Exercise intensity is an important determinant of energy expenditure (EE) during and following exercise. Recent evidence suggests that total energy expenditure, independent of exercise intensity, may be more important for weight loss programs. Moderate or low intensity exercise will allow for greater fat oxidation rates during exercise but little is known of post-exercise substrate utilisation. PUrPose:The purpose of this study was to determine the impact of low and moderate intensity exercise on substrate utilization and energy expenditure during and after exercise. METHODS:Nine untrained males (age: 23.7 ± 4.7yrs; VO2max: 42.4 ± 4.1ml.kg.min−1) expended 400 kcal in the post-absorptive state on two separate occasions. Exercise was performed at a low intensity (LI; 47 ± 1%VO max) or a moderate intensity (MI; 62 ± 2%VO2max). Substrate oxidation and EE were assessed for 3 hours post exercise using indirect calorimetry. RESULTS:The rate of EE was greater during MI exercise (13.2 ± 0.9 vs. 9.8 ± 0.9 kcal kg min−1, p<0.05) but the duration of exercise was shorter (39.7 ± 4.6 vs. 52.9 ± 6.7 mins, p<0.05). Total fat oxidation during exercise was greater in the LI trial (17.5 + 3.7 vs. 10.9 + 4.1 g, p<0.05). During recovery from exercise, there was a greater reliance on fat oxidation in both the LI trial (81.5 ± 9.6%EE) and the MI trial (79.3 ± 11.6%EE). The rates of fat oxidation and EE in the 3-hrs following exercise were similar between the two trials. CONCLUSIONS: Low intensity exercise elicits greater fat oxidation than isocaloric moderate intensity exercise. Exercise intensity does not affect post-exercise fat oxidation or EE following isocaloric exercise. Low intensity exercise is important for weight loss programs, as long as the duration of exercise is sufficient to allow for adequate energy expenditure.
Elevated postprandial lipemia (PPL) is associated with impaired endothelial function, an increase in adhesion molecule expression and inflammation. Acute exercise reduces PPL in adults. To our knowledge, no studies have reported the effect of acute exercise on PPL in adolescents. PURPOSE: To investigate the effect of an acute bout of exercise (600 kcal) on postprandial changes in triglycerides (TG), glucose, insulin, adhesion molecules (sICAM-1, sVCAM-1) and inflammatory markers (CRP, IL-6, TNF-α, WBC) following a high-fat meal in normal-weight (NW) and overweight (OW) adolescents. METHODS: 10NW(BMI: 20.9±1.7kg.m−2, 15.6±0.7y) and 8 OW(BMI: 28.3±3.6 kg.m−2, 15.9±0.4y) adolescent boys underwent two 6h oral fat tolerance tests (OFTT) separated by 7 d. On the evening prior to each OFTT, subjects rested (CTL) or completed a treadmill walk/run at 70% VO2max until 600 kcal had been expended (EX). Blood samples were obtained at baseline and at 30 min, 1, 2, 4 and 6 h postprandially. Dependent t-tests were used to compare summary postprandial responses and 3-way ANOVA with repeated measures were used to determine changes over the postprandial period. RESULTS: There was an 81. 1±40.7% increase in lipemia following the OFTT in the CTL trial, and a 75.3±21.2% increase in the EX trial, in both groups. Area under the TG vs. time curve was reduced during the EX trial in both groups (8.3±3.1 vs. 6.9±1.6 mmol L-1.6hrinNW, p=.054; 11.3±5.4vs. 8.3±2.3 mmol.L-1.6hr in OW, p=.056). The magnitude of the attenuation did not differ between NW and OW (p=.269). Insulin response to the test meal did not differ between the EX and CTL trials or between NW and OW. Glucose response was lower in both NW and OW groups in the CTL condition (CTL: 24.5±2.9 vs. EX: 28.9±3.2 mmol.L-1, p<0.001). IL-6 increased similarly in NW and OW following the OFTT in both experimental trials (CTL: 1.46±0.49 (0 h) vs. 2.72±1.60 (6 h) pg.ml-1, p=0.001;EX: 1.81±1.03 (0 h) vs. 3.71±2.21 (6 h) pg.ml-1, p=0.002) and was higher during the EX condition than the CTL condition (p=.043). TNF-α was higher in OW than NW (p<.001) but there was no main effect of exercise or the OFTT. WBC number was higher in OW than NW (p=.049), and increased similarly in both groups following the OFTT in both experimental conditions (p<.001). There were no changes in CRP, sVCAM-1 or sICAM-1 following the OFTT and there were no differences between experimental condition or BMI group. CONCLUSION: Acute exercise attenuates postprandial TG response but does not reduce inflammation or alter adhesion molecule expression in NW and OW adolescents. Supported by the Irish Research Council for Science, Engineering and Technology: funded by the National Development Plan.
