylation of the insulin signaling protein kinase B was reduced [2.86 ± 0.63 (CD) vs 1.02 ± 0.27 (HFD); P = 0.027] and mitochondrial complexes I, II, and V protein were downregulated by 50-68% (P < 0.005). On a normal diet, the male offspring of HFD-fed dams did not become obese adults but developed insulin resistance, with transcriptional evidence of muscle cytokine activation, inflammation, and mitochondrial dysfunction. These data indicate that maternal overnutrition, even in the absence of prepregnancy obesity, can promote metabolic dysregulation and predispose offspring to type 2 diabetes.