Longitudinal changes in blood metabolites, amino acid profile, and oxidative stress markers in American Foxhounds fed a nutrient-fortified diet.
J Anim Sci. 2018 Feb 21;:
Authors: Beloshapka AN, de Godoy MRC, Carter RA, Fascetti AJ, Yu Z, McIntosh BJ, Swanson KS, Buff PR
The objective of the present study was to evaluate the changes in blood metabolites, amino acid profile, and oxidative stress markers in American Foxhound dogs fed a nutrient-fortified endurance diet while undergoing unstructured endurance exercise over several months. Thirty-six adult American Foxhound dogs (mean age: 4.5, range 2-10 years and mean body weight (BW): 34.7, range: 23.1-46.9 kg) were selected to participate in the study. Prior to the study, all dogs consumed a commercial diet for 16 weeks. After collecting baseline blood samples, dogs were assigned to a standard commercial performance diet (control) or a nutrient-fortified dog food (test). Dogs were balanced by gender, age, body weight, and athletic performance between diets. During the study, dogs underwent 78 bouts of exercise, with approximately 22 kilometers/bout. Blood samples were collected after 40, 75, 138, and 201d on study (October 2012 to March 2013). All blood metabolites were similar at baseline and serum chemistry profile remained within normal ranges throughout the study. Over time, plasma taurine and vitamin E concentrations decreased (P < 0.05) in dogs fed the control diet, but were maintained or increased (P < 0.05) in dogs fed the treatment diet. Also, plasma creatinine and triglycerides were lower (P < 0.05) and blood phosphorus and alkaline phosphatase were higher (P<0.05) in dogs fed the treatment diet. Vitamin E and taurine status of dogs appear to be affected by extended endurance exercise. These data suggest dogs undergoing endurance exercise may benefit from supplementation of vitamin E and taurine to minimize oxidation and maintain taurine status.
PMID: 29474728 [PubMed - as supplied by publisher]
Systems-level computational modeling demonstrates fuel selection switching in high capacity running and low capacity running rats.
PLoS Comput Biol. 2018 Feb 23;14(2):e1005982
Authors: Moxley MA, Vinnakota KC, Bazil JN, Qi NR, Beard DA
High capacity and low capacity running rats, HCR and LCR respectively, have been bred to represent two extremes of running endurance and have recently demonstrated disparities in fuel usage during transient aerobic exercise. HCR rats can maintain fatty acid (FA) utilization throughout the course of transient aerobic exercise whereas LCR rats rely predominantly on glucose utilization. We hypothesized that the difference between HCR and LCR fuel utilization could be explained by a difference in mitochondrial density. To test this hypothesis and to investigate mechanisms of fuel selection, we used a constraint-based kinetic analysis of whole-body metabolism to analyze transient exercise data from these rats. Our model analysis used a thermodynamically constrained kinetic framework that accounts for glycolysis, the TCA cycle, and mitochondrial FA transport and oxidation. The model can effectively match the observed relative rates of oxidation of glucose versus FA, as a function of ATP demand. In searching for the minimal differences required to explain metabolic function in HCR versus LCR rats, it was determined that the whole-body metabolic phenotype of LCR, compared to the HCR, could be explained by a ~50% reduction in total mitochondrial activity with an additional 5-fold reduction in mitochondrial FA transport activity. Finally, we postulate that over sustained periods of exercise that LCR can partly overcome the initial deficit in FA catabolic activity by upregulating FA transport and/or oxidation processes.
PMID: 29474500 [PubMed - as supplied by publisher]
Fat max as an index of aerobic exercise performance in mice during uphill running.
PLoS One. 2018;13(2):e0193470
Authors: Ishihara K, Taniguchi H
Endurance exercise performance has been used as a representative index in experimental animal models in the field of health sciences, exercise physiology, comparative physiology, food function or nutritional physiology. The objective of the present study was to evaluate the effectiveness of Fatmax (the exercise intensity that elicits maximal fat oxidation) as an additional index of endurance exercise performance that can be measured during running at submaximal exercise intensity in mice. We measured both Fatmax and Vo2 peak of trained ICR mice that voluntary exercised for 8 weeks and compared them with a sedentary group of mice at multiple inclinations of 20, 30, 40, and 50° on a treadmill. The Vo2 at Fatmax of the training group was significantly higher than that of the sedentary group at inclinations of 30 and 40° (P < 0.001). The running speed at Fatmax of the training group was significantly higher than that of the sedentary group at inclinations of 20, 30, and 40° (P < 0.05). Blood lactate levels sharply increased in the sedentary group (7.33 ± 2.58 mM) compared to the training group (3.13 ± 1.00 mM, P < 0.01) when running speeds exceeded the Fatmax of sedentary mice. Vo2 at Fatmax significantly correlated to Vo2 peak, running time to fatigue, and lactic acid level during running (P < 0.05) although the reproducibility of Vo2 peak was higher than that of Vo2 at Fatmax. In conclusion, Fatmax can be used as a functional assessment of the endurance exercise performance of mice during submaximal exercise intensity.
