Matthew M. Schubert

Acute exercise and subsequent energy intake. A meta-analysis

The precise magnitude of the effect of acute exercise on subsequent energy intake is not well understood. Identifying how large a deficit exercise can produce in energy intake and whether this is compensated for, is important in design of long-term exercise programs for weight loss and weight maintenance. Thus, this paper sought to review and perform a meta-analysis on data from the existing literature. Twenty-nine studies, consisting of 51 trials, were identified for inclusion. Exercise duration ranged from 30 to 120min at intensities of 36-81% VO(2)max, with trials ranging from 2 to 14h, and ad libitum test meals offered 0-2h post-exercise. The outcome variables included absolute energy intake and relative energy intake. A random effects model was employed for analysis due to expected heterogeneity. Results indicated that exercise has a trivial effect on absolute energy intake (n=51; ES=0.14, 95% CI: -0.005 to 0.29) and a large effect on relative energy intake (creating an energy deficit, n=25; ES=-1.35, 95% CI: -1.64 to -1.05). Despite variability among studies, results suggest that exercise is effective for producing a short-term energy deficit and that individuals tend not to compensate for the energy expended during exercise in the immediate hours after exercise by altering food intake.

Flaxseed Consumption May Reduce Blood Pressure: A Systematic Review and Meta-Analysis of Controlled Trials

BACKGROUND High blood pressure is a major health burden positively associated with the risk of cardiovascular disease and other chronic diseases. Flaxseed is a rich dietary source of α-linolenic acid, lignans, and fiber, with a number of positive health benefits on blood pressure. OBJECTIVE The purpose of this study was to clarify the effect of flaxseed consumption on blood pressure. Further, the influence of baseline blood pressure, type of flaxseed supplementation, and duration of flaxseed supplementation on blood pressure was explored. METHOD PubMed (MEDLINE), Cumulative Index to Nursing and Allied Health Literature, and Cochrane Library (Central) were searched through July 2014 for studies in which humans supplemented their habitual diet with flaxseed or its extracts (i.e., oil, lignans, fiber) for ≥2 wk. RESULTS A total of 11 studies (14 trials) were included in the analysis. Random-effects meta-analyses were conducted for the mean difference in blood pressure. Results indicated that flaxseed supplementation reduced systolic blood pressure (-1.77 mm Hg; 95% CI: -3.45, -0.09 mm Hg; P = 0.04) and diastolic blood pressure (-1.58 mm Hg; 95% CI: -2.64, -0.52 mm Hg; P = 0.003). These results were not influenced by categorization of participants into higher baseline blood pressure (≥130 mm Hg). An improvement in diastolic blood pressure was observed in subgroup analysis for consuming whole flaxseed (-1.93 mm Hg; 95% CI: -3.65, -0.21 mm Hg; P < 0.05) and duration of consumption ≥12 wk (-2.17 mm Hg; 95% CI: -3.44, -0.89 mm Hg; P < 0.05). CONCLUSION The present meta-analysis suggests that consumption of flaxseed may lower blood pressure slightly. The beneficial potential of flaxseed to reduce blood pressure (especially diastolic blood pressure) may be greater when it is consumed as a whole seed and for a duration of >12 wk.

Effect of two doses of interval training on maximal fat oxidation in sedentary women.

INTRODUCTION The primary aim of the current study was to determine the effect of two doses of chronic high-intensity interval training (HIT) on changes in maximal fat oxidation (MFO) and body composition. METHODS Sedentary women (N = 23, age and V˙O2max = 24.2 ± 6.2 yr and 30.3 ± 5.2 mL·kg-1·min-1, respectively) completed either high (HI) (80%-90% maximal workload) or moderate (MOD) intensity (60%-80% maximal workload) HIT on a cycle ergometer 3 d·wk-1 for 12 wk consisting of 6-10 sixty-second bouts interspersed with active recovery. Seven women of similar age and fitness level served as controls. Every 3 wk, substrate oxidation was assessed during progressive exercise via indirect calorimetry to determine MFO and minimum fat oxidation, and body composition was assessed every 6 wk. Repeated-measures ANOVA was used to examine changes in substrate oxidation in response to training, with training group used as a between-subjects variable. RESULTS Results revealed improved MFO (P = 0.04, 19%-25%) and minimum fat oxidation (P = 0.001, 22-24 W) in response to HIT, yet the magnitude of improvement was similar (P > 0.05) between training paradigms. No change (P > 0.05) in body weight, percent body fat, or waist-hip circumference was revealed with training. CONCLUSION These data suggest that 12 wk of either moderate or more strenuous interval training similarly enhance fat oxidation in sedentary women but do not alter body weight or body composition.

