Journal of the International Society of Sports Nutrition

Shiu, Yi-Jie; Chen, Che-Hsiu; Tao, Wu-Shiun; Nai, Hui-Fang; Yu, Chen-Yi; Chiu, Chih-Hui

doi: 10.1080/15502783.2024.2414871pmid: 39390816

Background This study investigated the effects of caffeinated chewing gum on fatigue index and 400-meter performance in trained sprinters. Methods Nineteen participants (age: 20.9 ± 1.0 years; height: 175.6 ± 4.9 cm; mass: 66.5 ± 5.6 kg; training age: 7.9 ± 1.0 years) were randomly assigned to either a caffeine trial (CAF) or a placebo trial (PL) using a double-blind, randomized crossover design. The participants in the CAF trial chewed a gum containing 3 mg/kg of caffeine for a period of 10 minutes, while those in the PL trial chewed a gum containing a placebo with no caffeine. Following a 15-minute period of rest, the fatigue index was tested by six maximal 35-meter sprints with a 10-second rest between efforts. After this, at least 30 minutes of rest was permitted, during which time the participants engaged in brief warm-up activities prior to the commencement of the 400-meter sprint test. Saliva samples were collected before chewing gum, before the fatigue test and before 400-meters sprinting. Results The fatigue index was significantly lower in the CAF trial compared to the PL trial (CAF: 8.1 ± 2.5%; PL: 9.6 ± 4.8%; p = 0.046, Cohen’s d = 039). The CAF trial demonstrated significantly lower sprint time for the 300–400 meter segment (CAF: 14.73 ± 1.35 seconds; PL: 15.23 ± 1.30 seconds; p = 0.019, Cohen’s d = 0.37) and total sprint time compared to the PL trial (CAF: 53.87 ± 2.88 seconds; PL: 54.68 ± 3.37 seconds; p = 0.003, Cohen’s d = 0.27). Saliva caffeine and α-amylase concentration were significantly higher in the CAF trial compared to the PL trial (p < 0.05). Conclusion The present study demonstrated that caffeine gum supplementation prior to exercise significantly reduced the fatigue index and increased the capacity to maintain speed, particularly in the final 300 to 400 meters, as well as enhancing 400-meter sprint performance.

Lu, Tung-Lin; Zheng, Ai-Chi; Suzuki, Katsuhiko; Lu, Chi-Cheng; Wang, Chung-Yuan; Fang, Shih-Hua

doi: 10.1080/15502783.2023.2300259pmid: 38193521

Background Maintaining proper immune function and hormone status is important for athletes to avoid upper respiratory tract infection (URTI) and insufficient recovery, which is detrimental to sport performance and health. The aim of this study was to evaluate whether three-week supplementation of L-glutamine could benefit the mucosal immunity and hormonal status of combat-sport athletes as well as their rates of upper respiratory tract infection (URTI) and subjective feelings of well-being after intensive training. Methods Twenty-one combat-sport athletes from the National Taiwan University of Sport were recruited in this study. After intensive training, two groups of the participants were asked to consume powder form of 0.3 g/kg body weight of L-glutamine (GLU group) or maltodextrin (PLA group) with drinking water in a randomized design at the same time every day during 3 weeks. Saliva samples were collected to measure immunoglobulin A (IgA), nitric oxide (NO), testosterone (T) and cortisol (C) before and after three-week supplementation; moreover, Hooper’s index questionnaires were completed for wellness assessment. The incidence and duration of URTI were recorded by using a health checklist throughout the entire study period. Results Supplementation of L-glutamine significantly enhanced the concentrations of IgA and NO in saliva; additionally, the incidence of URTI was significantly reduced. Regarding hormones, T concentration was significantly decreased in the PLA group, whereas C concentration was significantly increased, resulting in a significant decrease of T/C ratio. In contrast, the GLU group showed a significant increase of T/C ratio, while the mood scores of the Hooper’s index questionnaire were higher in the PLA group. Conclusions Three-week supplementation of L-glutamine after intensive training enhanced the mucosal immunity, improved hormonal status and reduced the rate of URTI of combat-sport athletes while feelings of well-being were also enhanced. Therefore, L-glutamine would be beneficial for the sports performance and recovery of athletes.

