Marc A. Brown

Cooking attenuates the ability of high-amylose meals to reduce plasma insulin concentrations in rats

Postprandial glycaemic control is important in the prevention and therapy of type 2 diabetes and related diseases. Agents that may reduce postprandial glycaemia and/or insulinaemia, such as consumption of high-amylose foods, are considered beneficial; however, little is known about the dose-response relationship and the effects of cooking. The aim of the present study was to define the dose-response curve for postprandial glycaemic and insulinaemic excursions following meals of different amylose content and to compare the dose-response curves for meals containing cooked and uncooked starches. Following an overnight fast, rats ingested a test meal and blood was sampled over 2 h. The meal was given at 1.0 g carbohydrate/kg body weight, with an amylose content of 0, 270, 600 or 850 g/kg total starch. The area under the glucose curve did not differ under any condition investigated. For the uncooked-starch diets, area under the insulin curve was higher for the 0 g amylose/kg total starch meal than all other meals (P=0.0001). For the cooked-starch diets, area under the insulin curve was higher in the 0 than the 600 and 850 g amylose/kg total starch groups (P<0.01), but did not differ from the 270 amylose/kg total starch group. These results suggest that even a relatively small proportion of uncooked amylose (270 g/kg total starch) is sufficient to achieve a maximal attenuating effect on postprandial insulin concentrations as compared with 0 g amylose/kg total starch. Following cooking, however, a much higher proportion of amylose (>or=600 g/kg total starch) is needed to achieve a similar effect.

Consumption of resistant starch decreases postprandial lipogenesis in white adipose tissue of the rat

Chronic consumption of diets high in resistant starch (RS) leads to reduced fat cell size compared to diets high in digestible starch (DS) in rats and increases total and meal fat oxidation in humans. The aim of the present study was to examine the rate of lipogenesis in key lipogenic organs following a high RS or DS meal. Following an overnight fast, male Wistar rats ingested a meal with an RS content of 2% or 30% of total carbohydrate and were then administered an i.p bolus of 50 μCi 3H2O either immediately or 1 hour post-meal. One hour following tracer administration, rats were sacrificed, a blood sample collected, and the liver, white adipose tissue (WAT), and gastrocnemius muscle excised and frozen until assayed for total 3H-lipid and 3H-glycogen content. Plasma triglyceride and NEFA concentrations and 3H-glycogen content did not differ between groups. In all tissues, except the liver, there was a trend for the rate of lipogenesis to be higher in the DS group than the RS group which reached significance only in WAT at 1 h (p < 0.01). On a whole body level, this attenuation of fat deposition in WAT in response to a RS diet could be significant for the prevention of weight gain in the long-term.

Intrinsic heart rate recovery after dynamic exercise is improved with an increased omega-3 index in healthy males

Dietary fish consumption contributes to a reduced risk of cardiac mortality. In the present study, the effect of low-dose fish oil (FO) supplementation on heart rate (HR) response to intense exercise and recovery was investigated in physically fit males. The subjects (n 26) were supplemented (double-blind, parallel design) with (2 × 1 g/d) soya bean oil (control) or tuna FO providing the long-chain n-3 PUFA DHA (560 mg) and EPA (140 mg). Erythrocyte omega-3 index (%EPA+DHA), HR, HR variability and HR recovery were analysed during rest, intense exercise and recovery at baseline and after 8 weeks of supplementation. The mean erythrocyte omega-3 index, which did not differ between the groups at baseline (control 4.2 (sem 0.2), n 13; FO 4.7 (sem 0.2), n 13), remained unchanged in the control group (3.9 (sem 0.2)), but increased in the FO group (6.3 (sem 0.3); P< 0.01). The mean HR during supine resting conditions (control 56 (sem 10); FO 59 (sem 9)) was not affected by FO supplementation. Poincaré analysis of HR variability at rest exhibited a decreasing trend in parasympathetic activity in the FO group (SD1 (standard deviation of points perpendicular to the axis of line of identity)/SD2 (standard deviation of points along the axis of line of identity): control 0.02 (sem 0.01); FO - 0.05 (sem 0.02); P= 0.18). Peak HR was not affected by supplementation. However, during submaximal exercise over 5 min, fewer total heart beats were recorded in the FO group (-22 (sem 6) ( = -4.5 beats/min)), but not in the control group (+1 (sem 4)) (P< 0.05). Supine HR recovery (half-time) after cycling was significantly faster after FO supplementation (control - 0.4 (sem 1.2) s; FO - 8.0 (sem 1.7) s; P< 0.05). A low intake of FO increased the omega-3 index and reduced the mean exercise HR and improved HR recovery without compromising the peak HR. A direct influence of DHA via reductions in the cardiac intrinsic beat rate was balanced by a reciprocal decrease in vagal tone.

