You are looking at 101 - 110 of 24,847 items

Restricted access

Jason P. Brandenburg and Luisa V. Giles

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.

Restricted access

Osamu Yanagisawa, Kenta Wakamatsu and Hidenori Taniguchi

Context: Compared to shoulder and elbow functions, the hip functional characteristics of baseball pitchers have not been fully investigated. Therefore, little is known about the relationship between hip function and pitching performance. Objective: The purpose of this study was to evaluate the characteristics of hip flexibility and strength, focusing on their influences on the ball velocity in baseball pitchers. Design: Descriptive laboratory study. Setting: Laboratory and university baseball facility. Participants: Twenty-three college baseball pitchers. Interventions: Passive hip range of motion (ROM) and isometric hip muscle strength were bilaterally measured. The pitchers threw 20 fastballs at an official pitching distance. Main Outcome Measures: Bilateral hip ROM and strength in flexion, extension, abduction, adduction, and external and internal rotation; the maximal ball velocity. Results: The pivot side showed smaller hip external rotation ROM (P < .01), larger hip internal rotation ROM (P = .03), and greater hip adduction strength (P = .03) than the stride side. The hip extension ROM on the stride side had a negative correlation with the maximal ball velocity (r = −.58, P < .01). The maximal ball velocity (135.3 [4.1] km/h) positively correlated with the hip extension (r = .59, P < .01), flexion (r = .57, P < .01), abduction (r = .55, P < .01), and adduction (r = .55, P < .01) strength on the pivot leg, and the hip flexion (r = .53, P = .01), abduction (r = .67, P < .01), and adduction (r = .46, P = .03) strength on the stride leg. Conclusions: These findings suggest that baseball pitchers do not have marked side-to-side differences in hip flexibility and strength, and that an important fitness factor for increasing ball velocity is not the hip flexibility but the hip muscle strength of both legs.

Open access

Brianna J. Stubbs, Pete J. Cox, Tom Kirk, Rhys D. Evans and Kieran Clarke

Exogenous ketone drinks may improve athletic performance and recovery, but information on their gastrointestinal tolerability is limited. Studies to date have used a simplistic reporting methodology that inadequately represents symptom type, frequency, and severity. Herein, gastrointestinal symptoms were recorded during three studies of exogenous ketone monoester (KME) and salt (KS) drinks. Study 1 compared low- and high-dose KME and KS drinks consumed at rest. Study 2 compared KME with isocaloric carbohydrate (CHO) consumed at rest either when fasted or after a standard meal. Study 3 compared KME+CHO with isocaloric CHO consumed before and during 3.25 hr of bicycle exercise. Participants reported symptom type and rated severity between 0 and 8 using a Likert scale at regular intervals. The number of visits with no symptoms reported after ketone drinks was n = 32/60 in Study 1, n = 9/32 in Study 2, and n = 20/42 in Study 3. Following KME and KS drinks, symptoms were acute but mild and were fully resolved by the end of the study. High-dose KS drinks caused greater total-visit symptom load than low-dose KS drinks (13.8 ± 4.3 vs. 2.0 ± 1.0; p < .05) and significantly greater time-point symptom load than KME drinks 1–2 hr postdrink. At rest, KME drinks caused greater total-visit symptom load than CHO drinks (5.0 ± 1.6 vs. 0.6 ± 0.4; p < .05). However, during exercise, there was no significant difference in total-visit symptom load between KME+CHO (4.2 ± 1.0) and CHO (7.2 ± 1.9) drinks. In summary, exogenous ketone drinks cause mild gastrointestinal symptoms that depend on time, the type and amount of compound consumed, and exercise.

Restricted access

Claire E. Badenhorst, Katherine E. Black and Wendy J. O’Brien

Hepcidin, a peptide hormone with an acknowledged evolutionary function in iron homeostasis, was discovered at the turn of the 21st century. Since then, the implications of increased hepcidin activity have been investigated as a potential advocate for the increased risk of iron deficiency in various health settings. Such implications are particularly relevant in the sporting community where peaks in hepcidin postexercise (∼3–6 hr) are suggested to reduce iron absorption and recycling, and contribute to the development of exercise-induced iron deficiency in athletes. Over the last decade, hepcidin research in sport has focused on acute and chronic hepcidin activity following single and repeated training blocks. This research has led to investigations examining possible methods to attenuate postexercise hepcidin expression through dietary interventions. The majority of macronutrient dietary interventions have focused on manipulating the carbohydrate content of the diet in an attempt to determine the health of athletes adopting the low-carbohydrate or ketogenic diets, a practice that is a growing trend among endurance athletes. During the process of these macronutrient dietary intervention studies, an observable coincidence of increased cumulative hepcidin activity to low energy availability has emerged. Therefore, this review aims to summarize the existing literature on nutritional interventions on hepcidin activity, thus, highlighting the link of hepcidin to energy availability, while also making a case for the use of hepcidin as an individualized biomarker for low energy availability in males and females.

