Four Days of Blueberry Powder Supplementation Lowers the Blood Lactate Response to Running But Has No Effect on Time-Trial Performance.

Blueberries are abundant with anthocyanins possessing antioxidant and anti-inflammatory properties. As these properties combat fatigue and promote recovery, blueberry supplementation may enhance performance and recovery. Thus, the objectives were to examine the effects of two blueberry supplementation protocols on running performance, physiological responses, and short-term recovery. Using a randomized, double-blind, placebo (PLA)-controlled crossover design, 14 runners completed an 8-km time trial (TT) after supplementation with 4 days of blueberries (4DAY), 4 days of a PLA, or 2 days of placebo followed by 2 days of blueberries (2DAY). Heart rate and ratings of perceived exertion were monitored during the TT. Blood lactate, vertical jump, reactive strength index, and salivary markers were assessed before and after. No significant differences were observed for time to complete the TT (PLA: 3,010 ± 459 s; 2DAY: 3,014 ± 488 s; 4DAY: 3,011 ± 423 s), heart rate, ratings of perceived exertion, or any of the salivary markers. An interaction effect (p = .027) was observed for blood lactate, with lower post-TT concentrations in 4DAY (5.4 ± 2.0 mmol/L) than PLA (6.6 ± 2.5 mmol/L; p = .038) and 2DAY (7.4 ± 3.4 mmol/L; p = .034). Post-TT decreases in vertical jump height were not different, whereas the decline in reactive strength index was less following 4DAY (-6.1% ± 13.5%) than the other conditions (PLA: -12.6% ± 10.1%; 2DAY: -11.6% ± 11.5%; p = .038). Two days of supplementation did not influence performance or physiological stress. Although 4 days of supplementation did not alter performance, it blunted the increase in blood lactate, perhaps reflecting altered lactate production and/or clearance, and offset the decrease in dynamic muscle function post-TT, as indicated by the reactive strength index differences.

Fluid balance of elite female basketball players before and during game play.

This study determined the fluid balance of elite female basketball players before and during competition. Before and during 2 international games, 17 national-level players (age 24.2 ± 3 yr, height 180.5 ± 6 cm, mass 78.8 ± 8 kg) were assessed. Fluid-balance assessment included pregame hydration level as determined by urine specific gravity (USG), change in body mass during the game, ad libitum intake of water or sports drink, and estimated sweat losses. Mean (± SD) USG before Game 1 was 1.005 ± 0.002 and before Game 2 USG equaled 1.010 ± 0.005. Players lost an average of 0.7% ± 0.8% and 0.6% ± 0.6% of their body mass during Games 1 and 2, respectively. In each game, 3 players experienced a fluid deficit >1% of body mass, and 1 other, a fluid deficit >2%. Sweat losses in both games, from the beginning of the warm-up to the conclusion of the game (~125 min with average playing time 16-17 min), were approximately 1.99 ± 0.75 L. Fluid intake in Game 1 and Game 2 equaled 77.8% ± 32% and 78.0% ± 21% of sweat losses, respectively. Most players were hydrated before each game and did not become meaningfully dehydrated during the game. It is possible that the players who experienced the highest levels of dehydration also experienced some degree of playing impairment, and the negative relationship between change in body mass and shooting percentage in Game 2 provides some support for this notion.

Effects of wearing a cooling vest during the warm-up on 10-km run performance.

