Jeffrey S. Forsse

Time-restricted feeding in young men performing resistance training: A randomized controlled trial.

Abstract A randomized controlled trial was conducted to examine eight weeks of resistance training (RT) with and without time-restricted feeding (TRF) in order to assess nutrient intake and changes in body composition and muscular strength in young recreationally active males. The TRF programme consisted of consuming all calories within a four-hour period of time for four days per week, but included no limitations on quantities or types of foods consumed. The RT programme was performed three days per week and consisted of alternating upper and lower body workouts. For each exercise, four sets leading to muscular failure between 8 and 12 repetitions were employed. Research visits were conducted at baseline, four, and eight weeks after study commencement. Measurements of total body composition by dual-energy X-ray absorptiometry and muscle cross-sectional area by ultrasound were obtained. Upper and lower body strength and endurance were assessed, and four-day dietary records were collected. TRF reduced energy intake by ∼650 kcal per day of TRF, but did not affect total body composition within the duration of the study. Cross-sectional area of the biceps brachii and rectus femoris increased in both groups. Effect size data indicate a gain in lean soft tissue in the group that performed RT without TRF (+2.3 kg, d = 0.25). Upper and lower body strength and lower body muscular endurance increased in both groups, but effect sizes demonstrate greater improvements in the TRF group. Overall, TRF reduced energy intake and did not adversely affect lean mass retention or muscular improvements with short-term RT in young males.

Impact of Acute Dietary Manipulations on DXA and BIA Body Composition Estimates

Purpose To examine the effects of acute preassessment diets on body composition estimates obtained by dual-energy x-ray absorptiometry (DXA) and bioelectrical impedance analysis (BIA). Methods In a counterbalanced design, 48 males and females were provided with two 1-d diets: high-carbohydrate diet (9 g CHO·kg−1) and very low-carbohydrate diet (1 to 1.5 g CHO·kg−1). For each condition, body composition was assessed in the morning after an overnight fast, in the afternoon after feeding, and the following morning after a second overnight fast. Results Acute food ingestion, regardless of macronutrient content, altered DXA and BIA body composition estimates, and both sexes responded similarly. DXA total and regional lean soft tissue estimates increased up to 1.7% and 3% on average in response to feeding, with individual increases of over 4.5% and 9%. DXA total and trunk fat mass estimates decreased by up to 3% on average. All DXA-derived measures of body composition returned to baseline values after the second overnight fast. Impedance measured by BIA decreased by 4.4% in response to feeding, leading to a 2% increase in total body water and fat-free mass, with individual increases up to 4.5%. BIA fat mass estimates decreased 1.4% to 2.4%, with individual decreases of up to 10%. Unlike DXA, most BIA-derived estimates did not return to baseline values after a second overnight fast. Conclusions Acute food and fluid intake can artificially influence body composition estimates, regardless of macronutrient content. An overnight fast is likely sufficient preassessment dietary control for DXA and possibly sufficient for BIA.

Brachial Artery FMD Responses To Steady-State Moderate-Intensity And High-Intensity Interval Exercise In Mid-Spectrum Chronic Kidney Disease: 1202 Board #10 May 31 8

Brachial artery flow-mediated dilation (FMD) is a nitric oxide-dependent measure of conduit artery endothelial function that is transiently potentiated by moderate-intensity steady state exercise (SSE) in healthy adults. Whether exercise imparts similar effects in adults with Stage 3 or 4 chronic kidney disease (CKD) has not been reported. Moreover, a comparison of SSE and high-intensity interval exercise (HIIE) may add to clinically-relevant findings for improving vascular function in mid-spectrum CKD. PURPOSE: To determine the influence of SSE and a comparable amount of HIIE on post-exercise brachial artery FMD in patients diagnosed with secondary Stage 3 or 4 CKD. METHODS: Twenty participants (n = 10 men; n = 10 women; age 62.0 + 9.9 yr; weight 80.9 + 16.2 kg; body fat 37.3 + 8.5% of weight; VO2max 19.4 + 4.7 ml/kg/min) completed 30 min of SSE at 65% VO2reserve or HIIE by treadmill walking (90% and 20% of VO2reserve in 3:2 min ratio) in a randomized crossover design. Both exercise conditions averaged ~ 65% VO2reserve. Ultrasound measurements of brachial artery FMD were obtained by the same technician under standardized conditions just before, 1 hr and 24 hrs after exercise. FMD responses were analyzed using 2 (condition) by 3 (sample point) repeated measures ANOVAs. RESULTS: Brachial artery FMD responses were augmented 1 hr after exercise in both exercise conditions (p < 0.005 versus pre-exercise FMD). SSE (pre-exercise = 11.5 + 1.3; 1 hr = 17.2* + 1.8; 24 hr = 14.0* + 1.1%) HIIE (pre-exercise = 12.5 + 1.3; 1 hr = 15.6* + 1.5; 24 hr = 15.8* + 1.2%) CONCLUSION: We report for the first time that brachial artery FMD can be augmented by a single episode of exercise in mid-spectrum CKD. SSE and HIIE, averaging ~65% of VO2reserve, is equally effective at transiently improving conduit artery vascular function in this clinical population.