Restricted access

Komeil Dashti Rostami, Aynollah Naderi and Abbey Thomas

Context: Hamstring and quadriceps activity adaptations are well known in individuals with anterior cruciate ligament deficiency (ACLD) and reconstructed (ACLR) to potentially compensate for knee joint instability. However, few studies have explored hip muscles activity patterns after ACL injury. Objective: To examine the activation characteristics of gluteus medius (GMED) and adductor longus in ACLR and ACLD subjects compared with controls. Design: Case–control study. Setting: Athletic training room and university lab. Participants: Twelve healthy and 24 ACL-injured (12 ACLR and 12 ACLD) recreationally active male volunteers. Interventions: Surface electromyography of the GMED and adductor longus were recorded during a single-leg vertical drop landing and normalized to maximum voluntary isometric contractions. Main Outcome Measures: Preparatory and reactive muscle activity and coactivation were analyzed from 100 milliseconds prior to initial contact to 250 milliseconds postcontact. Results: During reactive activity, ACL-injured (ACLR and ACLD) participants demonstrated significantly lower peak GMED activity compared with controls (F = 4.33, P = .02). In addition, ACLR participants exhibited significantly lower reactive GMED:adductor longus coactivation muscle activity compared with controls (F = 4.09, P = .03). Conclusion: Our findings suggest neuromuscular adaptations of the hip musculature are present in people at least 2 years from ACL injury. GMED activation exercises should be considered in designing rehabilitation programs for ACL-injured individuals.

Restricted access

Julian A. Owen, Matthew B. Fortes, Saeed Ur Rahman, Mahdi Jibani, Neil P. Walsh and Samuel J. Oliver

Identifying mild dehydration (≤2% of body mass) is important to prevent the negative effects of more severe dehydration on human health and performance. It is unknown whether a single hydration marker can identify both mild intracellular dehydration (ID) and extracellular dehydration (ED) with adequate diagnostic accuracy (≥0.7 receiver-operating characteristic–area under the curve [ROC-AUC]). Thus, in 15 young healthy men, the authors determined the diagnostic accuracy of 15 hydration markers after three randomized 48-hr trials; euhydration (water 36 ml·kg−1·day−1), ID caused by exercise and 48 hr of fluid restriction (water 2 ml·kg−1·day−1), and ED caused by a 4-hr diuretic-induced diuresis begun at 44 hr (Furosemide 0.65 mg/kg). Body mass was maintained on euhydration, and dehydration was mild on ID and ED (1.9% [0.5%] and 2.0% [0.3%] of body mass, respectively). Urine color, urine specific gravity, plasma osmolality, saliva flow rate, saliva osmolality, heart rate variability, and dry mouth identified ID (ROC-AUC; range 0.70–0.99), and postural heart rate change identified ED (ROC-AUC 0.82). Thirst 0–9 scale (ROC-AUC 0.97 and 0.78 for ID and ED) and urine osmolality (ROC-AUC 0.99 and 0.81 for ID and ED) identified both dehydration types. However, only the thirst 0–9 scale had a common dehydration threshold (≥4; sensitivity and specificity of 100%; 87% and 71%, 87% for ID and ED). In conclusion, using a common dehydration threshold ≥4, the thirst 0–9 scale identified mild intracellular and ED with adequate diagnostic accuracy. In young healthy adults’, thirst 0–9 scale is a valid and practical dehydration screening tool.

Restricted access

Michele Merlini, Greg Whyte, Sam Marcora, Mike Loosemore, Neil Chester and John Dickinson

