M W. Hulver

The effect of prebiotic supplementation with inulin on cardiometabolic health: Rationale, design, and methods of a controlled feeding efficacy trial in adults at risk of type 2 diabetes

Prediabetes is associated with low-grade chronic inflammation that increases the risk for developing type 2 diabetes (T2D) and cardiovascular disease (CVD). An elevated lipopolysaccharide concentration, associated with dysbiosis of the intestinal microbiota, has been implicated in the development of both T2D and CVD. Selective modulation of the intestinal microbiota with prebiotics reduces intestinal permeability and endotoxin concentrations, inflammation, and metabolic dysfunction in rodents. The effect of prebiotic supplementation on cardio-metabolic function in humans at risk for T2D is not known. The primary aim of this trial is to determine the influence of prebiotic supplementation with inulin on insulin sensitivity and skeletal muscle metabolic flexibility in adults at risk for T2D. We hypothesize that prebiotic supplementation with inulin will improve insulin sensitivity and skeletal muscle metabolic flexibility. We will randomize 48 adults (40-75 yrs) with prediabetes or a score ≥ 5 on the American Diabetes Association (ADA) risk screener to 6 weeks of prebiotic supplementation with inulin (10 g/day) or placebo. Subjects will be provided with all food for the duration of the study, to avoid potential confounding through differences in dietary intake between individuals. Intestinal permeability, serum endotoxin concentrations, insulin sensitivity, skeletal muscle metabolic flexibility, endothelial function, arterial stiffness, and fecal bacterial composition will be measured at baseline and following treatment. The identification of prebiotic supplementation with inulin as an efficacious strategy for reducing cardio-metabolic risk in individuals at risk of T2D could impact clinical practice by informing dietary recommendations and increasing acceptance of prebiotics by the scientific and medical community.

EFFECTS OF PLYOMETRIC TRAINING AND RECOVERY ON VERTICAL JUMP PERFORMANCE AND ANAEROBIC POWER

We examined the effects of 2 plyometric training programs, equalized for training volume, followed by a 4-week recovery period of no plyometric training on anaerobic power and vertical jump performance. Physically active, college-aged men were randomly assigned to either a 4-week (n = 19, weight = 73.4 ± 7.5 kg) or a 7-week (n = 19, weight = 80.1 ± 12.5 kg) program. Vertical jump height, vertical jump power, and anaerobic power via the Margaria staircase test were measured pretraining (PRE), immediately posttraining (POST), and 4 weeks posttraining (POST-4). Vertical jump height decreased in the 4-week group PRE (67.8 ± 7.9 cm) to POST (65.4 ± 7.8 cm). Vertical jump height increased from PRE to POST-4 in 4-week (67.8 ± 7.9 to 69.7 ± 7.6 cm) and 7-week (64.6 ± 6.2 to 67.2 ± 7.6 cm) training programs. Vertical jump power decreased in the 4-week group from PRE (8,660.0 ± 546.5 W) to POST (8,541.6 ± 557.4 W) with no change in the 7-week group. Vertical jump power increased PRE to POST-4 in 4-week (8,660.0 ± 546.5 W to 8,793.6 ± 541.4 W) and 7-week (8,702.8 ± 527.4 W to 8,931.5 ± 537.6 W) training programs. Anaerobic power improved in the 7-week group from PRE (1,121.9 ± 174.7 W) to POST (1,192.2 ± 189.1 W) but not the 4-week group. Anaerobic power significantly improved PRE to POST-4 in both groups. There were no significant differences between the 2 training groups. Four-week and 7-week plyometric programs are equally effective for improving vertical jump height, vertical jump power, and anaerobic power when followed by a 4-week recovery period. However, a 4-week program may not be as effective as a 7-week program if the recovery period is not employed.