Jiang, Huanyu; Gao, Jiankun; Wang, Huan; Zhao, Lin; Yang, Yingduo; Ma, Jiahua; Gu, Shan; Hu, Fenglin; Du, Quanyu; Wang, Fei

doi: 10.1080/15502783.2024.2393364pmid: 39161283

Objective The aim of this study was to conduct a comprehensive evaluation of the rehydration efficacy of QSBYD and elucidate its potential underlying mechanism. Design 38 participants were randomly assigned to receive either QSBYD or placebo before and after exercise and heat-induced dehydration. Hydration indicators were measured over time. Blood tests assessed cellular anaerobic respiration metabolites, serum inflammatory markers, and coagulation markers. Perceptual measures of thirst, fatigue, and muscular soreness were also taken. Results QSBYD consumption resulted in lower urine volume (Control vs. QSBYD: 260.83 ± 167.99 ml vs. 187.78 ± 141.34 ml) and smaller decrease in percentage of nude body weight change from baseline (Control vs. QSBYD: −0.52 ± 0.89% vs. −0.07 ± 0.52%). Although no significant differences in urine specific gravity, QSBYD resulted in reduced urine volume at 120 min, suggesting improved fluid retention. Furthermore, QSBYD resulted in lower levels of IL-1β (Control vs. QSBYD: 2.40 ± 0.68 vs. 1.33 ± 0.66 pg/mL), suggesting QSBYD may provide benefits beyond hydration. Conclusion Further investigation into the underlying mechanisms and long-term effects of QSBYD on hydration is warranted. QSBYD may be an effective alternative to commercial sports drinks in mitigating dehydration effects.

Tallis, Jason; Duncan, Michael, J.; Clarke, Neil, D.; Morris, Rhys O.; Tamilio, Ryan, A.

doi: 10.1080/15502783.2024.2419385pmid: 39439175

Background There is growing interest in the potential of alternative modes of caffeine administration for enhancing sports performance. Given that alternative modes may evoke improved physical performance via distinct mechanisms, effects may not be comparable and studies directly comparing the erogenicity of alternative modes of caffeine administration are lacking. To address this knowledge gap, the present study evaluated the effect of 3 mg·kg−1 caffeine delivered in anhydrous form via capsule ingestion, chewing gum or mouth rinsing on measures of muscular strength, power, and strength endurance in male Rugby Union players. Methods Twenty-seven participants completed the study (Mean ± SD: Age 20 ± 2 yrs; daily caffeine consumption 188 ± 88 mg). Following assessments and reassessment of chest press (CP), shoulder press (SP), Deadlift (DL), and Squat (SQ) 1-repetition maximum (1RM) and familiarization to the experimental procedures, participants completed six experimental trials where they were administered 3 mg.kg−1 caffeine (Caff) or placebo (Plac) capsule(CAP), chewing gum(GUM) or mouth rinse(RINSE) in a randomized, double-blind and counterbalanced fashion prior to force platform assessment of countermovement jump, drop jump and isometric mid-thigh pull performance. Strength endurance was measured across two sets of CP, SP, DL, and SQ at 70% 1RM until failure. Pre-exercise perceptions of motivation and arousal were also determined. Results Caffeine increased perceived readiness to invest mental effort (p = .038; ηp2=.156), countermovement jump height (p = .035; ηp2=.160) and SQ repetitions until failure in the first set (p < .001; d = .481), but there was no effect of delivery mode (p > .687; ηp2<.015). Readiness to invest physical effort, felt arousal, drop jump height, countermovement jump, drop jump and isometric mid-thigh pull ground reaction force-time characteristics and repetitions until failure in CP, SP and DL were not affected by caffeine administration or mode of caffeine delivery (p > .0.052; ηp2< .136). Conclusion 3 mg.kg−1 caffeine administered via capsule, gum or mouth rinse had limited effects on muscular strength, power, and strength endurance. Small effects of caffeine on CMJ height could not be explained by changes in specific ground reaction force-time characteristics and were not transferable to DJ performance, and effects specific to the SQ RTP exercise underpin the complexity in understanding effects of caffeine on muscular function. Novel modes of caffeine administration proposed to evoke benefits via distinct mechanisms did not offer unique effects, and the small number of effects demonstrated may have little translation to a single performance trial when data examining direct comparison of each caffeine vehicle compared against a mode matched placebo is considered.