PMID: 29474428 [PubMed - in process]
Restoration of Muscle Glycogen and Functional Capacity: Role of Post-Exercise Carbohydrate and Protein Co-Ingestion.
Nutrients. 2018 Feb 23;10(2):
Authors: Alghannam AF, Gonzalez JT, Betts JA
The importance of post-exercise recovery nutrition has been well described in recent years, leading to its incorporation as an integral part of training regimes in both athletes and active individuals. Muscle glycogen depletion during an initial prolonged exercise bout is a main factor in the onset of fatigue and so the replenishment of glycogen stores may be important for recovery of functional capacity. Nevertheless, nutritional considerations for optimal short-term (3-6 h) recovery remain incompletely elucidated, particularly surrounding the precise amount of specific types of nutrients required. Current nutritional guidelines to maximise muscle glycogen availability within limited recovery are provided under the assumption that similar fatigue mechanisms (i.e., muscle glycogen depletion) are involved during a repeated exercise bout. Indeed, recent data support the notion that muscle glycogen availability is a determinant of subsequent endurance capacity following limited recovery. Thus, carbohydrate ingestion can be utilised to influence the restoration of endurance capacity following exhaustive exercise. One strategy with the potential to accelerate muscle glycogen resynthesis and/or functional capacity beyond merely ingesting adequate carbohydrate is the co-ingestion of added protein. While numerous studies have been instigated, a consensus that is related to the influence of carbohydrate-protein ingestion in maximising muscle glycogen during short-term recovery and repeated exercise capacity has not been established. When considered collectively, carbohydrate intake during limited recovery appears to primarily determine muscle glycogen resynthesis and repeated exercise capacity. Thus, when the goal is to optimise repeated exercise capacity following short-term recovery, ingesting carbohydrate at an amount of ≥1.2 g kg body mass-1·h-1 can maximise muscle glycogen repletion. The addition of protein to carbohydrate during post-exercise recovery may be beneficial under circumstances when carbohydrate ingestion is sub-optimal (≤0.8 g kg body mass-1·h-1) for effective restoration of muscle glycogen and repeated exercise capacity.
PMID: 29473893 [PubMed - in process]
Locomotor activity, growth hormones, and systemic robusticity: An investigation of cranial vault thickness in mouse lines bred for high endurance running.
Am J Phys Anthropol. 2018 Feb 23;:
Authors: Copes LE, Schutz H, Dlugsoz EM, Judex S, Garland T
OBJECTIVES: To use a mouse model to investigate the relationships among the components of the systemic robusticity hypothesis (SRH): voluntary exercise on wheels, spontaneous physical activity (SPA) in cages, growth hormones, and skeletal robusticity, especially cranial vault thickness (CVT).
MATERIALS AND METHODS: Fifty female mice from lines artificially selected for high running (HR) and 50 from nonselected control (C) lines were housed in cages with (Active) or without wheels (Sedentary). Wheel running and SPA were monitored daily. The experiment began at 24-27 days of age and lasted 12 weeks. Food consumption was measured weekly. Mice were skeletonized and their interparietal, parietal, humerus, and femur were µCT scanned. Mean total thickness of the parietal and interparietal bones was determined, along with thickness of the cortical and diploe layers individually. Geometric cross-sectional indicators of strength were calculated for the long bones. Blood samples were assayed for IGF-1 and IGFBP-3.
RESULTS: Physical activity differed significantly among groups, based both on linetype (C vs. HR) and activity (A vs. S). However, contrary to our predictions, the ratio of IGF-1 to IGFBP-3 was higher in C mice than in HR mice. Neither CVT nor postcranial robusticity was affected by linetype or activity, nor were most measures of CVT and postcranial robusticity significantly associated with one another.
