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Volume 32 (2022): Issue S1 (Feb 2022)

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Association Between Long-Term Regular Exercise and Gut Microbiota Among Middle-Aged and Older Urban Chinese

Jiajun Shi, Danxia Yu, Yaohua Yang, Hui Cai, Jie Wu, Qiuyin Cai, Jirong Long, Wei Zheng, Wanghong Xu, and Xiao-Ou Shu

Increasing evidence has suggested that physical activity may modulate gut microbiome composition. We investigated associations of long-term regular exercise with gut microbiota among middle-aged and older urban Chinese individuals. Gut microbiota was assessed using 16S ribosomal ribonucleic acid gene sequencing of stool samples from 2,151 participants from the Shanghai Women’s Health Study and Shanghai Men’s Health Study. Participants were free of cancer, diabetes, and cardiovascular diseases at the time of stool sample collection. Physical activity was assessed in repeat surveys between 1996 and 2015 using validated questionnaires. Regular exercise was defined as any type of leisure-time physical activity with a standard metabolic equivalent score >3.0. Stool samples were collected using the 95% ethanol method between 2015 and 2018 with an average of 3.0 years (SD = 0.9) after the latest exposure assessment. General linear regression and permutational multivariate analysis of variance were carried out to evaluate associations of microbial α- and β-diversity with regular exercise participation. Logistic regression and linear regression models were used to evaluate the prevalence and relative abundance of individual taxa in association with regular exercise. Regular exercise was significantly associated with β-diversity (Bray–Curtis and Jaccard dissimilarities, both false discovery rates = 0.03%, 0.12% and 0.09% variance explained, respectively) but not with α-diversity. Relative abundance of genus Ruminococcus was significantly lower among regular exercisers compared with nonexercisers (median relative abundance: 0.64% vs. 0.81%, false discovery rate <0.10). Further studies are needed to validate the findings from this study and evaluate health benefits of regular exercise on gut microbiota.

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Acute Ingestion of Ketone Monoesters and Precursors Do Not Enhance Endurance Exercise Performance: A Systematic Review and Meta-Analysis

Emma Brooks, Gilles Lamothe, Taniya S. Nagpal, Pascal Imbeault, Kristi Adamo, Jameel Kara, and Éric Doucet

There has been much consideration over whether exogenous ketone bodies have the capacity to enhance exercise performance through mechanisms such as altered substrate metabolism, accelerated recovery, or neurocognitive improvements. This systematic review aimed to determine the effects of both ketone precursors and monoesters on endurance exercise performance. A systematic search was conducted in PubMed, SPORTDiscus, and CINAHL for randomized controlled trials investigating endurance performance outcomes in response to ingestion of a ketone supplement compared to a nutritive or nonnutritive control in humans. A meta-analysis was performed to determine the standardized mean difference between interventions using a random-effects model. Hedge’s g and 95% confidence intervals (CI) were reported. The search yielded 569 articles, of which eight were included in this review (80 participants; 77 men and three women). When comparing endurance performance among all studies, no significant differences were found between ketone and control trials (Hedges g = 0.136; 95% CI [−0.195, 0.467]; p = .419). Subanalyses based on type of endurance tests showed no significant differences in time to exhaustion (Hedge’s g = −0.002; 95% CI [−0.312, 0.308]; p = .989) or time trial (Hedge’s g = 0.057; 95% CI [−0.282, 0.395]; p = .744) values. Based on these findings, exogenous ketone precursors and monoesters do not exert significant improvements on endurance exercise performance. While all studies reported an increase in blood ketone concentrations after ingestion, ketone monoesters appear to be more effective at raising concentrations than precursors.

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Erratum: Fensham et al. (2021)

International Journal of Sport Nutrition and Exercise Metabolism

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Whey Protein Supplementation Is Superior to Leucine-Matched Collagen Peptides to Increase Muscle Thickness During a 10-Week Resistance Training Program in Untrained Young Adults

Jeferson L. Jacinto, João P. Nunes, Stefan H.M. Gorissen, Danila M.G. Capel, Andrea G. Bernardes, Alex S. Ribeiro, Edilson S. Cyrino, Stuart M. Phillips, and Andreo F. Aguiar

The purpose of this study was to investigate the effects of supplementation of whey protein (WP) versus leucine-matched collagen peptides (CP) on muscle thickness MT and performance after a resistance training (RT) program in young adults. Twenty-two healthy untrained participants were randomly assigned to either a WP (n = 11) or leucine-matched CP (n = 11) group and then submitted to a supervised 10-week RT program (3 days/week). The groups were supplemented with an equivalent amount of WP (35 g, containing 3.0 g of leucine) and CP (35 g, containing 1.0 g of leucine and 2.0 g of free leucine) during the intervention period (after each workout and in the evening on nontraining days). MT of the vastus lateralis and biceps brachii, isokinetic peak torque and mean power output of the elbow flexors, and peak power output of the lower body were assessed before and after the RT program. The WP group experienced a greater (interaction, p < .05) increase in the vastus lateralis (effect size, WP = 0.68 vs. CP = 0.38; % Δ, WP = 8.4 ± 2.5 vs. CP = 5.6 ± 2.6%) and biceps brachii muscle thickness (effect size, WP = 0.61 vs. CP = 0.35; % , WP = 10.1 ± 3.8 vs. CP = 6.0 ± 3.2%), with a similar increase in muscle performance (peak torque, mean power output, and peak power output) between groups (time p < .05). Supplementation with WP was superior to leucine content-matched CP supplementation in increasing muscle size, but not strength and power, after a 10-week RT program in young adults.