A review of the bioactivity of coffee, caffeine and key coffee constituents on inflammatory responses linked to depression

Coffee is a widely consumed beverage containing numerous biologically active constituents predominantly belonging to the polyphenol and alkaloid classes. It has been established that coffee has a beneficial effect on numerous disease states including depression. A number of prospective and retrospective cohort studies have assessed the effects of coffee consumption on the relative risk of developing major depressive disorder in humans. These studies have identified an inverse relationship between the consumption of caffeinated coffee and the risk of developing depression. Caffeine, chlorogenic acid, ferulic acid and caffeic acid, all important constituents of coffee, have been shown to possess biological activities that highlight a possible mechanistic link to the pathology of depression. This review aims to assess the evidence from the biological evaluation of these constituents of coffee on markers of inflammation associated with depression in in vitro and in vivo models of inflammation, neuroinflammation and depression. The ability of bioactive coffee constituents to modulate the parameters of neuroinflammation has been shown with caffeine having strong antioxidant properties in vitro, chlorogenic acid and caffeic acid having strong anti-inflammatory and antioxidant properties in vitro and ferulic acid having activities in in vivo animal models of depression.

Individual responses to completion of short-term and chronic interval training: a retrospective study.

Alterations in maximal oxygen uptake (VO2max), heart rate (HR), and fat oxidation occur in response to chronic endurance training. However, many studies report frequent incidence of “non-responders” who do not adapt to continuous moderate exercise. Whether this is the case in response to high intensity interval training (HIT), which elicits similar adaptations as endurance training, is unknown. The aim of this retrospective study was to examine individual responses to two paradigms of interval training. In the first study (study 1), twenty active men and women (age and baseline VO2max = 24.0±4.6 yr and 42.8±4.8 mL/kg/min) performed 6 d of sprint interval training (SIT) consisting of 4–6 Wingate tests per day, while in a separate study (study 2), 20 sedentary women (age and baseline VO2max = 23.7±6.2 yr and 30.0±4.9 mL/kg/min) performed 12 wk of high-volume HIT at workloads ranging from 60–90% maximal workload. Individual changes in VO2max, HR, and fat oxidation were examined in each study, and multiple regression analysis was used to identify predictors of training adaptations to SIT and HIT. Data showed high frequency of increased VO2max (95%) and attenuated exercise HR (85%) in response to HIT, and low frequency of response for VO2max (65%) and exercise HR (55%) via SIT. Frequency of improved fat oxidation was similar (60–65%) across regimens. Only one participant across both interventions showed non-response for all variables. Baseline values of VO2max, exercise HR, respiratory exchange ratio, and body fat were significant predictors of adaptations to interval training. Frequency of positive responses to interval training seems to be greater in response to prolonged, higher volume interval training compared to similar durations of endurance training.

Caffeine consumption around an exercise bout: effects on energy expenditure, energy intake, and exercise enjoyment

Combining an exercise and nutritional intervention is arguably the optimal method of creating energy imbalance for weight loss. This study sought to determine whether combining exercise and caffeine supplementation was more effective for promoting acute energy deficits and manipulations to substrate metabolism than exercise alone. Fourteen recreationally active participants (mean ± SD body mass index: 22.7 ± 2.6 kg/m2) completed a resting control trial (CON), a placebo exercise trial (EX), and a caffeine exercise trial (EX+CAF, 2 × 3 mg/kg of caffeine 90 min before and 30 min after exercise) in a randomized, double-blinded design. Trials were 4 h in duration with 1 h of rest, 1 h of cycling at ∼65% power at maximum O2 consumption or rest, and a 2-h recovery. Gas exchange, appetite perceptions, and blood samples were obtained periodically. Two hours after exercise, participants were offered an ad libitum test meal where energy and macronutrient intake were recorded. EX+CAF resulted in significantly greater energy expenditure and fat oxidation compared with EX (+250 kJ; +10.4 g) and CON (+3,126 kJ; +29.7 g) (P < 0.05). A trend for reduced energy and fat intake compared with CON (-718 kJ; -8 g) (P = 0.055) was observed. Consequently, EX+CAF created a greater energy deficit (P < 0.05). Caffeine also led to exercise being perceived as less difficult and more enjoyable (P < 0.05). Combining caffeine with exercise creates a greater acute energy deficit, and the implications of this protocol for weight loss or maintenance over longer periods of time in overweight/obese populations should be further investigated.

The Effects of Caffeinated “Energy Shots” on Time Trial Performance

An emerging trend in sports nutrition is the consumption of energy drinks and “energy shots”. Energy shots may prove to be a viable pre-competition supplement for runners. Six male runners (mean ± SD age and VO2max: 22.5 ± 1.8 years and 69.1 ± 5.7 mL·kg−1·min−1) completed three trials [placebo (PLA; 0 mg caffeine), Guayakí Yerba Maté Organic Energy Shot™ (YM; 140 mg caffeine), or Red Bull Energy Shot™ (RB; 80 mg caffeine)]. Treatments were ingested following a randomized, placebo-controlled crossover design. Participants ran a five kilometer time trial on a treadmill. No differences (p > 0.05) in performance were detected with RB (17.55 ± 1.01 min) or YM ingestion (17.86 ± 1.59 min) compared to placebo (17.44 ± 1.25 min). Overall, energy shot ingestion did not improve time-trial running performance in trained runners.

