Physiological Responses to 90 s All Out Isokinetic Sprint Cycling in Boys and Men

The purpose of this study was to compare the VO₂ kinetic and mechanical power responses of boys and men to all out 90 s sprint cycle exercise. Eight boys (14.6 ± 0.3 y) and eight men (33.8 ± 6.5 y) volunteered to participate and completed a ramp test (to determine VO_2peak and ventilatory threshold, VT) and then on subsequent days, two 90 s all out cycle sprints on an isokinetic cycle ergometer. During each test, breath-by-breath pulmonary gas exchange and power output were measured. Parameters from the power output profiles were derived from the average response of the two tests including peak power (PP, highest power output in 1 s), end power (EP_60-90, power over the last 30 s), and mean power over the 90 s (MP₉₀). Independent pairwise and dependent t-tests were used to compare the data from tests between adults and boys subject groups. Significant differences between adults and boys were found for absolute PP (881.4 ± 60.7 vs 533.6 ± 50.7 W), EP_60-90 (288.6 ± 25.7 vs 134.3 ± 17.6 W) and MP₉₀ (434.5 ± 27.4 vs 238.4 ± 17.3 W, p =0.001) respectively. Relative to body mass significant differences between adults and boys were found for EP_60-90, MP₉₀ and total work (p < 0.002). The boys attained 90 s VO₂ values that were closer to VO_2peak than their adult counterparts (93.3 ± 2.6 vs 84.9 ± 2.3 %, p = 0.03). They also demonstrated faster VO₂ kinetics (10.8 ± 1.5 vs 17.6 ± 1.0 s, p < 0.01). In conclusion, during all out 90 s cycle sprinting boys were able to attain VO₂ values that were closer to VO_2peak and a faster time constant than adult men. These findings provide insight into the contribution and speed of response of the aerobic system during an ‘anaerobic’ test.

Key Points

• The results of this study confirm the significant contributions of the aerobic energy systems during so called ‘anaerobic tests’.
• Boys were able to attain VO₂ values from an all out 90 s sprint cycle that were closer to their aerobic VO₂ peak test than adults. More detailed studies are required to investigate the limiting factors that prevent VO₂ peak being reached in an all out sprint cycle.
• All out tests of a duration > 30 s and coupled with gas and power analyses offer paediatric physiologists considerable scope to examine the contributions of the anaerobic and aerobic energy systems until more ethically viable methods are found.

Key Words: VO_2peak, anaerobic, kinetics, aerobic, ergometry     

Familiarisation and Reliability of Sprint Test Indices During Laboratory and Field Assessment

The aim of the study was to assess the reliability of sprint performance in both field and laboratory conditions. Twenty-one male (mean ± s: 19 ± 1 years, 1.79 ± 0.07 m, 77.6 ± 7.1 kg) and seventeen female team sport players (mean ± s: 21 ± 4 years, 1.68 ± 0. 07 m, 62.7 ± 4.7 kg) performed a maximal 20-metre sprint running test on eight separate occasions. Four trials were conducted on a non-motorised treadmill in the laboratory; the other four were conducted outdoors on a hard-court training surface with time recorded by single-beam photocells. Trials were conducted in random order with no familiarisation prior to testing. There was a significant difference between times recorded during outdoor field trials (OFT) and indoor laboratory trials (ILT) using a non-motorised treadmill (3.47 ± 0.53 vs. 6.06 ±1.17s; p < 0.001). The coefficient of variation (CV) for time was 2.55-4.22% for OFT and 5.1-7.2% for ILT. During ILT peak force (420.9 ± 87.7N), mean force (147.2 ± 24.7N), peak power (1376.8 ± 451.9W) and mean power (514.8 ± 164.4W), and were measured. The CV for all ILT variables was highest during trial 1-2 comparison. The CV (95% confidence interval) for the trial 3-4 comparison yielded: 9.4% (7.7-12. 1%), 7.9% (6.4-10.2%), 10.1% (8.2-13.1%) and 6.2% (5.1-8.0%) for PF, MF, PP and MP and respectively. The results indicate that reliable data can be derived for single maximal sprint measures, using fixed distance protocols. However, significant differences in time/speed over 20-m exist between field and laboratory conditions. This is primarily due to the frictional resistance in the non- motorised treadmill. Measures of force and power during ILT require at least 3 familiarisations to reduce variability in test scores.

Key points

• Reliable data can be derived from single maximal sprint measures in both indoor and outdoor environments using fixed distance protocols.
• There may be significant time differences to complete fixed distance trials between the two environments.
• Measures of mean force, peak force and peak power during indoor trials may require multiple trials to reduce variability in test scores.

