The aim of this study was to examine the acute effects of different levels of hypoxia on maximal strength, muscular endurance, and cognitive function in males and females. In total, 13 males (mean ± SD: age, 23.6 ± 2.8 years; height, 176.6 ± 3.9 cm; body mass, 76.6 ± 2.1 kg) and 13 females (mean ± SD: age, 22.8 ± 1.4 years; height, 166.4 ± 1.9 cm; body mass, 61.6 ± 3.4 kg) volunteered for a randomized, double-blind, crossover study. Participants completed a one repetition strength and muscular endurance test (60% of one repetition maximum to failure) for squat and bench press following four conditions; (i) normoxia (900 m altitude; F_iO₂: 21%); (ii) low dose hypoxia (2000 m altitude; F_iO₂: 16%); (iii) moderate dose hypoxia (3000 m altitude; F_iO₂: 14%); and (iv) high dose hypoxia (4000 m altitude; F_iO₂: 12%). Heart rate, blood lactate, rating of perceived exertion, and cognitive function was also determined during each condition. The one repetition maximum squat (p = 0.33) and bench press (p = 0.68) did not differ between conditions or sexes. Furthermore, squat endurance did not differ between conditions (p = 0.34). There was a significant decrease in bench press endurance following moderate (p = 0.02; p = 0.04) and high (p = 0.01; p = 0.01) doses of hypoxia in both males and females compared to normoxia and low dose hypoxia, respectively. Cognitive function, ratings of perceived exertion, and lactate were also significantly different in high and moderate dose hypoxia conditions compared to normoxia (p < 0.05). Heart rate was not different between the conditions (p = 0.30). In conclusion, high and moderate doses of acute normobaric hypoxia decrease upper body muscular endurance and cognitive performance regardless of sex; however, lower body muscular endurance and maximal strength are not altered.

The effects of L-citrulline or L-arginine supplementation on exercise performance are equivocal, and the effects on swimming performance are unclear. We aimed to assess whether 8-day supplementation with L-arginine or L-citrulline supplementation would improve 200 m and 100 m freestyle swimming time-trial performances. After the baseline trial (first visit), in a double-blind, randomised design, 15 trained/developmental (5 females) swimmers and triathletes were assigned to three groups and underwent an 8-day supplementation period, with a daily dose of either 8 gr L-arginine (Arg, n = 5) or L-citrulline (Cit, n = 5) or placebo (Pla, n = 5). On day 9, participants completed experimental trial (second visit). In each trial, after blood sampling, participants performed both 200 m and 100 m freestyle swimming time-trials, with 30 min recovery between trials. Plasma nitric oxide (NOx) and blood lactate concentrations (BLa) were collected immediately before and after 200 m and 100 m TTs, respectively. No significant difference was observed in NOx between groups (p = 0.201). There was no significant difference in 200 m (p = 0.226) and 100 m swimming time-trials (p = 0.993) between groups. There was a main effect of time on BLa concentration (p < 0.001), but no trial × group (p = 0.243) and trial × lactate × group interaction effect (p = 0.276) was present. Furthermore, 8-day either L-citrulline or L-arginine supplementation did not enhance middle (200 m) and short-distance (100 m) swimming performance in trained/developmental swimmers and triathletes. These findings do not support the use of L-citrulline or L-arginine supplementation as ergogenic aids for swimming performance.

Carbohydrate mouth rinsing (CMR) has been shown to enhance exercise performance. However, the influence of CMR on repetitions to failure with different intensities (40% or 80% of 1 RM) is unknown. Therefore, the purpose of this study was to examine the effects of a 6% CMR solution on muscular endurance assessed at 40% and 80% of 1 RM in resistance-trained males. Sixteen resistance-trained males (age: 25 ± 3 years, height: 182 ± 6 cm, body mass: 86 ± 3 kg, body fat: 16 ± 3%, bench press 1 RM: 106 ± 16 kg, resistance training experience: 5 ± 1 years) completed four conditions in random order. The four conditions consisted of ten seconds of mouth rinsing with 25 mL solutions containing either maltodextrin or placebo (sweetened water) prior to performing a bench press muscular endurance test at either 40% of 1 RM or 80% of 1 RM. Total repetitions, heart rate (HR), ratings of perceived exertion (RPE), glucose (GLU) and felt arousal (FA) were recorded for each condition. There was a significant condition by intensity interaction (p = 0.02). CMR significantly increased total repetitions compared with placebo at the higher intensity (80% of 1 RM; p = 0.04), while there was no effect at the lower intensity (p = 0.20). In addition, HR, RPE, GLU and FA did not differ between conditions or across intensities (p > 0.05). In conclusion, CMR-enhanced muscular endurance performed at higher but not lower intensities.

Sprint interval training (SIT) is a concept that has been shown to enhance aerobic-anaerobic training adaptations and induce larger effects in hypoxia. The purpose of this study was to examine the effects of 4 weeks of SIT with 15 or 30 s in hypoxia on aerobic, anaerobic performance and critical power (CP). A total of 32 male team players were divided into four groups: SIT with 15 s at FiO₂: 0.209 (15 N); FiO₂: 0.135 (15 H); SIT with 30 s at FiO₂: 0.209 (30 N); and FiO₂: 0.135 (30 H). VO_2max did not significantly increase, however time-to-exhaustion (TTE) was found to be significantly longer in the post test compared to pre test (p = 0.001) with no difference between groups (p = 0.86). Mean power (MPw.kg) after repeated wingate tests was significantly higher compared to pre training in all groups (p = 0.001) with no difference between groups (p = 0.66). Similarly, CP was increased in all groups with 4 weeks of SIT (p = 0.001) with no difference between groups (p = 0.82). This study showed that 4 weeks of SIT with 15 and 30 s sprint bouts in normoxia or hypoxia did not increased VO_2max in trained athletes. However, anerobic performance and CP can be increased with 4 weeks of SIT both in normoxia or hypoxia with 15 or 30 s of sprint durations.

The use of nutritional strategies has become more widespread in recent years. This study investigates the effect of chocolate milk (CM) consumption on the recovery rate of elite male adolescent alpine skiers after intense training. Twelve male elite alpine skiers aged 13-16 years were randomly divided into two groups: chocolate milk (CM; n = 6) and placebo (PLA; n = 6). After exercise, the CM group was given 400 ml (200+200) of chocolate milk, and the PLA group took water (placebo) in the same regimen. Venous blood samples were taken before and 12 hours after drinking the fluids to determine the activity of selected enzymes, insulin, testosterone, glucose, and some minerals. It was observed that in the CM group, serum AST (Pre: 110.33±126.62 U/L vs. Post: 83.17±100.42 U/L) and CK (Pre: 2393.12±2542.22 U/L vs. Post: 1556.33±1401.45 U/L) activity, as well as testosterone (Pre: 21.12±3.59 ng/mL vs. Post: 15.19±4.96 ng/mL; p=0.028) and iron (Pre: 163.00±14.76 µg/dL vs. Post: 109.00±23.91 µg/dL; p=0.028), decreased significantly, but potassium (Pre: 4.38±0.16 mmol/L vs. Post: 4.64±0.09 mmol/L) and magnesium (Pre: 1.82±0.09 mg/dL vs. Post: 2.07±0.04 mg/dL) levels increased after supplementation compared to baseline levels (p<0.05). After taking into account the changes that occurred in the PLA group and significant differences in some variables in terms of between-group comparisons, it was found that the decrease in AST and CK activity, along with the presence of positive ionic changes in the serum after CM supplementation indicates a reduction in negative changes after training and improving the process of post-training regeneration in young male athletes.