Creatine monohydrate supplementation has been shown to enhance high-intensity exercise performance in some but not all studies. Part of the controversy surrounding the ergogenic effect(s) of creatine monohydrate supplementation may relate to design issues that result in low statistical power. A further question that remains unresolved in the creatine literature is whether or not males and females respond in a similar manner to supplementation. We studied the effect of creatine supplementation upon high intensity exercise performance in 24 subjects (n = 12 males, n = 12 females). Creatine monohydrate (Cr; 5g, 4x/d × 4d) and placebo (PI; glucose polymer × 4d) were provided using a randomized. double-blind crossover design (7 week washout). Outcome measures included: 2 × 30-S anaerobic cycle lest, with plasma lactate pre- and post-test; dorsi-flexor: maximal voluntary contraction (MVC), 2-min fatigue test, and electrically stimulated peak and tetanic torque; isokinetic knee extension torque and I -min ischeniic handgrip strength. Significant main effects of Cr treatment included: increased peak and relative peak anaerobic cycling power (↑3.7%; p < .05), dorsi-flexion MVC torque (↑6.6% p < .05), and increased lactate (↑20.8%; p < .05) with no gender specific responses. We concluded that short-term Cr supplementation can increase indices of high-intensity exercise performance for both males and females.
Mark A. Tarnopolsky and Dan P. MacLennan
Glen E. Duncan, Anthony D. Mahon, Cheryl A. Howe and Pedro Del Corral
This study examined the influence of test duration and anaerobic capacity on VO2max and the occurrence of a VO2 plateau during treadmill exercise in 25 boys (10.4 ± 0.8 years). Protocols with 1-min (P1) and 2-min (P2) stages, but identical speed and grade changes, were used to manipulate test duration. On separate days, VO2max was measured on P1 and P2, and 200-m run time was assessed. At maximal exercise, VO2, heart rate (HR), and pulmonary ventilation (VE) were similar between protocols, however, respiratory exchange ratio (RER) and treadmill elevation were higher (p < .05) on P1 than on P2. Plateau achievement was not significantly different. On P1, there were no differences between plateau achievers and nonachievers. On P2, test duration and 200-m run time were superior (p < .05), and relative VO2max tended to be higher (p < .10) in plateau achievers. Indices of aerobic and anaerobic capacity may influence plateau achievement on long, but not short duration tests.
Helen T. Douda, Argyris G. Toubekis, Alexandra A. Avloniti and Savvas P. Tokmakidis
To identify the physiological and anthropometric predictors of rhythmic gymnastics performance, which was defined from the total ranking score of each athlete in a national competition.
Thirty-four rhythmic gymnasts were divided into 2 groups, elite (n = 15) and nonelite (n = 19), and they underwent a battery of anthropometric, physical fitness, and physiological measurements. The principal-components analysis extracted 6 components: anthropometric, flexibility, explosive strength, aerobic capacity, body dimensions, and anaerobic metabolism. These were used in a simultaneous multiple-regression procedure to determine which best explain the variance in rhythmic gymnastics performance.
Based on the principal-component analysis, the anthropometric component explained 45% of the total variance, flexibility 12.1%, explosive strength 9.2%, aerobic capacity 7.4%, body dimensions 6.8%, and anaerobic metabolism 4.6%. Components of anthropometric (r = .50) and aerobic capacity (r = .49) were significantly correlated with performance (P < .01). When the multiple-regression model—y = 10.708 + (0.0005121 × VO2 max) + (0.157 × arm span) + (0.814 × midthigh circumference) - (0.293 × body mass)—was applied to elite gymnasts, 92.5% of the variation was explained by VO2max (58.9%), arm span (12%), midthigh circumference (13.1%), and body mass (8.5%).
Selected anthropometric characteristics, aerobic power, flexibility, and explosive strength are important determinants of successful performance. These findings might have practical implications for both training and talent identification in rhythmic gymnastics.