The purpose of this study was to examine whether wearing a cooling vest during an active warm-up would improve the 10-km time trial (TT) performance of endurance runners. Seven male runners completed 3 10-km TTs (1 familiarization and 2 experimental) on a treadmill after a 30-minute warm-up. During the warm-up of the experimental TTs, runners wore either a t-shirt (control [C]) or a cooling vest (V), the order of which was randomized. No differences were found between the C and V conditions for the 10-km TT times (2,533 ± 144 and 2,543 ± 149 seconds, respectively) (p = 0.746) or any of the 2-km split times. Heart rate (HR) at the start of the TT equaled 90 ± 17 b·min for C and 94 ± 16 b·min for V. The HR peaked at 184 ± 20 b·min in C and 181 ± 19 b·min in V. At the start of the TT Tc was 37.65 ± .72°C in C and 37.29 ± .73°C in V (p = 0.067). In C, Tc gradually increased until 39.34 ± 0.43°C while in V is reached 39.18 ± 0.72°C (p = 0.621). Although rating of perceived exertion (RPE) and Thermal sensation (TS) increased during both experimental TTs, there were no differences between V and C. Findings suggest wearing a cooling vest during a warm-up does not improve 10-km performance. The use of cooling vests during the warm-up did not produce any physiological (HR and Tc) or psychological (RPE and TS) benefit, perhaps accounting for the lack of improvement.

Blueberry supplementation reduces the blood lactate response to running in normobaric hypoxia but has no effect on performance in recreational runners.

BACKGROUND: Blueberries are concentrated with anthocyanins possessing antioxidant properties. As these properties counter fatigue, blueberry supplementation may improve performance and recovery, particularly in hypoxia, where oxidative stress is elevated. METHODS: This study examined the effects of blueberry supplementation on running performance, physiological responses, and recovery in normobaric hypoxia. Eleven experienced runners completed a 30-minute time-trial (TT) in normobaric hypoxia (%O2 = 15.5 %) on separate days after supplementation with four days of blueberries (BLU) or four days of placebo (PLA). Heart rate (HR), oxygen saturation (SaO2) and ratings of perceived exertion (RPE) were monitored during the TT. Blood lactate and fraction of exhaled nitric oxide (FENO) were assessed pre-TT, post-TT, and during recovery. RESULTS: No significant differences were observed in the distance run during the TT, HR, SaO2, and RPE. The post-TT increase in blood lactate was significantly lower in BLU than PLA (p = 0.036). Pre-TT and post-TT FENO did not differ between conditions. Blood lactate recovery following the TT was similar between conditions. CONCLUSIONS: Four days of blueberry supplementation did not alter running performance or cardiovascular and perceptual responses in normobaric hypoxia. Supplementation lowered the blood lactate response to running, however, the significance of this finding is uncertain given the absence of an ergogenic effect.

Does Higher Self-Reported Cardiorespiratory Fitness Reduce the Odds of Hospitalization From COVID-19?

BACKGROUND: Regular physical activity and higher cardiorespiratory (CR) fitness enhance immune function, possibly reducing coronavirus disease 2019 (COVID-19) infection severity. The aim was to assess the association between physical activity and self-reported CR fitness on COVID-19 infection characteristics. METHODS: Participants formerly testing positive for COVID-19 completed an online questionnaire measuring COVID-19 infection characteristics and complications, self-reported CR fitness level, physical activity, and sociodemographic and health-related characteristics. Self-reported CR fitness was determined as the pace to cover 4.8 km without becoming overly fatigued (with slow walking, brisk walking, jogging, and running corresponding to low, moderate, good, and excellent levels of fitness, respectively). RESULTS: A total of 263 individuals completed the survey. Compared with the lowest level of self-reported CR fitness, the odds of hospitalization significantly decreased by 64% (odds ratio = 0.36; 95% confidence interval, 0.13-0.98; P = .04) in individuals reporting the ability to maintain a brisk walk. In individuals reporting the ability to maintain a jogging pace, the further reduction in hospitalization was not significant (odds ratio = 0.22; 95% confidence interval, 0.05-1.04; P = .05). For COVID-19 symptom severity and number, there were no significant associations with self-reported CR fitness or physical activity levels. CONCLUSIONS: For individuals with low self-reported CR fitness, improving CR fitness represents a strategy to reduce the risk of hospitalization from COVID-19.

An electromyography analysis of 3 muscles surrounding the shoulder joint during the performance of a chest press exercise at several angles.