Zhao, Haotian; Zhu, Hongkang; Yun, Hezhang; Liu, Jingqi; Song, Ge; Teng, Jin; Zou, Dixin; Lu, Naiyan; Liu, Chang

doi: 10.1080/15502783.2024.2419388pmid: 39487653

Background This study aimed to investigate the impact of Urolithin A (UA) on muscle endurance, muscle strength, inflammatory levels, oxidative stress, and protein metabolism status in resistance-trained male athletes. Method An 8-week randomized, double-blind, placebo-controlled study was conducted with twenty resistance-trained male athletes. Participants were supplemented with 1 g of UA daily. Muscle strength and muscle endurance measures were assessed, and fasting venous blood samples and morning urine samples were collected to evaluate their oxidative stress levels, inflammatory markers, and protein metabolism status. Results There were no significant differences observed in terms of dietary energy intake and composition between the two assessments conducted within a 24-hour period. After 8 weeks of UA supplementation, compared to baseline measurements, the UA group exhibited increases in 1RM bench press and squat, although these changes were not statistically significant (Δ = 3.00 ± 0.17 kg, p = 0.051, Δ = 1.35 ± 2.73 kg, p = 0.499). However, significant improvements were noted in Maximum Voluntary Isometric Contraction (MVIC) and repetitions to failure (RTF) performance (Δ = 36.10 ± 0.62 NM, p = 0.000; Δ = 2.00 ± 0.56, p = 0.001). When compared to the placebo group, the UA supplementation for 8 weeks led to an increase in 1RM bench press and squat, although statistical significance was not reached (Δ = 3.50 ± 0.79 kg, p = 0.462; Δ = 2.55 ± 1.36 kg, p = 0.710). Furthermore, the group receiving UA supplementation, compared to the placebo group, showed significant improvements in MVIC and RTF (Δ = 43.50 ± 0.77 NM, p = 0.048; Δ = 2.00 ± 1.22, p = 0.011), indicating that the UA group exhibited superior performance enhancements in these metrics compared to the placebo group. After 8 weeks of UA supplementation, the UA group showed a significant decrease in 3-methylhistidine (3-MH) compared to baseline measurement (Δ=-2.38 ± 1.96 μmol/L, p = 0.049). Additionally, the UA group exhibited a significant increase in C-reactive protein (CRP) compared to baseline (Δ = 0.71 ± 0.21 mg/L, p = 0.001). However, there was no significant changes observed in Interleukin-6 (IL-6) (Δ=-1.00 ± 1.01 pg/mL, p = 0.076), or superoxide dismutase (SOD) (Δ=-0.004 ± 0.72 U/mL, p = 0.996) compared to baseline in the UA group. When compared to the placebo group, there was no significant difference observed in 3-MH in the UA group (Δ=-3.20 ± 0.31 μmol/L, p = 0.36). In terms of inflammation markers, the UA group exhibited a significant decrease in CRP (Δ=-0.79 ± 0.38 mg/L, p = 0.032) compared to the placebo group, whereas there was a decrease in IL-6 without statistical significance (Δ=-1.75 ± 0.45 pg/mL, p = 0.215). Furthermore, the UA group showed a significant decrease in SOD compared to the placebo group (Δ=-4.32 ± 0.90 U/mL, p = 0.041). Conclusions After 8 weeks of UA supplementation at 1 g/day, resistance-trained male athletes showed improvements in muscle strength and endurance. Additionally, UA supplementation was also associated with reduced oxidative stress levels and a decrease in inflammation response levels.