DISCUSSION: Our results fail to provide support for the systemic robusticity hypothesis, suggesting it is important to rethink the long-standing theory that increased CVT in Homo erectus reflects increased physical activity compared other hominin species.
PMID: 29473645 [PubMed - as supplied by publisher]
A Comparison between Different Methods of Estimating Anaerobic Energy Production.
Front Physiol. 2018;9:82
Authors: Andersson EP, McGawley K
Purpose: The present study aimed to compare four methods of estimating anaerobic energy production during supramaximal exercise. Methods: Twenty-one junior cross-country skiers competing at a national and/or international level were tested on a treadmill during uphill (7°) diagonal-stride (DS) roller-skiing. After a 4-minute warm-up, a 4 × 4-min continuous submaximal protocol was performed followed by a 600-m time trial (TT). For the maximal accumulated O2 deficit (MAOD) method the [Formula: see text]O2-speed regression relationship was used to estimate the [Formula: see text]O2 demand during the TT, either including (4+Y, method 1) or excluding (4-Y, method 2) a fixed Y-intercept for baseline [Formula: see text]O2. The gross efficiency (GE) method (method 3) involved calculating metabolic rate during the TT by dividing power output by submaximal GE, which was then converted to a [Formula: see text]O2 demand. An alternative method based on submaximal energy cost (EC, method 4) was also used to estimate [Formula: see text]O2 demand during the TT. Results: The GE/EC remained constant across the submaximal stages and the supramaximal TT was performed in 185 ± 24 s. The GE and EC methods produced identical [Formula: see text]O2 demands and O2 deficits. The [Formula: see text]O2 demand was ~3% lower for the 4+Y method compared with the 4-Y and GE/EC methods, with corresponding O2 deficits of 56 ± 10, 62 ± 10, and 63 ± 10 mL·kg-1, respectively (P < 0.05 for 4+Y vs. 4-Y and GE/EC). The mean differences between the estimated O2 deficits were -6 ± 5 mL·kg-1 (4+Y vs. 4-Y, P < 0.05), -7 ± 1 mL·kg-1 (4+Y vs. GE/EC, P < 0.05) and -1 ± 5 mL·kg-1 (4-Y vs. GE/EC), with respective typical errors of 5.3, 1.9, and 6.0%. The mean difference between the O2 deficit estimated with GE/EC based on the average of four submaximal stages compared with the last stage was 1 ± 2 mL·kg-1, with a typical error of 3.2%. Conclusions: These findings demonstrate a disagreement in the O2 deficits estimated using current methods. In addition, the findings suggest that a valid estimate of the O2 deficit may be possible using data from only one submaximal stage in combination with the GE/EC method.
PMID: 29472871 [PubMed]
Effects of order and sequence of resistance and endurance training on body fat in elementary school-aged girls.
Biol Sport. 2017 Dec;34(4):379-384
Authors: Alves AR, Marta CC, Neiva HP, Izquierdo M, Marques MC
The purpose of this study was to analyse the effects of order and sequence of concurrent resistance and endurance training on body fat percentage (BFP) in a large sample of elementary school-aged girls. One hundred and twenty-six healthy girls, aged 10-11 years (10.95 ± 0.48 years), were randomly assigned to six groups to perform different training protocols per week for 8 weeks: Resistance-only (R), Endurance-only (E), Concurrent Distinct Endurance-Resistance (CDER), Concurrent Parallel Endurance-Resistance (CPER), Concurrent Parallel Resistance-Endurance (CPRE), and a Control group (C). In R and E, the subjects performed single sessions of resistance or endurance exercises, respectively (two days per week). In CDER, resistance-endurance training was performed on different days each week (four days per week). CPER and CPRE performed single-session combined endurance-resistance training or combined resistance-endurance training, respectively, each week (two days per week). After an 8-week training period, BFP decreased in all experimental groups (CPER: 13.3%, p< 0.05; CPRE: 13.8%, p<0.001; E: 1.9%, p>0.05; R: 5.0%, p>0.05; and CDER: 5.6%, p>0.05). However, a significant difference was found in CPER and CPRE when compared to CDER, E, and R, indicating that training sequence may influence BFP. All programmes were effective, but CPER and CPRE obtained better results for BFP than CDER, E, or R. The effects of concurrent resistance and endurance training on body fat percentage can be mediated by order and sequence of exercise. These results provide insight into optimization of school-based fat loss exercise programmes in childhood.
