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Betaine supplementation improves CrossFit performance and increases testosterone levels, but has no influence on Wingate power: randomized crossover trial.
Zawieja, E, Durkalec-Michalski, K, Sadowski, M, Główka, N, Chmurzynska, A
Journal of the International Society of Sports Nutrition. 2023;20(1):2231411
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Betaine nutritional supplementation is often used by individuals who want to increase their athletic performance as it has been hypothesised to increase muscle strength and power. However, studies on this have been inconsistent. One study has shown no benefit of supplementation on muscle strength, however two have shown a benefit of betaine on muscle endurance, which is essential to perform cross fit-based exercises. The aim of this study was to determine the effect of betaine on body composition, cross fit performance, muscle power, and certain hormones after 3 weeks of supplementation. The results showed that workout performance was improved with betaine supplementation, however this did not translate into changes in body composition. Testosterone levels were increased by betaine supplementation. Individuals who had genetic variations that meant that their betaine requirements may be higher showed no benefit of taking betaine for cross-fit performance or any of the outcomes measured. There was also no difference to any of the outcomes with differing betaine doses (2.5 and 5.0 g/d). It was concluded that betaine supplementation may improve cross-fit performance and testosterone levels. However individuals with genetic variations that may mean their requirements for betaine are higher showed no benefit of supplementation on cross-fit performance.
Abstract
BACKGROUND Because betaine (BET) supplementation may improve muscular strength and endurance, it seems plausible that BET will also influence CrossFit performance (CF). PURPOSE The aim of this study was to evaluate the effects of three weeks of BET supplementation on body composition, CF performance, muscle power in the Wingate anaerobic test (WAnT), and the concentrations of selected hormones. The secondary aims were to analyze the effectiveness of two different BET doses (2.5 and 5.0 g/d) and their interaction with the methylenetetrahydrofolate reductase (MTHFR) genotype. METHODS The study was designed in a double-blinded randomized cross-over fashion. Forty-three CF practitioners completed the entire study. CF performance was measured using the Fight Gone Bad (FGB) workout and muscle power was evaluated in a 30-second WAnT. Body composition was determined by air-displacement plethysmography. Blood was drawn to assess hormone concentrations. The C677T single nucleotide polymorphism (rs180113) in the MTHFR gene was analyzed. RESULTS FGB total improved with BET by 8.7 ± 13.6% (p < 0.001), but no significant changes were observed with placebo (- 0.4 ± 10.0%, p = 0.128). No changes were also observed in WAnT and body composition. After BET supplementation testosterone concentration increased by 7.0 ± 15.4% with BET (p = 0.046) (no change with placebo: 1.5 ± 19.6%, p = 0.884) but had no effect on concentrations of insulin-like growth factor or cortisol. Finally, there were no significant interactions between MTHFR genotype and BET dose in any outcome. CONCLUSIONS BET supplementation may improve CF performance and increase testosterone concentration. However, there was no evidence of a difference between dosages (2.5 and 5.0 g/d) and MTHFR genotypes. The trial was registered on clinicaltrials.gov (NCT03702205) on 10 October 2018.
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Combined aerobic exercise and high-intensity respiratory muscle training in patients surgically treated for non-small cell lung cancer: a pilot randomized clinical trial.
Messaggi-Sartor, M, Marco, E, Martínez-Téllez, E, Rodriguez-Fuster, A, Palomares, C, Chiarella, S, Muniesa, JM, Orozco-Levi, M, Barreiro, E, Güell, MR
European journal of physical and rehabilitation medicine. 2019;55(1):113-122
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Lung cancer treatment initiates a deconditioning storm that further reduces the capacity to deliver and utilize oxygen and metabolic substrates during exercise, contributing to poor cardiorespiratory fitness. The main aim of this study was to assess the impact of aerobic exercise with inspiratory and expiratory muscle training on cardiovascular fitness and respiratory muscle dysfunction in non-small cell lung cancer patients. The study is a two-centre, prospective, single-blind, pilot randomized controlled trial. The eligible patients were randomly assigned to the exercise (n=16) or control groups (n=21). Study results showed strong improvement in respiratory muscle strength and exercise capacity following high-intensity inspiratory and expiratory muscle training. Authors conclude that structured and supervised exercise interventions should be recommended to patients with lung cancer.