Weight category sports are classified as those for which athletes must weigh in at a designated weight prior to competition. Due to the weight restrictive nature of such sports, body mass must take precedence over many other factors for these athletes. Accurate assessment of body composition for athletes competing in weight category sports is essential, to ensure that the most efficient use of body mass is made in order to optimise performance. PURPOSE: The purpose of this study was to compare skinfold assessment and DEXA as methods of estimating body composition in a group of weight category athletes. METHODS: 41 weight category athletes were recruited to take part in this study (29 horse racing jockeys and 12 boxers). The subjects (age: 24 ± 6yrs) anthropometric characteristics were, stature: 1.71 ± 0.08m, mass: 61.8 ± 11.38 kg and BMI: 21.01 ± 2.52. Body composition values were extrapolated from a dual energy x-ray absorptiometry (DEXA) total body scan. Subcutaneous fat was measured using the skinfold calliper technique from 7 sites: bicep, tricep, subscapular, supraspinale, abdominal, front thigh, and medial calf. Body density was estimated using a 7 site regression equation, and converted to percentage body fat using a standard equation. RESULTS: Mean ± SD for DEXA and skinfold estimates were 11.05 ± 5.36 and 9.13 ± 2.81 respectively. Significant differences were shown between the two estimates of body composition (p = 0.000). A strong positive correlation was found between both types of assessment (r = 0.920, r2 = 0.85). Mean percentage difference between both types of assessment was 2.37 ± 2.26 %, though this varied from 0.10 - 12.3 %. Variations in body composition assessments appeared to become more pronounced as DEXA total body scan estimates increased. CONCLUSIONS: Though skinfold assessment is a useful and practical tool for estimation of body composition, results differed significantly from those achieved using DEXA, which has been described as a level two measure of body composition assessment. Weight category athletes are a unique population, with specialised requirements in relation to management of body composition. Population specific regression equations for estimation of body density may be required, in order to provide a more accurate assessment of body composition in this population.
PURPOSE: Cardiovascular disease (CVD) is the leading cause of death in the Ireland and the EU and kills more people than all cancers combined. It accounts for 55% of all deaths in women across Europe and 43% of all deaths in men. The cost to the EU economy is 169 billion euro/year. Endothelial dysfunction induced by cardiovascular risk factors is considered to be one of the earliest stages in vascular damage and is associated independently with cardiovascular events. The balance between endothelial lesion and regeneration is critical for the maintenance of vessel integrity. Exposure to cardiovascular risk factors alters the homeostatic regulatory functions of the endothelium, subsequently progressing to pro-inflammatory activation, apoptosis, and undesirable vessel remodelling. The purpose of this study is to examine the effect of self-regulated exercise intensity on endothelial function in men with coronary artery disease. METHODS: Eight men with coronary artery disease (65.7 ± 4.5 yr, VO2max 18.6 ± 4.1 ml/kg/min, BMI 29.7±3.3 kg/m-2) underwent 20 min of treadmill walking at a self-regulated intensity. Endothelial dependent dilation of the brachial artery was assessed before and 1 h following the acute bout of exercise. Vessel diameter was determined using high resolution vascular ultrasonography (SonoSite, MicroMaxx) from flow mediated dilation (FMD) following 5 min of forearm occlusion. Endothelial independent vasodilation was measured at min 3, min 4 and min 5 following the administration of glyceryl trinitrate (0.4 mg). RESULTS: The subjects self-selected an average treadmill walking speed of 5.3 km/h and a grade of 0.7%. This intensity equated to 65.7% VO2max, and an RPE-O of 12.0. Compared to baseline, FMD was significantly increased (1 min (4.6 v 10.7%) and 3 min (6.2 v 11.0) post occlusion) at 60 min following the acute bout of self-regulated exercise. There was no change in endothelial independent dilation in response to the acute bout of exercise. CONCLUSION: These results indicate a beneficial effect of self regulated exercise on endothelial dependent vascular function in men with coronary artery disease. The study was supported with a grant from Science Foundation Ireland (PO7625 - SFI 07/CE/I1147).
