Energy System Contributions in Repeated Sprint Tests: Protocol and Sex Comparison.

The aim of this study was to investigate the energy system contributions to different repeated sprint protocols and also to determine sex-related differences in these contributions. Sixteen men and fourteen women team sport athletes randomly performed two cycling repeated sprint protocols with the same total duration (10 x 6 s and 6 x 10 s). Relative peak power (RPP), relative mean power (RMP), performance decrement (PD), oxygen uptake (VO2), blood lactate (LA), heart rate (HR) and ratings of perceived exertion (RPEs) were measured. The contributions of energy systems were calculated from oxygen consumption and lactate values during rest, exercise and recovery phases based on mathematical methods. Findings indicate that men had higher RPP and RMP. RPP did not differ according to protocols, while RMP was higher in the 10 x 6 s protocol. The sex effect in PD was similar; however, it was higher in the 6 x 10 s protocol. The effects of protocols on the maximum HR and LA were similar; however, the 6 x 10 s protocol resulted in higher RPEs. In both protocols women had higher ATP-PCr and men had higher glycolytic system contribution with similar oxidative system contribution. In addition, the 10 x 6 s protocol had higher ATP-PCr system contribution and the 6 x 10 s protocol had higher glycolytic system and oxidative system contributions. In conclusion, the contribution of energy systems, physiological and performance variables showed variations according to sex and different protocols.

The Contribution of Energy Systems in Repeated-Sprint Protocols: The Effect of Distance, Rest, and Repetition.

Purpose: This study aims to investigate the effects of rest intervals, sprint distance, and number of repetitions on performance variables, physiological responses, and energy system contributions in repeated-sprint protocols when total distance variable was the controlled (300 m). Method: Sixteen male soccer players participated in this study. The four protocols, each totaling a distance of 300 m, consisted of the combination of 15 and 30 m sprints with 30 s rest intervals (15meters30sec and 30meters30sec, respectively) and 1:5 work-rest ratios (15meters12sec and 30meters22sec, respectively). Aerobic, glycolytic, and phosphagen energy systems' contributions were calculated from the oxygen consumption (VO2) during the exercise, net lactate production, and the recovery VO2 kinetics using mono-exponential models. Repeated measures ANOVA with the Bonferroni correction was applied to examine the hypothesized differences. Results: The findings indicated that total sprint duration (F3:45=281.14; p<0.001), percentage of performance decline (F3:45=16.58; p<0.001), delta lactate (F3:45=39.72, p<0.001), rating of perceived exertion (F3:45=28.64; p<0.001), energy demand (F3:45=101.6; p<0.001), VO2 during the rest intervals (F3:45=42.72; p<0.001), and the absolute contribution of glycolytic (F3:45=119.6; p<0.001) and phosphagen energy systems (F3:45=72.9; p<0.001) were lowest in the 15meters30sec compared to other protocols. However, the relative contribution of aerobic system was greatest in the 15meters30sec compared to other protocols (F3:45=28.1, p<0.001). Both absolute (F3:45=119.6; p<0.001) and relative contribution of glycolytic system (F3:45=88.5, p<0.001) were greatest in the 30meters22sec compared to other protocols. Conclusion: This study showed that increasing sprint distance when rest interval is equal and decreasing rest interval when sprint distance is equal can increase the glycolytic system contribution.

Whole and segmental body composition changes during mid-follicular and mid-luteal phases of the menstrual cycle in recreationally active young women.

BACKGROUND: Changes in oestradiol and progesterone hormones and associated fluid retention during the menstrual cycle phases might affect body composition (BC) in women. AIM: The main objectives of this study were to determine the changes in whole and segmental BC by dual-energy x-ray absorptiometry (DXA) and bioelectrical impedance (BIA) during the mid-follicular (MFP) and mid-luteal (MLP) phases. SUBJECTS AND METHODS: Thirty recreationally active young women participated in this study. BC was measured by DXA and BIA during MFP and MLP. A mixed linear model for repeated measures analysis was used to determine the differences between the two phases. RESULTS: Body mass was higher during MLP than MFP, while total body water, total and segmental fat mass and fat percentages measured by both BIA and DXA were similar during the two phases. DXA-derived fat-free mass and soft lean mass in the android region were higher during MLP than MFP. Large variability in individual responses was evident. CONCLUSION: On average, whole and segmental BC variables do not change significantly between MFP and MLP. However, given the large variability among the individual responses, it is suggested to perform repeated BC measurements during the same phase of the menstrual cycle.