Eccentric cycling emphasising a low cardiopulmonary demand increases leg strength equivalent to workload matched concentric cycling in middle age sedentary males

OBJECTIVES This study determined if eccentric endurance cycling, eliciting a low cardiovascular demand, could stimulate muscle strength adaptations in sedentary middle-aged males. DESIGN Twenty-four middle-aged sedentary males were allocated to concentric (CON) or matched workload eccentric (ECC) cycling (60% peak concentric workload) according to their maximal voluntary isometric quadriceps strength. METHODS Seventeen participants [42.7±8.3 years, BMI 28.6±5.2, peak oxygen consumption [30.5±5.8mLkg-1min-1] completed 8 weeks (2 sessions per week) of CON (n=8) or ECC (n=9) cycle training. Incline leg press (6RM), maximal voluntary isometric contraction (MVIC) torque of the quadriceps and peak oxygen consumption were measured at baseline and 8 weeks. RESULTS Eccentric cycle training resulted in low cardiovascular demand (CON 154±2; ECC 95±3bmin-1P<0.05) and ratings of perceived exertion (CON 14.9±0.3; ECC 9.5±0.3/20 P<0.05). Peak oxygen consumption improved within the CON group (Baseline 27.4±2.1; 8 weeks: 30.0±1.7mLkg-1min-1P<0.05) and not within the ECC group (Baseline 33.2±1.5; 8 weeks 33.3±1.6mLkg-1min-1) following training. 6RM (CON 176±20; ECC 192±11kg) and MVIC (CON 199±25; ECC 199±25Nm) strength were equivalent at baseline (P>0.05). Both groups significantly increased 6RM (CON 13.0±3.0; ECC 10.7±3.2%) and MVIC (CON 12.9±4.3; ECC 18.8±3.0%) relative to their own baseline (P<0.05). Therefore, improved leg strength was equivalent between CON and ECC groups despite the varied training (P>0.05). CONCLUSIONS In sedentary middle age males, eccentric endurance cycling with a low cardiovascular demand, increased both quadriceps isometric and 6RM strength comparable to a matched workload concentric cycling program.

Is Moderate Intensity Cycling Sufficient To Induce Cardiorespiratory And Biomechanical Modifications Of Subsequent Running

Abstract Walsh, JA, Dawber, JP, Lepers, R, Brown, M, and Stapley, PJ. Is moderate intensity cycling sufficient to induce cardiorespiratory and biomechanical modifications of subsequent running? J Strength Cond Res 31(4): 1078–1086, 2017—This study sought to determine whether prior moderate intensity cycling is sufficient to influence the cardiorespiratory and biomechanical responses during subsequent running. Cardiorespiratory and biomechanical variables measured after moderate intensity cycling were compared with control running at the same intensity. Eight highly trained, competitive triathletes completed 2 separate exercise tests; (a) a 10-minute control run (no prior cycling) and, (b) a 30-minute transition run (TR) (preceded by 20-minute of variable cadence cycling, i.e., run versus cycle-run). Respiratory, breathing frequency (f b), heart rate (HR), cost of running (Cr), rate constant, stride length, and stride frequency variables were recorded, normalized, and quantified at the mean response time (MRT), third minute, 10th minute (steady state), and overall for the control run (CR) and TR. Cost of running increased (p ⩽ 0.05) at all respective times during the TR. The V[Combining Dot Above]E/V[Combining Dot Above]CO2 and respiratory exchange ratio (RER) were significantly (p < 0.01) elevated at the MRT and 10th minute of the TR. Furthermore, overall mean increases were recorded for Cr, V[Combining Dot Above]E, V[Combining Dot Above]E/V[Combining Dot Above]CO2, RER, f b (p < 0.01), and HR (p ⩽ 0.05) during the TR. Rate constant values for oxygen uptake were significantly different between CR and TR (0.48 ± 0.04 vs. 0.89 ± 0.15; p < 0.01). Stride length decreased across all recorded points during the TR (p ⩽ 0.05) and stride frequency increased at the MRT and 3 minutes (p < 0.01). The findings suggest that at moderate intensity, prior cycling influences the cardiorespiratory response during subsequent running. Furthermore, prior cycling seems to have a sustained effect on the Cr during subsequent running.