Jagim, Andrew R.; Tinsley, Grant M.; Oppliger, Robert A.; Horswill, Craig A.; Dobbs, Ward C.; Fields, Jennifer B.; Cushard, Cliff; Rademacher, Paul D.; Jones, Margaret T.

doi: 10.1080/15502783.2024.2304561pmid: 38226601

Background The estimation of body fat percentage (BF%) in wrestling is used to determine the minimum wrestling weight (MWW) and lowest allowable weight class (MWC) in which wrestlers are eligible to compete. A 12% minimum threshold is currently used for women wrestlers, yet a potential increase for safety has been discussed. Because of the novelty of collegiate women’s wrestling, there is a paucity of literature available on the body composition norms of this population. The purpose of this study was to provide a descriptive summary of BF% and MWW values of female wrestlers and how MWW values would change with the use of different BF% thresholds. Methods Data from the 2022–2023 collegiate season were retrospectively analyzed resulting in a sample of 1,683 collegiate women wrestlers from the National Association of Intercollegiate Athletics (NAIA, n = 868) and the National Collegiate Athletics Association (NCAA, n = 815). All wrestlers completed skinfold assessments for weight certification at the start of the competition season. The skinfold values were used to estimate BF% using the Slaughter skinfold prediction equation. Frequency statistics and descriptive analysis were performed to compute normative MWW and BF% profiles. BF% thresholds of 12% (12MWW) and the BF% value defined as the lowest 5th percentile, which would be considered unusually lean, were used to determine the resulting MWW and MWC for each method. The lowest recorded weight and weight class division throughout the season was also recorded for each wrestler. Results There was a positively skewed (0.94) and platykurtic (1.86) distribution of MWW values. The median ± interquartile range BF% for all wrestlers was 27.4 ± 10.22%, with 17% BF representing the 5th percentile. Only 354 out of 1,579 (22.4%) wrestlers competed in their lowest allowable weight class, based on the 12MWW. Of these 354 wrestlers, the mean BF% was 21.3 ± 5.2% at weight certification with only n = 17 being at or below 12% body fat and an average weight loss of 11.1 ± 8.8 lbs. from the time of weight certification. Throughout the season, wrestlers competed at weights that were, on average (mean ± SD), 19.4 ± 16.9 lbs. higher than their 12MWW (95% CI: 18.6, 20.2 lbs. p < 0.001; effect size [ES] = 1.1), 13.4 ± 19.0 lbs. higher than the 17MWW (p < 0.001; ES = 0.70), and 8.7 ± 8.3 lbs. lower than their weight at the certification (95% CI: 8.3, 9.1 lbs. p < 0.001; ES = 1.1). Conclusions Nearly all BF% values were well above the 12% threshold used to determine MWW. Increasing the minimum BF% threshold from 12% to 17% would affect a small percentage of wrestlers, likely reduce the need for excessive weight cutting, and minimize the deleterious health effects of an athlete at such a low BF%.

Roberts, Brandon M.; Geddis, Alyssa V.; Matheny, Ronald W.