PMID: 29472741 [PubMed]
Taurine supplementation improves economy of movement in the cycle test independently of the detrimental effects of ethanol.
Biol Sport. 2017 Dec;34(4):353-359
Authors: Paulucio D, Costa BM, Santos CGM, Nogueira F, Koch A, Machado M, Velasques B, Ribeiro P, Pompeu FA
Taurine (TA) ingestion has been touted as blunting the deleterious effects of ethanol (ET) ingestion on motor performance. This study investigated the effects of ingestion of 0.6 mL·kg-1 of ET, 6 grams of TA, and ethanol in combination with taurine (ET+TA) on economy of movement (EM) and heart rate (HR). Nine volunteers, five female (22 ± 3 years) and four male (26 ± 5 years), participated in a study that used a counterbalanced experimental design. EM and HR were measured for 6 min while the subjects were pedalling at a fixed load 10% below the anaerobic threshold. The blood alcohol concentration (BAC) was similar between ET and ET+TA treatments at 30 min after ingestion and after exercise (12.3 mmol·L-1 vs. 13.7 mmol·L-1, and 9.7 mmol • L-1 vs 10.9 mmol·L-1, respectively). EM was significantly different among treatments, with lower mL·W-1 following ingestion of TA (-7.1%, p<0.001) than placebo and ET+TA (-2.45%, p=0.001) compared to ET. HR (bpm) was significantly (p<0.05) higher for ET (137 ± 14 bpm) than the other three treatments (placebo = 129 ± 14 bpm; TA = 127 ± 11 bpm; TA+ET = 133 ± 12 and ET = 137 ± 14 bpm). Taurine improved EM when compared to placebo or ET, and reduced HR when compared to ET. The combination of ET+TA also enhanced EM compared to placebo, and reduced HR in comparison to ET alone. Therefore, these findings indicate that taurine improves EM and counteracts ethanol-induced increases in HR during submaximal exercise.
PMID: 29472738 [PubMed]
A randomized controlled trial comparing home-based isometric handgrip exercise versus endurance training for blood pressure management.
J Am Soc Hypertens. 2018 Feb 02;:
Authors: Goessler KF, Buys R, VanderTrappen D, Vanhumbeeck L, Cornelissen VA
Aerobic endurance exercise (AEX) is an effective treatment in the prevention and management of high blood pressure (BP). Growing evidence suggests potential benefits from isometric handgrip (IHG) exercise, which may promote similar or even larger reductions in BP than AEX. We compared the effects of home-based AEX and home-based IHG on BP. Sixty healthy individuals (31 men; mean age, 33.1 years; mean BP, 126.9 ± 1.6/84.7 ± 1.1 mm Hg) were randomized to IHG, AEX, or a control group. Both exercise interventions were performed in the home environment. The IHG group performed daily 4 × 2 minutes sustained grips at 30% of maximal volitional contraction. Participants in the AEX group were advised to perform at least 150 min/wk of aerobic exercise at moderate intensity. Outcome measurements were assessed at baseline and 8 weeks of follow-up. Compared with the control group, AEX resulted in a larger reduction in ambulatory BP; both AEX and IHG exercise tended to induce larger reductions in office systolic BP, and office diastolic BP was significantly more reduced after AEX but not IHG exercise. Responses to training were not significantly different between both the exercise interventions. Eight weeks of home-based AEX results in significant reductions in both ambulatory BP and office BP in healthy adults, whereas IHG reduces only office BP.
PMID: 29472030 [PubMed - as supplied by publisher]
History of erectile dysfunction as a predictor of poor physical performance after an acute myocardial infarction.