Gina Sobrero, Scott Arnett, Mark Schafer, Whitley Stone, T. A. Tolbert, Amanda Salyer-Funk, Jason Crandall, Lauren B. Farley, Josh Brown, Scott Lyons, Travis Esslinger, Keri Esslinger and Jill Maples
High intensity functional training (HIFT) emphasizes constantly varied, high intensity, functional activity by programming strength and conditioning exercises, gymnastics, Olympic weightlifting, and specialty movements. Conversely, traditional circuit training (TCT) programs aim to improve muscular fitness by utilizing the progressive overload principle, similar movements weekly, and specified work-to-rest ratios. The purpose of this investigation was to determine if differences exist in health and performance measures in women participating in HIFT or TCT after a six-week training program. Recreationally active women were randomly assigned to a HIFT (n = 8, age 26.0 + 7.3 yrs) or TCT (n = 11, age 26.3 + 9.6 yrs) group. Participants trained three days a week for six weeks with certified trainers. Investigators examined body composition (BC), aerobic and anaerobic capacity, muscular strength, endurance, flexibility, power, and agility. Repeated-measures ANOVA were used for statistical analyses with an alpha level of 0.05. Both groups increased body mass (p = .011), and improved muscular endurance (p < .000), upper body strength (p = .007), lower body power (p = .029) and agility (p = .003). In addition, the HIFT group decreased body fat (BF) %, while the TCT group increased BF% (p = .011). No changes were observed in aerobic or anaerobic capacity, flexibility, upper body power, or lower body stair climbing power. Newer, high intensity functional exercise programs such as HIFT may have better results on BC and similar effects when compared with TCT programs on health and fitness variables such as musculoskeletal strength and performance.
Jason D. Vescovi, Teena M. Murray and Jaci L. VanHeest
The primary purpose of this study was to determine whether positional profiling is possible for elite ice hockey players by examining anthropometric characteristics and physiological performance. In addition, performance ranges and percentiles were determined for each position (forwards, defensemen, and goalkeepers) on all dependent variables.
A retrospective, cross-sectional study design was used with performance data from ice hockey players (mean age = 18.0 ± 0.6 years) attending the 2001 (n = 74), 2002 (n = 84), and 2003 (n = 92) Combines. Four anthropometric characteristics and 12 performance tests were the dependent variables. A 3 × 3 (position × year) 2-way ANOVA was used to determine whether any significant interactions were present. No significant interactions were observed, so the data were collapsed over the 3-year period and positional characteristics were analyzed using a 1-way ANOVA.
Defenders were heavier and/or taller compared with the other 2 positions (P ≤ .01), whereas goalkeepers showed greater body-fat percentage compared with that of forwards (P = .001). It was found that goalkeepers had significantly lower strength measures for the upper body (P ≤ .043) and lower anaerobic capacity (P ≤ .039) values compared with at least one other position, but they had greater flexibility (P ≤ .013). No positional differences were observed for the broad jump, vertical jump, aerobic power, or curl-ups.
The current findings provide evidence supporting the use of anthropometric measurements, upper body strength, and anaerobic capacity to effectively distinguish among positions for elite-level ice hockey players.
Kelly de Jesus, Ross Sanders, Karla de Jesus, João Ribeiro, Pedro Figueiredo, João P. Vilas-Boas and Ricardo J. Fernandes
Coaches are often challenged to optimize swimmers’ technique at different training and competition intensities, but 3-dimensional (3D) analysis has not been conducted for a wide range of training zones.
To analyze front-crawl 3D kinematics and interlimb coordination from low to severe swimming intensities.
Ten male swimmers performed a 200-m front crawl at 7 incrementally increasing paces until exhaustion (0.05-m/s increments and 30-s intervals), with images from 2 cycles in each step (at the 25- and 175-m laps) being recorded by 2 surface and 4 underwater video cameras. Metabolic anaerobic threshold (AnT) was also assessed using the lactate-concentration–velocity curve-modeling method.
Stroke frequency increased, stroke length decreased, hand and foot speed increased, and the index of interlimb coordination increased (within a catch-up mode) from low to severe intensities (P ≤ .05) and within the 200-m steps performed above the AnT (at or closer to the 4th step; P ≤ .05). Concurrently, intracyclic velocity variations and propelling efficiency remained similar between and within swimming intensities (P > .05).
Swimming intensity has a significant impact on swimmers’ segmental kinematics and interlimb coordination, with modifications being more evident after the point when AnT is reached. As competitive swimming events are conducted at high intensities (in which anaerobic metabolism becomes more prevalent), coaches should implement specific training series that lead swimmers to adapt their technique to the task constraints that exist in nonhomeostatic race conditions.
