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The present study tested the hypothesis that acute metformin would increase peak power measured during a Wingate test. Fourteen men (24 ± 6 years; 75.8 ± 10.2 kg; 177 ± 7 cm) participated in four test sessions, conducted in a crossover, counterbalanced, double-blind model. The first and second sessions consisted of anthropometric measurements and one Wingate test per day to assess test-retest reliability. In the last two sessions, the Wingate tests were performed on metformin (500 mg capsule, 1 hour before) or placebo (cellulose capsule, 1 hour before) condition. No differences were found between the placebo and metformin for peak power (1056.8 ± 215.8 W vs. 1095.2 ± 199.3 W, respectively; p = 0.24). Mean power (630.9 ± 87.8 W vs. 613.1 ± 94.8 W, respectively; p=0.01) and total work (18928 ± 2633 kJ vs. 18393 ± 2845 kJ, respectively; p = 0.01) in the metformin condition were higher than the placebo. The power were greater in metformin when compared to the placebo in moments 3 (p = 0.01), 4 (p = 0.01), 5 (p = 0.04), 6 (p = 0.04), 7 (p = 0.02), 8 (p = 0.03) and 9 (p = 0.01) seconds. There were no differences between conditions for the peak lactate (p = 0.08) and the rating of perceived exertion (p = 0.84). Acute metformin administration increased the early power phase and the mean power of a Wingate test. [ABSTRACT FROM AUTHOR]

Sodium bicarbonate (SB) is considered an effective ergogenic supplement for improving high-intensity exercise capacity and performance, although recent data suggests that women may be less amenable to its ergogenic effects than men. Currently, an apparent paucity of data on women means no consensus exists on whether women benefit from SB supplementation. The aim of the current study was to quantify the proportion of the published literature on SB supplementation that includes women, and to synthesise the evidence regarding its effects on blood bicarbonate and exercise performance in women by performing a systematic review and meta-analysis. Electronic searches of the literature were undertaken using three databases (MEDLINE, Embase, SPORTDiscus) to identify relevant articles. All meta-analyses were performed within a Bayesian framework. A total of 149 SB articles were identified, 11 of which contained individual group data for women. Results indicated a pooled blood bicarbonate increase of 7.4 [95%CrI: 4.2–10.4 mmol·L−1] following supplementation and a pooled standardised exercise effect size of 0.37 [95%CrI: −0.06–0.92]. The SB literature is skewed, with only 20% (30 studies) of studies employing female participants, of which only 11 studies (7.4%) provided group analyses exclusively in women. Despite the small amount of available data, results are consistent in showing that SB supplementation in women leads to large changes in blood bicarbonate and that there is strong evidence for a positive ergogenic effect on exercise performance that is likely to be small to medium in magnitude. This study aimed to quantify the proportion of the published literature on sodium bicarbonate supplementation that includes women and to synthesise the evidence regarding its ergogenic effect on women, using a systematic review and meta-analytic approach. The sodium bicarbonate literature is skewed, with only 30 studies (20%) employing female participants, of which only 11 studies (7.4%) provided group analyses exclusively in women. Despite the small amount of available data, results are consistent in showing that sodium bicarbonate supplementation in women leads to large changes in blood bicarbonate and that there is strong evidence for a positive ergogenic effect on exercise performance that is likely small to medium in magnitude. Based on these findings, we do not believe there is any evidence to support sex-specific sodium bicarbonate dosing recommendations and that current recommendations of 0.2–0.3 g·kg−1BM of SB taken 60–180 min prior to high-intensity exercise appear appropriate for the female athlete. [ABSTRACT FROM AUTHOR]

Anthocyanin-rich blackcurrant extract (BC) has been shown to ergogenically aid high-intensity exercise. Capacity for such exercise is evaluated by the hyperbolic speed–tolerable duration (S–Dtol) relationship. Therefore, in double-blinded and cross-over randomised controlled trials, 15 males underwent treadmill running incremental exercise testing and were assessed for S–Dtol, quantified by critical speed (CS) and D' (distance), and assessments of time to exhaustion performance to empirically test the limits of the S–Dtol relationship, after daily supplementation of 300 mg/d BC (105 mg/d anthocyanin) or placebo. Supplementation with BC did not change CS (placebo 12.1 ± 1.0 km/h vs BC 11.9 ± 1.0 km/h, p >.05) or D' (placebo 918.6 ± 223.2 m vs BC 965.2 ± 231.2 m, p >.05), although further analysis indicated D' increased in 60% of subject (p =.08), indicating a trend toward cohorts potentially benefiting from BC supplementation. BC supplementation did not change time to exhaustion at or above CS, maximal oxygen uptake (VO2max), lactate threshold (LT), submaximal running economy (CR), or substrate utilisation during exercise (all p >.05). In conclusion, we could not detect any beneficial effect of BC supplementation during high-intensity running exercise, including the determining factors S–Dtol relationship, VO2max, LT or CR. Hence, no ergogenic effect was observed. [ABSTRACT FROM AUTHOR]