Short-term effects of on-field combined core strength and small-sided games training on physical performance in young soccer players.

This study aimed to compare the effects of 6-weeks combined core strength and small-sided games training (SSGcore) vs. small-sided games (SSG) training on the physical performance of young soccer players. Thirty-eight amateur soccer players (age: 16.50 ± 0.51 years) were randomly assigned to either a SSGcore (n = 20) or a SSG group (n = 18). The SSGcore group performed upper and lower body core strength exercises combined with SSG including 2-, 3- and 4-a-sided soccer games third a week. The SSG group performed only the SSG periodization. Baseline and after the 6-week training period the Yo-Yo Intermittent Recovery Test level 1 (YYIRTL-1), 5-20-m sprint test, countermovement jump (CMJ), squat jump (SJ), triple-hop distance (THD), zigzag agility with ball (ZAWB) and without ball (ZAWOB), three corner run test (TCRT) and Y-balance test. The SSGcore group demonstrated meaningful improvements in 20 m sprint time (SSGcore: -9.1%, d = 1.42; SSG: -4.4%, d = 0.76), CMJ (SSGcore: 11.4%, d = 2.67; SSG: -7.7%, d = 1.43), SJ (SSGcore: 12.0%, d = 2.14; SSG: 5.7%, d = 1.28), THD (SSGcore: 5.0%, d = 1.39; SSG: 2.7%, d = 0.52) and TCRT (SSGcore: -3.7%, d = 0.69; SSG: -1.9%, d = 0.38). Furthermore, the SSGcore group demonstrated meaningfully higher improvement responses in both leg balance score (d = ranging from 2.11 to 2.75) compared with SSG group. These results suggest that the inclusion of core strength training to a SSG periodization is greatly effective to improve speed and strength-based conditioning in young soccer players.

Effects of beta-blockers on archery performance, body sway and aiming behaviour.

OBJECTIVES: This study aimed to determine the effect of selective (bisoprolol-5 mg) and non-selective (propranolol-40 mg) beta-blockers on archery performance, body sway and aiming behaviour. METHODS: Fifteen male archers participated in a randomised, double-blind, placebo-controlled, cross-over study and competed four times (control, placebo, selective (bisoprolol) and non-selective (propranolol) beta-blocker trials). Mechanical data related to the changes in the centre of pressure during body sway and aim point fluctuation and when shooting was collected. During the shots, heart rate was recorded continuously. RESULTS: Results indicated that, in beta-blocker trials, although shooting heart rates were lowered by 12.8% and 8.6%, respectively, for bisoprolol and propranolol, no positive effect of beta-blockers was observed on shooting scores. Also, the use of beta-blockers did not affect shooting behaviour and body sway. CONCLUSION: The use of either selective or non-selective single dose beta-blockers had no positive effect on shooting performance in archery during simulated match conditions.

Effects of the Menstrual Cycle on Running Economy: Oxygen Cost Versus Caloric Cost.

