Critical power (CP) is defined as the highest sustainable rate of aerobic metabolism without a continuous loss of homeostasis. 1 It separates power-output (PO) intensities, for which exercise tolerance is predictable (PO > CP), from those of longer sustainable durations (PO < CP). The second
Bettina Karsten, Jonathan Baker, Fernando Naclerio, Andreas Klose, Antonino Bianco and Alfred Nimmerichter
Ryland Morgans, Rocco Di Michele and Barry Drust
indicative of the supercompensation that follows an exercise stimulus. 6 The quantification of jump performance at relevant times after matches may therefore provide a way to evidence the potential for match play to act as a training stimulus for muscle power in soccer players. Methods Fifteen male
Kenneth W. Kambis and Sarah K. Pizzedaz
Creatine monohydrate (CrH2O) supplementation has been demonstrated to increase skeletal muscle power output in men. However, its effect upon women is not as clearly defined. This study investigated the effect of oral creatine supplementation upon muscle function, thigh circumference, and body weight in women. Twenty-two consenting college-age women were assigned to 1 of 2 groups matched for dietary and exercise habits, phase of menstrual cycle, and fat-free mass (FFM). After familiarization with testing procedures, pretrial measures of muscle function (5 repetitions 60 deg · s−1 and 50 repetitions 180 deg · s−1) were conducted during maximal voluntary concentric contraction of the preferred quadriceps muscle using an isokinetic dynamometer. Subjects then ingested 0.5 g · kg−1 FFM of either CrH2O or placebo (one fourth dosage 4 times daily) in a double-blind design for 5 days. Resistance exercise was prohibited. After the ingestion phase was completed, all measures were repeated at the same time of day as during pretrials. Statistical analysis revealed time to peak torque in quadriceps extension decreased from pre-test values of 255 ± 11 ms (mean ± SEM) to post-test values of 223 ± 3 ms; average power in extension increased from 103 ± 7 W pre-test to 112 ± 7 W post-test; and, during flexion, average power increased from 59 ± 5 W pre-test to 65 ± 5 W post-test in the creatine group as compared to controls (p ≤ .05). FFM, percent body fat, mid-quadriceps circumference, skinfold thickness of the measured thigh, and total body weight did not change for both groups between trials. We conclude that CrH2O improves muscle performance in women without significant gains in muscle volume or body weight.
Anni Vanhatalo, Andrew M. Jones and Mark Burnley
The critical power (CP) is mathematically defined as the power-asymptote of the hyperbolic relationship between power output and time-to-exhaustion. Physiologically, the CP represents the boundary between the steady-state and nonsteady state exercise intensity domains and therefore may provide a more meaningful index of performance than other well-known landmarks of aerobic fitness such as the lactate threshold and the maximal O2 uptake. Despite the potential importance to sports performance, the CP is often misinterpreted as a purely mathematical construct which lacks physiological meaning and only in recent years has this concept begun to emerge as valid and useful technique for monitoring endurance fitness. This commentary defines the basic principles of the CP concept, outlines its importance to high-intensity exercise performance, and provides an overview of the current methods available for its assessment. Interventions including training, pacing and prior exercise can be used to alter the parameters of the power-time relationship. A future challenge lies in optimizing such interventions in order to positively affect the parameters of the power-time relationship and thereby enhance sports performance in specific events.
Todd C. Pataky, Greg P. Slota, Mark L. Latash and Vladimir M. Zatsiorsky
During power grasp, the number of local force maxima reflects either the central nervous system’s preferential use of particular hand regions, or anatomical constraints, or both. Previously, both bimodal and trimodal force maxima have been hypothesized for power grasp of a cylindrical handle. Here we measure the number of local force maxima, with a resolution of 4.8°, when performing pushing and pulling efforts in the plane perpendicular to the cylinder’s long axis. Twelve participants produced external forces to eight targets. The number of contacts was defined as the number of local maxima exceeding background variance. A minimum of four and a maximum of five discrete contacts were observed in all subjects at the distal phalanges and metacarpal heads. We thus reject previous hypotheses of bimodal or trimodal force control for cylindrical power grasping. Since we presently observed only 4–5 contacts, which is rather low considering the hand’s kinematic flexibility in the flexion plane, we also reject hypotheses of continuous contact, which are inherent to current grasping taxonomy. A modification to current grasping taxonomy is proposed wherein power grasp contains separate branches for continuous and discrete contacts, and where power and precision grasps are distinguished only by grasp manipulability.