This study compared the activation of the clavicular head and the sternocostal head of the pectoralis major and the anterior deltoid when performing the bench press at several different angles. Fifteen healthy male subjects participated in this study. Subjects performed the chest press exercise at 0 (flat bench), 28, 44, and 56 degrees above horizontal using 70% of their respective 1 repetition maximum for each angle. Electromyographic activity was recorded during each repetition. Activation of the clavicular head of the pectoralis major was significantly greater at 44 degrees compared to 0 degrees (p = 0.010), at 56 degrees compared to 0 degrees (p = 0.013), and at 44 degrees compared to 28 degrees (p = 0.003). Activation of the sternocostal head of the pectoralis major was significantly greater at 0 degrees compared to 28 degrees (p = 0.013), at 0 degrees compared to 44 degrees (p = 0.018), at 0 degrees compared to 56 degrees (p = 0.001), at 28 degrees compared to 56 degrees (p = 0.003), and at 44 degrees compared to 56 degrees (p = 0.001). Activation of the anterior deltoid was significantly greater at 28 degrees compared to 0 degrees (p = 0.002), at 44 degrees compared to 0 degrees (p = 0.012), and at 56 degrees compared to 0 degrees (p = 0.014). To optimize recruiting the involved musculature, it would seem that performing both the flat and incline chest press exercises is necessary.

Protein supplement users among high school athletes have misconceptions about effectiveness.

Protein supplements commonly are ingested by athletes to improve strength, agility, and speed. While athletes require a higher amount of protein (g.kg body weight) than nonathletes do to support protein synthesis, they do not necessarily need to consume protein from supplemental sources. To date, no studies have shown an advantage of ingesting protein supplements over natural, protein-containing foods; therefore, dietary sources of protein may be just as effective as protein supplemental sources in the regulation of muscle protein synthesis. Misconceptions regarding protein supplement effectiveness may originate from athletes' nutrition information sources. A survey questionnaire queried high school football players about sources of information and measured protein supplement misconceptions by using scores on a Protein Supplement Misconceptions Index. Sixty-one high school football players participated in the study; 39 were protein supplementers, and 22 were non-protein supplementers. There was a significant difference between index scores of protein supplementers and non-protein supplementers (t = -3.4, p = 0.001), indicating that protein supplementers had a greater level of misconceptions than non-protein supplementers did. Bonferroni post hoc procedures used with individual index items revealed that protein supplementers were more likely than non-protein supplementers to agree that "athletes should take protein supplements" (p = 0.001) and needed them "to gain as much muscle as possible" (p = 0.001). Greater misconceptions for protein supplementers may have resulted from the sources chosen for information and advice. Since coaches, parents, and friends were the primary sources of advice about protein supplements for protein supplementers, it would be valuable to provide nutrition education to these groups concurrently with educating young athletes to dispel ongoing misconceptions regarding the need for and effectiveness of protein supplements.

Physiological responses to diesel exhaust exposure are modified by cycling intensity.