Tatiane Gorski, Thomas Rosser, Hans Hoppeler and Michael Vogt
To describe the development of anthropometric and physical characteristics of young Swiss alpine skiers between 2004 and 2011, to compare them between age and performance-level groups, and to identify age- and sex-dependent reference values for the tests performed.
The Swiss-Ski Power Test includes anthropometric measures and physical tests for coordination and speed, strength, anaerobic capacity, and endurance. The authors analyzed the results of 8176 tests performed by 1579 male and 1109 female alpine skiers between 2004 and 2011. Subjects ranged between regional and national level of performance and were grouped according to their competition age groups (U12, 11 y; U14, 12–13 y; U16, 14–15 y; U18, 16–17 y; U21, 18–20 y) and performance level.
A progressive increase in anthropometric measures and improvements in tests results with increasing age were found. For all tests, male athletes had better results than female athletes. Minor differences were observed in anthropometric characteristics between 2004 and 2011 (mostly <5%), while results of physical and coordinative tests showed significant improvements (up to more than 50% enhancement) or stability over the years. Differences between higher- and lower-level athletes were more pronounced in tests for lower-limb strength and anaerobic capacity.
The presented profile of young Swiss alpine skiers highlights the improvements in different physical aspects along the maturation process and chronologically over a period of 7 y. Furthermore, reference values are provided for comparisons with alpine skiers or athletes from other sports.
Abdou Temfemo, Thierry Lelard, Christopher Carling, Samuel Honoré Mandengue, Mehdi Chlif and Said Ahmaidi
This study investigated the feasibility and reliability of a 12 × 25-m repeated sprint test with sprints starting every 25-s in children aged 6–8 years (36 boys, 41 girls). In all subjects, total sprint time (TST) demonstrated high test-retest reliability (ICC: r = .98; CV: 0.7% (95% CI: 0.6–0.9)). While sprint time varied over the 12 sprints in all subjects (p < .001) with a significant increase in time for the third effort onwards compared with the first sprint (p < .001), there was no difference in performance between genders. In all subjects, TST decreased with age (p < .001) and was accompanied by an increase in estimated anaerobic power (p < .001) but also in sprint time decrement percentage (p < .001). Gender did not effect these changes. The present study demonstrates the practicability and reliability of a repeated sprint test with respect to age and gender in young children.
Amanda J. Griffin, Viswanath B. Unnithan and Peter Ridges
The purpose of this study was to assess the effects of a weekend of swimming competition on various physiological parameters in a group of elite female swimmers. Eight female swimmers (age, 16.6 ± 0.5 years) participated in this study. Resting blood lactate (Bla) and heart rate (HR) were taken at the beginning of each testing session. Testing involved a discontinuous incremental peak VO2 treadmill test during which on-line, measures of VO2 were obtained. HR and Bla measurements were taken at the end of each exercise increment. A 30-s leg Wingate test (WAnT) was used to measure anaerobic power. Paired t-tests were carried out on all data. Resting HR was significantly higher and submaximal and maximal HR were significantly lower comparing pre- and postcompetition (p < .005). Resting Bla and submaximal VO2 were significantly higher postcompetition (p < .005). The results suggest that swimming competition causes a number of the recognized symptoms related to excitatory (acute) overtraining
Thomas W. Rowland and Tasha A. Rimany
This study compared aerobic, cardiac, and ventilatory changes in 11 premenarcheal girls ages 9–13 years with those of 13 women ages 20–31 during 40 min of steady-load cycling at an intensity of 63% VO2max. Forty-five percent of the girls were cycling above their ventilatory anaerobic threshold, compared to 77% of the women. Between 10 and 40 min of exercise, mean VO2 increased 8.6% (SD = 3.8) and 8.3% (SD = 6.3) in the girls and women, respectively (p > .05), with no significant differences in rise in body temperature. Pattern and magnitude of ventilatory drift (increased VE and respiratory rate with fall in tidal volume) were similar in the two groups. Likewise, the rise in cardiac output and heart rate (with no change in stroke volume) was not significantly different in the two groups. These findings indicate that physiological responses to prolonged aerobic exercise are both quantitatively and qualitatively similar in girls and young women.