Key words: Non-motorised treadmill, force, power, familiarisation, sprint running     

A Combined Hot and Hypoxic Environment during Maximal Cycling Sprints Reduced Muscle Oxygen Saturation: A Pilot Study

The present study investigated the effects of a combined hot and hypoxic environment on muscle oxygenation during repeated 15-s maximal cycling sprints. In a single-blind, cross-over study, nine trained sprinters performed three 15-s maximal cycling sprints interspersed with 7-min passive recovery in normoxic (NOR; 23℃, 50%, FiO₂ 20.9%), normobaric hypoxic (HYP; 23℃, FiO₂ 14.5%), and hot normobaric hypoxic (HH; 35℃, FiO₂ 14.5%) environments. Relative humidity was set to 50% in all trials. The vastus lateralis muscle oxygenation was evaluated during exercise using near-infrared spectroscopy. The oxygen uptake (VO₂) and arterial oxygen saturation (SpO₂) were also monitored. There was no significant difference in peak or mean power output among the three conditions. The reduction in tissue saturation index was significantly greater in the HH (-17.0 ± 2.7%) than in the HYP (-10.4 ± 2.8%) condition during the second sprint (p < 0.05). The average VO₂ and SpO₂ were significantly lower in the HYP (VO₂ = 980 ± 52 mL/min, SpO₂ = 82.9 ± 0.8%) and HH (VO₂ = 965 ± 42 mL/min, SpO₂ = 83.2 ± 1.2%) than in the NOR (VO₂ = 1149 ± 40 mL/min, SpO₂ = 90.6 ± 1.4%; p < 0.05) condition. In conclusion, muscle oxygen saturation was reduced to a greater extent in the HH than in the HYP condition during the second bout of three 15-s maximal cycling sprints, despite the equivalent hypoxic stress between HH and HYP. Key points

• The muscle oxygen saturation was reduced to a greater extent in the combined hot and hypoxia than in hypoxia alone during the second bout of three 15-s maximal cycling sprints, despite similar arterial oxygen saturation.
• There was no significant difference among conditions for peak and mean power outputs during three 15-s maximal sprints.
• These results suggest that acute exposure to a combined hot and hypoxia would partially promote local hypoxia in the working muscles without a negative effect on sprint performance.

Key words: Heat stress, normobaric hypoxia, environmental stressor, muscle oxygenation     

Jump Kinetic Determinants of Sprint Acceleration Performance from Starting Blocks in Male Sprinters

The purpose of this research was to identify the jump kinetic determinants of sprint acceleration performance from a block start. Ten male (mean ± SD: age 20 ± 3 years; height 1.82 ± 0.06 m; weight 76.7 ± 7.9 kg; 100 m personal best: 10.87 + 0.36 s {10.37 - 11.42}) track sprinters at a national and regional competitive level performed 10 m sprints from a block start. Anthropometric dimensions along with squat jump (SJ), countermovement jump (CMJ), continuous straight legged jump (SLJ), single leg hop for distance, and single leg triple hop for distance measures of power were also tested. Stepwise multiple regression analysis identified CMJ average power (W/kg) as a predictor of 10 m sprint performance from a block start (r = 0.79, r² = 0.63, p<0.01, SEE = 0.04 (s), %SEE = 2.0). Pearson correlation analysis revealed CMJ force and power (r = -0.70 to -0.79; p = 0.011 - 0.035) and SJ power (r = -0.72 to -0.73; p = 0.026 - 0.028) generating capabilities to be strongly related to sprint performance. Further linear regression analysis predicted an increase in CMJ average and peak take-off power of 1 W/kg (3% & 1.5% respectively) to both result in a decrease of 0.01 s (0.5%) in 10 m sprint performance. Further, an increase in SJ average and peak take-off power of 1 W/kg (3.5% & 1.5% respectively) was predicted to result in a 0.01 s (0.5%) reduction in 10 m sprint time. The results of this study seem to suggest that the ability to generate power both elastically during a CMJ and concentrically during a SJ to be good indicators of predicting sprint performance over 10 m from a block start.

Key Points

• The relative explosive ability of the hip and knee extensors during a countermovement jump can predict 10 m sprint performance from a block start.
• The relative power outputs of male competitive sprinters during a squat jump can predict 10 m sprint performance from a block start.

Key words: Anthropometry, horizontal jumps, sprint performance, vertical jumps     

Reliability of the Woodway CurveTM Non-Motorized Treadmill for Assessing Anaerobic Performance

A curved treadmill offers a practical method of assessing anaerobic power by enabling unrestricted running motion and greater sport specificity. The purpose of this research was to determine reliability of a curved treadmill (cTM) sprint test and to compare performance measures to the traditional Wingate anaerobic power test (WAnT) performed on a cycle ergometer. Thirty-two recreationally active men and women (22.4 ± 2.8 yrs; 1.73 ± 0.08 m; 74. 2 ± 13.2 kg) performed four familiarization trials on cTM, followed by two randomly assigned experimental trials consisting of one 30-second maximum effort on either cTM or WAnT. Each trial was separated by at least 48 hours. Repeated measures analysis of variance (ANOVA), interclass correlations (ICC), standard error of measurement (SEM), and minimal differences (MD) were used to determine reliability of familiarization trials on cTM, and Pearson product moment correlations were calculated to compare cTM and WAnT. ANOVA results showed significant differences (p < 0.05) during the four familiarization trials. Post hoc analysis showed significant differences (p < 0. 05) between the first two trials. Familiarization trials 3 and 4 showed a high reliability for each performance variable (distance: ICC_2,1 = 0.969, %SEM = 2.645, p = 0.157; mean velocity: ICC_2,1 = 0. 969, %SEM = 2.622, p = 0.173; peak velocity: ICC_2,1 = 0.966, %SEM = 3.142, p = 0.033; mean power: ICC_2,1 = 0.940, %SEM = 4.140, p = 0.093; and peak power: ICC_2,1 = 0.887, %SEM = 11.244, p = 0.669). Participants elicited an average peak power of 1050.4 ± 338.5 Watts on cTM and 1031.4 ± 349.8 Watts on WAnT. Pearson product moment coefficients indicated high correlations between peak power, mean power, and peak velocity (r = 0.75, p < 0.001; r = 0.84, p < 0.001; and r = 0.76, p < 0. 001, respectively) derived from cTM and WAnT. In conclusion, results suggest that after two familiarization trials, cTM is a reliable sprint test for recreationally active men and women. In addition, there are strong relationships between cTM and WAnT in assessing anaerobic performance.