Purpose: This study investigated the effects of the menstrual cycle on running economy (RE). Method: Eleven eumenorrheic female athletes (mean age: 21.18 ± 3.65 years, height: 170.2 ± 6.6 cm, VO2max: 49.25 ± 9.15 mL·kg-1·min-1, and menstrual cycle: 29.8 ± 0.98 days) were tested for anthropometric variables, physiological responses (oxygen consumption [VO2], blood lactate [LA], heart rate [HR], and respiratory exchange ratio [RER]) at rest and while running. The RE was measured at speeds of 75%, 85%, and 95% of the lactate threshold at 3.5 mmol·L-1 during the follicular (FP) and luteal phases (LP) of the menstrual cycle. The RE was evaluated as oxygen consumption (mL·kg·min-1 [O2C_min], mL·kg-1·km-1 [O2C_km]) and caloric unit cost (kcal·kg-1·km-1 [EC]) during both phases. Results: There were no significant differences in body composition or resting physiological measurements between the LP and FP (p > .05). Physiological responses measured during RE tests were similar in both phases (p > .05). The RE measured as O2C_min, O2C_km, and EC was significantly lower during the LP than during the FP (p < .05). The RE defined as O2C_ min significantly increased with speed (p < .05), but RE defined as O2C_km and EC was unaffected by speed increment (p > .05). Conclusions: The RE is better in the LP than the FP and is independent of running speed when RE is evaluated as O2C_km and EC. The menstrual cycle had no effect on body composition and physiological variables measured at rest.

Effect of heart rate on shooting performance in elite archers.

AIM: The aim of the present study was to examine the effect of heart rate on shooting performance in elite archers. METHODS: Regularly trained 13 (7 female, 6 male) international level elite archers performed a (specific) protocol twice with 3 days interval in an indoor area. In order to raise the heart rate (HR) and related physiological stress the archers performed 4 sets of steady pace shuttle runs (males 10 km h-1; females 8 km h-1) for 3 minutes in a 20 m course following with 1 minute stop during which they performed 3 shots to 18 meter distance indoor target, and followed by 1 minute rest, where blood sample was collected from ear lobe for blood lactate (BL) analysis. Heart rate monitors were used for heart rate (HR) recordings with 5 seconds intervals for resting, running, shooting, and recovery periods. The score of the shots were recorded as in the normal archery indoor competition. Average (overall) results were taken into account for statistical analysis. RESULTS: Mean HR and BL during resting shoot in 1st and 2nd tests were 119.0 and 112.2 bpm (range 1st test: 101-142 bpm, 2nd test: 96-135 bpm) and 1.72 and 1.65 mmol.L-1 (range 1st test: 0.9-2.6 mmol.L-1, 2nd test: 0.8-2.3 mmol.L-1) respectively. Mean HR and BL during post exercise shooting in 1st and 2nd tests were 168 and 166 bpm (range 1st test: 152-191 bpm, 2nd test: 147-188 bpm) and 4.21 and 3.44 mmol.L-1 (range 1st test: 1.3-7.0 mmol.L-1, 2nd test: 1.3-5.7 mmol.L-1) respectively. There was not any statistically difference between shooting scores (27.50-27.23 points) after running exercise and resting (p > 0.05). CONCLUSION: It was concluded that, under simulated indoor competition environment, high HR values do not influence short distance shooting scores.

Effects of Passive and Active Rest on Physiological Responses and Time Motion Characteristics in Different Small Sided Soccer Games.

The purpose of this study was to investigate the effects of resting regimes on physiological responses and time motion characteristics between bouts during small sided games (SSGs) in young soccer players. Sixteen players (average age 16.87 ± 0.34 years; body height 176.69 ± 3.21 cm; body mass 62.40 ± 2.59 kg; training experience 3.75 ± 0.44 years) performed four bouts 2-a-side, 3-a-side and 4-a-side games with three minutes active (SSGar: Running at 70% of HRmax) and passive (SSGpr) rest between bouts at two-day intervals. The heart rate (HR) along with total distance covered in different speed zones - walking (W, 0-6.9 km·h-1), low-intensity running (LIR, 7.0-12.9 km·h-1), moderate-intensity running (MIR, 13.0-17.9 km·h-1) and high-intensity running (HIR, >18km·h-1), were monitored during all SSGs, whereas the rating of perceived exertion (RPE, CR-20) and venous blood lactate (La-) were determined at the end of the last bout of each SSG. The results demonstrated that all SSGpr elicited significantly higher physiological responses compared to SSGar in terms of the RPE and La- (p < 0.05). In addition, 2-a-side SSGpr induced significantly lower %HRmax responses and total distance covered than 2-a-side SSGar (p < 0.05). Moreover, the distance covered at HIR was significantly higher in 4-a-side SSGar than 4-side SSGpr. The results of this study indicate that both SSGs with passive and active rest can be used for soccer specific aerobic endurance training. Furthermore, all SSGs with active recovery should be performed in order to increase players and teams' performance capacity for subsequent bouts.

