International journal of sport nutrition and exercise metabolism最新文献

The sport of tennis involves unique nutritional demands for the physical and technical aspects of match play and training, as well as the nutritional challenges associated with extensive travel and a lengthy competition calendar. An expert group assembled by The International Tennis Federation, the Women's Tennis Association, and the Association of Tennis Professionals has produced a scientific review of current evidence to inform practical recommendations for high-performance tennis. The narrative summary considers the diversity within the tennis community, including male and female players, youth players, and wheelchair players. The Expert Group Statement addresses nine specific topics: (a) introduction to tennis; (b) physiological characteristics of tennis training and match play; (c) training nutrition; (d) body composition, low energy availability, and relative energy deficiency in sport; (e) match-day nutrition; (f) dietary supplements for tennis performance; (g) environmental and travel issues; (h) nutrition guidelines during periods of illness and injury rehabilitation; and (i) special population groups. The statement advocates for an evidence-based approach to nutrition in high-performance tennis and emphasizes a "food first" philosophy, prioritizing food over supplements to meet nutrient requirements effectively. In recognition of the benefits of sound nutrition, strategies in supporting health and performance over a player's career, academies, national federations, and international organizations are encouraged to engage professionals with appropriate nutrition-related qualifications and professional registrations to support players effectively.

Sports supplements composed of carbohydrate and protein are widely used by endurance athletes and recreational practitioners, mostly aimed at improving performance. This study investigated the effect of a novel carbohydrate + protein honey powder (HP) product on endurance cycling performance and physiological and perceptual responses using a double-blind, crossover, counterbalanced, placebo-controlled (PLA) design. Twelve male cyclists exercised for 100 min (i.e., 5 min at 1 W/kg of body mass, followed by three sets of 10-min stages at 1.5, 2.0, and 2.5 W/kg, followed by 5 min at 1 W/kg), followed by a 20-min self-paced time trial (20-min TT). Blood glucose, lactate, pH, bicarbonate, heart rate, ratings of perceived exertion, and side effects were analyzed throughout the 100-min cycling protocol and the 20-min TT. The 20-min TT performance was similar between HP and PLA (total work done: 294 ± 40 vs. 292 ± 44 kJ, p = .72; mean power output: 245 ± 33 vs. 243 ± 37 W, p = .61), as was blood glucose, lactate, pH, and ratings of perceived exertion either during the 100 or 20-min TT protocols (all p > .05). Blood bicarbonate was lower in HP compared with PLA throughout the 100-min protocol (p = .01), and heart rate was higher in HP compared with PLA during the 20-min TT (p = .01). Finally, HP supplementation did not elicit greater side effects compared with PLA, either during the 100 or the 20-min TT protocols (all p > .05). This novel HP supplement did not improve endurance performance in this study, though future research with higher doses is encouraged.

Background: Time-restricted eating (TRE), a subtype of intermittent fasting, has gained significant popularity in recent years. This dietary approach, when combined with resistance training (RT), has demonstrated potential benefits for body composition and physiological parameters.

Objective: This study aimed to investigate the effects of TRE and high-protein consumption on visceral adipose tissue (VAT), subcutaneous adipose tissue, leptin, and ghrelin levels in young women with overweight engaged in RT.

Methods: Thirty-two women with overweight (body mass index 25-30 kg/m2), aged 18-30 years, were randomly assigned to four groups: TRE with high protein (THP), TRE with regular protein, high protein only (HP), and regular protein only. All participants underwent RT and adhered to a 25% calorie-restricted diet. The high-protein groups received 1.6 g·kg-1·day-1 of protein. Body composition, blood biomarkers, and muscle functions were assessed.

Results: Significant reductions in VAT (p < .001) and subcutaneous adipose tissue (p < .001) were observed across all groups, with the THP group exhibiting the greatest decrease in VAT (Δ = -146.98 ± 12.66, d = -1.867). Leptin levels also showed a significant decrease in all groups (p < .001). However, significant differences in leptin reduction were detected only between THP versus regular protein only (p = .045) and TRE with regular protein versus regular protein only (p = .034) groups. Plasma ghrelin levels remained unchanged across all groups. Notably, the high-protein groups (THP and high protein only) demonstrated a significant increase in fat-free mass (Δ THP = 1.06 ± 1.75, Δ HP = 2.37 ± 0.64).