Perceptual Changes in Response to Two Regimens of Interval Training in Sedentary Women.

Abstract Astorino, TA, Schubert, MM, Palumbo, E, Stirling, D, McMillan, DW, Gallant, R, and Dewoskin, R. Perceptual changes in response to two regimens of interval training in sedentary women. J Strength Cond Res 30(4): 1067–1076, 2016—This study examined acute and chronic changes in perceptual measures (rating of perceived exertion [RPE], affect, and arousal) in response to 2 regimens of high-intensity interval training (HIIT). Twenty-three healthy sedentary women (mean ± SD age and V[Combining Dot Above]O2max = 23.0 ± 5.7 years and 30.1 ± 4.4 ml·kg−1·min−1, respectively) were randomized to complete 12 weeks of one of 2 HIIT regimes, whereas an additional 7 women served as sedentary controls. Training was performed 3 days per week on a cycle ergometer and consisted of up to ten 1-minute bouts at moderate (60–80%Wmax = moderate intensity [MOD]) or more intense (80–90%Wmax = HI) workloads separated by active recovery. At baseline and every 3 weeks, RPE, affect, and arousal were measured during training using validated scales. Repeated measures analysis of variance was used to examine acute and chronic changes in these variables to HIIT. Data revealed significant (p < 0.001) increases in RPE and arousal and decreases (p < 0.001) in affect during acute HIIT, with RPE responses differing (p ⩽ 0.05) between HI and MOD. However, acute changes in affect and arousal were similar in HI and MOD. Training led to a significant reduction in RPE, whereas both affect and arousal were unchanged (p > 0.05) after HIIT. Completion of moderate or more intense interval training reduces perceptions of RPE during training yet does not alter arousal or affect. RPE was reduced via training, yet large dependence on anaerobic metabolism during HIIT may minimize training-induced changes in affect.

Impact of 4 weeks of interval training on resting metabolic rate, fitness, and health-related outcomes

Resting metabolic rate (RMR) and substrate oxidation (respiratory exchange ratio; RER) are important indicators of health. The effects of interval training on RMR have not been thoroughly investigated, which was the purpose of the present study. Thirty men and women (mean ± SD age and maximal oxygen uptake: 28.8 ± 7.6 years and 33.0 ± 8.3 mL·kg-1·min-1) completed 4 weeks of Wingate-based sprint interval training (SIT), repeated 1-min high-intensity intervals (HIIT), or served as controls. Before and after training, RMR, resting RER, maximal oxygen uptake, body composition, physical activity, and energy intake were recorded. Data were analyzed using a repeated-measures ANOVA. RMR increased in response to 4 weeks of SIT training (1789 ± 293 to 1855 ± 320 kcal·day-1; p = 0.003) but did not increase after HIIT (1670 ± 324 to 1704 ± 329 kcal·day-1; p = 0.06). While SIT increased RMR by ∼2× the magnitude of HIIT, the difference was not significant (p = 0.5). Fasting substrate oxidation and RER did not change (p > 0.05). Maximal oxygen uptake increased, and small changes were also observed in percent body fat and fat mass (p < 0.05 for all). In conclusion, SIT provided a time-efficient stimulus to increase RMR after 4 weeks in healthy adults. However, the clinical relevance of the changes observed in this study remains to be determined. Further studies should be conducted in obese individuals and those with diabetes or insulin resistance to examine if interval training (≥4 weeks) influences resting metabolic rate in magnitudes similar to that reported here.

Breakfast Intake and Composition Is Associated with Superior Academic Achievement in Elementary Schoolchildren

Objective: To determine whether breakfast consumption or content affects academic achievement measured by standardized tests. Methods: Baseline data were collected in fall of 2011 from 698 students (50.5% female, age = 7.5 ± 0.6 years) living in the state of Kansas. Academic achievement was assessed using 3 components from the Wechsler Individual Achievement Test (WIAT-III). Prior to taking the WIAT-III, participants completed a breakfast recall of all foods and drinks consumed that morning, which was analyzed using Nutrition Data System for Research (NDS-R). WIAT-III scores were compared between breakfast and non-breakfast consumers in a sample (n = 162) matched for age, sex, race, education level of both parents, household income, body mass index (BMI), and cardiovascular fitness, and Pearson correlations were calculated from all breakfast eaters (n = 617) between test performance and components of the breakfast. Results: When compared to non-breakfast consumers, the breakfast consumers had significantly higher scores in all 3 WIAT-III components (all p < 0.05). In breakfast consumers, servings of fruit juice were negatively correlated with reading comprehension and fluency standard score and mathematics standard score (both p < 0.0001), and greater servings of whole grains were significantly related to higher scores in reading comprehension and fluency and mathematics (both p < 0.05). Conclusion: Both breakfast consumption and the content may be associated with improved standardized test performance in elementary school students.