The aim of this study was to determine the effect of low and moderate doses of caffeine ingestion via caffeinated coffee on repeated sprint test (RST) and plasma catecholamine concentration in trained female team-sport athletes. In a randomized, double-blind, crossover design, 13 female team-sport athletes (VO_2max: 48.7 ± 4 mL·kg·min⁻¹) completed three RST trials, separated by 4-day, 60 min post-ingestion of either 3 mg·kg⁻¹ (LCOF) or 6 mg·kg⁻¹ (MCOF) or placebo (PLA). The RST consisted of 12 × 4 s sprints on a cycle ergometer interspersed with 20 s of active recovery. Blood lactate (BLa) and glucose (GLU) and epinephrine and norepinephrine concentrations were collected before and 60 min after coffee ingestion, and after RST. Heart rate (HR) and ratings of perceived exertion (RPE) were measured at the beginning of RST, and after the 6th and 12th sprints. Average peak power score during RST was significantly improved after LCOF (p = 0.016) and MCOF (p = 0.041) compared to PLA, but peak and mean power output of the individual sprints, and fatigue index were not different between trials (all p > 0.05). Epinephrine and norepinephrine concentrations were significantly higher before and after RST in LCOF and MCOF compared to PLA (all p < 0.05). BLa was also higher after RST in both LCOF and MCOF compared to PLA (p = 0.005). HR, RPE, and GLU were not different between conditions (p > 0.05). In conclusion, low and moderate dose of caffeine ingestion can enhance the average peak power score during repeated sprints. These findings partly support low and moderate doses of caffeine supplementation via coffee as a nutritional ergogenic aid for trained female team-sport players during repeated sprint exercise.

Although preliminary studies suggested sex-related differences in physiological responses to hypoxia, the effects of sex on sprint interval training (SIT) performance in different degrees of hypoxia are largely lacking. The aim of this study was to examine the acute effect of different doses of normobaric hypoxia on SIT performance as well as heart rate variability (HRV) and cognitive performance (CP) in amateur-trained team sport players by comparing potential sex differences. In a randomized, double-blind, crossover design, 26 (13 females) amateur team-sport (football, basketball, handball, rugby) players completed acute SIT (6 × 15 s all-out sprints, separated with 2 min active recovery, against a load equivalent to 9% of body weight) on a cycle ergometer, in one of four conditions: (I) normoxia without a mask (F_iO₂: 20.9%) (CON); (II) normoxia with a mask (F_iO₂: 20.9%) (NOR); (III) moderate hypoxia (F_iO₂: 15.4%) with mask (MHYP); and (IV) high hypoxia (F_iO₂: 13.4%) with mask (HHYP). Peak (PPO) and mean power output (MPO), HRV, heart rate (HR), CP, capillary lactate (BLa), and ratings of perceived exertion (RPE) pre- and post-SIT were compared between CON, NOR, MHYP and HHYP. There were no significant differences found between trials for PPO (p = 0.55), MPO (p = 0.44), RPE (p = 0.39), HR (p = 0.49), HRV (p > 0.05) and CP (response accuracy: p = 0.92; reaction time: p = 0.24). The changes in MP, PP, RPE, HR, CP and HRV were similar between men and women (all p > 0.05). While BLa was similar (p = 0.10) between MHYP and HHYP trials, it was greater compared to CON (p = 0.01) and NOR (p = 0.01), without a sex-effect. In conclusion, compared to normoxia, hypoxia, and wearing a mask, have no effect on SIT acute responses (other than lactate), including PP, MP, RPE, CP, HR, and cardiac autonomic modulation either in men or women.

Background: The Loughborough Soccer Passing Test (LSPT) has proven to be a valid and reliable method for assessing soccer skill performance. However, there are various preparation protocols that exist for the LSPT. The aim of this study is to determine how many trials are required to gather reliable data during LSPT familiarisation. Methods: 81 subelite male youths (12.70 ± 2.67 years; 158.32 ± 17.21 cm; 49.01 ± 14.19 kg) and 17 professional female soccer players (21.47 ± 2.37 years; 164.70 ± 5.00 cm; 57.11 ± 4.27 kg) participated in the study. Following a brief explanation, the participants underwent five repetitions of the LSPT, after which differences between trials were analysed using mixed ANOVA for original time, penalty time, and performance time of LSPT. Adjusted residual values and the Smallest Worthwhile Change (SWC) approach were employed to assess the distributions across repetitions and the practical significance of the observed differences. Results: Mixed-repeated measures ANOVA showed that Trial 1 significantly underperformed relative to the subsequent four trials across all LSPT values ( p < .05). There were no statistical differences observed within other trials. Considerable improvement was noted solely between the first trials and subsequent attempts; exceeding the smallest worthwhile change (SWC) thresholds of 1.38 s, 2.29 s, and 3.36 s for original time, penalty time, and total performance time, respectively. Performance time enhanced by 5% between first two trials, however strength of acquisitions remain inconsistent and negligible subsequent trials. Conclusion: A single trial primarily diminishes the learning effect in LSPT preparation, especially in young sub-elite athletes and professional female athletes. In particular, in situations where samples are large or testing time is limited, implementing a single familiarisation trial seems a practical and efficient option. At the same time, given the higher variability of penalty time, specialists can consider adapting the number of trials depending on the testing objectives. This finding has applicative value for coaches, physical trainers and researchers, as it allows them to reduce the time and resources required for the testing protocol without compromising the validity and reproducibility of the results.