Insulin Secretion, Sensitivity, and Kidney Function in Young Individuals With Type 2 Diabetes.

OBJECTIVE: ß-Cell dysfunction and insulin resistance magnify the risk of kidney injury in type 2 diabetes. The relationship between these factors and intraglomerular hemodynamics and kidney oxygen availability in youth with type 2 diabetes remains incompletely explored. RESEARCH DESIGN AND METHODS: Fifty youth with type 2 diabetes (mean age ± SD 16 ± 2 years; diabetes duration 2.3 ± 1.8 years; 60% female; median HbA1c 6.4% [25th, 75th percentiles 5.9, 7.6%]; BMI 36.4 ± 7.4 kg/m2; urine albumin-to-creatinine ratio [UACR] 10.3 [5.9, 58.0] mg/g) 21 control participants with obesity (OCs; age 16 ± 2 years; 29% female; BMI 37.6 ± 7.4 kg/m2), and 20 control participants in the normal weight category (NWCs; age 17 ± 3 years; 70% female; BMI 22.5 ± 3.6 kg/m2) underwent iohexol and p-aminohippurate clearance to assess glomerular filtration rate (GFR) and renal plasma flow, kidney MRI for oxygenation, hyperglycemic clamp for insulin secretion (acute C-peptide response to glucose [ACPRg]) and disposition index (DI; ×103 mg/kg lean/min), and DXA for body composition. RESULTS: Youth with type 2 diabetes exhibited lower DI (0.6 [0.0, 1.6] vs. 3.8 [2.4, 4.5] × 103 mg/kg lean/min; P < 0.0001) and ACPRg (0.6 [0.3, 1.4] vs. 5.3 [4.3, 6.9] nmol/L; P < 0.001) and higher UACR (10.3 [5.9, 58.0] vs. 5.3 [3.4, 14.3] mg/g; P = 0.003) and intraglomerular pressure (77.8 ± 11.5 vs. 64.8 ± 5.0 mmHg; P < 0.001) compared with OCs. Youth with type 2 diabetes and OCs had higher GFR and kidney oxygen availability (relative hyperoxia) than NWCs. DI was associated inversely with intraglomerular pressure and kidney hyperoxia. CONCLUSIONS: Youth with type 2 diabetes demonstrated severe ß-cell dysfunction that was associated with intraglomerular hypertension and kidney hyperoxia. Similar but attenuated findings were found in OCs.

Improving Power Output in Older Adults Using Plyometrics in a Body Mass-Supported Treadmill.

Dobbs, TJ, Simonson, SR, and Conger, SA. Improving power output in older adults using plyometrics in a body mass-supported treadmill. J Strength Cond Res 32(9): 2458-2465, 2018-The purpose of this study was to determine if performing plyometrics in a body mass-supported treadmill would lead to greater increases in power output and functional strength in older adults compared with traditional strength training. Twenty-three participants were randomized to strength (SG, n = 8), plyometric (PG, n = 8), or control (CG, n = 7) groups. The SG and PG exercised 3 times per week for 8 weeks, whereas the CG performed no exercise. Timed sit-to-stand and stair climb, estimated maximal muscular isotonic strength, and isokinetic strength were assessed pre- and posttraining. Significant improvements occurred in the PG vs. CG in the timed chair sit-to-stand (22.11 ± 8.48%; p = 0.013), timed stair climb (14.68 ± 6.28%; p = 0.002), and stair climb power (16.59 ± 9.07%; p < 0.001). PG and SG significantly increased their estimated 1 repetition maximum in the leg extension and single leg lunge (p < 0.05), and PG was significantly more powerful at all 3 velocities in both flexion and extension compared with SG and CG ranging from 24.54 to 61.85% (p < 0.001) except for 60°·s extension during isokinetic testing. Eight weeks of plyometrics in a body mass-supported treadmill can significantly improve functional strength and power in older adults. In this study, the PG increased muscular strength at the same rate or better than the SG without performing any resistance training. The PG also outperformed SG during the functional tests. These results suggest that plyometrics, if modified and performed in a safe environment, can increase muscular strength and power and improve functional abilities in older adults.