Conclusion: An 8-week program combining TRE, high-protein intake, and RT effectively reduced VAT, subcutaneous adipose tissue, and leptin levels while preserving muscle mass in women with overweight. This intervention did not significantly alter plasma ghrelin levels.

The ergogenic effects of caffeine for endurance performance at sea level are well established. However, whether caffeine enhances exercise capacity or modulates cardiorespiratory responses in hypoxia remains unclear. Twenty-nine healthy, active volunteers (14 women) completed four tests in a pseudorandomized order, comprising 10 min of steady-state cycling (40% normoxic maximal aerobic power) followed by incremental exercise tests to exhaustion. Participants consumed 6 mg/kg body mass anhydrous caffeine, or placebo, 45 min before exercise. Tests were performed while breathing room air or a hypoxic gas mixture (simulating ∼3,500 m). At peak exercise intensity, oxygen uptake was affected by condition (hypoxia vs. normoxia; 44.8 ± 7.3 vs. 51.4 ± 7.9 ml·kg-1·min-1; p < .001) but not supplement (caffeine vs. placebo; 48.2 ± 8.2 vs. 48.0 ± 8.4 ml·kg-1·min-1; p = .501). Maximal aerobic power and pulse oxygen saturation were lower in hypoxia (both p < .001), but unaffected by caffeine (p = .061 and .898, respectively). Pulmonary ventilation was unaffected by hypoxia (p = .154) or caffeine (p = .117). Heart rate was higher in normoxia and with caffeine (both p < .001). During steady-state cycling, hypoxia (p < .001) and caffeine (p = .026) increased pulmonary ventilation. However, the hypoxia-induced pulse oxygen saturation decrease (p < .001) was not attenuated with caffeine (interaction p = .283). Perceived exertion was higher in hypoxia (p < .001) and lower with caffeine (p = .026). Caffeine increased vastus lateralis oxygenation in hypoxia (caffeine vs. placebo; 52 ± 8 vs. 50 ± 10%; p = .020) but not in normoxia (caffeine vs. placebo; 59 ± 7 vs. 59 ± 8%; p > .999). Overall, caffeine did not enhance exercise capacity in either environmental condition. However, during steady-state cycling, caffeine enhanced pulmonary ventilation, reduced perceived exertion, and mitigated hypoxia-induced muscle oxygenation reductions.

The present study investigated the effects of honey compared with a traditional carbohydrate based sports nutrition product (TRAD-CHO) on metabolic and gastrointestinal responses during exercise, as well as exercise capacity. In a randomized crossover design 12 trained males ingested 90 g × hr-1 of carbohydrate in the form of TRAD-CHO, or honey (HONEY) during 180 min of steady-state cycling undertaken at 90% lactate threshold, followed by a capacity test consisting of a time to fatigue at 120% of lactate threshold. Mean total CHO oxidation (HONEY 2.47 ± 0.37 g × min-1, TRAD-CHO 2.41 ± 0.39 g × min-1) and fat oxidation (HONEY 0.44 ± 0.12 g/min, TRAD-CHO 0.42 ± 0.10 g/min) were not different between trials during steady-state cycling (p = .517). The overall incidence of gastrointestinal symptoms rated as "moderately severe" or worse was low. There was no difference in time to fatigue (p = .517). There was no difference in breath hydrogen postexercise (p = .319) and the number of participants in each condition, with >20 parts per million rise from baseline not significantly different between conditions (6: SPORT, 7 HONEY: p = 1.00). From these data, honey could be a potentially alternative fueling option to commercial TRAD-CHO, with the current data providing no evidence of any systematic differences between the conditions on whole-body carbohydrate oxidation and endurance capacity test.