This study examined the acute performance, cardiovascular and local muscular responses to perceived exertion-based high-intensity interval exercise using either double- or single-leg cycling. Fifteen healthy middle-aged adults completed, on separate occasions, ten 30-s double-leg intervals interspersed with 60 s passive recovery and twenty (ten with each leg) 30-s single-leg intervals interspersed with 60 s passive recovery. Impedance cardiography, blood pressure, muscle oxygenation and total haemoglobin content (near-infrared spectroscopy), oxygen consumption and power output were measured throughout each session. Normalised to the lean mass used during each trial, single-leg cycling resulted in lower power output (single-leg: 8.92 ± 1.74 W kg−1 and double-leg: 10.41 ± 3.22 W kg−1; p < 0.05) but greater oxygen consumption (single-leg: 103 ± 11 mL kg−1 min−1 and double-leg: 84 ± 21 mL kg−1 min−1; p < 0.01) and cardiac output (single-leg: 1407 ± 334 mL kg−1 min−1 and double-leg: 850 ± 222 mL kg−1 min−1; p < 0.01), compared with double-leg cycling. Mean arterial pressure (double-leg: 108 ± 11 mmHg and single-leg: 102 ± 10 mmHg), change in total haemoglobin content (double-leg: 8.76 ± 10.65 µM cm s−1 and single-leg: 13.42 ± 4.10 µM cm s−1) and change in tissue oxygenation index (double-leg: −4.51 ± 3.56% and single-leg: −3.97 ± 3.91%) were not different between double-leg and single-leg cycling. When compared to double-leg cycling, single-leg cycling elicited a higher cardiac output relative to the lean mass, but this did not result in greater power output. The dissociation between blood availability and power output is consistent with an ageing model characterised by a decrease in local oxygen delivery and distribution capability. [ABSTRACT FROM AUTHOR]

The current study examined the effect of acute caffeine ingestion on mean and peak power production, fatigue index and rating of perceived exertion (RPE) during upper body and lower body Wingate anaerobic test (WANT) performance. Using a double-blind design, 22 males undertook one upper body and one lower body WANT, 60 min following ingestion of caffeine (5 mg*kg−1) and one upper body and one lower body WANT following ingestion of placebo (5 mg*kg−1 Dextrose). Peak power was significantly higher (P =.001) following caffeine ingestion in both upper and lower body WANT. Peak power and mean power was also significantly higher during lower body, compared to upper body WANTs irrespective of substance ingested. However, caffeine ingestion did not enhance mean power neither in upper nor lower-body WANT. There were no significant differences in mean fatigue index as a consequence of substance ingested or mode of exercise (all P > 0.05). For RPE there was also a significant substance ingested X mode interaction (P =.001) where there were no differences in RPE between caffeine and placebo conditions in lower body WANTs but significantly lower RPE during upper body WANT in the presence of caffeine compared to placebo (P =.014). This is the first study to compare the effects of caffeine ingestion on upper and lower body 30-second WANT performance and suggests that caffeine ingestion in the dose of 5 mg*kg−1 ingested 60 min prior to exercise significantly enhances peak power when data from upper and lower body WANTs are combined. [ABSTRACT FROM AUTHOR]

The current study examined the effect of acute caffeine ingestion on mean and peak power production during upper body Wingate test (WANT) performance, rating of perceived exertion, readiness to invest effort and cognitive performance. Using a double-blind design, 12 males undertook upper body WANTs, following ingestion of caffeine (5 mg*kg−1) or placebo. Pre-substance ingestion, 60 mins post substance ingestion and post exercise participants completed measures of readiness to invest physical and mental effort and cognitive performance. Peak power was significantly higher (P = .026), fatigue index greater (P = .02) and rating of perceived exertion lower (P = .025) in the presence of caffeine. Readiness to invest physical effort was also higher (P = .016) in the caffeine condition irrespective of time point (pre, 60 mins post ingestion and post exercise). Response accuracy for incongruent trials on the Flanker task was superior in the presence of caffeine (P = .006). There was a significant substance × time interaction for response speed in both congruent and incongruent conditions (both P = .001) whereby response speeds were faster at 60 mins post ingestion and post exercise in the caffeine condition, compared to placebo. This is the first study to examine the effects of caffeine ingestion on this modality of exercise and suggests that caffeine ingestion significantly enhances peak power, readiness to invest physical effort, and cognitive performance during WANT performance. [ABSTRACT FROM AUTHOR]