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Interaction Between Caffeine and Creatine When Used as Concurrent Ergogenic Supplements: A Systematic Review

Sara Elosegui, Jaime López-Seoane, María Martínez-Ferrán, and Helios Pareja-Galeano

There is some controversy regarding the interactions between creatine (CRE) and caffeine (CAF) supplements. The aim of this systematic review was to study whether such ergogenic interaction occurs and to analyze the protocol to optimize their synchronous use. The PubMed, Web of Science, MEDLINE, CINAHL, and SPORTDiscus databases were searched until November 2021 following the PRISMA guidelines. Ten studies were included. Three studies observed that CRE loading before an acute dose of CAF before exercise did not interfere in the beneficial effect of CAF, whereas one study reported that only an acute supplementation (SUP) of CAF was beneficial but not the acute SUP of both. When chronic SUP with CRE + CAF was used, two studies reported that CAF interfered in the beneficial effect of CRE, whereas three studies did not report interaction between concurrent SUP, and one study reported synergy. Possible mechanisms of interaction are opposite effects on relaxation time and gastrointestinal distress derived from concurrent SUP. CRE loading does not seem to interfere in the acute effect of CAF. However, chronic SUP of CAF during CRE loading could interfere in the beneficial effect of CRE.

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The Effects of Supervised Exercise Training on Weight Control and Other Metabolic Outcomes in Patients With Type 2 Diabetes: A Meta-Analysis

Xingyun Zhu, Fang Zhang, Jing Chen, Yingxi Zhao, Tianhao Ba, Chu Lin, Yingli Lu, Tao Yu, Xiaoling Cai, Li Zhang, and Linong Ji

Few studies have investigated the dose–response relationship between exercise and weight control. This study aimed to assess the effects of different types of supervised exercise training on weight control and other metabolic outcomes in patients with type 2 diabetes mellitus and explore the dose–response relationship between exercise volume/duration and these outcomes. PubMed/MEDLINE, Embase, and Cochrane databases were searched for studies between January 1980 and June 2019. Randomized control trials in type 2 diabetes mellitus patients with supervised exercise training versus control treatment were included. The primary outcome was changes in body weight (kg). The secondary outcomes included changes in waist circumference (cm) and total body fat percentage (%). Forty-two randomized control trials, including 3,625 patients with type 2 diabetes mellitus were included. Overall, exercise treatment was associated with significant reduction in body weight (weighted mean differences, −1.10 kg; 95% CI [−1.58, −0.62], p < .01), waist circumference (weighted mean differences, −2.51 cm; 95% CI [−3.25, −1.77], p < .01), and total body fat (weighted mean differences, −1.16%; 95% CI [−1.58%, −0.75%], p < .01). The percentage of total body fat was reduced by all types of exercise, with a significant difference between aerobic exercise and resistance exercise (p = .02) and a significant difference between combined exercise and resistance exercise (p < .01). A higher volume of aerobic exercise and a higher volume of resistance exercise were superior in reducing body weight. In conclusion, supervised exercise training improved metabolic outcomes in general, while different types and volume of exercises have their own merits.

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Volume 32 (2022): Issue 1 (Jan 2022)

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Erratum: Kirk, Langan-Evans, & Morton (2020)

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Sustained Exposure to High Carbohydrate Availability Does Not Influence Iron-Regulatory Responses in Elite Endurance Athletes

Alannah K.A. McKay, Peter Peeling, David B. Pyne, Nicolin Tee, Marijke Welveart, Ida A. Heikura, Avish P. Sharma, Jamie Whitfield, Megan L. Ross, Rachel P.L. van Swelm, Coby M. Laarakkers, and Louise M. Burke

This study implemented a 2-week high carbohydrate (CHO) diet intended to maximize CHO oxidation rates and examined the iron-regulatory response to a 26-km race walking effort. Twenty international-level, male race walkers were assigned to either a novel high CHO diet (MAX = 10 g/kg body mass CHO daily) inclusive of gut-training strategies, or a moderate CHO control diet (CON = 6 g/kg body mass CHO daily) for a 2-week training period. The athletes completed a 26-km race walking test protocol before and after the dietary intervention. Venous blood samples were collected pre-, post-, and 3 hr postexercise and measured for serum ferritin, interleukin-6, and hepcidin-25 concentrations. Similar decreases in serum ferritin (17–23%) occurred postintervention in MAX and CON. At the baseline, CON had a greater postexercise increase in interleukin-6 levels after 26 km of walking (20.1-fold, 95% CI [9.2, 35.7]) compared with MAX (10.2-fold, 95% CI [3.7, 18.7]). A similar finding was evident for hepcidin levels 3 hr postexercise (CON = 10.8-fold, 95% CI [4.8, 21.2]; MAX = 8.8-fold, 95% CI [3.9, 16.4]). Postintervention, there were no substantial differences in the interleukin-6 response (CON = 13.6-fold, 95% CI [9.2, 20.5]; MAX = 11.2-fold, 95% CI [6.5, 21.3]) or hepcidin levels (CON = 7.1-fold, 95% CI [2.1, 15.4]; MAX = 6.3-fold, 95% CI [1.8, 14.6]) between the dietary groups. Higher resting serum ferritin (p = .004) and hotter trial ambient temperatures (p = .014) were associated with greater hepcidin levels 3 hr postexercise. Very high CHO diets employed by endurance athletes to increase CHO oxidation have little impact on iron regulation in elite athletes. It appears that variations in serum ferritin concentration and ambient temperature, rather than dietary CHO, are associated with increased hepcidin concentrations 3 hr postexercise.