Mouth Rinsing with Maltodextrin Solutions Fails to Improve Time Trial Endurance Cycling Performance in Recreational Athletes.

The carbohydrate (CHO) concentration of a mouth rinsing solution might influence the CHO sensing receptors in the mouth, with consequent activation of brain regions involved in reward, motivation and regulation of motor activity. The purpose of the present study was to examine the effects of maltodextrin mouth rinsing with different concentrations (3%, 6% and 12%) after an overnight fast on a 20 km cycling time trial performance. Nine recreationally active, healthy males (age: 24 ± 2 years; V ˙ O 2 m a x : 47 ± 5 mL·kg(-1)·min(-1)) participated in this study. A double-blind, placebo-controlled randomized study was conducted. Participants mouth-rinsed every 2.5 km for 5 s. Maltodextrin mouth rinse with concentrations of 3%, 6% or 12% did not change time to complete the time trial and power output compared to placebo (p > 0.05). Time trial completion times were 40.2 ± 4.0, 40.1 ± 3.9, 40.1 ± 4.4, and 39.3 ± 4.2 min and power output 205 ± 22, 206 ± 25, 210 ± 24, and 205 ± 23 W for placebo, 3%, 6%, and 12% maltodextrin conditions, respectively. Heart rate, lactate, glucose, and rating of perceived exertion did not differ between trials (p > 0.05). In conclusion, mouth rinsing with different maltodextrin concentrations after an overnight fast did not affect the physiological responses and performance during a 20 km cycling time trial in recreationally active males.

The Effects of a 6-Week Strength Training on Critical Velocity, Anaerobic Running Distance, 30-M Sprint and Yo-Yo Intermittent Running Test Performances in Male Soccer Players.

UNLABELLED: The objectives of this study were to examine the effects of a moderate intensity strength training on changes in critical velocity (CV), anaerobic running distance (D'), sprint performance and Yo-Yo intermittent running test (Yo-Yo IR1) performances. METHODS: two recreational soccer teams were divided in a soccer training only group (SO; n = 13) and a strength and soccer training group (ST; n = 13). Both groups were tested for values of CV, D', Yo-Yo IR1 distance and 30-m sprint time on two separate occasions (pre and post intervention). The ST group performed a concurrent 6-week upper and lower body strength and soccer training, whilst the SO group performed a soccer only training. RESULTS: after the re-test of all variables, the ST demonstrated significant improvements for both, YoYo IR1 distance (p = 0.002) and CV values (p<0.001) with no significant changes in the SO group. 30-m sprint performance were slightly improved in the ST group with significantly decreased performance times identified in the SO group (p<0.001). Values for D' were slightly reduced in both groups (ST -44.5 m, 95% CI = -90.6 to 1.6; SO -42.6 m, 95% CI = -88.7 to 3.5). CONCLUSIONS: combining a 6-week moderate strength training with soccer training significantly improves CV, Yo-Yo IR1 whilst moderately improving 30-m sprint performances in non-previously resistance trained male soccer players. Critical Velocity can be recommended to coaches as an additional valid testing tool in soccer.

Metabolic demands of match performance in young soccer players.