Key points

• The Woodway Curve 3.0^TM is a non-motorized treadmill utilizing a curved platform which allows individuals to simulate an unrestricted sprint test in a laboratory setting, offering a practical and sport specific method of assessing anaerobic power.
• The curved treadmill provides a reliable sprint test for recreationally active men and women.
• There are strong relationships between the curved treadmill and cycle ergometer in assessing anaerobic performance.

Key words: Anaerobic capacity, power, Wingate anaerobic power test, sprint speed     

Physiological Responses during Cycling With Oval Chainrings (Q-Ring) and Circular Chainrings

The aim of this study was to compare the physiological responses of cyclists using round (C-ring) or oval (Q-ring) chainrings during an incremental test until exhaustion. Following a randomized design, twelve male elite cyclists [age (mean ± SD): 21.1 ± 2.1 yr; VO_2max: 78.1 ± 5.3 mL·kg^-1min^-1] performed two incremental maximal tests separated by 48 h (one with C-rings, the other with Q-rings). Starting at 100 W, the workload was increased by 25 W every 3 min until volitional exhaustion. Maximal heart rate, power output and oxygen consumption were compared. Blood lactate was monitored throughout the test. After the incremental test, 4 intermittent 20-s maximal sprints with a 60-s recovery period in between were performed. Maximal isometric voluntary contractions were performed at rest and immediately after each 20-s maximal sprint, and the force and EMG RMS amplitude were recorded from the vastus medialis and vastus lateralis muscles. For the incremental exercise test, no significant differences were found in the maximal power output (P=0.12), oxygen consumption (P=0.39), and heart rate (P=0.32) between Q-rings and C-rings. Throughout the incremental test, lactate levels were comparable when using both the C-rings and Q-rings (P=0.47). During the short sprints, power output was 2.5–6.5% greater for Q-rings than for C-rings (P=0.22). The decline in EMG RMS amplitude observed during the incremental tests was comparable for Q-rings and C-rings (0.42). These findings indicate that the oval chainring design, presented here as “Q-rings”, did not significantly influence the physiological response to an incremental exercise test as compared to a conventional chainring.

Key points

• During the incremental exercise test, no significant differences were found in power output, oxygen consumption or heart rate between oval “Q-rings” and conventional chainrings.
• Over the course of the incremental test, blood lactate levels were comparable for the oval “Q-rings” and conventional chainrings.
• During the short sprints performed after the incremental test, there were no statistical differences in power production between oval “Q-rings” and conventional chainrings.

Key Words: Pedaling, chainring, blood lactate, fatigue, biomechanics     

Pronounced Muscle Deoxygenation During Supramaximal Exercise Under Simulated Hypoxia in Sprint Athletes

The purpose of this study was to determine whether acute hypoxia alters the deoxygenation level in vastus lateralis muscle during a 30 s Wingate test, and to compare the muscle deoxygenation level between sprint athletes and untrained men. Nine male track sprinters (athletic group, VO₂max 62.5 ± 4.1 ml/kg/min) and 9 healthy untrained men (untrained group, VO₂max 49.9 ± 5.2 ml·kg^-1·min^-1) performed a 30 s Wingate test under simulated hypoxic (F_IO₂ = 0.164 and P_IO₂ = 114 mmHg) and normoxic conditions. During the exercise, changes in oxygenated hemoglobin (OxyHb) in the vastus lateralis were measured using near infrared continuous wave spectroscopy. Decline in OxyHb, that is muscle deoxygenation, was expressed as percent change from baseline. Percutaneous arterial oxygen saturation (SpO₂), oxygen uptake (VO₂), and ventilation (VE) were measured continuously. In both groups, there was significantly greater muscle deoxygenation, lower SpO₂, lower peakVO₂, and higher peakVE during supramaximal exercise under hypoxia than under normoxia, but no differences in peak and mean power output during the exercise. Under hypoxia, the athletic group experienced significantly greater muscle deoxygenation, lower SpO₂, greater decrement in peakVO₂ and increment in peakVE during the exercise than the untrained group. When the athletic and untrained groups were pooled, the increment of muscle deoxygenation was strongly correlated with lowest SpO₂ in the 30 s Wingate test under hypoxia. These results suggest that acute exposure to hypoxia causes a greater degree of peripheral muscle deoxygenation during supramaximal exercise, especially in sprint athletes, and this physiological response would be explained mainly by lower arterial oxygen saturation.

