Gestational weight gain and preterm birth in obese women: a systematic review and meta-analysis.

BACKGROUND: Prepregnant obesity is a global concern and gestational weight gain has been found to influence the risks of preterm birth. OBJECTIVE: To assess the relationship between gestational weight gain and risk for preterm birth in obese women. SEARCH STRATEGY: Four electronic databases were searched from 18 February through to 28 April 2015. SELECTION CRITERIA: Primary research reporting preterm birth as an outcome in obese women and gestational weight gain as a variable that could be compared to the 2009 Institute of Medicine's recommendations. DATA COLLECTION AND ANALYSIS: Two reviewers independently assessed trials for inclusion. The Newcastle Ottawa Scale was used to assess study bias. MAIN RESULTS: Our search identified six studies meeting the inclusion criteria; five were conducted in the USA and one in Peru. Four studies with a total of 10 171 obese women were meta-analysed. Significant heterogeneity was found between studies in the pooled analysis. Results for indicated preterm birth in obese women with gestational weight gain above the Institute of Medicine's recommendations showed increased risk (adjusted odds ratio 1.54; 95% CI 1.09-2.16). CONCLUSIONS: Available science on this topic is limited to special populations of obese pregnant women. Generalisable research is needed to assess the variation in risk for preterm birth in obese women by differences in gestational weight gain and class of obesity controlling for significant variables in the pathway to preterm birth. This research has the potential to illuminate new science impacting preterm birth and interventions for prevention.

Effects of resistance training and protein plus amino acid supplementation on muscle anabolism, mass, and strength.

This study examined 10 wks of resistance training and the ingestion of supplemental protein and amino acids on muscle performance and markers of muscle anabolism. Nineteen untrained males were randomly assigned to supplement groups containing either 20 g protein (14 g whey and casein protein, 6 g free amino acids) or 20 g dextrose placebo ingested 1 h before and after exercise for a total of 40 g/d. Participants exercised 4 times/wk using 3 sets of 6-8 repetitions at 85-90% of the one repetition maximum. Data were analyzed with two-way ANOVA (p < 0.05). The protein supplement resulted in greater increases in total body mass, fat-free mass, thigh mass, muscle strength, serum IGF-1, IGF-1 mRNA, MHC I and IIa expression, and myofibrillar protein. Ten-wks of resistance training with 20 g protein and amino acids ingested 1 h before and after exercise is more effective than carbohydrate placebo in up-regulating markers of muscle protein synthesis and anabolism along with subsequent improvements in muscle performance.

Interleukin-6 expression after repeated bouts of eccentric exercise.

Plasma interleukin-6 (IL-6) is known to increase in response to eccentric exercise due to an acute-phase immune response. However, the severity of muscle injury is reduced with repeated bouts of eccentric exercise, possibly as a result of decreases in plasma IL-6. This study determined the response of IL-6 mRNA and IL-6, troponin-I (sTnI), muscle strength, and soreness as a result of repeated bouts of eccentric exercise. Eight males underwent two eccentric exercise bouts (3 wk apart) involving 7 sets of 10 repetitions at 150 % of the isotonic 1-RM of the dominant knee extensors. Blood samples were taken before, after and 2, 4, 6, 24, 48 and 96 h post-exercise. Strength and soreness ratings were assessed before and at 24, 48 and 96 h-post. Data were analyzed with 2 x 4 and 2 x 8 ANOVAs and the non-parametric Friedman test (p < 0.05). Both IL-6 mRNA and IL-6 underwent peak increases (p < 0.05) at 4 h-post and 6 h-post, respectively, but were not different between bouts. However, there were significant changes (p < 0.05) in sTnI, strength, and soreness that were greater after the first bout than the second, characteristic of the repeated bout effect. These results indicate that changes in sTnI, strength and soreness were less with the second eccentric exercise bout whereas the changes in both IL-6 mRNA and protein were not effected between bouts.

Effects of oral creatine and resistance training on myosin heavy chain expression.

PURPOSE: This study examined 12 wk of creatine (Cr) supplementation and heavy resistance training on muscle strength and myosin heavy chain (MHC) isoform mRNA and protein expression. METHODS: Twenty-two untrained male subjects were randomly assigned to either a control (CON), placebo (PLC), or Cr (CRT) group in a double-blind fashion. Muscle biopsies were obtained before and after 12 wk of heavy resistance training. PLC and CRT trained thrice weekly using three sets of 6-8 repetitions at 85-90% 1-RM on the leg press, knee extension, and knee curl exercises. CRT ingested 6 g.d-1 of Cr for 12 wk, whereas PLC consumed the equal concentration of placebo. RESULTS: There were no significant differences for percent body fat (P > 0.05). However, for total body mass, fat-free mass, thigh volume, muscle strength, and myofibrillar protein, CRT and PLC exhibited significant increases after training when compared to CON (P < 0.05), whereas CRT was also significantly greater than PLC (P < 0.05). For Type I, IIa, and IIx MHC mRNA expression, CRT was significantly greater than CON and PLC, whereas PLC was greater than CON (P < 0.05). For MHC protein expression, CRT was significantly greater than CON and PLC for Type I and IIx (P < 0.05) but was equal to PLC for IIa. CONCLUSION: Long-term Cr supplementation increases muscle strength and size, possibly as a result of increased MHC synthesis.

Myosin heavy chain isoform and ubiquitin protease mRNA expression after passive leg cycling in persons with spinal cord injury.

OBJECTIVE: To determine the effects of passive leg cycling exercise on myosin heavy chain (MHC) isoform and ubiquitin (UBI) protease mRNA expression in patients with spinal cord injury (SCI). STUDY DESIGN: Case series. INTERVENTION: Eight SCI subjects (5 men, 3 women) participated in a 12-week exercise program involving the Psycle ergometer. Training occurred 2 days a week at 75% of each subject's maximum heart rate. Anthropometric measures (body weight, thigh girth, and body mass index) and muscle biopsy specimens were obtained before and after training. Analyses were performed to determine the mRNA expression of types I, IIa, and IIx MHC, as well as UBI, a UBI-conjugating enzyme (E2), and 20S proteasome (20S). RESULTS: Despite small increases, paired t tests (p < .05) to assess changes from pretraining to posttraining failed to locate significant differences for the three anthropometric measures. For mRNA expression, there were significant increases in expression of MHC types IIa and IIx and significant decreases in expression for UBI, E2, and 20S. CONCLUSION: Exercise using passive leg cycling increases the expression of fast MHC isoforms while concomitantly decreasing proteolytic activity associated with muscle degradation, thus helping to possibly ameliorate muscle atrophy in patients with SCI.