Caffeine and coffee are widely used among active individuals to enhance performance. The purpose of the current study was to compare the effects of acute coffee (COF) and caffeine anhydrous (CAF) intake on strength and sprint performance. Fifty-four resistance-trained males completed strength testing, consisting of one-rep max (1RM) and repetitions to fatigue (RTF) at 80% of 1RM for leg press (LP) and bench press (BP). Participants then completed five, 10-second cycle ergometer sprints separated by one minute of rest. Peak power (PP) and total work (TW) were recorded for each sprint. At least 48 hours later, participants returned and ingested a beverage containing CAF (300 mg flat dose; yielding 3–5 mg/kg bodyweight), COF (8.9 g; 303 mg caffeine), or placebo (PLA; 3.8 g non-caloric flavouring) 30 minutes before testing. LP 1RM was improved more by COF than CAF (p = .04), but not PLA (p = .99). Significant interactions were not observed for BP 1RM, BP RTF, or LP RTF (p > .05). There were no sprint × treatment interactions for PP or TW (p > .05). 95% confidence intervals revealed a significant improvement in sprint 1 TW for CAF, but not COF or PLA. For PLA, significant reductions were observed in sprint 4 PP, sprint 2 TW, sprint 4 TW, and average TW; significant reductions were not observed with CAF or COF. Neither COF nor CAF improved strength outcomes more than PLA, while both groups attenuated sprint power reductions to a similar degree. Coffee and caffeine anhydrous may be considered suitable pre-exercise caffeine sources for high-intensity exercise. [ABSTRACT FROM PUBLISHER]

The aim of this study was to examine the match activities of top-class female assistant referees (mean age 34.8 years, s=3.5; stature 1.64 m, s=0.05; weight 58.1 kg, s=7.4; body mass index 21.6 kg · m-2, s=2.4) in relation to the offside line. Computerized match analyses were performed on 14 top-class assistant referees during 10 matches (a total of 20 observations) from the 2006 Federation Internationale de Football Association (FIFA) under-20 Women's World Championship held in Russia. In addition, the position of the second last defensive player of both teams was calculated throughout the matches to determine the distance from the assistant referee to the offside line. The total distance covered during a game was 5594 m (s=473), of which 27% was sideways movements (1492 m, s=135). High-intensity activities (>13 km · h-1) accounted for 1999 m (s=371). Mean distance from the offside line during the entire match was 1.06 m (s=0.26). Total distance covered, high-intensity activities, and distance from the offside line were not different (P>0.05) between the two halves of the game or consecutive 15-min match periods. Our results show that: (1) the kinematic demands placed on top-class female assistant referees are similar to those of top-class male assistant refereeing except for the amount of high-intensity activities, and (2) assistant referees were able to maintain the distance from the offside line during the match, which suggests an ability to keep up with the pace of the play throughout the match. [ABSTRACT FROM AUTHOR]

The aim of this study was to determine whether an exogenous sodium lactate infusion increases blood lactate concentration and decreases performance during a 20-km time-trial. Highly trained male cyclists performed a 20-km time-trial with a saline (control) or sodium lactate infusion. Sodium lactate was infused at rates previously observed to raise blood lactate concentration by 2 mmol·l-1 in trained individuals cycling at 65% of maximum oxygen uptake. Blood lactate concentration increased (P≤0.0001) during both the control and sodium lactate trials compared with rest, with peak values of 9.6 and 10.6 mmol·l-1, respectively. The increase in sodium lactate over time was not significantly different from the control (P=0.34). Time to complete the time-trial and average power for the time-trial were not significantly different between the control (25.72±0.80 min; 348.0±32.4 W) and sodium lactate trials (25.58±0.93 min; 352.6±39.3 W). In addition, rating of perceived exertion, heart rate, and respiratory parameters did not differ between trials. In conclusion, when exogenous lactate is infused during a 20-km cycling time-trial, an exercise bout performed above the maximal lactate steady state, blood lactate concentration did not increase. Furthermore, exogenous lactate infusion did not decrease exercise performance, increase perceived exertion, or change respiratory parameters. Because lactate per se did not change performance outcomes or measured perceived exertion, we suggest that alternative objective measures of exercise intensity and performance be explored. [ABSTRACT FROM AUTHOR]