ß-Cell function during a high-fat meal in young versus old adults: role of exercise.

The acute effect of exercise on ß-cell function during a high-fat meal (HFM) in young adults (YA) versus old adults (OA) is unclear. In this randomized crossover trial, YA (n = 5 M/7 F, 23.3 ± 3.9 yr) and OA (n = 8 M/4 F, 67.7 ± 6.0 yr) underwent a 180-min HFM (12 kcal/kg body wt; 57% fat, 37% CHO) after a rest or exercise [∼65% heart rate peak (HRpeak)] condition ∼12 h earlier. After an overnight fast, plasma lipids, glucose, insulin, and free fatty acid (FFA) were determined to estimate peripheral, or skeletal muscle, insulin sensitivity (Matsuda index) as well as hepatic [homeostatic model assessment of insulin resistance (HOMA-IR)] and adipose insulin resistance (adipose-IR). ß-Cell function was derived from C-peptide and defined as early-phase (0-30 min) and total-phase (0-180 min) disposition index [DI, glucose-stimulated insulin secretion (GSIS) adjusted for insulin sensitivity/resistance]. Hepatic insulin extraction (HIE), body composition [dual-energy X-ray absorptiometry (DXA)], and peak oxygen consumption (V̇o2peak) were also assessed. OA had higher total cholesterol (TC), LDL, HIE, and DI across organs as well as lower adipose-IR (all, P < 0.05) and V̇o2peak (P = 0.056) despite similar body composition and glucose tolerance. Exercise lowered early-phase TC and LDL in OA versus YA (P < 0.05). However, C-peptide area under the curve (AUC), total phase GSIS, and adipose-IR were reduced postexercise in YA versus OA (P < 0.05). Skeletal muscle DI increased in YA and OA after exercise (P < 0.05), whereas adipose DI tended to decline in OA (P = 0.06 and P = 0.08). Exercise-induced skeletal muscle insulin sensitivity (r = -0.44, P = 0.02) and total-phase DI (r = -0.65, P = 0.005) correlated with reduced glucose AUC180min. Together, exercise improved skeletal muscle insulin sensitivity/DI in relation to glucose tolerance in YA and OA, but only raised adipose-IR and reduced adipose-DI in OA.NEW & NOTEWORTHY High-fat diets may induce ß-cell dysfunction. This study compared how young and older adults responded to a high-fat meal with regard to ß-cell function and whether exercise comparably impacted glucose regulation. Older adults secreted more insulin during the high-fat meal than younger adults. Although exercise increased ß-cell function adjusted for skeletal muscle insulin sensitivity in relation to glucose tolerance, it raised adipose insulin resistance and reduced pancreatic ß-cell function relative to adipose tissue in older adults. Additional work is needed to discern nutrient-exercise interactions across age to mitigate chronic disease risk.

Acute Exercise and the Systemic and Airway Inflammatory Response to a High-Fat Meal in Young and Older Adults.

The purpose of the present study was to determine fasting and high-fat meal (HFM)-induced post-prandial systemic inflammation and airway inflammation (exhaled nitric oxide (eNO)) in older adults (OAs) compared to younger adults (YAs) before and after acute exercise. Twelve YAs (23.3 ± 3.9 y n = 5 M/7 F) and 12 OAs (67.7 ± 6 y, n = 8 M/4 F) completed two HFM challenges. After an overnight fast, participants underwent an HFM session or pre-prandial exercise (EX, 65% VO2Peak to expend 75% of the caloric content of the HFM) plus HFM (EX + HFM) in a randomized order. Systemic inflammatory cytokines were collected at 0, 3, and 6 h, while eNO was determined at 0, 2, and 4 h after the HFM (12 kcal/kg body weight: 61% fat, 35% CHO, 4% PRO). TNF-α was higher in OAs compared to YAs (p = 0.005) and decreased across time from baseline to 6 h post-HFM (p = 0.007). In response to the HFM, IL-6 decreased from 0 to 3 h but increased at 6 h regardless of age or exercise (p = 0.018). IL-8 or IL-1ß did not change over the HFM by age or exercise (p > 0.05). eNO was also elevated in OAs compared to YAs (p = 0.003) but was not altered by exercise (p = 0.108). There was a trend, however, towards significance post-prandially in OAs and YAs from 0 to 2 h (p = 0.072). TNF-α and eNO are higher in OAs compared to YAs but are not elevated more in OAs post-prandially compared to YAs. Primary systemic inflammatory cytokines and eNO were not modified by acute exercise prior to an HFM.

Acute exercise improves glucose and TAG metabolism in young and older adults following high-fat, high-carbohydrate meal intake.

A single high-fat, high-carbohydrate meal (HFHC) results in elevated postprandial glucose (GLU), triglycerides (TAG) and metabolic load index (MLI; TAG (mg/dl) + GLU (mg/dl)) that contributes to chronic disease risk. While disease risk is higher in older adults (OA) compared to younger adults (YA), the acute effects of exercise on these outcomes in OA is understudied. Twelve YA (age 23.3 ± 3.9 yrs, n = 5 M/7 F) and 12 OA (age 67·7 ± 6.0 yrs, n = 8 M/4 F) visited the laboratory in random order to complete a HFHC with no exercise (NE) or acute exercise (EX) condition. EX was performed 12 hours prior to HFHC at an intensity of 65 % of maximal heart rate to expend 75 % of the kcals consumed in HFHC (Marie Callender's Chocolate Satin Pie; 12 kcal/kgbw; 57 % fat, 37 % CHO). Blood samples were taken at 0, 30, 60, 90 minutes, and then every hour until 6 hours post-meal. TAG levels increased to a larger magnitude in OA (Δ∼61 ± 31 %) compared to YA (Δ∼37 ± 34 %, P < 0·001), which were attenuated in EX compared to NE (P < 0·05) independent of age. There was no difference in GLU between OA and YA after the HFM, however, EX had attenuated GLU independent of age (NE: Δ∼21 ± 26 %; EX: Δ∼12 ± 18 %, P = 0·027). MLI was significantly lower after EX compared to NE in OA and YA (P < 0·001). Pre-prandial EX reduced TAG, GLU and MLI post-HFHC independent of age.