Key points

• The deoxygenation trends in the vastus lateralis muscle during 30 s Wingate test in track sprinters and untrained men under simulated hypoxic and normoxic conditions was investigated using near infrared spectroscopy.
• Acute hypoxia caused a greater degree of peripheral muscle deoxygenation than normoxia, whereas there were no changes in performance such as power output during 30 s Wingate test.
• Sprint athletes show a greater degree of peripheral muscle deoxygenation during 30 s Wingate test in hypoxia when compared with untrained subjects.
• A larger difference in muscle deoxygenation between hypoxia and normoxia is accompanied by lowest SpO2 at the 30 s Wingate test in hypoxia.

Key words: NIRcws, muscle deoxygenation, hypoxic, 30s Wingate test, athletes     

The Effects of a Carbohydrate-Protein Gel Supplement on Alpine Slalom Ski Performance

Alpine slalom ski racing is a high intensity, complex sport in which racers execute turns every second. Acute fatigue can make the difference in not finishing a run (DNF) or finishing out of contention. The quantity and quality of training often dictates racing success. It is not known if nutritional supplementation can improve performance in this high intensity, short duration activity. The objective of this study was to determine if ingesting a carbohydrate-protein energy gel (GEL) improves finishing success and number of gates completed during 2 hr slalom sessions on two consecutive days of training. Twenty-four racers were matched; one group ingested the GEL, the second group received a liquid placebo (PLA). Total carbohy-drate, protein, and water ingested by the GEL group were 60g, 15g, and 450 mL, while the PLA group ingested 450 mL of PLA. The GEL group had significantly fewer DNF’s (7/48 vs. 18/48; p = 0.02) on both days, completed a greater number of training gates on Day 2 (260.3 ± 20.1 vs. 246.3 ± 17.5 gates; p = 0.03), and had a lower RPE (3.9 ± 1.2 vs. 5.3 ± 1.2 on Day 2 (p = 0.004) vs. PLA. The statistical analysis of combined finishing times was not possible due to the high number of DNF’s in the PLA group. High intensity slalom performance can be im-proved by the ingestion of an energy gel. The GEL allowed the athletes to improve training quantity and quality and their per-ception of effort was less than skiers who ingested a placebo.

Key points

• Nutritional supplementation with a carbohydrate/protein sports gel during high intensity ski training improved training volume as measured by the number gates completed.
• Supplementation also reduced the number of DNF’s during training.
• Racers’ perception of effort was significantly lower with the supplement ingestion compared to a non-caloric placebo.
• This applied study was conducted under real life field conditions and training environments.

Key words: Alpine ski racing, nutritional supplementation, performance     

Effects Of Cadence on Aerobic Capacity Following a Prolonged,Varied Intensity Cycling Trial

We determined if high cadences, during a prolonged cycling protocol with varying intensities (similar to race situations) decrease performance compared to cycling at a lower, more energetically optimal, cadence. Eight healthy, competitive male road cyclists (35 ± 2 yr) cycled for 180 min at either 80 or 100 rpm (randomized) with varying intensities of power outputs corresponding to 50, 65 and 80% of VO₂max. At the end of this cycling period, participants completed a ramped exercise test to exhaustion at their preferred cadence (90 ± 7 rpm). There were no cadence differences in blood glucose, respiratory exchange ratio or rate of perceived exertion. Heart Rate, VO₂ and blood lactate were higher at 100 rpm vs. 80 rpm. The total energy cost while cycling during the 65% and 80% VO₂max intervals at 100 rpm (15.2 ± 2.7 and 19.1 ± 2.5 kcal∙min^-1, respectively) were higher than at 80 rpm (14.3 ± 2.7 and 18.3± 2.2 kcal∙min^-1, respectively) (p < 0.05). Gross efficiency was higher at 80 rpm vs. 100 rpm during both the 65% (22.8 ± 1.0 vs. 21.3 ± 4.5%) and the 80% (23.1 vs. 22.1 ± 0.9%) exercise intensities (P< 0.05). Maximal power during the performance test (362 ± 38 watts) was greater at 80 rpm than 100 rpm (327 ± 27 watts) (p < 0.05). Findings suggest that in conditions simulating those seen during prolonged competitive cycling, higher cadences (i.e., 100 vs. 80 rpm) are less efficient, resulting in greater energy expenditure and reduced peak power output during maximal performance.

Key Points

• When competitive cyclists perform prolonged exercise that simulates racing conditions (i.e., variable, low-moderate submaximal cycling), a higher cadence results in excess energy expenditure and lower gross efficiency compared to a lower cadence at the same power output.
• Consequently, maximal power output is reduced during a subsequent exercise bout to exhaustion after using a higher cadence.
• Selection of a lower, more energetically optimal cadence during prolonged cycling exercise may allow competitive cyclists to enhance maximal performance later in a race.