Purpose: To investigate the impact of twice-daily inhalation of 100 µg of salmeterol (SAL) or 12 µg of formoterol (FOR) in addition to a strength- and power-training program over a 5-wk period on a 30-m sprint, strength, power, mood, stress, and skinfold thickness. Methods: In a randomized, single-blind study, 23 male and 15 female nonasthmatic, recreationally active individuals were recruited (mean [SD] age 26.3 [5.4] y, weight 76.2 [11.5] kg, height 176.9 [8.5] cm). Participants completed 3 standardized whole-body strength- and power-training sessions per week for 5 wk during which they were assigned to an SAL, FOR, or placebo group. Participants used their inhaler twice per day as instructed and completed assessments of sprint, strength, and power at baseline and 1 wk after cessation of the training program. The assessments included a 30-m sprint, vertical jump, 1-repetition-maximum (1RM) bench press, 1RM leg press, peak torque flexion and extension, anthropometric evaluation, and Rest-Q questionnaires. Results: After 5 wk of strength and power training, 30-m sprint time reduced in the FOR (0.29 [0.11] s, P = .049) and SAL (0.35 [0.05] s, P = .040) groups compared with placebo (+0.01 [0.11] s). No significant change was found in other assessments of strength, mood, or skinfold thickness. Conclusions: When strength and power training are combined with the inhalation of FOR or SAL over a 5-wk period, moderately trained individuals experience an improvement in 30-m sprint performance.

Restricted access

Bob Heere, Henry Wear, Adam Jones, Tim Breitbarth, Xiaoyan Xing, Juan Luis Paramio Salcines, Masayuki Yoshida and Inge Derom

The purpose of this study is to examine how effective the international promotion of a sport event is on changing the destination image prior to the event if the sport event lacks global popularity. The authors conducted a quasi-experimental posttest research design, in which they used promotional information of a Tour de France stage to manipulate the destination image nonvisitors (N = 3,505) from nine different nations have of the hosting city, 5 months prior to the actual event. Results show that treating the international market as a homogeneous entity might be deceptive, as the effect of the event was different from nation to nation, pending on the popularity of the event or sport in the specific nation, and whether the nation itself offered similar events.

Restricted access

Brittany Mann, Allison H. Gruber, Shane P. Murphy and Carrie L. Docherty

Context: The lateral ankle sprain is one of the most common lower-extremity injuries in sports. Previous research has found that some prophylactic ankle supports reduce the risk of recurrent ankle sprains and provide extra support to the joint. However, there is a continued concern that these supports may negatively influence performance. Objective: To determine if wearing an ankle brace influences athlete performance and ankle kinematics during functional performance tests. Design: Repeated measures. Setting: University gymnasium. Other Participants: Male and female recreational or competitive athletes (n = 20). Intervention: Participants performed 3 trials of a standing long jump, vertical jump, 40-yard sprint, and T-drill under each of the following 3 conditions: wearing traditional lace-up brace (brace 1), modified lace-up brace (brace 2), and no-brace. Main Outcome Measures: A 2-dimensional motion capture camera was used to measure ankle range of motion (ROM) in the sagittal plane during the vertical and standing long jumps and in the frontal plane during the cutting phase of the T-drill. Performance of each test and ankle ROM were compared between each of the braced conditions. Results: Ankle braces did not influence performance in speed or agility functional performance tests (P > .05). Ankle braces negatively affected performance of the standing long jump (P = .01) and vertical jump (P = .01). There was no significant difference between brace or no-brace conditions in ankle inversion ROM during the T-drill (P > .05). Both brace conditions restricted ROM in the sagittal plane during the vertical and standing long jumps (P < .05). Conclusions: Braced conditions restricted sagittal plane ROM during the vertical jump and long jump. This decrease in ROM explains the decline in functional performance also seen during these tests.

Restricted access

Teun van Erp, Marco Hoozemans, Carl Foster and Jos J. de Koning

Purpose: A valid measure for training load (TL) is an important tool for cyclists, trainers, and sport scientists involved in professional cycling. The aim of this study was to explore the influence of exercise intensity on the association between kilojoules (kJ) spent and different measures of TL to arrive at valid measures of TL. Methods: Four years of field data were collected from 21 cyclists of a professional cycling team, including 11,716 training and race sessions. kJ spent was obtained from power output measurements, and others TLs were calculated based on the session rating of perceived exertion (sRPE), heart rate (Lucia training impulse [luTRIMP]), and power output (training stress score [TSS]). Exercise intensity was expressed by the intensity factor (IF). To study the effect of exercise intensity on the association between kJ spent and various other TLs (sRPE, luTRIMP, and TSS), data from low- and high-intensity sessions were subjected to regression analyses using generalized estimating equations. Results: This study shows that the IF is significantly different for training and race sessions (0.59 [0.03] vs 0.73 [0.03]). Significant regression coefficients show that kJ spent is a good predictor of sRPE, and luTRIMP, as well as TSS. However, IF does not influence the associations between kJ spent and sRPE and luTRIMP, while the association with TSS is different when sessions are done with low or high IF. Conclusion: It seems that the TSS reacts differently to exercise intensity than sRPE and luTRIMP. A possible explanation could be the quadratic relation between IF and TSS.