Higher carbohydrate availability, achieved through combined intake of glucose and fructose, has been shown to enhance endurance performance. This study examined the effects of higher carbohydrate doses containing a fructose-glucose mixture (1:2 ratio) compared with lower doses containing only glucose on performance during a 120-min simulated soccer match. Fifteen semiprofessional soccer players (seven males and eight females) completed two 120-min soccer-specific exercise sessions in a randomized and crossover design. Participants consumed either 60 g/hr glucose or a combination of 0.5 g/min fructose and 1.0 g/min glucose (90 g/hr) at preexercise, halftime, full time, and midway through extra time. Measures, including gastrointestinal discomfort, mental fatigue, passing accuracy, neuromuscular performance (reactive strength index, countermovement jump height, and peak power output), and sprint performance (15- and 30-m sprints), were assessed at 0, 45, 90, and 120 min. Blood glucose and lactate concentrations were assessed every 15 min. Fructose-glucose coingestion elevated blood glucose concentration from 105 min (p = .006, d = 1.2) but did not maintain performance (p > .05). Gastrointestinal symptoms of gastric reflux at 45 min (p = .011, d = 0.9), fullness at 90 min (p = .013, d = 0.9), and flatulence at 120 min worsened in the glucose group (p = .003, d = 1.1). Abdominal cramps were greater in the fructose-glucose group at 45 (p < .001, d = 1.7) and 90 min (p < .001, d = 1.6). Although supplementation did not influence any other variables (p > .05), countermovement jump height, peak power output, and sprint performance were negatively influenced by exercise in both conditions (p < .05). A higher carbohydrate dosage of fructose-glucose coingestion increases blood glucose concentrations but does not mitigate technical and neuromuscular performance impairments during a prolonged simulated soccer match.

Oral magnesium supplementation can reduce muscle soreness and muscle damage markers after unaccustomed exercise. However, the effectiveness of topical magnesium applications remains unclear. This randomized, double-blind, parallel-design study investigated whether a commercial magnesium gel could reduce the perception of muscle soreness and muscle damage markers following an acute bout of unaccustomed exercise. Healthy active participants (n = 35) performed a 40-min bout of downhill treadmill running. Magnesium (Mg) or placebo (Pla) gels were administered to each thigh 10 min before and immediately after exercise. Measurements were made before (Pre) and immediately (Post), 24 hr, and 48 hr after exercise. The primary outcome was muscle soreness using a 0-100 visual analog scale after a sit-to-stand maneuver. Secondary outcomes included peak isometric knee extensor strength, plasma creatine kinase, and serum interleukin-6. There were no differences between treatments on any outcome. Compared with Pre (Mg: 4 ± 5, Pla: 4 ± 5 a.u.), muscle soreness was higher post (Mg: 28 ± 20, Pla: 21 ± 14) and after 24 hr (Mg: 43 ± 27, Pla: 41 ± 26) and 48 hr (Mg: 42 ± 31, Pla: 32 ± 23) (all main effects, p < .0001). Interleukin-6 was higher Post (Mg: 1.8 ± 0.7, Pla: 1.6 ± 0.7 pg/ml) versus Pre (Mg: 1.1 ± 0.8, Pla: 1.1 ± 0.6; main effect, p = .006), and creatine kinase was higher Post (Mg: 111 ± 57, Pla: 121 ± 44 U/L), 24 hr (Mg: 216 ± 113, Pla: 228 ± 97), and 48 hr (Mg: 136 ± 45, Pla: 179 ± 85) versus Pre (Mg: 93 ± 54, Pla: 91 ± 30; all main effects, p < .001). Knee extensor strength was reduced after exercise (main effect, p = .04). The Mg gel did not reduce muscle soreness or muscle damage markers after unaccustomed exercise compared with Pla. The dose (0.53 mg/ml) or application protocol may have been insufficient to elicit a meaningful effect.

Fat oxidation rates are key determinants of exercise capacity and metabolic health, evaluated by indirect calorimetry during step graded exercise test. We sought to verify whether indirect calorimetry applied to ramp graded exercise test provides comparable results to the reference test and to identify the physiological bases of possible dissimilarities. To this aim, 14 healthy volunteers performed two cardiopulmonary exercise tests with concomitant stress echocardiography according to standard protocols until limit of tolerance on separate days, in randomized order. Compared at matched exercise intensities, expressed as percentage of estimated maximal rate of oxygen uptake (%V˙O2max), indirect calorimetry applied to ramp provided identical kinetics of macronutrient oxidation, with a negligible (7%, p > .05) constant overestimation of fat and underestimation of carbohydrate oxidation rates. Despite identical hemodynamic and ventilatory parameters throughout the tests, we observed a minute downward shift of the Δ V˙CO2/Δ V˙O2 intercept with ramp in comparison to step (-0.05 ± 0.09 L/min; p = .077) due to delayed alignment of gas exchange to work rate, which explains the differences in substrate oxidation values between the two tests. Ramp macronutrient oxidation rates were fully normalized by correcting the stoichiometric equations for the Δ V˙CO2/Δ V˙O2 intercept difference. In conclusion, cardiopulmonary and metabolic responses are dependent on exercise intensity and not on the protocol used. Indirect calorimetry applied to ramp protocols correctly identifies the kinetics of macronutrient oxidation while introducing minimal differences in the absolute values due to different gas-exchange response that can be mathematically corrected by applying the Δ V˙CO2/Δ V˙O2 correction factor.

