Annie A. Bane

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.

Cardiorespiratory and Biomechanical Responses to Simulated Recreational Horseback Riding in Healthy Children.

Purpose: The purpose of this study was to determine the reliability of cardiorespiratory and pelvic kinematic responses to simulated horseback riding (SHBR) and to characterize responses to SHBR relative to walking in apparently healthy children. Method: Fifteen healthy children (Mage = 9.5 ± 2.6 years) completed SHBR on a commercially available simulator at low intensity (0.27 Hz) and high intensity (0.65 Hz) during 3 sessions on different occasions. Heart rate (HR), blood pressure, and respiratory gases were measured at rest and during steady-state exercise at both intensities. Pelvic displacement was measured during steady-state exercise. Rate of energy expenditure, mean arterial pressure, and rate pressure product (RPP) were calculated. Participants also walked on a treadmill for 26.8 m/min to 80.5 m/min in 13.4-m/min increments at 0% grade during 1 session to compare cardiorespiratory responses with those of SHBR. Results: Physiological variables across all 3 SHBR sessions were similar at both intensities (p>.05 for all). Intraclass correlation coefficients (ICCs) and coefficients of variation indicate good to modest reliability of cardiorespiratory measures during SHBR (ICCs = .542–.996 for oxygen consumption, energy expenditure, and RPP). Cardiorespiratory variables, except for HR, were 2% to 19% greater, and pelvic displacement was up to 37% greater with high-intensity riding. Treadmill walking at all speeds elicited greater physiological responses compared with SHBR (p < .05). Conclusion: Cardiorespiratory responses and pelvic kinematics are reproducible with SHBR in young children, and these responses were lower than those elicited by slow treadmill walking.

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.

Cardiorespiratory and Biomechanical Responses to Simulated Horseback Riding in Healthy Children: 3018 Board #304 May 30, 3

The movement of specific body segments during horseback riding is similar to common physical activities such as walking. Yet, little is known regarding the cardiovascular responses to horseback riding (HBR) which may be due to how difficult it is to quantify the physical work of HBR. The purpose of this study was to characterize cardiorespiratory and pelvic kinematic responses to simulated horseback riding (SHR) in apparently healthy children. These responses were compared to walking on a treadmill at different intensities. Fifteen healthy children (8 females, 7 males; 9+3 years of age; height 56+6 in; weight 92.0+41.0 lb; body fat 27+8%) walked at steady state on a treadmill (1-3 mph in 0.5 mph increments, 0% grade) during one session and completed SHR [low intensity (0.27 Hz) and high intensity (0.65 Hz)] during three sessions on differnet occasions. Physiologic variables, such as HR, VO2, VE, SBP, DBP, were measured at rest and steady-state exercise at each intensity. Mean arterial pressure (MAP) and rate pressure product (RPP) were calculated. Pelvic kinematics were measured in a similar manner during SHR. Physiological variables across all three SHR sessions were similar at each intensity (p>0.05). VO2, VE, MAP and RPP were greater with high-intensity riding compared to low-intensity riding and rest. Pelvic kinematics followed the same pattern and were reproducible across SHR sessions. Treadmill walking at all speeds elicited greater magnitudes in the physiological variables compared to SHR. The ICC for RPP, an important variable used to index cardiorespiratory fitness, was 0.057 indicating good reproducibility across SHR sessions. The results of the present study suggest that cardiorespiratory responses and pelvic kinematics are reproducible with SHR in young children and these responses were lower than those elicited by treadmill walking at 1 mph. Table 1: Means of cardiorespiratory variables at rest and during simulated horseback riding Variable Rest Low Intensity Riding High Intensity Riding Absolute VO2 (ml/min) 0.219 0.236 0.284 (p<0.0001) Relative VO2 (ml/kg/min) 5.712 6.095 7.035 (p<0.0001) VE (L/min) 7.744 8.340 9.898 (p<0.0001) MAP (mmHg) 75.225 75.783 77.488 (p<0.0002) RPP 96.072 96.742 102.736 (p<0.0001)