doi: 10.1080/15502783.2024.2302046pmid: 38198469

Background Non-steroidal anti-inflammatory drugs (NSAIDs) like ibuprofen, flurbiprofen, naproxen sodium, and indomethacin are commonly employed for their pain-relieving and inflammation-reducing qualities. NSAIDs work by blocking COX-1 and/or COX-2, enzymes which play roles in inflammation, fever, and pain. The main difference among NSAIDs lies in their affinity to these enzymes, which in turn, influences prostaglandin secretion, and skeletal muscle growth and regeneration. The current study investigated the effects of NSAIDs on human skeletal muscle cells, focusing on myoblast proliferation, differentiation, and muscle protein synthesis signaling. Methods Using human primary muscle cells, we examined the dose-response impact of flurbiprofen (25–200 µM), indomethacin (25–200 µM), ibuprofen (25–200 µM), and naproxen sodium (25–200 µM), on myoblast viability, myotube area, fusion, and prostaglandin production. Results We found that supraphysiological concentrations of indomethacin inhibited myoblast proliferation (−74 ± 2% with 200 µM; −53 ± 3% with 100 µM; both p < 0.05) compared to control cells and impaired protein synthesis signaling pathways in myotubes, but only attenuated myotube fusion at the highest concentrations (−18 ± 2% with 200 µM, p < 0.05) compared to control myotubes. On the other hand, ibuprofen had no such effects. Naproxen sodium only increased cell proliferation at low concentrations (+36 ± 2% with 25 µM, p < 0.05), and flurbiprofen exhibited divergent impacts depending on the concentration whereby low concentrations improved cell proliferation (+17 ± 1% with 25 µM, p < 0.05) but high concentrations inhibited cell proliferation (−32 ± 1% with 200 µM, p < 0.05). Conclusion Our findings suggest that indomethacin, at high concentrations, may detrimentally affect myoblast proliferation and differentiation via an AKT-dependent mechanism, and thus provide new understanding of NSAIDs’ effects on skeletal muscle cell development.

Cheng, I-Shiung; Tsao, Jung-Piao; Bernard, Jeffrey R.; Tsai, Tsen-Wei; Chang, Chia-Chen; Liao, Su-Fen

doi: 10.1080/15502783.2024.2336095pmid: 38576169

Purpose Garlic extract (GA) is purported to enhance antioxidant and anti-inflammatory activity and glucose regulation in humans. The present study investigated the effects of post-exercise GA supplementation on GLUT4 expression, glycogen replenishment, and the transcript factors involved with mitochondrial biosynthesis in exercised human skeletal muscle. Methods The single-blinded crossover counterbalanced study was completed by 12 participants. Participants were randomly divided into either GA (2000 mg of GA) or placebo trials immediately after completing a single bout of cycling exercise at 75% Maximal oxygen uptake (VO2max) for 60 minutes. Participants consumed either GA (2000 mg) or placebo capsules with a high glycemic index carbohydrate meal (2 g carb/body weight) immediately after exercise. Muscle samples were collected at 0-h and 3-h post-exercise. Muscle samples were used to measure glycogen levels, GLUT4 protein expression, as well as transcription factors for glucose uptake, and mitochondria biogenesis. Plasma glucose, insulin, glycerol, non-esterified fatty acid (NEFA) concentrations, and respiratory exchange ratio (RER) were also analyzed during the post-exercise recovery periods. Results Skeletal muscle glycogen replenishment was significantly elevated during the 3-h recovery period for GA concurrent with no difference in GLUT4 protein expression between the garlic and placebo trials. PGC1-α gene expression was up-regulated for both GA and placebo after exercise (p < 0.05). Transcript factors corresponding to muscle mitochondrial biosynthesis were significantly enhanced under acute garlic supplementation as demonstrated by TFAM and FIS1. However, the gene expression of SIRT1, ERRα, NFR1, NFR2, MFN1, MFN2, OPA1, Beclin-1, DRP1 were not enhanced, nor were there any improvements in GLUT4 expression, following post-exercise garlic supplementation. Conclusion Acute post-exercise garlic supplementation may improve the replenishment of muscle glycogen, but this appears to be unrelated to the gene expression for glucose uptake and mitochondrial biosynthesis in exercised human skeletal muscle.