Key Words: Power output, energy expenditure, varied intensity, cycling efficiency, lactate, oxygen consumption     

Recovery of Power Output and Heart Rate Kinetics During Repeated Bouts of Rowing Exercise with Different Rest Intervals

This study examined the effect of recovery time on the maintenance of power output and the heart rate response during repeated maximal rowing exercise. Nine male, junior rowers (age: 16 ± 1 years; body mass: 74.0 ± 9.1 kg; height: 1.78 ± 0.03 m) performed two consecutive all-out 1000 m bouts on a rowing ergometer on three separate occasions. The rest interval between the two bouts was 1.5 (INT1.5), 3 (INT3) and 6 min (INT6), allocated in random order. Power output was averaged for each 1000 m bout and for the first and last 500 m of each bout. Heart rate kinetics were determined using a two-component exponential model. Performance time and mean power output for the first bout was 209 ± 3 s and 313 ± 10 W respectively. Recovery of mean power output was incomplete even after 6 min (78 ± 2, 81 ± 2 and 84 ± 2 % for INT1.5, INT3 and INT6 respectively). Mean power output after INT6 was higher (p < 0.01) only compared with INT1.5. Power output during the first 500 m of bout 2 after INT6 was 10% higher compared with the second 500 m. During INT1.5 and INT3 power output during the first and the second 500 m of bout 2 was similar. Peak heart rate (~197 b·min^-1) and the HR time constant (~13 s) were unaffected by prior exercise and recovery time. However, when the recovery was short (INT1.5), HR during the first 50 s of bout 2 was significantly higher compared with corresponding values during bout 1. The present study has shown that in order to maintain similar power outputs during repeated maximal rowing exercise, the recovery interval must be greater than 6 min. The influence of a longer recovery time (INT6) on maintenance of power output was only evident during the first half of the second 1000 m bout.

Key Points

• The recovery of mean power output during two repeated maximal 1000 m bouts of rowing exercise was incomplete even after a 6 min rest interval.
• The benefit of the longer rest interval was apparent only during the first 500 m of bout 2.
• The HR time constant was unaffected by prior exercise and the time of recovery. However, when the recovery was short, HR during the first 50 s of bout 2 was significantly higher compared with the corresponding values of bout 1.

Key words: Interval training, maintenance of power output     

Nutrient Intakes of Men and Women Collegiate Athletes with Disordered Eating

The objective of this study was to assess the macro- and micronutrient intakes of men and women collegiate athletes with disordered eating behaviors and to compare the nutrient intakes of athletes with restrictive- versus binge-eating behaviors. National Collegiate Athletic Association (NCAA) Division I University athletes (n = 232) were administered an anonymous, written questionnaire to compare nutrient intakes, desired weight change, and weight control behaviors in athletes with restrictive- (R) and binge- (B) eating behaviors to those in asymptomatic (A) athletes. T-tests, χ² statistic, and ANOVA were used to test for differences among disordered eating groups within genders (p < 0.05). Data are means ± standard error of the mean. Among men athletes, those with disordered eating consumed a smaller percentage of energy from carbohydrate compared to controls (R = 49.7 ± 1.5; B = 48.7 ± 2.3; A = 53.4 ± 0.7%). Among female athletes, those with disordered eating wanted to lose a greater percentage of their current body weight than did asymptomatic athletes (B = -6.1 ± 1.4; R = -6.7 ± 1.1; A = -3.7 ± 0.4%). Women who were classified with binge eating consumed significantly more alcohol than did controls (B = 6.8 ± 1.3; A = 3.9 ± 0.4 g alcohol per day). Athletes with disordered eating were more likely to report restricting their intake of carbohydrate and fat and using supplements to control their weight than asymptomatic athletes. Disordered eating was not associated with greater frequencies of inadequate micronutrient intake in either gender. Athletes with disordered eating may be at significantly greater risk for nutritional inadequacies than athletes who are asymptomatic due to macronutrient restriction and greater alcohol consumption.

Key Points

• Athletes with disordered eating were more likely to report restricting their intake of carbohydrate and fat and using supplements to control their weight than asymptomatic athletes
• Among female athletes, those with disordered eating wanted to lose a greater percentage of their current body weight than did asymptomatic athletes
• Disordered eating was not associated with greater frequencies of inadequate micronutrient intake in either gender
• Athletes with disordered eating may be at significantly greater risk for nutritional inadequacies than athletes who are asymptomatic due to macronutrient restriction and greater alcohol consumption.

Key Words: Eating disorder, Female Athlete Triad     

The Influence of Fluid Ingestion on Performance of Soccer Players During a Match

The purpose of this study was to verify the effects of a carbohydrate-electrolyte drink on soccer performance. Twenty soccer players volunteered to participate in the study. Players were allocated to two assigned trials according to their positional roles in the team: CHO group (ingesting a 6% carbohydrate-electrolyte solution at regular 15 minutes intervals) and NCHO (ingesting no fluid) during 75 min on-field soccer game. During the trials, body mass loss, heart rate, time spent running, number of sprints and core temperature were measured. There were statistically significant changes (p < 0.05) in body mass loss (CHO: 1.14 ± 0.37 kg vs. NCHO: 1.75 ± 0.47 kg) and number of sprints performed (CHO: 14.70 ± 4.38 vs. NCHO: 10.70 ± 5.80) between groups. The main finding of the present study indicates that supplementation with a carbohydrate-electrolyte drink during a soccer match is beneficial in helping to prevent deterioration in performance.