Commencement address given by Paul L. O'Connor, President of Xavier University, to the Autumn 1960 graduating class of The Ohio State University, St. John Arena, Columbus, Ohio, December 16, 1960.
Abstract Cullen, BD, Roantree, M, McCarren, A, Kelly, DT, O'Connor, PL, Hughes, SM, Daly, PG, and Moyna1, NM. Physiological profile and activity pattern of minor Gaelic football players. J Strength Cond Res 31(7): 1811–1820, 2017—The purpose of this study was to evaluate the physiological profile and activity pattern in club- and county-level under-18 (U-18) Gaelic football players relative to playing position. Participants ( n = 85) were analyzed during 17 official 15-a-side matches using global positioning system technology (SPI Pro X II; GPSports Systems, Canberra, Australia) and heart rate (HR) telemetry. During the second part of this study, 63 participants underwent an incremental treadmill test to assess their maximal oxygen uptake (V̇o 2 max) and peak HR (HRmax). Players covered a mean distance of 5,774 ± 737 m during a full 60-minute match. The mean %HRmax and %V̇ o 2 max observed during the match play were 81.6 ± 4.3% and 70.1 ± 7.75%, respectively. The playing level had no effect on the distance covered, player movement patterns, or %HRmax observed during match play. Midfield players covered significantly greater distance than defenders ( p = 0.033). Playing position had no effect on %HRmax or the frequency of sprinting or high-intensity running during match play. The frequency of jogging, cruise running, striding ( p = 0.000), and walking ( p = 0.003) was greater in the midfield position than in the forward position. Time had a significant effect ( F (1,39) = 33.512, p -value = 0.000, and JOURNAL/jscr/04.03/00124278-201707000-00008/inline-formula1/v/2023-08-19T002737Z/r/image-tiff = 0.462) on distance covered and %HRmax, both of which showed a reduction between playing periods. Gaelic football is predominantly characterized by low-to-moderate intensity activity interspersed with periods of high-intensity running. The information provided may be used as a framework for coaches in the design and prescription of training strategies. Positional specific training may be warranted given the comparatively greater demands observed in the midfield playing position. Replicating the demands of match play in training may reduce the decline in distance covered and %HRmax observed during the second half of match play.
Adaptation of skeletal muscle to repeated bouts of endurance exercise increases aerobic capacity and improves mitochondrial function. However, the adaptation of human skeletal muscle mitochondrial proteome to short-term endurance exercise training has not been investigated. Eight sedentary males cycled for 60 min at 80% of peak oxygen consumption (VO(2peak) ) each day for 14 consecutive days, resulting in an increase in VO(2peak) of 17.5±3.8% (p<0.01). Mitochondria-enriched protein fractions from skeletal muscle biopsies taken from m. vastus lateralis at baseline, and on the morning following the 7th and 14th training sessions were subjected to 2-D DIGE analysis with subsequent MS followed by database interrogation to identify the proteins of interest. Thirty-one protein spots were differentially expressed after either 7 or 14 days of training (ANOVA, p<0.05). These proteins included subunits of the electron transport chain, enzymes of the tricarboxylic acid cycle, phosphotransfer enzymes, and regulatory factors in mitochondrial protein synthesis, oxygen transport, and antioxidant capacity. Several proteins demonstrated a time course-dependent induction during training. Our results illustrate the phenomenon of skeletal muscle plasticity with the extensive remodelling of the mitochondrial proteome occurring after just 7 days of exercise training suggestive of enhanced capacity for adenosine triphosphate generation at a cellular level.
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