Farmani, Azam; Hemmatinafar, Mohammad; Koushkie Jahromi, Maryam; Pirmohammadi, Sepideh; Imanian, Babak; Jahan, Zeinab

doi: 10.1080/15502783.2024.2340556pmid: 39663645

Background Athletes require proper nutrition to enhance training and performance. Studies indicate that alternative sources of caffeine, such as caffeinated chewing gum, mouth rinses, energy gels, and coffee can improve performance. Therefore, this study investigated the impact of consuming caffeinated gum (CG) and repeated coffee mouth rinsing (CMR) on professional male table tennis players’ aerobic capacity and explosive power. Method A randomized, cross-over, placebo-controlled, and double-blinded study was conducted with eighteen male table tennis players (Age: 21.86 ± 2.40 yr, Height: 173.80 ± 6.88 cm, Weight: 61.81 ± 10.32 kg). In each test session, the participants were randomly placed in one of the three conditions including i) Chewing caffeinated gum (CG, n = 6), ii) Coffee mouth rinsing (CMR, n = 6), iii) Starch capsule as a placebo (PLA, n = 6). All participants consumed caffeine with an average dose of ∼3 to 4.5 mg·kg−1. Also, a one-week interval was considered a washout period for each condition. First, the participants were given the required supplement and performed functional tests such as throwing medicine balls and Sargent’s jump tests. Then, the maximum oxygen consumption (VO2max), time to exhaustion (TTE), oxygen consumption equivalent at primary ventilatory threshold (VO2 at VT1), and oxygen consumption equivalent at respiratory compensation point (VO2 at RCP) were measured during the Bruce test. All data were analyzed using SPSS Windows software, repeated measure analysis ANOVA, and Bonferroni post hoc tests at p < 0.05. Results The current study’s findings illustrated that TTE significantly increased in CG (p = 0.000) and CMR (p = 0.012) conditions compared to PLA, but no significant difference was observed between CMR and CG (p = 1.00). VO2 at VT1 was significantly higher in CG (p = 0.004) and CMR (p = 0.000) compared to PLA; however, no significant difference was observed between CMR and CG (p = 0.335). VO2 at RCP increased significantly in CG (p = 0.000) and CMR (p = 0.000) compared to the PLA condition, and despite this, no significant difference was observed between CG and CMR (p = 1.000). Nevertheless, there were no significant differences between the three conditions in VO2max, throwing a medicine ball, and Sarjent’s jump height. Conclusion The study found that CMR and CG had a relatively positive impact on male table tennis players’ aerobic capacity; however, they did not significantly improve their explosive power.

Esen, Ozcan; Walshe, Ian; Goodall, Stuart

doi: 10.1080/15502783.2024.2345358pmid: 38708971

Background Nutritional intake and sleep, play an important role for recovery and performance in elite sport but little work has been undertaken in archery. The present study aimed to assess energy intake (EI), hydration status, and sleep parameters in world-class male archers over the course of a four-day competition. Methods Results, Conclusions Six male, elite-standard archers participated in the study and measurements of hydration status, EI, competition load, and sleep were recorded throughout each day of competition. Results Daily energy, carbohydrate, and protein intake ranged between 2,563 and 3,986 kcal, 4 and 7.1 g/kg BM, 2.2 and 3.6 g/kg BM per day, respectively. Thus, archers practiced elements of periodized nutrition such that energy and carbohydrate intake was greater on the high-volume competition days (i.e. days 1 and 3; more numbers of arrows, longer duration, and walking distance) in comparison to low-volume days (days 2 and 4) over the tournament (all p > 0.01). Additionally, urine specific gravity was higher after waking, compared to pre- and post-competition, and before bed (all p < 0.05). This indicates that archers were euhydrated pre- and post-competition and before bedtime, while they were slightly hypohydrated after waking up. Sleep data show that disturbances were kept to a minimum. Conclusions Collectively, archers appear capable of periodizing their nutritional intake according to daily physical loading during a tournament whilst, staying euhydrated and maintaining sleep quality. In part, such data can help to explain why these archers experience a sustained level of success.