Key Points

• Supplementation with a carbohydrate-electrolyte drink during a soccer match is beneficial in helping to prevent deterioration in performance.

Key Words: Sports drink, carbohydrate, soccer performance, heart rate, core temperature     

Training at the Optimum Power Zone Produces Similar Performance Improvements to Traditional Strength Training

The purpose of this study was to test if substituting a regular maximum strength-oriented training regimen by a power-oriented one at the optimal power load in the first phase of a traditional periodization produces similar performance improvements later on into the training period. Forty five soldiers of the Brazilian brigade of special operations with at least one year of army training experience were divided into a control group (CG - n = 15, 20.18 ± 0.72 yrs, 1.74 ± 0.06 m, 66.7 ± 9.8 kg, and 1RM/weight ratio = 1.14 ± 0.12), a traditional periodization group (TG - n = 15, 20.11 ± 0.7 yrs, 1.72 ± 0.045 m, 63.1 ± 3.6 kg, and 1RM/weight ratio = 1.21 ± 0.16); and a maximum-power group (MPG - n = 15, 20.5 ± 0.6 yrs, 1.73 ± 0.049m, 67.3 ± 9.8 kg, 1RM/weight ratio = 1.20 ± 0.14). Maximum strength (26.2% and 24.6%), CMJ height (30.8% and 39.1%) and sprint speed (11.6% and 14.5%) increased significantly (p < 0.05) and similarly for the MPG and TG, respectively, from pre- to post-assessments. Our data suggests that a power training regimen may be used in the initial phase of the training cycle without impairing performance later on into the training period.

Key points

• Training at the optimal power zone during two mesocycles of a traditional periodization did not hamper strength, speed and power performance improvements.
• Additional research is required in order to find out if longer periods of training at optimal power zone are capable of producing similar performance improvements to traditional strength training regimen.

Key words: Maximum-power zone, maximum strength, mean propulsive power, mean power     

Effects of Combined Foot/Ankle Electromyostimulation and Resistance Training on the In-Shoe Plantar Pressure Patterns during Sprint in Young Athletes

Several studies have already reported that specific foot/ankle muscle reinforcement strategies induced strength and joint position sense performance enhancement. Nevertheless the effects of such protocols on sprint performance and plantar loading distribution have not been addressed yet. The objective of the study is to investigate the influence of a 5-wk foot/ankle strength training program on plantar loading characteristics during sprinting in adolescent males. Sixteen adolescent male athletes of a national training academy were randomly assigned to either a combined foot/ankle electromyostimulation and resistance training (FAST) or a control (C) group. FAST consisted of foot medial arch and extrinsic ankle muscles reinforcement exercises, whereas C maintained their usual training routine. Before and after training, in-shoe loading patterns were measured during 30-m running sprints using pressure sensitive insoles (right foot) and divided into nine regions for analysis. Although sprint times remained unchanged in both groups from pre- to post- training (3.90 ± 0.32 vs. 3.98 ± 0.46 s in FAST and 3.83 ± 0.42 vs. 3.81 ± 0.44 s in C), changes in force and pressure appeared from heel to forefoot between FAST and C. In FAST, mean pressure and force increased in the lateral heel area from pre- to post- training (67.1 ± 44.1 vs. 82.9 ± 28.6 kPa [p = 0.06]; 25.5 ± 17.8 vs. 34.1 ± 14.3 N [p = 0.05]) and did not change in the medial forefoot (151.0 ± 23.2 vs. 146.1 ± 30.0 kPa; 142.1 ± 29.4 vs. 136.0 ± 33.8; NS). Mean area increased in FAST under the lateral heel from pre- to post- (4.5 ± 1.3 vs. 5.7 ± 1.6 cm² [p < 0.05]) and remained unchanged in C (5.5 ± 2.8 vs. 5.0 ± 3.0 cm²). FAST program induced significant promising lateral and unwanted posterior transfer of the plantar loads without affecting significantly sprinting performance.

Key points

• We have evaluated the effects of a foot/ankle strength training program on sprint performance and on related plantar loading characteristics in teenage athletes, and this have not been examined previously.
• Our results showed no significant pre- to post- changes in sprint performance.
• This study revealed initially a lateral transfer and secondly a posterior transfer of the plantar loads after the foot/ankle strength training program.

Key words: Track and field, medial arch, reinforcement, injury prevention     

The Effects of Bicycle Frame Geometry on Muscle Activation and Power During a Wingate Anaerobic Test

The purpose of this study was to compare the effects of bicycle seat tube angles (STA) of (72° and 82°) on power production and EMG of the vastus laeralis (VL), vastus medialis (VM), semimembranous (SM), biceps femoris (BF) during a Wingate test (WAT). Twelve experienced cyclists performed a WAT at each STA. Repeated measures ANOVA was used to identify differences in muscular activation by STA. EMG variables were normalized to isometric maximum voluntary contraction (MVC). Paired t-tests were used to test the effects of STA on: peak power, average power, minimum power and percent power drop. Results indicated BF activation was significantly lower at STA 82° (482.9 ± 166.6 %MVC·s) compared to STA 72° (712.6 ± 265.6 %MVC·s). There were no differences in the power variables between STAs. The primary finding was that increasing the STA from 72° to 82° enabled triathletes’ to maintain power production, while significantly reducing the muscular activation of the biceps femoris muscle.