The aim of the present study was to determine metabolic responses, movement patterns and distance covered at running speeds corresponding to fixed blood lactate concentrations (FBLs) in young soccer players during a match play. A further aim of the study was to evaluate the relationships between FBLs, maximal oxygen consumption (VO2max) and distance covered during a game. A multistage field test was administered to 32 players to determine FBLs and VO2max. Blood lactate (LA), heart rate (HR) and rate of perceived exertion (RPE) responses were obtained from 36 players during tournament matches filmed using six fixed cameras. Images were transferred to a computer, for calibration and synchronization. In all players, values for LA and HR were higher and RPE lower during the 1(st) half compared to the 2(nd) half of the matches (p < 0.01). Players in forward positions had higher LA levels than defenders, but HR and RPE values were similar between playing positions. Total distance and distance covered in jogging, low-moderate-high intensity running and low intensity sprint were higher during the 1(st) half (p < 0.01). In the 1(st) half, players also ran longer distances at FBLs [p<0.01; average running speed at 2mmol·L(-1) (FBL2): 3.32 ± 0.31m·s(-1) and average running speed at 4mmol·L(-1) (FBL4): 3.91 ± 0.25m·s(-1)]. There was a significant difference between playing positions in distance covered at different running speeds (p < 0.05). However, when distance covered was expressed as FBLs, the players ran similar distances. In addition, relationships between FBLs and total distance covered were significant (r = 0.482 to 0.570; p < 0.01). In conclusion, these findings demonstrated that young soccer players experienced higher internal load during the 1(st) half of a game compared to the 2(nd) half. Furthermore, although movement patterns of players differed between playing positions, all players experienced a similar physiological stress throughout the game. Finally, total distance covered was associated to fixed blood lactate concentrations during play. Key pointsBased on LA, HR and RPE responses, young top soccer players experienced a higher physiological stress during the 1(st) half of the matches compared to the 2(nd) half.Movement patterns differed in accordance with the players' positions but that all players experienced a similar physiological stress during match play.Approximately one quarter of total distance was covered at speeds that exceeded the 4 mmol·L(-1) fixed LA threshold.Total distance covered was influenced by running speeds at fixed lactate concentrations in young soccer players during match play.

Influence of Ramadan Fasting on Anaerobic Performance and Recovery Following Short time High Intensity Exercise.

The aim of this study was to investigate the effects of Ramadan fasting on anaerobic power and capacity and the removal rate of lactate after short time high intensity exercise in power athletes. Ten male elite power athletes (2 wrestlers, 7 sprinters and 1 thrower, aged 20-24 yr, mean age 22.30 ± 1.25 yr) participated in this study. The subjects were tested three times [3 days before the beginning of Ramadan (Pre-RF), the last 3 days of Ramadan (End-RF) and the last 3 days of the 4(th) week after the end of Ramadan (After-RF)]. Anaerobic power and capacity were measured by using the Wingate Anaerobic Test (WAnT) at Pre-RF, End-RF and After- RF. Capillary blood samples for lactate analyses and heart rate recordings were taken at rest, immediately after WAnT and throughout the recovery period. Repeated measures of ANOVA indicated that there were no significant changes in body weight, body mass index, fat free mass, percentage of body fat, daily sleeping time and daily caloric intake associated with Ramadan fasting. No significant changes were found in total body water either, but urinary density measured at End-RF was significantly higher than After-RF. Similarity among peak HR and peak LA values at Pre-RF, End- RF and After-RF demonstrated that cardiovascular and metabolic stress caused by WAnT was not affected by Ramadan fasting. In addition, no influence of Ramadan fasting on anaerobic power and capacity and removal rate of LA from blood following high intensity exercise was observed. The results of this study revealed that if strength-power training is performed regularly and daily food intake, body fluid balance and daily sleeping time are maintained as before Ramadan, Ramadan fasting will not have adverse effects on body composition, anaerobic power and capacity, and LA metabolism during and after high intensity exercise in power athletes. Key pointsNo significant changes were assessed on body composition, daily sleeping time and caloric intake, and body fluid balance in regularly trained power athletes during Ramadan fasting.Ramadan fasting has no adverse effect on power outputs of short time high intensity exercise.No influence of Ramadan fasting on LA metabolism during high intensity exercise and passive recovery in regularly trained power athletes.