Eur J Prev Cardiol. 2017 Mar;24(5):460-467
Authors: Compostella L, Compostella C, Truong LV, Russo N, Setzu T, Iliceto S, Bellotto F
Background Erectile dysfunction may predict future cardiovascular events and indicate the severity of coronary artery disease in middle-aged men. The aim of this study was to evaluate whether erectile dysfunction (expression of generalized macro- and micro-vascular pathology) could predict reduced effort tolerance in patients after an acute myocardial infarction. Patients and methods One hundred and thirty-nine male patients (60 ± 12 years old), admitted to intensive cardiac rehabilitation 13 days after a complicated acute myocardial infarction, were evaluated for history of erectile dysfunction using the International Index of Erectile Function questionnaire. Their physical performance was assessed by means of two six-minute walk tests (performed two weeks apart) and by a symptom limited cardiopulmonary exercise test (CPET). Results Patients with erectile dysfunction (57% of cases) demonstrated poorer physical performance, significantly correlated to the degree of erectile dysfunction. After cardiac rehabilitation, they walked shorter distances at the final six-minute walk test (490 ± 119 vs. 564 ± 94 m; p < 0.001); at CPET they sustained lower workload (79 ± 28 vs. 109 ± 34 W; p < 0.001) and reached lower oxygen uptake at peak effort (18 ± 5 vs. 21 ± 5 ml/kg per min; p = 0.003) and at anaerobic threshold (13 ± 3 vs.16 ± 4 ml/kg per min; p = 0.001). The positive predictive value of presence of erectile dysfunction was 0.71 for low peak oxygen uptake (<20 ml/kg per min) and 0.69 for reduced effort capacity (W-max <100 W). Conclusions As indicators of generalized underlying vascular pathology, presence and degree of erectile dysfunction may predict the severity of deterioration of effort tolerance in post-acute myocardial infarction patients. In the attempt to reduce the possibly associated long-term risk, an optimization of type, intensity and duration of cardiac rehabilitation should be considered.
PMID: 28067536 [PubMed - indexed for MEDLINE]
Physical Employment Standards for UK Firefighters: Minimum Muscular Strength and Endurance Requirements.
J Occup Environ Med. 2017 Jan;59(1):74-79
Authors: Stevenson RD, Siddall AG, Turner PF, Bilzon JL
OBJECTIVE: The aim of this study was to assess sensitivity and specificity of surrogate physical ability tests as predictors of criterion firefighting task performance and to identify corresponding minimum muscular strength and endurance standards.
METHODS: Fifty-one (26 male; 25 female) participants completed three criterion tasks (ladder lift, ladder lower, ladder extension) and three corresponding surrogate tests [one-repetition maximum (1RM) seated shoulder press; 1RM seated rope pull-down; repeated 28 kg seated rope pull-down]. Surrogate test standards were calculated that best identified individuals who passed (sensitivity; true positives) and failed (specificity; true negatives) criterion tasks.
RESULTS: Best sensitivity/specificity achieved were 1.00/1.00 for a 35 kg seated shoulder press, 0.79/0.92 for a 60 kg rope pull-down, and 0.83/0.93 for 23 repetitions of the 28 kg rope pull-down.
CONCLUSIONS: These standards represent performance on surrogate tests commensurate with minimum acceptable performance of essential strength-based occupational tasks in UK firefighters.
PMID: 28045801 [PubMed - indexed for MEDLINE]
Electromyography and economy of walking in chronic heart failure and heart transplant patients.
Eur J Prev Cardiol. 2017 Mar;24(5):544-551
Authors: Bona RL, Bonezi A, Silva PF, Biancardi CM, Castro FA, Clausel NO
Background Patients with chronic heart failure frequently report intolerance to exercise and present with changes in walk pattern, but information about heart transplant patients is lacking. Alterations of the gait pattern are related to interaction changes between the metabolism, neurological system and the mechanical demands of the locomotor task. The aim of this study was to investigate the electromyographic cost, coactivation and cost of transport of walking of chronic heart failure and heart transplant patients. Design This research was of an exploratory, cross-sectional design. Methods Twelve chronic heart failure patients, twelve healthy controls and five heart transplant patients participated in the study. Electromyographic data and oxygen uptake were collected simultaneously at five walking speeds. Results In the experimental groups, the electromyographic cost, percentage of coactivation in the leg and cost of transport were higher than in controls. The electromyographic cost was in line with the cost of transport. The minimum electromyographic cost matched with the self-selected walking speed in controls, while in chronic heart failure and heart transplant patients, it was reached at speeds higher than the self-selected walking speed. Conclusion The largest postural isometric activation and antagonist activation resulted in the highest metabolic demand. These findings are of great clinical relevance because they support the concept that interventions in order to improve the muscle performance in these patients can increase the self-selected walking speed and therefore the metabolic economy of walking.
PMID: 27956556 [PubMed - indexed for MEDLINE]