Alex Ross, Nicholas D. Gill and John B. Cronin
Anthropometrical and physical characteristics have been used to distinguish players of different competition levels and position groups; however, there is no literature on rugby sevens.
To compare the anthropometrical and physical characteristics of international and provincial rugby sevens players and between forwards and backs.
To assess whether differences exist, 65 rugby sevens players including 22 international players and 43 provincial-level players were assessed for height, mass, body composition, speed, repeated-sprint ability, lower-body power, upper-body strength, and maximal aerobic endurance during in-season preparation for tournaments.
Clear differences (2.8−32%; small to very large effect sizes) were observed in all anthropometrical and physical measures between international and provincial players, with the largest differences observed in repeated-sprint ability (5.7%; very large effect size), 40-m-sprint time (4.4%; large effect size), 50-kg squat-jump peak power (32%; large effect size), and multistage fitness-test performance (19%; large effect size). Fewer and smaller differences (0.7−14%; trivial to large effect sizes) were found when comparing forwards and backs, with body height being the most discriminant characteristic (3.5%; large effect size).
Lower-level rugby sevens players should seek to improve their overall physical profile, particularly their repeated-sprint ability, to reach higher levels in rugby sevens. Furthermore, positional status may have little importance when preparing for rugby sevens.
Steven J. Elmer and James C. Martin
Eccentric cycling serves a useful exercise modality in clinical, research, and sport training settings. However, several constraints can make it difficult to use commercially available eccentric cycle ergometers. In this technical note, we describe the process by which we built an isokinetic eccentric cycle ergometer using exercise equipment modified with commonly available industrial parts. Specifically, we started with a used recumbent cycle ergometer and removed all the original parts leaving only the frame and seat. A 2.2 kW electric motor was attached to a transmission system that was then joined with the ergometer. The motor was controlled using a variable frequency drive, which allowed for control of a wide range of pedaling rates. The ergometer was also equipped with a power measurement device that quantified work, power, and pedaling rate and provided feedback to the individual performing the exercise. With these parts along with some custom fabrication, we were able to construct an isokinetic eccentric cycle ergometer suitable for research and training. This paper offers a guide for those individuals who plan to use eccentric cycle ergometry as an exercise modality and wish to construct their own ergometer.
Nicola Giovanelli, Filippo Vaccari, Mirco Floreani, Enrico Rejc, Jasmine Copetti, Marco Garra, Lea Biasutti and Stefano Lazzer
massagers. SMFR can promote short-term flexibility improvement, and it does not seem to have negative effects on performance. 2 , 3 , 9 – 11 In fact, no differences in maximal force and power were detected after an SMFR protocol. 2 , 12 Moreover, SMFR has been shown effective for reducing delayed
Karin Roeleveld, Eric Lute, Dirkjan Veeger, Luc van der Woude and Tom Gwinn
To assess power output, force application, and kinematics of wheelchair propulsion in peak exercise, nine wheelchair athletes with medical lesion levels of T8 or lower performed a 30-s sprint test on a stationary wheelchair ergometer. Mean power output, calculated for the right wheel only, was 59.4 ± 8.5 W. The ratio between effective force and total propulsive force was 60 ± 6%. A negative torque around the hand and a not tangentially directed total force accounted for this low effectiveness. Since the subject group was highly trained, their technique was considered to be optimal for the given circumstances. Therefore, athletes who want to improve power output by increasing effectiveness should keep in mind the existence of a nontangential propulsive force and a braking torque applied by the hands onto the hand rim surface. It is likely that both aspects will be influenced by the geometry of the wheelchair, for example, hand rim dimension or seat position.
Terry J. Housh, Glen O. Johnson and Dona J. Housh
The purpose of this investigation was to examine age related changes in muscular power of high school wrestlers. A total of 155 high school wrestlers (M age±SD = 16.5±2.4 yrs) volunteered as subjects for this investigation. The sample included only wrestlers who were ≤ 16.00 years (younger group, n=75) or >17.00 years (older group, n=80). All subjects completed a Wingate anaerobic test to determine mean (MP) and peak (PP) power as well as underwater weighing for body composition assessment. The results indicated significant (p<0.05) group differences for absolute MP and PP but no differences when adjusted for BW and FFW. Thus the enhanced muscular power in the older group of high school wrestlers was associated with increases in BW and FFW.