BACKGROUND: Outdoor exercisers are frequently exposed to diesel exhaust (DE) that contains particulate matter (PM) air pollution. How the respiratory and metabolic responses to exercise are affected by DE exposure and how these responses change with exercise intensity are unknown. PURPOSE: This study aimed to determine the respiratory and metabolic responses to low- and high-intensity cycling with DE exposure containing high levels of PM. METHODS: Eighteen males age 24.5 ± 6.2 yr performed 30-min trials of low-intensity (30% of power at V˙O2peak) and high-intensity (60% of power at V˙O2peak) cycling as well as rest. Each trial was performed once while breathing filtered air (FA) and once while breathing DE (300 µg·m of PM2.5) for a total of six trials, each separated by 7 d. During the trials, minute ventilation (V˙E), oxygen consumption (V˙O2), CO2 production (V˙CO2), RER, and perceived exertion for lungs (RPELungs) and legs (RPELegs) were measured. Work of breathing, respiratory muscle V˙O2, ratio of O2 consumption to power output, and gross efficiency were estimated. RESULTS: The RER was significantly lower (0.02 lower, P = 0.008), and the RPELungs (0.9 greater, P = 0.001) and the RPELegs (0.6 greater, P = 0.017) were significantly greater, in DE compared with FA. During low-intensity exercise, V˙E (44.5 ± 8.9 vs 40.5 ± 8.0 L·min, P < 0.001), V˙O2 (27.9 ± 5.4 vs 24.9 ± 4.4 mL·kg·min, P = 0.001), and V˙CO2 (25.9 ± 5.3 vs 23.5 ± 4.5 mL·kg·min, P = 0.006) were significantly greater in DE. This pattern was not seen during high-intensity cycling. CONCLUSIONS: Respiratory and metabolic responses to low-intensity, but not high-intensity, cycling in DE exceed FA. Practically, the greater responses during low-intensity exercise in DE could have implications for individuals with cardiopulmonary disease. Also, the elevated RPE during DE could impair performance in self-paced exercise.

The acute effects of prior dynamic resistance exercise using different loads on subsequent upper-body explosive performance in resistance-trained men.

The purpose of this study was to determine if explosive upper-body performance could be improved when it was preceded by conditioning contraction protocols that incorporate resistance exercise. Providing that performance was enhanced, it was also the intention to determine the optimal conditioning contraction load for enhancing performance. Eight recreationally trained men completed 4 experimental sessions. Each session consisted of a warm-up, 3 bench press throws (pre), a conditioning protocol, and 3 bench press throws (post). The different conditioning protocols consisted of 5 bench press repetitions using 100, 75, or 50% of 5 repetition maximum (5RM) strength. The fourth protocol, in which no repetitions were completed, acted as a control. Participants performed each conditioning protocol on a different day, and the order in which the protocols were performed was randomized. Average power, assessed during the bench press throws, was determined for the starting segment and the end segment (point of bar release) for each throw. Comparisons in average power, for each segment of the bench press 1RM, were made between the pre- and postconditioning protocol bench press throws. None of the conditioning protocols had an effect on bench press throw performance in either of the 2 segments of the movement. The results suggest there is no performance advantage when explosive upper-body movement is preceded by resistance exercise of varying loads. Alternatively, the performance of a set of resistance exercise did not compromise explosive upper-body performance. Considering this, training methods that combine both resistance exercise and plyometric-like exercise may offer a practical and time-efficient training system.

The effects of accentuated eccentric loading on strength, muscle hypertrophy, and neural adaptations in trained individuals.

The purpose of this study was to compare the strength and neuromuscular adaptations for dynamic constant external resistance (DCER) training and dynamic accentuated external resistance (DAER) training (resistance training employing an accentuated load during eccentric actions). Male subjects active in resistance training were assigned to either a DCER training group (n = 10) or a DAER training group (n = 8) for 9 weeks. Subjects in the DCER group performed 4 sets of 10 repetitions with a load of 75% concentric 1 repetition maximum (RM). Subjects in the DAER group performed 3 sets of 10 repetitions with a concentric load of 75% of 1RM and an eccentric load of approximately 120% of concentric 1RM. Three measures reflecting adaptation of elbow flexors and extensors were recorded pretraining and posttraining: concentric 1RM, muscle cross-sectional area (CSA), and specific tension. Strength was assessed at midtraining periods. No significant changes in muscle CSA were observed in either group. Both training groups experienced significant increases in concentric 1RM and specific tension of both the elbow flexors and extensors, but compared with DCER training, DAER training produced significantly greater increases in concentric 1RM of the elbow extensors. These results suggest that, for some exercises, DAER training may be more effective than DCER training in developing strength within a 9-week training phase. However, for trained subjects, neither protocol is effective in eliciting muscle hypertrophy.