Dual-energy X-ray absorptiometry visceral adipose tissue estimates: reproducibility and impact of pre-assessment diet

We examined the reproducibility of dual-energy x-ray absorptiometry (DXA) visceral adipose tissue (VAT) estimates as well as the impact of pre-assessment diet. In a counterbalanced design, 41 adults received 6 DXA scans, while consuming standardized high- and low-carbohydrate (LC) diets. The impact of pre-assessment diet was examined via repeated-measures analysis of variance and reproducibility of VAT estimates was evaluated by technical error of measurement (TEM) and s.e. of a single determination (SESD). VAT area, mass and volume were acutely decreased by ~ 6.5% after the LC diet (P ≤ 0.001), but not the high-carbohydrate diet (P > 0.3). Differences persisted after an overnight fast. TEMs for VAT area, mass and volume were < 5 cm2, ≤ 0.2 kg and < 25 cm3. SESDs for all VAT variables were ≤ 5.5%. In conclusion, DXA VAT estimates exhibit good reproducibility in controlled conditions, but may be impacted by pre-assessment diet.

BAIBA Does Not Regulate UCP-3 Expression in Human Skeletal Muscle as a Response to Aerobic Exercise

ABSTRACT Objective: β-Aminoisobutyric acid (BAIBA) has shown to modulate uncoupling protein (UCP)-1 expression, which is mainly expressed in white adipose tissue; however, no studies to date have analyzed its potential effect on the main uncoupling protein of skeletal muscle, UCP-3. The main goal of this study was to assess the potential effect of acute aerobic exercise on serum BAIBA and skeletal muscle UCP-3. The secondary goal was to assess the potential involvement of the transcription factors proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) and peroxisome proliferator–activated receptor alpha (PPARα), as well as free fatty acids (FFAs) in UCP-3 expression. A tertiary goal of the study was to evaluate the potential effect of consuming a preexercise meal on the outcome of the first 2 objectives. Methods: In a randomized crossover design, untrained participants performed 2 acute cycling sessions (350 kcal at 70% of their VO2peak) after 2 experimental conditions: (1) consumption of a multi-macronutrient shake and (2) a fasting period of 8 hours. Blood samples were taken at baseline, preexercise, postexercise, 1 hour, and 4 hours postexercise, and muscle biopsies were taken at the last 4 time points. UCP-3 protein concentration and expression, as well as the mRNA expression of PGC-1α and PPARα, were measured in muscle, and BAIBA, glucose, and FFA were measured in serum. Results: Aerobic exercise failed to induce a significant effect on serum BAIBA, PGC-1α, and PPARα regardless on the feeding condition. Despite the lack of effect of exercise on the previous variables, UCP-3 expression and protein concentration significantly increased in the shake condition. Conclusion: The expression of human skeletal muscle UCP-3 as a result of exercise might be controlled by factors other than BAIBA.

Brachial Artery FMD And Endothelial Responses To High-intensity Interval And Steady-State Moderate-Intensity Exercise: 1139 Board #4 June 1, 3: 15 PM - 5: 15 PM.

Brachial artery flow-mediated dilation (FMD) is a nitric oxide-dependent measure of conduit artery endothelial function that is potentiated by moderateand high-intensity steady state exercise (SSE) for up to an hour after exercise; however, it is unclear whether high-intensity interval exercise (HIIE) provides a longer-lasting stimulus for enhancing FMD or greater oxidative and nitrative stress on the vascular endothelium than a comparable or greater amount of SSE. PURPOSE: Determine the influence of HIIE on post-exercise brachial artery FMD and the relationship between FMD and markers of endothelial function relative to a comparable amount of moderate-intensity SSE and a dose that is half that of SSE. METHODS: Seventeen male participants (age 27.8 + 6.4 yr; weight 80.6 + 9.0 kg; BMI 25.1 + 2.4 kg/m2; VO2max 52.1 + 7.5 ml/kg/min) underwent HIIE by treadmill running (90% and 40% of VO2reserve in 3:2 min ratio) to expend 500 kcals; HIIE to expend 250 kcals, and; SSE at 70% VO2reserve to expend 500 kcals in a randomized crossover design. All exercise conditions averaged 70% VO2reserve. Ultrasound measurements of brachial artery FMD and blood measures of total antioxidant capacity (TAC) in copper reducing equivalents, apolipoprotein A-1 (ApoA1: g/L), PON1 concentration (PON1c: g/mL), arylesterase activity (PON1a: kU/L), soluble vascular adhesion molecule-1 (sVCAM-1: ng/mL) and nitrotyrosine (NT: nM) were obtained just before and 2 hr after exercise. FMD responses to exercise were analyzed using 3 (condition) by 2 (sample point) repeated measures ANOVAs. Pearson product-moment correlations of change variables (2 hr post-exercise – pre-exercise values) were calculated to determine relationships between FMD responses and blood variable responses to exercise. RESULTS: Brachial artery FMD responses were unaltered 2 hr after exercise in all three conditions (p > 0.05). FMD responses were correlated with changes in PON1c (r = 0.221, p < 0.0001) and inversely with changes TAC (r = -0.170, p < 0.0001). Changes in s-VCAM1 were correlated with change in NT (r = 0.423, p < 0.0001) and inversely with changes in PON1c (r = -0.177, p < 0.0001). SUMMARY: Brachial artery FMD is unaltered 2 hr after HIIE or SSE of moderate duration in young fit men and does not appear to be related to responses in other markers of endothelial function.