Objective: This study aims to investigate the potential effects of carotenoid supplementation on mitigating exercise-induced oxidative stress and to provide guidance for future research.

Methods: We conducted a systematic review and meta-analysis using Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. We searched multiple databases from inception to August 2024 for randomized clinical trials investigating the effects of carotenoid supplementation on biomarkers of oxidative stress, inflammatory markers, antioxidant levels, and metabolic parameters in the context of exercise-induced oxidative stress. The search terms included "carotenoids," "supplementation," "exercise," "oxidative stress," "inflammation," "antioxidants," "metabolic parameters," and their synonyms. Two reviewers independently extracted study data, with disagreements resolved by a third reviewer. Quality was assessed by the Cochrane risk-of-bias method. Random and fixed effects models were used for the analysis of standard mean differences (SMD) or weighted mean differences (MDs) with 95% confidence intervals (CI).

Results: A total of 12 studies were included in the final analysis. Carotenoid supplementation led to significant effects in assessing oxidative stress induced by exercise (overall oxidative stress: SMD = -0.55, 95% CI [-1.04, -0.06]; malondialdehyde: MD = -0.05, 95% CI [-0.09,-0.02]; total antioxidant capacity: MD = 0.03, 95% CI [0.02, 0.03]; 8-isoprostane: MD = -35.70, 95% CI [-59.32, -12.09]; lipid peroxide: SMD = -1.07, 95% CI [-1.94, -0.20]; and nitric oxide: MD = -8.07, 95% CI [-12.54,-3.59]), inflammatory markers (inflammatory levels: SMD = 1.63, 95% CI [0.81, 2.46]; interleukin levels: SMD = 1.54, 95% CI [0.69, 2.40]; and C-reactive protein: MD = 4.56, 95% CI [0.97, 8.14]), antioxidant levels (SMD = 0.84, 95% CI [0.14, 1.53]), and metabolic parameters (energy expenditure: SMD = -0.52, 95% CI [-0.78, -0.26]; p < .05).

Conclusion: Carotenoid supplementation appears to attenuate exercise-induced oxidative stress and the inflammatory response and improve antioxidant levels and metabolic capabilities. However, these results may be influenced by participant variability or methodological differences. Further research with larger sample sizes, longer supplementation periods, higher doses, and carotenoid bioavailability is needed to confirm these findings.

Blood flow in exercised skeletal muscle remains elevated postexercise, potentially playing a critical role in recovery and adaptation process. However, effective and easily implementable interventions that augment this response have yet to be identified. In this study, we investigated whether caffeine intake enhances sustained postexercise hyperemia in previously active leg in competitive long-distance runners. Ten competitive male long-distance runners participated in baseline measurements, during which cardiorespiratory responses, including leg blood flow measured by ultrasound Doppler equipment, were assessed in a supine position. Subsequently, they ingested either (a) placebo capsules or (b) capsules containing 6 mg/kg caffeine in a randomized, counterbalanced, double-blind, and crossover manner. They then completed 8-min high-intensity treadmill running at 98% of the average running speed of their estimated 10,000-m best time, followed by postexercise measurements assessing the same cardiorespiratory responses. Postexercise leg blood flow was elevated from baseline, and this response was 17% higher in caffeine relative to placebo condition (between-trial difference in average with [95% CI] = 182 [2.33, 363] ml/min, p = .048, d = 1.03). Caffeine ingestion also increased minute ventilation (2.06 [0.603, 3.53] L/min, p = .011, d = 1.17), whereas it reduced end-tidal CO2 partial pressure (-2.09 [-3.68, -0.504] mmHg, p = .015, d = 1.15) postexercise relative to placebo condition. We show that preexercise 6 mg/kg caffeine intake increases postexercise leg blood flow following high-intensity running in male competitive long-distance runners. Our results stimulate future studies to assess if caffeine-induced elevations in leg blood flow accelerates recovery and/or adaptations.