DHA-rich Fish Oil Increases the Omega-3 Index and Lowers the Oxygen Cost of Physiologically Stressful Cycling in Trained Individuals

Dietary fish oil, providing docosahexaenoic acid (DHA) modulates oxygen consumption and fatigue in animal models. However, in humans predominately supplemented with high eicosapentaenoic acid (EPA), there is no evidence of endurance performance enhancement. Therefore, this study examined if DHA-rich fish oil could improve repeated bouts of physiologically stressful cycling and a subsequent time trial in a state of fatigue. Twenty-six trained males took part in a double-blind study and were supplemented with either 2 × 1g/day soy oil, Control) or DHA-rich tuna fish oil (Nu-Mega) (FO) (560mg DHA / 140mg eicosapentaenoic acid (EPA), for 8 weeks. Maximal cycling power (3 × 6s), isometric quadriceps strength (MVC), Wingate cycling protocol (6 × 30s) and a 5min cycling time-trial were assessed at baseline and eight weeks. The Omega-3 Index was not different at baseline (Control: 4.2 ± 0.2; FO: 4.7 ± 0.2%) and increased in the FO group after eight weeks (Control: 3.9 ± 0.2; FO: 6.3 ± 0.3%, p < .01). There was no effect of DHA-rich fish oil on power output of maximal 6s cycle sprinting (Control: Pre 1100 ± 49 Post 1067 ± 51; FO: Pre 1070 ± 46 Post 1042 ± 46W), during 5min time trail (Control: Pre 267 ± 19 Post 278 ± 20; FO: Pre 253 ± 16 Post 265 ± 16 W) or maximal voluntary contraction force (Control: Pre 273 ± 19 Post 251 ± 19; FO: Pre 287 ± 17 Post 283 ± 16 Nm). Nevertheless, relative oxygen consumption was reduced the FO group during the cycling time trial (Control: -23 ± 26; FO: -154 ± 59ml O2/min/100W p < .05) suggesting improved economy of cycling. We conclude that DHA-rich fish oil, successful at elevating the Omega-3 Index, and reflective of skeletal muscle membrane incorporation, can modulate oxygen consumption during intense exercise.

Graduate destinations: where do our graduates go and how can we improve their journey?

This study aimed to determine the career and study paths that University of Wollongong (UOW) graduates take once they complete their qualifications in either nutrition, dietetics, exercise science or exercise physiology and to establish how prepared they and their employers felt they were. Three online surveys (December 2012 graduates, July 2007-July 2012 graduates and employers) were conducted via Survey Monkey® in late 2012 that asked about work and study experiences pre and post-graduation, strengths and weaknesses of programs, ideas for further curriculum development and experiences employing UOW graduates. 23 responses were received from the December graduating students, 96 from earlier graduates and 11 from employers.The Australasian Nutrition Care Day Survey (ANCDS) reported two-in-five patients in Australian and New Zealand hospitals consume ≤50% of the offered food. The ANCDS found a significant association between poor food intake and increased in-hospital mortality after controlling for confounders (nutritional status, age, disease type and severity)1. Evidence for the effectiveness of medical nutrition therapy (MNT) in hospital patients eating poorly is lacking. An exploratory study was conducted in respiratory, neurology and orthopaedic wards of an Australian hospital. At baseline, 24-hour food intake (0%, 25%, 50%, 75%, 100% of offered meals) was evaluated for patients hospitalised for ≥2 days and not under dietetic review. Patients consuming ≤50% of offered meals due to nutrition-impact symptoms were referred to ward dietitians for MNT with food intake re-evaluated on day-7. 184 patients were observed over four weeks. Sixty-two patients (34%) consumed ≤50% of the offered meals. Simple interventions (feeding/menu assistance, diet texture modifications) improved intake to ≥75% in 30 patients who did not require further MNT. Of the 32 patients referred for MNT, baseline and day-7 data were available for 20 patients (68±17years, 65% females, BMI: 22±5kg/m2, median energy, protein intake: 2250kJ, 25g respectively). On day-7, 17 participants (85%) demonstrated significantly higher consumption (4300kJ, 53g; p<0.01). Three participants demonstrated no improvement due to ongoing nutrition-impact symptoms. “Percentage food intake” was a quick tool to identify patients in whom simple interventions could enhance intake. MNT was associated with improved dietary intake in hospital patients. Further research is needed to establish a causal relationship.