Abstract
BACKGROUND Lung resection surgery further decreases exercise capacity and negatively affects respiratory muscle function in patients with non-small cell lung cancer (NSCLC). The best design for exercise interventions in these patients has not been determined yet. AIM: To assess the impact of aerobic exercise and high-intensity respiratory muscle training on patient outcomes following lung cancer resection surgery. DESIGN Prospective, single-blind, pilot randomized controlled trial. SETTING Outpatient cardiopulmonary rehabilitation unit of two university hospitals. POPULATION Thirty-seven patients with NSCLC after tumor resection. METHODS Patients were randomly assigned to exercise training or usual post-operative care. The training program consisted of aerobic exercises and high-intensity respiratory muscle training (24 supervised sessions, 3 per week, 8 weeks). Primary outcome was exercise capacity assessed with peak oxygen uptake (VO2peak) during cardiopulmonary exercise test. Secondary outcomes included changes in respiratory muscle strength, levels of serum insulin growth factor I (IGF-I) and IGF binding protein 3 (IGFBP-3), and quality of life assessed with the European Organization for Research and Treatment of Cancer (EORTC QLQ-C30) questionnaire. RESULTS The 8-week training program was associated with significant improvement in VO2peak (2.13 mL/Kg/min [95%CI 0.06 to 4.20]), maximal inspiratory and expiratory pressures (18.96 cmH2O [95% CI 2.7 to 24.1] and 18.58 cmH2O [95% CI 4.0 to 33.1], respectively) and IGFBP-3 (0.61 µg/mL [%95 CI 0.1 to 1.12]). No significant differences were observed in the EORTC QLQ-C30. CONCLUSIONS An 8-week exercise program consisting of aerobic exercise and high-intensity respiratory muscle training improved exercise capacity, respiratory muscle strength, and serum IGFBP-3 levels in NSCLC patients after lung resection. There was no impact on the other outcomes assessed. CLINICAL REHABILITATION IMPACT A combination of aerobic exercise and respiratory muscle training could be included in the rehabilitation program of deconditioned patients with NSCLC after lung resection surgery.
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Effects of Low Versus Moderate Glycemic Index Diets on Aerobic Capacity in Endurance Runners: Three-Week Randomized Controlled Crossover Trial.
Durkalec-Michalski, K, Zawieja, EE, Zawieja, BE, Jurkowska, D, Buchowski, MS, Jeszka, J
Nutrients. 2018;10(3)
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During athletic performance, adequate amounts of carbohydrates are required to prolong the onset of fatigue. Research on whether the glycaemic index (GI) of ingested carbohydrates effects performance has been explored but has produced equivocal results. The aim of this randomised crossover study was to assess the effect of low- and moderate- GI diets on the aerobic capacity and endurance performance in 21 runners. Participants consumed a low- and moderate- GI, high carbohydrate and nutrient balanced diets for three weeks each with a two-week washout period. Aerobic capacity and body composition were measured at the beginning and end of each diet period through various athletic performance tests. This study found that after a low-GI, high-carbohydrate diet, improvements were seen in time to exhaustion and running performance. Gas exchange was improved by both diets. The low-GI carbohydrate diet helped athletes to maintain a more stable blood glucose concentration during exertion tests. Based on these results the authors suggest considering GI when planning a diet for performance athletes, and also urge further research be completed to better understand the effects of long-term GI diets with regards to exercise performance.
Abstract
The glycemic index (GI) of ingested carbohydrates may influence substrate oxidation during exercise and athletic performance. Therefore, the aim of this study was to assess the effect of low- and moderate-GI three-week diets on aerobic capacity and endurance performance in runners. We conducted a randomized crossover feeding study of matched diets differing only in GI (low vs. moderate) in 21 endurance-trained runners. Each participant consumed both, low- (LGI) and moderate-GI (MGI) high-carbohydrate (~60%) and nutrient-balanced diets for three weeks each. At the beginning and end of each diet, participants had their aerobic capacity and body composition measured and performed a 12-min running test. After LGI, time to exhaustion during incremental cycling test (ICT) and distance covered in the 12-min run were significantly increased. The MGI diet led to an increase in maximal oxygen uptake ( V ˙ O₂max), but no performance benefits were found after the MGI diet. The LGI and MGI diets improved time and workload at gas exchange threshold (GET) during ICT. The results indicate that a three-week high-carbohydrate LGI diet resulted in a small but significant improvement in athletic performance in endurance runners. Observed increase in V ˙ O₂max on MGI diet did not affect performance.