3-nitrotyrosine And Soluble Vascular And Intracellular Adhesion Molecule Responses To High-intensity Interval And Steady-state Moderate-intensity Exercise: 626 Board #22 May 27, 2

Vascular endothelium may respond differently to high-intensity interval exercise (HIIE) when compared to moderate-intensity steady state exercise (SSE). We hypothesized that greater sympathetic stimulation of soluble vascular adhesion molecule-1 (sVCAM-1) and intracellular adhesion molecule-1 (sICAM-1) and greater oxidative and nitrative stress on the vascular endothelium may transiently result from HIIE. PURPOSE: Determine the influence of HIIE on sVCAM-1, sICAM-1 and 3-nitrotyrosine (NT), a marker of nitric oxide-dependent reactive nitrogen species and nitrative stress, relative to a comparable amount of moderate-intensity SSE and a dose that is half that of SSE. METHODS: Seventeen male participants (age 27.8 + 6.4 yr; weight 80.6 + 9.0 kg; BMI 25.1 + 2.4 kg/m2; %fat = 19 + 5; VO2max 52.1 + 7.5 ml/kg/min) underwent HIIE by treadmill running (90% and 40% of VO2reserve in 3:2 min ratio) to expend 500 kcals (H500); HIIE to expend 250 kcals (H250), and; SSE at 70% VO2reserve to expend 500 kcals (M500) in a randomized crossover design. Intensities of all exercise conditions averaged 70% VO2reserve. Blood measures of sVCAM-1 (ng/mL), sICAM-1 (ng/mL), NT (nM), epinephrine (EPI) and norepinephrine (NE) in pg/mL, were obtained just before, immediately after, 2 hr and 24 hr after exercise. Significant differences were determined using 3 by 4 repeated measures ANOVAs. Effect sizes were calculated to determine the magnitude of dependent variable responses to exercise. RESULTS: HIIE resulted in 2 to 2.5 fold greater EPI responses immediately after exercise versus SSE (p = 0.0059, H250 ES = 1.89; H500 ES = 3.04). NE increased an average of 5.4 times above pre-exercise values across all exercise conditions (p < 0.0001). NT decreased immediately after HIIE (H250 ES = 0.39; H500 ES = -0.97) and returned to baseline by 2 hr post-exercise; whereas, NT was elevated 111% 2 hr (ES = 2.46) and remained 24 hr after SSE (p = 0.0001). sVCAM-1 was unchanged with HIIE but increased 6% immediately following moderate-intensity SSE and remained elevated 24 hr post-exercise (p < 0.0005, ES = 1.01). SUMMARY: Our results are in direct opposition to our hypothesis. Transient elevations in NT and sVCAM-1 after moderate-intensity SSE but not HIIE of similar average intensity and duration may indicate unique effects of interval exercise. NT and sVCAM-1 were not elevated after HIIE in spite of a greater sympathetic response than what was observed after moderate-intensity SSE.

Intermittent fasting combined with resistance training: effects on body composition, muscular performance, and dietary intake

Background Intermittent fasting (IF) is a dietary strategy that has recently gained popularity due to a number of potential health benefits. One form of IF, termed time-restricted feeding (TRF), only allows caloric intake during a limited window of time each day (often 4 to 8 hours in duration). One concern of IF is the potential loss of lean mass due to the fasting periods. Resistance training is known to help mitigate loss of lean mass during hypocaloric diets. The purpose of this experiment was to examine the effects of TRF in combination with resistance training on body composition, muscular performance, and dietary intake in young untrained males.