Key Points

• Road cyclists claim that bicycle seat tube angles between 72° and 76° are most effective for optimal performance in racing.
• Triathletes typically use seat tube angles greater than 76°. It is thought that a seat tube angle greater than 76° facilitates a smoother bike to run transition in the triathlon.
• Increasing the seat tube angle from 72 to 82 enabled triathletes’ to maintain power production, while significantly reducing the muscular activation of the biceps femoris muscle.
• Reduced hamstring muscular activation in the triathlon frame (82 seat tube angle) may serve to reduce hamstring tightness following the bike phase of the triathlon, allowing the runner to use a longer stride length.

Key words: Cycling, anaerobic power, triathlon, efficiency, EMG     

Kinematics of the Typical Beach Flags Start for Young Adult Sprinters

This study profiled beach flags start kinematics for experienced young adult sprinters. Five males and three females (age = 20.8 ± 2.1 years; height = 1.70 ± 0.06 meters [m]; mass = 63.9 ± 6.0 kilograms) completed four sprints using their competition start technique. A high-speed camera, positioned laterally, filmed the start. Data included: start time; hand clearance time; posterior movement from the start line; feet spacing during the start; elbow, hip, knee, trunk lean, and trajectory angles at take-off; and first step length. Timing gates recorded 0-2, 0-5, and 0-20 m time. Spearman’s correlations identified variables relating (p ≤ 0.05) to faster start and sprint times. The beach flags start involved sprinters moving 0.18 ± 0.05 m posterior to the start line by flexing both legs underneath the body before turning. Following the turn, the feet were positioned 0.47 ± 0.07 apart. This distance negatively correlated with start (ρ = -0.647), 0-2 (ρ = -0.683), and 0-5 m (ρ = -0.766) time. Beach flags start kinematics at take-off resembled research analyzing track starts and acceleration. The elbow extension angle (137.62 ± 13.45°) of the opposite arm to the drive leg correlated with 0-2 (ρ = -0.762), 0-5 (ρ = -0.810), and 0-20 m (ρ = -0.810) time. Greater arm extension likely assisted with stability during the start, leading to enhanced sprint performance. The drive leg knee extension angle (146.36 ± 2.26°) correlated with start time (ρ = -0.677), indicating a contribution to a faster start completion. A longer first step following the start related to faster 0-5 m time (ρ = -0.690). Sprinters quicker over 0-2 and 0-5 m were also quicker over 20 m (ρ = 0.881-0.952). Beach flags sprinters must ensure their start is completed quickly, such that they can attain a high speed throughout the race.

Key points

• There are specific movement patterns adopted by beach flags sprinters during the start. Sprinters will move posterior to the start time prior to turning. Following the turn, sprinters must position their feet such that force output is optimized and low body position at take-off can be attained.
• The body position at take-off from the beach flags start is similar to that of established technique parameters for track sprinters leaving starting blocks, and field sport athletes during acceleration. A greater range of motion at the arms can aid with stability during the turn and at take-off from the start. Greater knee extension of the drive leg at take-off can assist with reducing the duration of the start.
• The beach flags start must allow for a quick generation of speed through the initial stages of the sprint, as this can benefit the later stages. A longer first step following the start can help facilitate speed over the initial acceleration period. Beach flags sprinters must also attempt to maintain their speed throughout the entirety of the race.

Key words: Biomechanics, surf lifesaving, sprint start, acceleration, beach sprinting.     

Internal and External Oblique Muscle Asymmetry in Sprint Hurdlers and Sprinters: A Cross-Sectional Study

The abdominal muscles are vital in providing core stability for functional movements during most activities. There is a correlation between side asymmetry of these muscles and dysfunction. Thus, the purpose of this study was to evaluate and compare trunk muscle morphology and trunk rotational strength between sprint hurdlers, an asymmetrical sport, and sprinters, a symmetrical sport. Twenty-one trained collegiate sprint hurdlers and sprinters were recruited for the study (Hurdlers: 4M, 7F; Sprinters: 8M, 2F), average age (years) hurdlers: 20 ± 1.2; sprinters: 20.4 ± 1.9, height (cm) hurdlers: 172.6 ± 10.2; sprinters: 181.7 ± 4.5, and weight (kg) hurdlers: 67.6 ± 12.0; sprinters: 73.9 ± 5.6. Using real-time ultrasound, panoramic images of the internal oblique (IO) and external oblique (EO) were obtained at rest and contracted (flexion and rotation) in a seated position for both right and left sides of the trunk. While wearing a specially crafted shoulder harness, participants performed three maximal voluntary trunk rotational contractions (MVC). The three attempts were then averaged to obtain an overall MVC score for trunk rotation strength. Average MVC trunk rotational strength to the right was greater among all participants, p < 0.001. The IO showed greater and significant thickness changes from resting to contracted state than the EO, this was observed in all participants. The IO side asymmetry was significantly different between groups p < 0.01. Hurdlers, involved in a unilaterally demanding sport, exhibited the expected asymmetry in muscle morphology and in trunk rotational strength. Interestingly, sprinters, although involved in a seemingly symmetrical sport, also exhibited asymmetrical trunk morphology and trunk rotational strength. Key points

• The internal and external oblique muscles exhibit a morphological asymmetry in collegiate hurdlers and sprinters.
• A greater thickness change from rest to contraction was seen in the internal oblique compared to the external oblique among the hurdlers and sprinters.
• A statistically significant difference in asymmetry of the internal oblique between left and right sides was seen between the hurdlers and sprinters.

Key words: Asymmetry, internal oblique, external oblique, trunk muscle thickness, panoramic ultrasound     

A Laboratory Test for the Examination of Alactic Running Performance

A new testing procedure is introduced to evaluate the alactic running performance in a 10s sprint task with near-maximal movement velocity. The test is performed on a motor-equipped treadmill with inverted polarity that increases mechanical resistance instead of driving the treadmill belt. As a result, a horizontal force has to be exerted against the treadmill surface in order to overcome the resistant force of the engine and to move the surface in a backward direction. For this task, subjects lean with their hands towards the front safety barrier of the treadmill railing with a slightly inclined body posture. The required skill resembles the pushing movement of bobsleigh pilots at the start of a race. Subjects are asked to overcome this mechanical resistance and to cover as much distance as possible within a time period of 10 seconds. Fifteen male students (age: 27.7 ± 4.1 years, body height: 1.82 ± 0.46 m, body mass: 78.3 ± 6.7 kg) participated in a study. As the resistance force was set to 134 N, subjects ran 35.4 ± 2.6 m on the average corresponding to a mean running velocity of 3.52 ± 0.25 m·s^-1. The validity of the new test was examined by statistical inference with various measures related to alactic performance including a metabolic equivalent to estimate alactic capacity (2892 ± 525 mL O₂), an estimate for the oxygen debt (2662 ± 315 ml), the step test by Margaria to estimate alactic energy flow (1691 ± 171 W), and a test to measure the maximal strength in the leg extensor muscles (2304 ± 351 N). The statistical evaluation showed that the new test is in good agreement with the theoretical assumptions for alactic performance. Significant correlation coefficients were found between the test criteria and the measures for alactic capacity (r = 0.79, p < 0.01) as well as alactic power (r = 0.77, p < 0.01). The testing procedure is easy to administer and it is best suited to evaluate the alactic capacity for bobsleigh pilots as well as for any other running discipline.

Key Points

• New testing procedure for the evaluation of alactic running performance.
• 10s treadmill sprint task with near-maximal movement velocity similar to a bob sleigh start.
• Treadmill motor is used with inverted polarity to establish mechanical resistance rather than acceleration.
• Highly significant correlations found between test criteria and alactic performance measures.

Key words: Alactic capacity, alactic power, metabolic cost, treadmill test, bobsleigh     

A Self-Paced Intermittent Protocol on a Non-Motorised Treadmill: A Reliable Alternative to Assessing Team-Sport Running Performance

This study assessed the reliability of a ‘self-paced’ 30-min, team-sport running protocol on a Woodway Curve 3.0 non-motorised treadmill (NMT). Ten male team-sport athletes (20.3 ± 1.2 y, 74.4 ± 9.7 kg, VO_2peak 57.1 ± 4.5 ml·kg^-1·min^-1) attended five sessions (VO_2peak testing + familiarisation; four reliability trials). The 30-min protocol consisted of three identical 10-min activity blocks, with visual and audible commands directing locomotor activity; however, actual speeds were self-selected by participants. Reliability of variables was estimated using typical error ± 90% confidence limits expressed as a percentage [coefficient of variation (CV)] and intraclass correlation coefficient. The smallest worthwhile change (SWC) was calculated as 0.2 × between participant standard deviation. Peak/mean speed and distance variables assessed across the 30-min protocol exhibited a CV < 5%, and < 6% for each 10-min activity block. All power variables exhibited a CV < 7.5%, except walking (CV 8.3-10.1%). The most reliable variables were maximum and mean sprint speed (CV < 2%). All variables produced a CV% greater than the SWC. A self-paced, team-sport running protocol performed on a NMT produces reliable speed/distance and power data. Importantly, a single familiarisation session allowed for adequate test-retest reliability. The self-paced design provides an ecologically-valid alternative to externally-paced team-sport running simulations.

Key points

• Self-paced team-sport running protocols on a curved NMT that closely match the locomotor demands of competition deliver reliable test-retest measures of speed, distance and power.
• Such protocols may be sensitive to changes in running profile following an intervention that may not be detectable during externally-paced protocols.
• One familiarisation session is adequate to ensure test-retest reliability.

Key words: Exercise test, athletic performance, running, reproducibility of results